From c4991eedcaee15c132edff0a9fc5ec3caf895fcb Mon Sep 17 00:00:00 2001
From: Larry Gritz <lg@larrygritz.com>
Date: Sun, 6 Oct 2024 08:28:59 -0700
Subject: [PATCH] Color management nomenclature improvements

A round of color management improvements (I hope).

We were pretty squirrelly about what "linear" meant. Get more exact.
Now we will treat "linear" as a semi-obsolete synonym for "lin_rec709"
(sRGB primaries, but linear response). Change file format readers to
say "lin_rec709" when they mean it, and not use the more generic alias
"linear".

"scene_linear", on the other hand, is the internal working color space
for math. Which concrete color space it is an alias for is determined
by the OCIO config in use.

Use "g18_rec709" and "g22_rec709" for rec709 + gamma 1.8 or 2.2,
respectvely.

A few new API calls help out: equivalent_colorspace(),
set_colorspace(spec,name), set_colorspace_rec709_gamma().

OpenEXR always tagged files as linear by default. It was too
aggressive about this, so with this PR, now it defaults to lin_rec709
only for files that appear to be RGB and not have any other clues
about the color space.

Similarly, the raw reader was too eager to set the Exif:ColorSpace to
look like sRGB even when it wasn't.

Lots of reference outputs needed to be updated.

This is a potentially big behavior change. But I think it's for the
better.

Signed-off-by: Larry Gritz <lg@larrygritz.com>
---
 src/cineon.imageio/cineoninput.cpp            |   9 +-
 src/dds.imageio/ddsinput.cpp                  |   2 +-
 src/doc/imageioapi.rst                        |   6 +
 src/doc/imageoutput.rst                       |   4 +-
 src/doc/pythonbindings.rst                    |  48 +++++-
 src/doc/stdmetadata.rst                       |  17 +-
 src/dpx.imageio/dpxinput.cpp                  |  13 +-
 src/gif.imageio/gifinput.cpp                  |   2 +-
 src/hdr.imageio/hdrinput.cpp                  |  10 +-
 src/heif.imageio/heifinput.cpp                |   2 +-
 src/iconvert/iconvert.cpp                     |   2 +-
 src/include/OpenImageIO/color.h               |  17 ++
 src/include/OpenImageIO/imagebufalgo.h        |  12 +-
 src/include/OpenImageIO/imageio.h             |  27 ++++
 src/jpeg.imageio/jpeginput.cpp                |   2 +-
 src/jpeg.imageio/jpegoutput.cpp               |   3 +-
 src/jpeg2000.imageio/jpeg2000input.cpp        |   2 +-
 src/libOpenImageIO/color_ocio.cpp             | 153 ++++++++++--------
 src/libOpenImageIO/exif.cpp                   |   2 +-
 src/libOpenImageIO/formatspec.cpp             |  21 +--
 src/oiiotool/oiiotool.cpp                     |  14 +-
 src/openexr.imageio/exr_pvt.h                 |  23 ++-
 src/openexr.imageio/exrinput.cpp              |  45 +++++-
 src/openexr.imageio/exrinput_c.cpp            |  11 +-
 src/png.imageio/png_pvt.h                     |  27 ++--
 src/pnm.imageio/pnminput.cpp                  |   2 +-
 src/python/py_colorconfig.cpp                 |   5 +-
 src/python/py_oiio.cpp                        |  13 ++
 src/raw.imageio/rawinput.cpp                  |   7 +-
 src/rla.imageio/rlainput.cpp                  |   8 +-
 src/rla.imageio/rlaoutput.cpp                 |  10 +-
 src/targa.imageio/targainput.cpp              |  11 +-
 src/targa.imageio/targaoutput.cpp             |  15 +-
 src/tiff.imageio/tiffinput.cpp                |   3 +
 src/tiff.imageio/tiffoutput.cpp               |   3 +-
 src/webp.imageio/webpinput.cpp                |   2 +-
 testsuite/dds/ref/out.txt                     |   4 +-
 testsuite/dup-channels/ref/out.txt            |   4 +-
 testsuite/hdr/ref/out.txt                     |   2 +-
 testsuite/iinfo/ref/out-fmt6.txt              |   6 +-
 testsuite/iinfo/ref/out.txt                   |   6 +-
 testsuite/maketx/ref/out-macarm.txt           |   7 +-
 testsuite/maketx/ref/out.txt                  |   7 +-
 testsuite/oiiotool-attribs/ref/out-jpeg9d.txt |   8 +-
 testsuite/oiiotool-attribs/ref/out.txt        |   8 +-
 testsuite/oiiotool-copy/ref/out.txt           |  14 +-
 testsuite/oiiotool-deep/ref/out-fmt6.txt      |   3 -
 testsuite/oiiotool-deep/ref/out.txt           |   3 -
 testsuite/oiiotool-fixnan/ref/out.txt         |   6 +-
 testsuite/oiiotool-maketx/ref/out-macarm.txt  |   7 +-
 testsuite/oiiotool-maketx/ref/out-rhel7.txt   |   5 +-
 testsuite/oiiotool-maketx/ref/out-win.txt     |   7 +-
 testsuite/oiiotool-maketx/ref/out.txt         |   7 +-
 testsuite/oiiotool-subimage/ref/out.txt       |   8 +-
 testsuite/oiiotool/ref/out.txt                |   2 +-
 testsuite/openexr-chroma/ref/out.txt          |   5 +-
 testsuite/openexr-decreasingy/ref/out.txt     |   8 +-
 .../ref/out-macarm.txt                        |  12 +-
 .../openexr-luminance-chroma/ref/out.txt      |  12 +-
 testsuite/openexr-multires/ref/out.txt        |  35 ++--
 testsuite/openexr-suite/ref/out.txt           |  41 +++--
 testsuite/openexr-v2/ref/out.txt              |  26 +--
 testsuite/openexr-window/ref/out.txt          |  32 ++--
 .../python-colorconfig/ref/out-ocio23.txt     |   2 +-
 .../python-colorconfig/ref/out-ocio24.txt     |   2 +-
 testsuite/python-colorconfig/ref/out.txt      |   2 +-
 testsuite/rational/ref/out.txt                |   4 +-
 testsuite/raw/ref/out-libraw-0.20.2-gh.txt    |  18 +--
 testsuite/raw/ref/out-libraw-0.20.2.txt       |  20 +--
 testsuite/raw/ref/out-libraw0.20.0-gh.txt     |  17 +-
 testsuite/raw/ref/out-libraw0.20.0.txt        |  20 +--
 testsuite/raw/ref/out-libraw0.21.0-gh.txt     |  18 +--
 testsuite/raw/ref/out-libraw0.21.0-mac.txt    |  20 +--
 testsuite/raw/ref/out.txt                     |  20 +--
 testsuite/rla/ref/out.txt                     |   6 +-
 75 files changed, 542 insertions(+), 445 deletions(-)

diff --git a/src/cineon.imageio/cineoninput.cpp b/src/cineon.imageio/cineoninput.cpp
index a7656a8a8a..d64ac4ab3d 100644
--- a/src/cineon.imageio/cineoninput.cpp
+++ b/src/cineon.imageio/cineoninput.cpp
@@ -169,7 +169,7 @@ CineonInput::open(const std::string& name, ImageSpec& newspec)
     // This is not very smart, but it seems that as a practical matter,
     // all Cineon files are log. So ignore the gamma field and just set
     // the color space to KodakLog.
-    m_spec.attribute("oiio:ColorSpace", "KodakLog");
+    m_spec.set_colorspace("KodakLog");
 #else
     // image linearity
     // FIXME: making this more robust would require the per-channel transfer
@@ -177,19 +177,18 @@ CineonInput::open(const std::string& name, ImageSpec& newspec)
     switch (m_cin.header.ImageDescriptor(0)) {
     case cineon::kRec709Red:
     case cineon::kRec709Green:
-    case cineon::kRec709Blue: m_spec.attribute("oiio:ColorSpace", "Rec709");
+    case cineon::kRec709Blue: m_spec.set_colorspace("Rec709");
     default:
         // either grayscale or printing density
         if (!std::isinf(m_cin.header.Gamma()) && m_cin.header.Gamma() != 0.0f)
             // actual gamma value is read later on
-            m_spec.attribute("oiio:ColorSpace",
-                             Strutil::fmt::format("Gamma{:.2g}", g));
+            set_colorspace_rec709_gamma(m_spec, float(m_cin.header.Gamma()));
         break;
     }
 
     // gamma exponent
     if (!std::isinf(m_cin.header.Gamma()) && m_cin.header.Gamma() != 0.0f)
-        m_spec.attribute("oiio:Gamma", (float)m_cin.header.Gamma());
+        set_colorspace_rec709_gamma(m_spec, float(m_cin.header.Gamma()));
 #endif
 
     // general metadata
diff --git a/src/dds.imageio/ddsinput.cpp b/src/dds.imageio/ddsinput.cpp
index 95af4cd6ce..52cf302ef3 100644
--- a/src/dds.imageio/ddsinput.cpp
+++ b/src/dds.imageio/ddsinput.cpp
@@ -845,7 +845,7 @@ DDSInput::seek_subimage(int subimage, int miplevel)
     // linear color space for HDR-ish images
     if (colorspace == nullptr
         && (basetype == TypeDesc::HALF || basetype == TypeDesc::FLOAT))
-        colorspace = "linear";
+        colorspace = "lin_rec709";
 
     m_spec.set_colorspace(colorspace);
 
diff --git a/src/doc/imageioapi.rst b/src/doc/imageioapi.rst
index ccebfd68f0..f294024d80 100644
--- a/src/doc/imageioapi.rst
+++ b/src/doc/imageioapi.rst
@@ -285,6 +285,12 @@ just exist in the OIIO namespace as general utilities. (See
 
 .. doxygenfunction:: get_extension_map
 
+.. doxygenfunction:: OIIO::set_colorspace
+
+.. doxygenfunction:: OIIO::set_colorspace_rec709_gamma
+
+.. doxygenfunction:: OIIO::equivalent_colorspace
+
 |
 
  .. _sec-startupshutdown:
diff --git a/src/doc/imageoutput.rst b/src/doc/imageoutput.rst
index 895df378fb..8b06fd679a 100644
--- a/src/doc/imageoutput.rst
+++ b/src/doc/imageoutput.rst
@@ -888,12 +888,12 @@ color space:
    .. code-tab:: c++
 
       ImageSpec spec (width, length, channels, format);
-      spec.attribute ("oiio:ColorSpace", "scene_linear");
+      spec.set_colorspace("scene_linear");
 
    .. code-tab:: py
 
       spec = ImageSpec(width, length, channels, format)
-      spec.attribute ("oiio:ColorSpace", "scene_linear")
+      spec.set_colorspace("scene_linear")
 
 If a particular ``ImageOutput`` implementation is required (by the rules of
 the file format it writes) to have pixels in a fixed color space,
diff --git a/src/doc/pythonbindings.rst b/src/doc/pythonbindings.rst
index 65eee9ff75..8a06bc537d 100644
--- a/src/doc/pythonbindings.rst
+++ b/src/doc/pythonbindings.rst
@@ -732,7 +732,6 @@ Section :ref:`sec-ImageSpec`, is replicated for Python.
         spec.set_colorspace ("sRGB")
 
 
-
 .. py:method:: ImageSpec.undefined ()
 
     Returns `True` for a newly initialized (undefined) ImageSpec.
@@ -3885,6 +3884,53 @@ details.
         formats = oiio.get_string_attribute ("format_list")
 
 
+.. py:method:: set_colorspace (spec, name)
+
+    Set the metadata of the `spec` to presume that color space is `name` (or
+    to assume nothing about the color space if `name` is empty).
+
+    Example:
+
+    .. code-block:: python
+
+        spec = oiio.ImageSpec()
+        oiio.set_colorspace (spec, "lin_rec709")
+
+    This function was added in OpenImageIO 3.0.
+
+
+.. py:method:: set_colorspace_rec709_gamma (spec, name)
+
+    Set the metadata of the `spec` to reflect Rec709 color primaries and the
+    given gamma.
+
+    Example:
+
+    .. code-block:: python
+
+        spec = oiio.ImageSpec()
+        oiio.set_colorspace_rec709_gamma (spec, 2.2)
+
+    This function was added in OpenImageIO 3.0.
+
+
+.. py:method:: equivalent_colorspace (a, b)
+
+    Return `True` if the color spaces `a` and `b` are equivalent in the
+    default active color config.
+
+    Example:
+
+    .. code-block:: python
+
+        # ib is an ImageBuf
+        cs = ib.spec().get_string_attribute("oiio:ColorSpace")
+        if oiio.equivalent_colorspace(cs, "sRGB") :
+            print ("The image is sRGB")
+
+    This function was added in OpenImageIO 3.0.
+
+
 .. py:method:: is_imageio_format_name (name)
 
     Returns True if `name` is the name of a known and supported file format,
diff --git a/src/doc/stdmetadata.rst b/src/doc/stdmetadata.rst
index a66cbb54c1..69f17f052b 100644
--- a/src/doc/stdmetadata.rst
+++ b/src/doc/stdmetadata.rst
@@ -143,18 +143,19 @@ Color information
     
     - `"scene_linear"` :  Color pixel values are known to be scene-linear and
       using facility-default color primaries as defined by the OpenColorIO
-      configuration. Note that `"linear"` is treated as a synonym. (Note: when
-      no color config is found, this are presumed to use sRGB/Rec709 color
-      primaries when built against OpenColorIO 2.1 or earlier, or when no OCIO
-      support is available, but is presumed to be ACEScg when built against
-      OCIO 2.2 or higher and using its built-in config.)
-    - `"lin_srgb"` :  Color pixel values are known to be linear and
-      using sRGB/Rec709 color primaries.
+      configuration.
+    - `"lin_srgb"`, `"lin_rec709"` :  Color pixel values are known to be
+      linear and using sRGB/Rec709 color primaries. Note that `"linear"` is
+      treated as a synonym.
     - `"sRGB"` :  Using standard sRGB response and primaries.
     - `"Rec709"` :  Using standard Rec709 response and primaries.
     - `"ACEScg"` :  ACEScg color space encoding.
     - `"AdobeRGB"` :  Adobe RGB color space.
     - `"KodakLog"` :  Kodak logarithmic color space.
+    - `"g22_rec709"` : Rec709/sRGB primaries, but using a response curve
+      corresponding to gamma 2.2.
+    - `"g18_rec709"` : Rec709/sRGB primaries, but using a response curve
+      corresponding to gamma 1.8.
     - `"GammaX.Y"` :  Color values have been gamma corrected
       (raised to the power :math:`1/\gamma`). The `X.Y` is the numeric value
       of the gamma exponent.
@@ -230,7 +231,7 @@ Disk file format info/hints
     `piz`, `pxr24`, `b44`, `b44a`, `dwaa`, or `dwab`.
 
     he compression name is permitted to have a quality value to be appended
-    fter a colon, for example `dwaa:60`.  The exact meaning and range of
+    after a colon, for example `dwaa:60`.  The exact meaning and range of
     he quality value can vary between different file formats and compression
     odes, and some don't support quality values at all (it will be ignored if
     ot supported, or if out of range).
diff --git a/src/dpx.imageio/dpxinput.cpp b/src/dpx.imageio/dpxinput.cpp
index 9b8fdf8498..5dfadd919f 100644
--- a/src/dpx.imageio/dpxinput.cpp
+++ b/src/dpx.imageio/dpxinput.cpp
@@ -312,17 +312,12 @@ DPXInput::seek_subimage(int subimage, int miplevel)
 
     // image linearity
     switch (m_dpx.header.Transfer(subimage)) {
-    case dpx::kLinear: m_spec.attribute("oiio:ColorSpace", "Linear"); break;
-    case dpx::kLogarithmic:
-        m_spec.attribute("oiio:ColorSpace", "KodakLog");
-        break;
-    case dpx::kITUR709: m_spec.attribute("oiio:ColorSpace", "Rec709"); break;
+    case dpx::kLinear: m_spec.set_colorspace("Linear"); break;
+    case dpx::kLogarithmic: m_spec.set_colorspace("KodakLog"); break;
+    case dpx::kITUR709: m_spec.set_colorspace("Rec709"); break;
     case dpx::kUserDefined:
         if (!std::isnan(m_dpx.header.Gamma()) && m_dpx.header.Gamma() != 0) {
-            float g = float(m_dpx.header.Gamma());
-            m_spec.attribute("oiio:ColorSpace",
-                             Strutil::fmt::format("Gamma{:.2}", g));
-            m_spec.attribute("oiio:Gamma", g);
+            set_colorspace_rec709_gamma(m_spec, float(m_dpx.header.Gamma()));
             break;
         }
         // intentional fall-through
diff --git a/src/gif.imageio/gifinput.cpp b/src/gif.imageio/gifinput.cpp
index 45cd33cc9e..b0e033cac0 100644
--- a/src/gif.imageio/gifinput.cpp
+++ b/src/gif.imageio/gifinput.cpp
@@ -259,7 +259,7 @@ GIFInput::read_subimage_metadata(ImageSpec& newspec)
     newspec.nchannels = 4;
     newspec.default_channel_names();
     newspec.alpha_channel = 4;
-    newspec.attribute("oiio:ColorSpace", "sRGB");
+    newspec.set_colorspace("sRGB");
 
     m_previous_disposal_method = m_disposal_method;
     m_disposal_method          = DISPOSAL_UNSPECIFIED;
diff --git a/src/hdr.imageio/hdrinput.cpp b/src/hdr.imageio/hdrinput.cpp
index 7d491d11ae..650e403b58 100644
--- a/src/hdr.imageio/hdrinput.cpp
+++ b/src/hdr.imageio/hdrinput.cpp
@@ -291,7 +291,7 @@ HdrInput::RGBE_ReadHeader()
     if (!line.size())
         return false;
 
-    m_spec.attribute("oiio:ColorSpace", "lin_srgb");
+    m_spec.set_colorspace("lin_rec709");
     // presume linear w/ srgb primaries -- seems like the safest assumption
     // for this old file format.
 
@@ -310,13 +310,7 @@ HdrInput::RGBE_ReadHeader()
             // 2.2, not 2.19998.
             float g = float(1.0 / tempf);
             g       = roundf(100.0 * g) / 100.0f;
-            m_spec.attribute("oiio:Gamma", g);
-            if (g == 1.0f)
-                m_spec.attribute("oiio:ColorSpace", "linear");
-            else
-                m_spec.attribute("oiio:ColorSpace",
-                                 Strutil::fmt::format("Gamma{:.2g}", g));
-
+            set_colorspace_rec709_gamma(m_spec, g);
         } else if (Strutil::parse_values(line,
                                          "EXPOSURE=", span<float>(tempf))) {
             m_spec.attribute("hdr:exposure", tempf);
diff --git a/src/heif.imageio/heifinput.cpp b/src/heif.imageio/heifinput.cpp
index 228c567bbf..75f5febe43 100644
--- a/src/heif.imageio/heifinput.cpp
+++ b/src/heif.imageio/heifinput.cpp
@@ -243,7 +243,7 @@ HeifInput::seek_subimage(int subimage, int miplevel)
                          m_himage.get_height(heif_channel_interleaved), bits / 8,
                          TypeUInt8);
 
-    m_spec.attribute("oiio:ColorSpace", "sRGB");
+    m_spec.set_colorspace("sRGB");
 
 #if LIBHEIF_HAVE_VERSION(1, 12, 0)
     // Libheif >= 1.12 added API call to find out if the image is associated
diff --git a/src/iconvert/iconvert.cpp b/src/iconvert/iconvert.cpp
index 0c68fe190e..75a5201121 100644
--- a/src/iconvert/iconvert.cpp
+++ b/src/iconvert/iconvert.cpp
@@ -224,7 +224,7 @@ adjust_spec(ImageInput* in, ImageOutput* out, const ImageSpec& inspec,
 
     outspec.attribute("oiio:Gamma", gammaval);
     if (sRGB) {
-        outspec.attribute("oiio:ColorSpace", "sRGB");
+        outspec.set_colorspace("sRGB");
         if (!strcmp(in->format_name(), "jpeg")
             || outspec.find_attribute("Exif:ColorSpace"))
             outspec.attribute("Exif:ColorSpace", 1);
diff --git a/src/include/OpenImageIO/color.h b/src/include/OpenImageIO/color.h
index 32d3854918..f2b05626a7 100644
--- a/src/include/OpenImageIO/color.h
+++ b/src/include/OpenImageIO/color.h
@@ -371,6 +371,23 @@ class OIIO_API ColorConfig {
     /// Return a filename or other identifier for the config we're using.
     std::string configname() const;
 
+    /// Set the spec's metadata to presume that color space is `name` (or to
+    /// assume nothing about the color space if `name` is empty). The core
+    /// operation is to set the "oiio:ColorSpace" attribute, but it also removes
+    /// or alters several other attributes that may hint color space in ways that
+    /// might be contradictory or no longer true.
+    ///
+    /// @version 3.0
+    void set_colorspace(ImageSpec& spec, string_view name) const;
+
+    /// Set the spec's metadata to reflect Rec709 color primaries and the given
+    /// gamma. The core operation is to set the "oiio:ColorSpace" attribute, but
+    /// it also removes or alters several other attributes that may hint color
+    /// space in ways that might be contradictory or no longer true.
+    ///
+    /// @version 3.0
+    void set_colorspace_rec709_gamma(ImageSpec& spec, float gamma) const;
+
     /// Return if OpenImageIO was built with OCIO support
     static bool supportsOpenColorIO();
 
diff --git a/src/include/OpenImageIO/imagebufalgo.h b/src/include/OpenImageIO/imagebufalgo.h
index 41b24b2570..ac99c08fb3 100644
--- a/src/include/OpenImageIO/imagebufalgo.h
+++ b/src/include/OpenImageIO/imagebufalgo.h
@@ -1817,12 +1817,9 @@ bool OIIO_API erode (ImageBuf &dst, const ImageBuf &src,
 /// transformed, and the fourth channel (if it exists) is presumed to be
 /// alpha. Any additional channels will be simply copied unaltered.
 ///
-/// If OIIO was built with OpenColorIO support enabled, then the
-/// transformation may be between any two spaces supported by the active
+/// The transformation may be between any two spaces supported by the active
 /// OCIO configuration, or may be a "look" transformation created by
-/// `ColorConfig::createLookTransform`.  If OIIO was not built with
-/// OpenColorIO support enabled, then the only transformations available are
-/// from "sRGB" to "linear" and vice versa.
+/// `ColorConfig::createLookTransform`.
 ///
 /// @param  fromspace/tospace
 ///             For the varieties of `colorconvert()` that use named color
@@ -1927,7 +1924,8 @@ bool OIIO_API colormatrixtransform (ImageBuf &dst, const ImageBuf &src,
 ///             The looks to apply (comma-separated).
 /// @param  fromspace/tospace
 ///             For the varieties of `colorconvert()` that use named color
-///             spaces, these specify the color spaces by name.
+///             spaces, these specify the color spaces by name.  If either
+///             is the empty string, it will use `"scene_linear"`.
 /// @param  unpremult
 ///             If true, unpremultiply the image (divide the RGB channels by
 ///             alpha if it exists and is nonzero) before color conversion,
@@ -1979,7 +1977,7 @@ bool OIIO_API ociolook (ImageBuf &dst, const ImageBuf &src, string_view looks,
 ///             If `fromspace` is not supplied, it will assume that the
 ///             source color space is whatever is indicated by the source
 ///             image's metadata or filename, and if that cannot be deduced,
-///             it will be assumed to be scene linear.
+///             it will be assumed to be `"scene_linear"`.
 /// @param  looks
 ///             The looks to apply (comma-separated). This may be empty,
 ///             in which case no "look" is used. Note: this parameter value
diff --git a/src/include/OpenImageIO/imageio.h b/src/include/OpenImageIO/imageio.h
index 7d3499b7c1..dc0c823927 100644
--- a/src/include/OpenImageIO/imageio.h
+++ b/src/include/OpenImageIO/imageio.h
@@ -3254,6 +3254,33 @@ inline string_view get_string_attribute (string_view name,
 }
 
 
+/// Set the metadata of the `spec` to presume that color space is `name` (or
+/// to assume nothing about the color space if `name` is empty). The core
+/// operation is to set the "oiio:ColorSpace" attribute, but it also removes
+/// or alters several other attributes that may hint color space in ways that
+/// might be contradictory or no longer true. This uses the current default
+/// color config to adjudicate color space name equivalencies.
+///
+/// @version 3.0
+OIIO_API void set_colorspace(ImageSpec& spec, string_view name);
+
+/// Set the metadata of the `spec` to reflect Rec709 color primaries and the
+/// given gamma. The core operation is to set the "oiio:ColorSpace" attribute,
+/// but it also removes or alters several other attributes that may hint color
+/// space in ways that might be contradictory or no longer true. This uses the
+/// current default color config to adjudicate color space name equivalencies.
+///
+/// @version 3.0
+OIIO_API void set_colorspace_rec709_gamma(ImageSpec& spec, float gamma);
+
+
+/// Are the two named color spaces equivalent, based on the default color
+/// config in effect?
+///
+/// @version 3.0
+OIIO_API bool equivalent_colorspace(string_view a, string_view b);
+
+
 /// Register the input and output 'create' routines and list of file
 /// extensions for a particular format.
 OIIO_API void declare_imageio_format (const std::string &format_name,
diff --git a/src/jpeg.imageio/jpeginput.cpp b/src/jpeg.imageio/jpeginput.cpp
index f2c302a353..b45e06d1f3 100644
--- a/src/jpeg.imageio/jpeginput.cpp
+++ b/src/jpeg.imageio/jpeginput.cpp
@@ -257,7 +257,7 @@ JpgInput::open(const std::string& name, ImageSpec& newspec)
         return false;
 
     // Assume JPEG is in sRGB unless the Exif or XMP tags say otherwise.
-    m_spec.attribute("oiio:ColorSpace", "sRGB");
+    m_spec.set_colorspace("sRGB");
 
     if (m_cinfo.jpeg_color_space == JCS_CMYK)
         m_spec.attribute("jpeg:ColorSpace", "CMYK");
diff --git a/src/jpeg.imageio/jpegoutput.cpp b/src/jpeg.imageio/jpegoutput.cpp
index 04237d8aff..923dc62796 100644
--- a/src/jpeg.imageio/jpegoutput.cpp
+++ b/src/jpeg.imageio/jpegoutput.cpp
@@ -229,7 +229,8 @@ JpgOutput::open(const std::string& name, const ImageSpec& newspec,
                           comment.size() + 1);
     }
 
-    if (Strutil::iequals(m_spec.get_string_attribute("oiio:ColorSpace"), "sRGB"))
+    if (equivalent_colorspace(m_spec.get_string_attribute("oiio:ColorSpace"),
+                              "sRGB"))
         m_spec.attribute("Exif:ColorSpace", 1);
 
     // Write EXIF info
diff --git a/src/jpeg2000.imageio/jpeg2000input.cpp b/src/jpeg2000.imageio/jpeg2000input.cpp
index 10bb0be688..70b8c7cca5 100644
--- a/src/jpeg2000.imageio/jpeg2000input.cpp
+++ b/src/jpeg2000.imageio/jpeg2000input.cpp
@@ -330,7 +330,7 @@ Jpeg2000Input::open(const std::string& name, ImageSpec& p_spec)
     m_spec.full_height = m_image->y1;
 
     m_spec.attribute("oiio:BitsPerSample", maxPrecision);
-    m_spec.attribute("oiio:ColorSpace", "sRGB");
+    m_spec.set_colorspace("sRGB");
 
     if (m_image->icc_profile_len && m_image->icc_profile_buf) {
         m_spec.attribute("ICCProfile",
diff --git a/src/libOpenImageIO/color_ocio.cpp b/src/libOpenImageIO/color_ocio.cpp
index e85c8e6d04..8eac1e044a 100644
--- a/src/libOpenImageIO/color_ocio.cpp
+++ b/src/libOpenImageIO/color_ocio.cpp
@@ -26,10 +26,6 @@
 
 #include <OpenColorIO/OpenColorIO.h>
 
-#define OCIO_v2 1
-#ifndef OIIO_DISABLE_BUILTIN_OCIO_CONFIGS
-#    define OCIO_HAS_BUILTIN_CONFIGS 1
-#endif
 namespace OCIO = OCIO_NAMESPACE;
 
 
@@ -43,9 +39,9 @@ static const Imath::C3f test_colors[n_test_colors]
 }  // namespace
 
 
-#if 0 || !defined(NDEBUG) /* allow color configuration debugging */
+#if 1 || !defined(NDEBUG) /* allow color configuration debugging */
 static bool colordebug = Strutil::stoi(Sysutil::getenv("OIIO_DEBUG_COLOR"))
-                       || Strutil::stoi(Sysutil::getenv("OIIO_DEBUG_ALL"));
+                         || Strutil::stoi(Sysutil::getenv("OIIO_DEBUG_ALL"));
 #    define DBG(...)    \
         if (colordebug) \
         Strutil::print(__VA_ARGS__)
@@ -592,7 +588,8 @@ ColorConfig::Impl::classify_by_name(CSInfo& cs)
         cs.setflag(CSInfo::is_Rec709, Rec709_alias);
     } else if (Strutil::iequals(cs.name, "lin_srgb")
                || Strutil::iequals(cs.name, "lin_rec709")
-               || Strutil::iequals(cs.name, "Linear Rec.709 (sRGB)")) {
+               || Strutil::iequals(cs.name, "Linear Rec.709 (sRGB)")
+               || Strutil::iequals(cs.name, "linear")) {
         cs.setflag(CSInfo::is_lin_srgb | CSInfo::is_linear_response,
                    lin_srgb_alias);
     } else if (Strutil::iequals(cs.name, "ACEScg")
@@ -1328,13 +1325,14 @@ ColorConfig::Impl::resolve(string_view name) const
     spin_rw_write_lock lock(m_mutex);
     if (Strutil::iequals(name, "sRGB") && !srgb_alias.empty())
         return srgb_alias;
-    if (Strutil::iequals(name, "lin_srgb") && lin_srgb_alias.size())
+    if ((Strutil::iequals(name, "lin_srgb")
+         || Strutil::iequals(name, "lin_rec709")
+         || Strutil::iequals(name, "linear"))
+        && lin_srgb_alias.size())
         return lin_srgb_alias;
     if (Strutil::iequals(name, "ACEScg") && !ACEScg_alias.empty())
         return ACEScg_alias;
-    if ((Strutil::iequals(name, "linear")
-         || Strutil::iequals(name, "scene_linear"))
-        && !scene_linear_alias.empty()) {
+    if (Strutil::iequals(name, "scene_linear") && !scene_linear_alias.empty()) {
         return scene_linear_alias;
     }
     if (Strutil::iequals(name, "Rec709") && Rec709_alias.size())
@@ -1386,6 +1384,14 @@ ColorConfig::equivalent(string_view color_space1,
 
 
 
+bool
+equivalent_colorspace(string_view a, string_view b)
+{
+    return ColorConfig::default_colorconfig().equivalent(a, b);
+}
+
+
+
 inline OCIO::BitDepth
 ocio_bitdepth(TypeDesc type)
 {
@@ -1770,59 +1776,6 @@ ColorConfig::createColorProcessor(ustring inputColorSpace,
         }
     }
 
-#if OCIO_VERSION_HEX < MAKE_OCIO_VERSION_HEX(2, 2, 0)
-    // For version 2.2 and later, missing OCIO config will always fall back on
-    // built-in configs, so we don't need any of these secondary fallback
-    // heuristics.
-    if (!handle) {
-        // Either not compiled with OCIO support, or no OCIO configuration
-        // was found at all.  There are a few color conversions we know
-        // about even in such dire conditions.
-        using namespace Strutil;
-        if (equivalent(inputColorSpace, outputColorSpace)) {
-            handle = ColorProcessorHandle(new ColorProcessor_Ident);
-        } else if ((equivalent(inputColorSpace, "lin_srgb")
-                    || equivalent(inputColorSpace, "linear"))
-                   && equivalent(outputColorSpace, "sRGB")) {
-            handle = ColorProcessorHandle(new ColorProcessor_linear_to_sRGB);
-        } else if (equivalent(inputColorSpace, "sRGB")
-                   && (equivalent(outputColorSpace, "lin_srgb")
-                       || equivalent(outputColorSpace, "linear"))) {
-            handle = ColorProcessorHandle(new ColorProcessor_sRGB_to_linear);
-        } else if ((equivalent(inputColorSpace, "lin_srgb")
-                    || equivalent(inputColorSpace, "linear"))
-                   && equivalent(outputColorSpace, "Rec709")) {
-            handle = ColorProcessorHandle(new ColorProcessor_linear_to_Rec709);
-        } else if (equivalent(inputColorSpace, "Rec709")
-                   && equivalent(outputColorSpace, "lin_srgb")) {
-            handle = ColorProcessorHandle(new ColorProcessor_Rec709_to_linear);
-        } else if ((equivalent(inputColorSpace, "linear")
-                    || equivalent(inputColorSpace, "lin_srgb"))
-                   && istarts_with(outputColorSpace, "Gamma")) {
-            string_view gamstr = outputColorSpace;
-            Strutil::parse_word(gamstr);
-            float g = from_string<float>(gamstr);
-            handle  = ColorProcessorHandle(new ColorProcessor_gamma(1.0f / g));
-        } else if (istarts_with(inputColorSpace, "Gamma")
-                   && (equivalent(outputColorSpace, "linear")
-                       || iequals(outputColorSpace, "lin_srgb"))) {
-            string_view gamstr = inputColorSpace;
-            Strutil::parse_word(gamstr);
-            float g = from_string<float>(gamstr);
-            handle  = ColorProcessorHandle(new ColorProcessor_gamma(g));
-        } else {
-            DBG("No heuristic non-OCIO color processor for '{}' -> '{}'\n",
-                inputColorSpace, outputColorSpace);
-            DBG("  is input equiv to srgb? {}\n",
-                equivalent(inputColorSpace, "sRGB"));
-            DBG("  is output equiv to linear? {}\n",
-                equivalent(outputColorSpace, "linear"));
-        }
-        if (handle)
-            pending_error.clear();
-    }
-#endif
-
     if (!handle && p) {
         // If we found a processor from OCIO, even if it was a NoOp, and we
         // still don't have a better idea, return it.
@@ -2197,7 +2150,8 @@ ImageBufAlgo::colorconvert(ImageBuf& dst, const ImageBuf& src, string_view from,
 {
     pvt::LoggedTimer logtime("IBA::colorconvert");
     if (from.empty() || from == "current") {
-        from = src.spec().get_string_attribute("oiio:Colorspace", "linear");
+        from = src.spec().get_string_attribute("oiio:Colorspace",
+                                               "scene_linear");
     }
     if (from.empty() || to.empty()) {
         dst.errorfmt("Unknown color space name");
@@ -2504,11 +2458,11 @@ ImageBufAlgo::ociolook(ImageBuf& dst, const ImageBuf& src, string_view looks,
 {
     pvt::LoggedTimer logtime("IBA::ociolook");
     if (from.empty() || from == "current") {
-        auto linearspace = colorconfig->resolve("linear");
+        auto linearspace = colorconfig->resolve("scene_linear");
         from = src.spec().get_string_attribute("oiio:Colorspace", linearspace);
     }
     if (to.empty() || to == "current") {
-        auto linearspace = colorconfig->resolve("linear");
+        auto linearspace = colorconfig->resolve("scene_linear");
         to = src.spec().get_string_attribute("oiio:Colorspace", linearspace);
     }
     if (from.empty() || to.empty()) {
@@ -2571,8 +2525,8 @@ ImageBufAlgo::ociodisplay(ImageBuf& dst, const ImageBuf& src,
         if (!colorconfig)
             colorconfig = &ColorConfig::default_colorconfig();
         if (from.empty() || from == "current") {
-            auto linearspace = colorconfig->resolve("linear");
-            from = src.spec().get_string_attribute("oiio:Colorspace",
+            auto linearspace = colorconfig->resolve("scene_linear");
+            from = src.spec().get_string_attribute("oiio:ColorSpace",
                                                    linearspace);
         }
         if (from.empty()) {
@@ -2768,4 +2722,65 @@ ImageBufAlgo::colorconvert(span<float> color, const ColorProcessor* processor,
 
 
 
+void
+ColorConfig::set_colorspace(ImageSpec& spec, string_view colorspace) const
+{
+    // If we're not changing color space, don't mess with anything
+    string_view oldspace = spec.get_string_attribute("oiio:ColorSpace");
+    if (oldspace.size() && colorspace.size() && oldspace == colorspace)
+        return;
+
+    // Set or clear the main "oiio:ColorSpace" attribute
+    if (colorspace.empty()) {
+        spec.erase_attribute("oiio:ColorSpace");
+    } else {
+        spec.attribute("oiio:ColorSpace", colorspace);
+    }
+
+    // Clear a bunch of other metadata that might contradict the colorspace,
+    // including some format-specific things that we don't want to propagate
+    // from input to output if we know that color space transformations have
+    // occurred.
+    if (!equivalent(colorspace, "sRGB"))
+        spec.erase_attribute("Exif:ColorSpace");
+    spec.erase_attribute("tiff:ColorSpace");
+    spec.erase_attribute("tiff:PhotometricInterpretation");
+    spec.erase_attribute("oiio:Gamma");
+}
+
+
+
+void
+ColorConfig::set_colorspace_rec709_gamma(ImageSpec& spec, float gamma) const
+{
+    gamma = std::round(gamma * 100.0f) / 100.0f;
+    if (fabsf(gamma - 1.0f) <= 0.01f) {
+        set_colorspace(spec, "lin_srgb");
+        // Presume that Targa files are sRGB primaries
+    } else if (fabsf(gamma - 1.8f) <= 0.01f) {
+        set_colorspace(spec, "g18_rec709");
+        spec.attribute("oiio:Gamma", 1.8f);
+    } else if (fabsf(gamma - 2.2f) <= 0.01f) {
+        set_colorspace(spec, "g22_rec709");
+        spec.attribute("oiio:Gamma", 2.2f);
+    } else {
+        set_colorspace(spec, Strutil::fmt::format("Gamma{:.2}", gamma));
+        spec.attribute("oiio:Gamma", gamma);
+    }
+}
+
+
+void
+set_colorspace(ImageSpec& spec, string_view colorspace)
+{
+    ColorConfig::default_colorconfig().set_colorspace(spec, colorspace);
+}
+
+void
+set_colorspace_rec709_gamma(ImageSpec& spec, float gamma)
+{
+    ColorConfig::default_colorconfig().set_colorspace_rec709_gamma(spec, gamma);
+}
+
+
 OIIO_NAMESPACE_END
diff --git a/src/libOpenImageIO/exif.cpp b/src/libOpenImageIO/exif.cpp
index d2206c8c85..203ee6376f 100644
--- a/src/libOpenImageIO/exif.cpp
+++ b/src/libOpenImageIO/exif.cpp
@@ -1216,7 +1216,7 @@ decode_exif(cspan<uint8_t> exif, ImageSpec& spec)
         // Exif spec says that anything other than 0xffff==uncalibrated
         // should be interpreted to be sRGB.
         if (cs != 0xffff)
-            spec.attribute("oiio:ColorSpace", "sRGB");
+            spec.set_colorspace("sRGB");
     }
 
     // Look for a maker note offset, now that we have seen all the metadata
diff --git a/src/libOpenImageIO/formatspec.cpp b/src/libOpenImageIO/formatspec.cpp
index 11515f6b4e..4f7b7eef25 100644
--- a/src/libOpenImageIO/formatspec.cpp
+++ b/src/libOpenImageIO/formatspec.cpp
@@ -9,6 +9,7 @@
 
 #include <OpenImageIO/half.h>
 
+#include <OpenImageIO/color.h>
 #include <OpenImageIO/dassert.h>
 #include <OpenImageIO/fmath.h>
 #include <OpenImageIO/imagebuf.h>
@@ -1229,25 +1230,7 @@ pvt::check_texture_metadata_sanity(ImageSpec& spec)
 void
 ImageSpec::set_colorspace(string_view colorspace)
 {
-    // If we're not changing color space, don't mess with anything
-    string_view oldspace = get_string_attribute("oiio:ColorSpace");
-    if (oldspace.size() && colorspace.size() && oldspace == colorspace)
-        return;
-
-    // Set or clear the main "oiio:ColorSpace" attribute
-    if (colorspace.empty()) {
-        erase_attribute("oiio:ColorSpace");
-    } else {
-        attribute("oiio:ColorSpace", colorspace);
-    }
-
-    // Clear a bunch of other metadata that might contradict the colorspace,
-    // including some format-specific things that we don't want to propagate
-    // from input to output if we know that color space transformations have
-    // occurred.
-    erase_attribute("Exif:ColorSpace");
-    erase_attribute("tiff:ColorSpace");
-    erase_attribute("tiff:PhotometricInterpretation");
+    ColorConfig::default_colorconfig().set_colorspace(*this, colorspace);
 }
 
 
diff --git a/src/oiiotool/oiiotool.cpp b/src/oiiotool/oiiotool.cpp
index bdeb415aeb..3381eb388f 100644
--- a/src/oiiotool/oiiotool.cpp
+++ b/src/oiiotool/oiiotool.cpp
@@ -5195,7 +5195,7 @@ input_file(Oiiotool& ot, cspan<const char*> argv)
                     print("  Metadata of {} indicates color space \"{}\"\n",
                           colorspace, filename);
             }
-            std::string linearspace = ot.colorconfig().resolve("linear");
+            std::string linearspace = ot.colorconfig().resolve("scene_linear");
             if (colorspace.size()
                 && !ot.colorconfig().equivalent(colorspace, linearspace)) {
                 std::string cmd = "colorconvert:strict=0";
@@ -5504,7 +5504,7 @@ output_file(Oiiotool& ot, cspan<const char*> argv)
         }
     }
     if (autocc) {
-        string_view linearspace = ot.colorconfig().resolve("linear");
+        string_view linearspace = ot.colorconfig().resolve("scene_linear");
         std::string currentspace
             = ir->spec()->get_string_attribute("oiio:ColorSpace", linearspace);
         // Special cases where we know formats should be particular color
@@ -6008,12 +6008,16 @@ print_ocio_info(Oiiotool& ot, std::ostream& out)
         out << "No OpenColorIO";
     out << "\nColor config: " << colorconfig.configname() << "\n";
     out << "Known color spaces: \n";
-    const char* linear = colorconfig.getColorSpaceNameByRole("linear");
+    const char* linear       = colorconfig.getColorSpaceNameByRole("linear");
+    const char* scene_linear = colorconfig.getColorSpaceNameByRole(
+        "scene_linear");
     for (int i = 0, e = colorconfig.getNumColorSpaces(); i < e; ++i) {
         const char* n = colorconfig.getColorSpaceNameByIndex(i);
         out << "    - " << quote_if_spaces(n);
-        if ((linear && !colorconfig.equivalent(n, "linear")
-             && colorconfig.equivalent(n, linear))
+        if ((scene_linear && !colorconfig.equivalent(n, "scene_linear")
+             && colorconfig.equivalent(n, scene_linear))
+            || (linear && !colorconfig.equivalent(n, "linear")
+                && colorconfig.equivalent(n, linear))
             || colorconfig.isColorSpaceLinear(n))
             out << " (linear)";
         out << "\n";
diff --git a/src/openexr.imageio/exr_pvt.h b/src/openexr.imageio/exr_pvt.h
index 9250bcb5cd..366febc10d 100644
--- a/src/openexr.imageio/exr_pvt.h
+++ b/src/openexr.imageio/exr_pvt.h
@@ -44,20 +44,17 @@ static bool exrdebug = Strutil::stoi(Sysutil::getenv("OIIO_DEBUG_OPENEXR"))
 #endif
 
 
+namespace pvt {
+
 // Split a full channel name into layer and suffix.
-inline void
-split_name(string_view fullname, string_view& layer, string_view& suffix)
-{
-    size_t dot = fullname.find_last_of('.');
-    if (dot == string_view::npos) {
-        suffix = fullname;
-        layer  = string_view();
-    } else {
-        layer  = string_view(fullname.data(), dot + 1);
-        suffix = string_view(fullname.data() + dot + 1,
-                             fullname.size() - dot - 1);
-    }
-}
+void
+split_name(string_view fullname, string_view& layer, string_view& suffix);
+
+// Do the channels appear to be R, G, B (or known common aliases)?
+bool
+channels_are_rgb(const ImageSpec& spec);
+
+}  // namespace pvt
 
 
 
diff --git a/src/openexr.imageio/exrinput.cpp b/src/openexr.imageio/exrinput.cpp
index 49796305d4..0613867949 100644
--- a/src/openexr.imageio/exrinput.cpp
+++ b/src/openexr.imageio/exrinput.cpp
@@ -148,6 +148,40 @@ namespace pvt {
 void
 set_exr_threads();
 
+
+// Split a full channel name into layer and suffix.
+void
+split_name(string_view fullname, string_view& layer, string_view& suffix)
+{
+    size_t dot = fullname.find_last_of('.');
+    if (dot == string_view::npos) {
+        suffix = fullname;
+        layer  = string_view();
+    } else {
+        layer  = string_view(fullname.data(), dot + 1);
+        suffix = string_view(fullname.data() + dot + 1,
+                             fullname.size() - dot - 1);
+    }
+}
+
+
+inline bool
+str_equal_either(string_view str, string_view a, string_view b)
+{
+    return Strutil::iequals(str, a) || Strutil::iequals(str, b);
+}
+
+
+// Do the channels appear to be R, G, B (or known common aliases)?
+bool
+channels_are_rgb(const ImageSpec& spec)
+{
+    return spec.nchannels >= 3
+           && str_equal_either(spec.channel_name(0), "R", "Red")
+           && str_equal_either(spec.channel_name(1), "G", "Green")
+           && str_equal_either(spec.channel_name(2), "B", "Blue");
+}
+
 }  // namespace pvt
 
 
@@ -357,8 +391,13 @@ OpenEXRInput::PartInfo::parse_header(OpenEXRInput* in,
 
     spec.deep = Strutil::istarts_with(header->type(), "deep");
 
-    // Unless otherwise specified, exr files are assumed to be linear.
-    spec.attribute("oiio:ColorSpace", "Linear");
+    // Unless otherwise specified, exr files are assumed to be linear Rec709
+    // if the channels appear to be R, G, B.  I know this suspect, but I'm
+    // betting that this heuristic will guess the right thing that users want
+    // more often than if we pretending we have no idea what the color space
+    // is.
+    if (pvt::channels_are_rgb(spec))
+        spec.set_colorspace("lin_rec709");
 
     if (levelmode != Imf::ONE_LEVEL)
         spec.attribute("openexr:roundingmode", roundingmode);
@@ -666,7 +705,7 @@ struct ChanNameHolder {
         , xSampling(exrchan.xSampling)
         , ySampling(exrchan.ySampling)
     {
-        split_name(fullname, layer, suffix);
+        pvt::split_name(fullname, layer, suffix);
     }
 
     // Compute canoninical channel list sort priority
diff --git a/src/openexr.imageio/exrinput_c.cpp b/src/openexr.imageio/exrinput_c.cpp
index 46bdb331a7..22d64ade1b 100644
--- a/src/openexr.imageio/exrinput_c.cpp
+++ b/src/openexr.imageio/exrinput_c.cpp
@@ -528,8 +528,13 @@ OpenEXRCoreInput::PartInfo::parse_header(OpenEXRCoreInput* in,
     spec.deep = (storage == EXR_STORAGE_DEEP_TILED
                  || storage == EXR_STORAGE_DEEP_SCANLINE);
 
-    // Unless otherwise specified, exr files are assumed to be linear.
-    spec.attribute("oiio:ColorSpace", "Linear");
+    // Unless otherwise specified, exr files are assumed to be linear Rec709
+    // if the channels appear to be R, G, B.  I know this suspect, but I'm
+    // betting that this heuristic will guess the right thing that users want
+    // more often than if we pretending we have no idea what the color space
+    // is.
+    if (pvt::channels_are_rgb(spec))
+        spec.set_colorspace("lin_rec709");
 
     if (levelmode != EXR_TILE_ONE_LEVEL)
         spec.attribute("openexr:roundingmode", (int)roundingmode);
@@ -806,7 +811,7 @@ struct CChanNameHolder {
         , xSampling(exrchan.x_sampling)
         , ySampling(exrchan.y_sampling)
     {
-        split_name(fullname, layer, suffix);
+        pvt::split_name(fullname, layer, suffix);
     }
 
     // Compute canoninical channel list sort priority
diff --git a/src/png.imageio/png_pvt.h b/src/png.imageio/png_pvt.h
index 9119e19f65..a4a96269a1 100644
--- a/src/png.imageio/png_pvt.h
+++ b/src/png.imageio/png_pvt.h
@@ -224,23 +224,18 @@ read_info(png_structp& sp, png_infop& ip, int& bit_depth, int& color_type,
     int srgb_intent;
     double gamma = 0.0;
     if (png_get_sRGB(sp, ip, &srgb_intent)) {
-        spec.attribute("oiio:ColorSpace", "sRGB");
+        spec.set_colorspace("sRGB");
     } else if (png_get_gAMA(sp, ip, &gamma) && gamma > 0.0) {
         // Round gamma to the nearest hundredth to prevent stupid
         // precision choices and make it easier for apps to make
         // decisions based on known gamma values. For example, you want
         // 2.2, not 2.19998.
         float g = float(1.0 / gamma);
-        g       = roundf(100.0 * g) / 100.0f;
-        spec.attribute("oiio:Gamma", g);
-        if (g == 1.0f)
-            spec.attribute("oiio:ColorSpace", "linear");
-        else
-            spec.attribute("oiio:ColorSpace",
-                           Strutil::fmt::format("Gamma{:.2g}", g));
+        g       = roundf(100.0f * g) / 100.0f;
+        set_colorspace_rec709_gamma(spec, g);
     } else {
         // If there's no info at all, assume sRGB.
-        spec.attribute("oiio:ColorSpace", "sRGB");
+        set_colorspace(spec, "sRGB");
     }
 
     if (png_get_valid(sp, ip, PNG_INFO_iCCP)) {
@@ -607,7 +602,7 @@ write_info(png_structp& sp, png_infop& ip, int& color_type, ImageSpec& spec,
     const ColorConfig& colorconfig = ColorConfig::default_colorconfig();
     string_view colorspace = spec.get_string_attribute("oiio:ColorSpace");
     if (colorconfig.equivalent(colorspace, "scene_linear")
-        || colorconfig.equivalent(colorspace, "linear")) {
+        || colorconfig.equivalent(colorspace, "lin_rec709")) {
         if (setjmp(png_jmpbuf(sp)))  // NOLINT(cert-err52-cpp)
             return "Could not set PNG gAMA chunk";
         png_set_gAMA(sp, ip, 1.0);
@@ -621,6 +616,18 @@ write_info(png_structp& sp, png_infop& ip, int& color_type, ImageSpec& spec,
             return "Could not set PNG gAMA chunk";
         png_set_gAMA(sp, ip, 1.0f / gamma);
         srgb = false;
+    } else if (colorconfig.equivalent(colorspace, "g22_rec709")) {
+        gamma = 2.2f;
+        if (setjmp(png_jmpbuf(sp)))  // NOLINT(cert-err52-cpp)
+            return "Could not set PNG gAMA chunk";
+        png_set_gAMA(sp, ip, 1.0f / gamma);
+        srgb = false;
+    } else if (colorconfig.equivalent(colorspace, "g18_rec709")) {
+        gamma = 1.8f;
+        if (setjmp(png_jmpbuf(sp)))  // NOLINT(cert-err52-cpp)
+            return "Could not set PNG gAMA chunk";
+        png_set_gAMA(sp, ip, 1.0f / gamma);
+        srgb = false;
     } else if (colorconfig.equivalent(colorspace, "sRGB")) {
         if (setjmp(png_jmpbuf(sp)))  // NOLINT(cert-err52-cpp)
             return "Could not set PNG gAMA and cHRM chunk";
diff --git a/src/pnm.imageio/pnminput.cpp b/src/pnm.imageio/pnminput.cpp
index 1b08c0d35e..2642a47083 100644
--- a/src/pnm.imageio/pnminput.cpp
+++ b/src/pnm.imageio/pnminput.cpp
@@ -337,7 +337,7 @@ PNMInput::read_file_header()
         m_spec.attribute("pnm:bigendian", m_scaling_factor < 0 ? 0 : 1);
         m_spec.attribute("pnm:binary", 1);
     }
-    m_spec.attribute("oiio:ColorSpace", "Rec709");
+    m_spec.set_colorspace("Rec709");
     return true;
 }
 
diff --git a/src/python/py_colorconfig.cpp b/src/python/py_colorconfig.cpp
index 0ce914b4cc..89a158e05a 100644
--- a/src/python/py_colorconfig.cpp
+++ b/src/python/py_colorconfig.cpp
@@ -136,7 +136,10 @@ declare_colorconfig(py::module& m)
                 return self.equivalent(color_space, other_color_space);
             },
             "color_space"_a, "other_color_space"_a)
-        .def("configname", &ColorConfig::configname);
+        .def("configname", &ColorConfig::configname)
+        .def_static("default_colorconfig", []() -> const ColorConfig& {
+            return ColorConfig::default_colorconfig();
+        });
 
     m.attr("supportsOpenColorIO")     = ColorConfig::supportsOpenColorIO();
     m.attr("OpenColorIO_version_hex") = ColorConfig::OpenColorIO_version_hex();
diff --git a/src/python/py_oiio.cpp b/src/python/py_oiio.cpp
index 2479e5916c..d51531981a 100644
--- a/src/python/py_oiio.cpp
+++ b/src/python/py_oiio.cpp
@@ -337,6 +337,19 @@ OIIO_DECLARE_PYMODULE(PYMODULE_NAME)
         },
         py::arg("name"), py::arg("defaultval") = "");
     m.def("getattribute", &oiio_getattribute_typed);
+    m.def(
+        "set_colorspace",
+        [](ImageSpec& spec, const std::string& name) {
+            set_colorspace(spec, name);
+        },
+        py::arg("spec"), py::arg("name"));
+    m.def("set_colorspace_rec709_gamma", [](ImageSpec& spec, float gamma) {
+        set_colorspace_rec709_gamma(spec, gamma);
+    });
+    m.def("equivalent_colorspace",
+          [](const std::string& a, const std::string& b) {
+              return equivalent_colorspace(a, b);
+          });
     m.def(
         "is_imageio_format_name",
         [](const std::string& name) {
diff --git a/src/raw.imageio/rawinput.cpp b/src/raw.imageio/rawinput.cpp
index 610110448b..0f2ba393ed 100644
--- a/src/raw.imageio/rawinput.cpp
+++ b/src/raw.imageio/rawinput.cpp
@@ -570,11 +570,14 @@ RawInput::open_raw(bool unpack, const std::string& name,
         m_processor->imgdata.params.gamm[0]      = 1.0 / 2.4;
         m_processor->imgdata.params.gamm[1]      = 12.92;
     } else if (Strutil::iequals(cs, "sRGB-linear")
+               || Strutil::iequals(cs, "lin_srgb")
+               || Strutil::iequals(cs, "lin_rec709")
                || Strutil::iequals(cs, "linear") /* DEPRECATED */) {
         // Request "sRGB" primaries, linear response
         m_processor->imgdata.params.output_color = 1;
         m_processor->imgdata.params.gamm[0]      = 1.0;
         m_processor->imgdata.params.gamm[1]      = 1.0;
+        cs                                       = "lin_rec709";
     } else if (Strutil::iequals(cs, "Adobe")) {
         // Request Adobe color space with 2.2 gamma (no linear toe)
         m_processor->imgdata.params.output_color = 2;
@@ -613,7 +616,7 @@ RawInput::open_raw(bool unpack, const std::string& name,
 #endif
     } else if (Strutil::iequals(cs, "Rec2020")) {
 #if LIBRAW_VERSION >= LIBRAW_MAKE_VERSION(0, 21, 0)
-        // ACES linear
+        // Rec2020
         m_processor->imgdata.params.output_color = 8;
         m_processor->imgdata.params.gamm[0]      = 1.0;
         m_processor->imgdata.params.gamm[1]      = 1.0;
@@ -626,7 +629,7 @@ RawInput::open_raw(bool unpack, const std::string& name,
         errorfmt("raw:ColorSpace set to unknown value \"{}\"", cs);
         return false;
     }
-    m_spec.attribute("oiio:ColorSpace", cs);
+    m_spec.set_colorspace(cs);
 
     // Exposure adjustment
     float exposure = config.get_float_attribute("raw:Exposure", -1.0f);
diff --git a/src/rla.imageio/rlainput.cpp b/src/rla.imageio/rlainput.cpp
index d1bd739988..706f508089 100644
--- a/src/rla.imageio/rlainput.cpp
+++ b/src/rla.imageio/rlainput.cpp
@@ -402,13 +402,7 @@ RLAInput::seek_subimage(int subimage, int miplevel)
         // decisions based on known gamma values. For example, you want
         // 2.2, not 2.19998.
         gamma = roundf(100.0 * gamma) / 100.0f;
-        if (gamma == 1.f)
-            m_spec.attribute("oiio:ColorSpace", "Linear");
-        else {
-            m_spec.attribute("oiio:ColorSpace",
-                             Strutil::fmt::format("Gamma{:.2g}", gamma));
-            m_spec.attribute("oiio:Gamma", gamma);
-        }
+        set_colorspace_rec709_gamma(m_spec, gamma);
     }
 
     float aspect = Strutil::stof(m_rla.AspectRatio);
diff --git a/src/rla.imageio/rlaoutput.cpp b/src/rla.imageio/rlaoutput.cpp
index 4b7e644c55..fec2736d51 100644
--- a/src/rla.imageio/rlaoutput.cpp
+++ b/src/rla.imageio/rlaoutput.cpp
@@ -7,7 +7,7 @@
 #include <cstdlib>
 #include <ctime>
 
-#include <OpenImageIO/dassert.h>
+#include <OpenImageIO/color.h>
 #include <OpenImageIO/filesystem.h>
 #include <OpenImageIO/fmath.h>
 #include <OpenImageIO/imageio.h>
@@ -260,9 +260,15 @@ RLAOutput::open(const std::string& name, const ImageSpec& userspec,
     //           << m_rla.NumOfMatteChannels << " z " << m_rla.NumOfAuxChannels << "\n";
     m_rla.Revision = 0xFFFE;
 
+    const ColorConfig& colorconfig = ColorConfig::default_colorconfig();
     string_view colorspace = m_spec.get_string_attribute("oiio:ColorSpace");
-    if (Strutil::iequals(colorspace, "Linear"))
+    if (colorconfig.equivalent(colorspace, "linear")
+        || colorconfig.equivalent(colorspace, "scene_linear"))
         Strutil::safe_strcpy(m_rla.Gamma, "1.0", sizeof(m_rla.Gamma));
+    else if (colorconfig.equivalent(colorspace, "g22_rec709"))
+        Strutil::safe_strcpy(m_rla.Gamma, "2.2", sizeof(m_rla.Gamma));
+    else if (colorconfig.equivalent(colorspace, "g18_rec709"))
+        Strutil::safe_strcpy(m_rla.Gamma, "1.8", sizeof(m_rla.Gamma));
     else if (Strutil::istarts_with(colorspace, "Gamma")) {
         Strutil::parse_word(colorspace);
         float g = Strutil::from_string<float>(colorspace);
diff --git a/src/targa.imageio/targainput.cpp b/src/targa.imageio/targainput.cpp
index a6eb7a046d..2a5aca30eb 100644
--- a/src/targa.imageio/targainput.cpp
+++ b/src/targa.imageio/targainput.cpp
@@ -440,14 +440,7 @@ TGAInput::read_tga2_header()
             // decisions based on known gamma values. For example, you want
             // 2.2, not 2.19998.
             gamma = roundf(100.0 * gamma) / 100.0f;
-            if (gamma == 1.f) {
-                m_spec.attribute("oiio:ColorSpace", "lin_srgb");
-                // Presume that Targa files are sRGB primaries
-            } else {
-                m_spec.attribute("oiio:ColorSpace",
-                                 Strutil::fmt::format("Gamma{:.2g}", gamma));
-                m_spec.attribute("oiio:Gamma", gamma);
-            }
+            set_colorspace_rec709_gamma(m_spec, gamma);
         }
 
         // offset to colour correction table
@@ -531,7 +524,7 @@ TGAInput::get_thumbnail(ImageBuf& thumb, int subimage)
         // the thumbnail is in the same format as the main image but
         // uncompressed.
         ImageSpec thumbspec(res[0], res[1], m_spec.nchannels, TypeUInt8);
-        thumbspec.attribute("oiio:ColorSpace", "sRGB");
+        thumbspec.set_colorspace("sRGB");
         thumb.reset(thumbspec);
         int bytespp    = (m_tga.bpp == 15) ? 2 : (m_tga.bpp / 8);
         int palbytespp = (m_tga.cmap_size == 15) ? 2 : (m_tga.cmap_size / 8);
diff --git a/src/targa.imageio/targaoutput.cpp b/src/targa.imageio/targaoutput.cpp
index 88a8e25258..0d7be1ccf6 100644
--- a/src/targa.imageio/targaoutput.cpp
+++ b/src/targa.imageio/targaoutput.cpp
@@ -6,7 +6,7 @@
 #include <cstdio>
 #include <cstdlib>
 
-#include <OpenImageIO/dassert.h>
+#include <OpenImageIO/color.h>
 #include <OpenImageIO/filesystem.h>
 #include <OpenImageIO/fmath.h>
 #include <OpenImageIO/imagebuf.h>
@@ -370,8 +370,17 @@ TGAOutput::write_tga20_data_fields()
         }
 
         // gamma -- two shorts, giving a ratio
+        const ColorConfig& colorconfig = ColorConfig::default_colorconfig();
         string_view colorspace = m_spec.get_string_attribute("oiio:ColorSpace");
-        if (Strutil::istarts_with(colorspace, "Gamma")) {
+        if (colorconfig.equivalent(colorspace, "g22_rec709")) {
+            m_gamma = 2.2f;
+            write(uint16_t(m_gamma * 10.0f));
+            write(uint16_t(10));
+        } else if (colorconfig.equivalent(colorspace, "g18_rec709")) {
+            m_gamma = 1.8f;
+            write(uint16_t(m_gamma * 10.0f));
+            write(uint16_t(10));
+        } else if (Strutil::istarts_with(colorspace, "Gamma")) {
             // Extract gamma value from color space, if it's there
             Strutil::parse_word(colorspace);
             float g = Strutil::from_string<float>(colorspace);
@@ -381,7 +390,7 @@ TGAOutput::write_tga20_data_fields()
             // NOTE: the spec states that only 1 decimal place of precision
             // is needed, thus the expansion by 10
             // numerator
-            write(uint16_t(m_gamma * 10.0f));
+            write(uint16_t(std::round(m_gamma * 10.0f)));
             write(uint16_t(10));
         } else {
             // just dump two zeros in there
diff --git a/src/tiff.imageio/tiffinput.cpp b/src/tiff.imageio/tiffinput.cpp
index 99e1d44b97..3e4331db3f 100644
--- a/src/tiff.imageio/tiffinput.cpp
+++ b/src/tiff.imageio/tiffinput.cpp
@@ -1254,6 +1254,9 @@ TIFFInput::readspec(bool read_meta)
             // should be interpreted to be sRGB.
             if (m_spec.get_int_attribute("Exif:ColorSpace") != 0xffff)
                 m_spec.attribute("oiio:ColorSpace", "sRGB");
+            // NOTE: We must set "oiio:ColorSpace" explicitly, not call
+            // set_colorspace, or it will erase several other TIFF attribs we
+            // need to preserve.
         }
         // TIFFReadEXIFDirectory seems to do something to the internal state
         // that requires a TIFFSetDirectory to set things straight again.
diff --git a/src/tiff.imageio/tiffoutput.cpp b/src/tiff.imageio/tiffoutput.cpp
index 053ad690f3..d552ba32d6 100644
--- a/src/tiff.imageio/tiffoutput.cpp
+++ b/src/tiff.imageio/tiffoutput.cpp
@@ -873,7 +873,8 @@ TIFFOutput::open(const std::string& name, const ImageSpec& userspec,
             TIFFSetField(m_tif, TIFFTAG_ICCPROFILE, length, icc_profile);
     }
 
-    if (Strutil::iequals(m_spec.get_string_attribute("oiio:ColorSpace"), "sRGB"))
+    if (equivalent_colorspace(m_spec.get_string_attribute("oiio:ColorSpace"),
+                              "sRGB"))
         m_spec.attribute("Exif:ColorSpace", 1);
 
     // Deal with missing XResolution or YResolution, or a PixelAspectRatio
diff --git a/src/webp.imageio/webpinput.cpp b/src/webp.imageio/webpinput.cpp
index f5c215eaac..fe93c6101d 100644
--- a/src/webp.imageio/webpinput.cpp
+++ b/src/webp.imageio/webpinput.cpp
@@ -161,7 +161,7 @@ WebpInput::open(const std::string& name, ImageSpec& spec,
 
     m_spec = ImageSpec(w, h, (m_demux_flags & ALPHA_FLAG) ? 4 : 3, TypeUInt8);
     m_scanline_size = m_spec.scanline_bytes();
-    m_spec.attribute("oiio:ColorSpace", "sRGB");  // webp is always sRGB
+    m_spec.set_colorspace("sRGB");  // webp is always sRGB
     if (m_demux_flags & ANIMATION_FLAG) {
         m_spec.attribute("oiio:Movie", 1);
         m_frame_count       = (int)WebPDemuxGetI(m_demux, WEBP_FF_FRAME_COUNT);
diff --git a/testsuite/dds/ref/out.txt b/testsuite/dds/ref/out.txt
index 9748b7fe14..5ca18c59a0 100644
--- a/testsuite/dds/ref/out.txt
+++ b/testsuite/dds/ref/out.txt
@@ -41,14 +41,14 @@ Reading ../oiio-images/dds/dds_bc6hu.dds
     channel list: R, G, B
     compression: "BC6HU"
     textureformat: "Plain Texture"
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
 Reading ../oiio-images/dds/dds_bc6hu_hdr.dds
 ../oiio-images/dds/dds_bc6hu_hdr.dds :  128 x   64, 3 channel, half dds
     SHA-1: 86FE86288649F5375DB51CDF19C91C3651992726
     channel list: R, G, B
     compression: "BC6HU"
     textureformat: "Plain Texture"
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
 Reading ../oiio-images/dds/dds_bc7.dds
 ../oiio-images/dds/dds_bc7.dds :   16 x    8, 4 channel, uint8 dds
     SHA-1: 18D1977AD74C3C19E5B30459D212EBC8C7F8BC54
diff --git a/testsuite/dup-channels/ref/out.txt b/testsuite/dup-channels/ref/out.txt
index 58163ca4a8..51dddf9515 100644
--- a/testsuite/dup-channels/ref/out.txt
+++ b/testsuite/dup-channels/ref/out.txt
@@ -6,7 +6,7 @@ out.exr              :   64 x   64, 6 channel, half openexr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Reading out2.exr
 out2.exr             :   64 x   64, 6 channel, half openexr
@@ -17,7 +17,7 @@ out2.exr             :   64 x   64, 6 channel, half openexr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimagename: "Aimg"
     oiio:subimages: 1
     openexr:chunkCount: 4
diff --git a/testsuite/hdr/ref/out.txt b/testsuite/hdr/ref/out.txt
index 7f1b7b95f4..23aa29bf05 100644
--- a/testsuite/hdr/ref/out.txt
+++ b/testsuite/hdr/ref/out.txt
@@ -2,7 +2,7 @@ Reading MtTamWest.hdr
 MtTamWest.hdr        : 1214 x  732, 3 channel, float hdr
     channel list: R, G, B
     Orientation: 1 (normal)
-    oiio:ColorSpace: "lin_srgb"
+    oiio:ColorSpace: "lin_rec709"
     Stats Min: 0.000183 0.000240 0.000000 (float)
     Stats Max: 3.875000 3.875000 4.875000 (float)
     Stats Avg: 0.220837 0.352995 0.493945 (float)
diff --git a/testsuite/iinfo/ref/out-fmt6.txt b/testsuite/iinfo/ref/out-fmt6.txt
index 2ee140f242..b0b0a9df97 100644
--- a/testsuite/iinfo/ref/out-fmt6.txt
+++ b/testsuite/iinfo/ref/out-fmt6.txt
@@ -146,7 +146,7 @@ src/tiny-az.exr :     screenWindowCenter: 0, 0
 src/tiny-az.exr :     screenWindowWidth: 1
 src/tiny-az.exr :     Software: "OpenImageIO 2.5.0.0spi : oiiotool -pattern constant:color=0.25,0.5,0.75 4x4 3 --origin +2+2 --fullsize 20x20+1+1 -o tiny-az.exr"
 src/tiny-az.exr :     Exif:ImageHistory: "oiiotool -pattern constant:color=0.25,0.5,0.75 4x4 3 --origin +2+2 --fullsize 20x20+1+1 -o tiny-az.exr"
-src/tiny-az.exr :     oiio:ColorSpace: "Linear"
+src/tiny-az.exr :     oiio:ColorSpace: "lin_rec709"
 src/tiny-az.exr :     oiio:subimages: 1
 src/tiny-az.exr :     Stats Min: 0.250000 0.500000 0.750000 (float)
     Stats Max: 0.250000 0.500000 0.750000 (float)
@@ -173,7 +173,7 @@ src/tiny-az.exr      :    4 x    4, 3 channel, float openexr
     screenWindowWidth: 1
     Software: "OpenImageIO 2.5.0.0spi : oiiotool -pattern constant:color=0.25,0.5,0.75 4x4 3 --origin +2+2 --fullsize 20x20+1+1 -o tiny-az.exr"
     Exif:ImageHistory: "oiiotool -pattern constant:color=0.25,0.5,0.75 4x4 3 --origin +2+2 --fullsize 20x20+1+1 -o tiny-az.exr"
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
     Pixel (2, 2): 0.250000000 0.500000000 0.750000000
     Pixel (3, 2): 0.250000000 0.500000000 0.750000000
@@ -212,7 +212,6 @@ src/tinydeep.exr :    4 x    4, 2 channel, deep float openexr
     Software: "OpenImageIO 2.5.0.0spi : oiiotool -pattern constant:color=1e38,0 4x4 2 --chnames Z,A --point:color=10.0,1.0 2,2 --deepen -o tinydeep.exr"
     version: 1
     Exif:ImageHistory: "oiiotool -pattern constant:color=1e38,0 4x4 2 --chnames Z,A --point:color=10.0,1.0 2,2 --deepen -o tinydeep.exr"
-    oiio:ColorSpace: "Linear"
     oiio:subimages: 1
     openexr:chunkCount: 4
     Stats Min: 1.000000 10.000000 (float)
@@ -247,7 +246,6 @@ src/tinydeep.exr     :    4 x    4, 2 channel, deep float openexr
     Software: "OpenImageIO 2.5.0.0spi : oiiotool -pattern constant:color=1e38,0 4x4 2 --chnames Z,A --point:color=10.0,1.0 2,2 --deepen -o tinydeep.exr"
     version: 1
     Exif:ImageHistory: "oiiotool -pattern constant:color=1e38,0 4x4 2 --chnames Z,A --point:color=10.0,1.0 2,2 --deepen -o tinydeep.exr"
-    oiio:ColorSpace: "Linear"
     oiio:subimages: 1
     openexr:chunkCount: 4
     Pixel (0, 0): 0 samples 
diff --git a/testsuite/iinfo/ref/out.txt b/testsuite/iinfo/ref/out.txt
index adc549a06a..78b7844cff 100644
--- a/testsuite/iinfo/ref/out.txt
+++ b/testsuite/iinfo/ref/out.txt
@@ -146,7 +146,7 @@ src/tiny-az.exr :     screenWindowCenter: 0, 0
 src/tiny-az.exr :     screenWindowWidth: 1
 src/tiny-az.exr :     Software: "OpenImageIO 2.5.0.0spi : oiiotool -pattern constant:color=0.25,0.5,0.75 4x4 3 --origin +2+2 --fullsize 20x20+1+1 -o tiny-az.exr"
 src/tiny-az.exr :     Exif:ImageHistory: "oiiotool -pattern constant:color=0.25,0.5,0.75 4x4 3 --origin +2+2 --fullsize 20x20+1+1 -o tiny-az.exr"
-src/tiny-az.exr :     oiio:ColorSpace: "Linear"
+src/tiny-az.exr :     oiio:ColorSpace: "lin_rec709"
 src/tiny-az.exr :     oiio:subimages: 1
 src/tiny-az.exr :     Stats Min: 0.250000 0.500000 0.750000 (float)
     Stats Max: 0.250000 0.500000 0.750000 (float)
@@ -173,7 +173,7 @@ src/tiny-az.exr      :    4 x    4, 3 channel, float openexr
     screenWindowWidth: 1
     Software: "OpenImageIO 2.5.0.0spi : oiiotool -pattern constant:color=0.25,0.5,0.75 4x4 3 --origin +2+2 --fullsize 20x20+1+1 -o tiny-az.exr"
     Exif:ImageHistory: "oiiotool -pattern constant:color=0.25,0.5,0.75 4x4 3 --origin +2+2 --fullsize 20x20+1+1 -o tiny-az.exr"
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
     Pixel (2, 2): 0.250000000 0.500000000 0.750000000
     Pixel (3, 2): 0.250000000 0.500000000 0.750000000
@@ -212,7 +212,6 @@ src/tinydeep.exr :    4 x    4, 2 channel, deep float openexr
     Software: "OpenImageIO 2.5.0.0spi : oiiotool -pattern constant:color=1e38,0 4x4 2 --chnames Z,A --point:color=10.0,1.0 2,2 --deepen -o tinydeep.exr"
     version: 1
     Exif:ImageHistory: "oiiotool -pattern constant:color=1e38,0 4x4 2 --chnames Z,A --point:color=10.0,1.0 2,2 --deepen -o tinydeep.exr"
-    oiio:ColorSpace: "Linear"
     oiio:subimages: 1
     openexr:chunkCount: 4
     Stats Min: 1.000000 10.000000 (float)
@@ -247,7 +246,6 @@ src/tinydeep.exr     :    4 x    4, 2 channel, deep float openexr
     Software: "OpenImageIO 2.5.0.0spi : oiiotool -pattern constant:color=1e38,0 4x4 2 --chnames Z,A --point:color=10.0,1.0 2,2 --deepen -o tinydeep.exr"
     version: 1
     Exif:ImageHistory: "oiiotool -pattern constant:color=1e38,0 4x4 2 --chnames Z,A --point:color=10.0,1.0 2,2 --deepen -o tinydeep.exr"
-    oiio:ColorSpace: "Linear"
     oiio:subimages: 1
     openexr:chunkCount: 4
     Pixel (0, 0): 0 samples 
diff --git a/testsuite/maketx/ref/out-macarm.txt b/testsuite/maketx/ref/out-macarm.txt
index c631384d36..fc26a43e20 100644
--- a/testsuite/maketx/ref/out-macarm.txt
+++ b/testsuite/maketx/ref/out-macarm.txt
@@ -315,7 +315,7 @@ nan.exr              :   64 x   64, 3 channel, half openexr
     textureformat: "Plain Texture"
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5"
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:SHA-1: "44B96A7C3AFBF8D7621E7C6453266E5DD1962D36"
     oiio:subimages: 1
     openexr:levelmode: 0
@@ -343,7 +343,7 @@ checker-exr.pdq      :  128 x  128, 4 channel, half openexr
     textureformat: "Plain Texture"
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     oiio:subimages: 1
     openexr:roundingmode: 0
@@ -435,7 +435,6 @@ bumpslope.exr        :   64 x   64, 6 channel, half openexr
     uvslopes_scale: 0
     wrapmodes: "black,black"
     oiio:AverageColor: "0.499779,-0.000457942,-4.17233e-05,0.00197116,0.00178894,3.45764e-05"
-    oiio:ColorSpace: "Linear"
     oiio:SHA-1: "49B533110A914CE89BE0B14753A6A4CC037C964F"
     oiio:subimages: 1
     openexr:roundingmode: 0
@@ -456,7 +455,6 @@ cdf.exr              :   64 x   64, 1 channel, half openexr
     textureformat: "Plain Texture"
     wrapmodes: "black,black"
     oiio:AverageColor: "0.499779"
-    oiio:ColorSpace: "Linear"
     oiio:SHA-1: "00DFB31D0260CC466CDCF9FE42446D4896E655FE"
     oiio:subimages: 1
     openexr:roundingmode: 0
@@ -488,7 +486,6 @@ bumpslope-cdf.exr    :   64 x   64, 6 channel, half openexr
     uvslopes_scale: 0
     wrapmodes: "black,black"
     oiio:AverageColor: "0.499779,-0.000457942,-4.17233e-05,0.00197116,0.00178894,3.45764e-05"
-    oiio:ColorSpace: "Linear"
     oiio:SHA-1: "49B533110A914CE89BE0B14753A6A4CC037C964F"
     oiio:subimages: 1
     openexr:roundingmode: 0
diff --git a/testsuite/maketx/ref/out.txt b/testsuite/maketx/ref/out.txt
index c9e0185d61..0c0090b4e9 100644
--- a/testsuite/maketx/ref/out.txt
+++ b/testsuite/maketx/ref/out.txt
@@ -315,7 +315,7 @@ nan.exr              :   64 x   64, 3 channel, half openexr
     textureformat: "Plain Texture"
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5"
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:SHA-1: "44B96A7C3AFBF8D7621E7C6453266E5DD1962D36"
     oiio:subimages: 1
     openexr:levelmode: 0
@@ -343,7 +343,7 @@ checker-exr.pdq      :  128 x  128, 4 channel, half openexr
     textureformat: "Plain Texture"
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     oiio:subimages: 1
     openexr:roundingmode: 0
@@ -435,7 +435,6 @@ bumpslope.exr        :   64 x   64, 6 channel, half openexr
     uvslopes_scale: 0
     wrapmodes: "black,black"
     oiio:AverageColor: "0.499779,-0.000457942,-4.17233e-05,0.00197116,0.00178894,3.45764e-05"
-    oiio:ColorSpace: "Linear"
     oiio:SHA-1: "49B533110A914CE89BE0B14753A6A4CC037C964F"
     oiio:subimages: 1
     openexr:roundingmode: 0
@@ -456,7 +455,6 @@ cdf.exr              :   64 x   64, 1 channel, half openexr
     textureformat: "Plain Texture"
     wrapmodes: "black,black"
     oiio:AverageColor: "0.499779"
-    oiio:ColorSpace: "Linear"
     oiio:SHA-1: "00DFB31D0260CC466CDCF9FE42446D4896E655FE"
     oiio:subimages: 1
     openexr:roundingmode: 0
@@ -488,7 +486,6 @@ bumpslope-cdf.exr    :   64 x   64, 6 channel, half openexr
     uvslopes_scale: 0
     wrapmodes: "black,black"
     oiio:AverageColor: "0.499779,-0.000457942,-4.17233e-05,0.00197116,0.00178894,3.45764e-05"
-    oiio:ColorSpace: "Linear"
     oiio:SHA-1: "49B533110A914CE89BE0B14753A6A4CC037C964F"
     oiio:subimages: 1
     openexr:roundingmode: 0
diff --git a/testsuite/oiiotool-attribs/ref/out-jpeg9d.txt b/testsuite/oiiotool-attribs/ref/out-jpeg9d.txt
index 67ca7c7f1a..76e6b10fd0 100644
--- a/testsuite/oiiotool-attribs/ref/out-jpeg9d.txt
+++ b/testsuite/oiiotool-attribs/ref/out-jpeg9d.txt
@@ -68,7 +68,7 @@ attrib2.exr          :   64 x   64, 3 channel, half openexr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimagename: "subimage00"
     oiio:subimages: 2
     openexr:chunkCount: 4
@@ -81,7 +81,7 @@ attrib2.exr          :   64 x   64, 3 channel, half openexr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimagename: "subimage01"
     oiio:subimages: 2
     openexr:chunkCount: 4
@@ -96,7 +96,7 @@ attrib0.exr          :   64 x   64, 3 channel, half openexr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimagename: "subimage00"
     oiio:subimages: 2
     openexr:chunkCount: 4
@@ -108,7 +108,7 @@ attrib0.exr          :   64 x   64, 3 channel, half openexr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimagename: "subimage01"
     oiio:subimages: 2
     openexr:chunkCount: 4
diff --git a/testsuite/oiiotool-attribs/ref/out.txt b/testsuite/oiiotool-attribs/ref/out.txt
index cc3ac3cc76..10dcddfe76 100644
--- a/testsuite/oiiotool-attribs/ref/out.txt
+++ b/testsuite/oiiotool-attribs/ref/out.txt
@@ -68,7 +68,7 @@ attrib2.exr          :   64 x   64, 3 channel, half openexr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimagename: "subimage00"
     oiio:subimages: 2
     openexr:chunkCount: 4
@@ -81,7 +81,7 @@ attrib2.exr          :   64 x   64, 3 channel, half openexr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimagename: "subimage01"
     oiio:subimages: 2
     openexr:chunkCount: 4
@@ -96,7 +96,7 @@ attrib0.exr          :   64 x   64, 3 channel, half openexr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimagename: "subimage00"
     oiio:subimages: 2
     openexr:chunkCount: 4
@@ -108,7 +108,7 @@ attrib0.exr          :   64 x   64, 3 channel, half openexr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimagename: "subimage01"
     oiio:subimages: 2
     openexr:chunkCount: 4
diff --git a/testsuite/oiiotool-copy/ref/out.txt b/testsuite/oiiotool-copy/ref/out.txt
index 7914eda674..1294d0bd3e 100644
--- a/testsuite/oiiotool-copy/ref/out.txt
+++ b/testsuite/oiiotool-copy/ref/out.txt
@@ -13,7 +13,7 @@ allhalf.exr          :   38 x   38, 5 channel, half openexr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Reading rgbahalf-zfloat.exr
 rgbahalf-zfloat.exr  :   38 x   38, 5 channel, half/half/half/half/float openexr
@@ -26,7 +26,7 @@ rgbahalf-zfloat.exr  :   38 x   38, 5 channel, half/half/half/half/float openexr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 explicit -d uint save result: 
 uint8.tif            :  128 x  128, 3 channel, uint8 tiff
@@ -66,7 +66,7 @@ chname.exr           :   38 x   38, 5 channel, float openexr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Reading green.exr
 green.exr            :   64 x   64, 3 channel, half openexr
@@ -76,7 +76,7 @@ green.exr            :   64 x   64, 3 channel, half openexr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Reading greenmeta.exr
 greenmeta.exr        :   64 x   64, 3 channel, half openexr
@@ -89,7 +89,7 @@ greenmeta.exr        :   64 x   64, 3 channel, half openexr
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
     weight: 20.5
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Reading nometamerge.exr
 nometamerge.exr      :   64 x   64, 6 channel, float openexr
@@ -100,7 +100,7 @@ nometamerge.exr      :   64 x   64, 6 channel, float openexr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Reading metamerge.exr
 metamerge.exr        :   64 x   64, 6 channel, float openexr
@@ -112,7 +112,7 @@ metamerge.exr        :   64 x   64, 6 channel, float openexr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Testing -o with no image
 oiiotool WARNING: -o : out.tif did not have any current image to output.
diff --git a/testsuite/oiiotool-deep/ref/out-fmt6.txt b/testsuite/oiiotool-deep/ref/out-fmt6.txt
index 2562bebdd4..2ae408b557 100644
--- a/testsuite/oiiotool-deep/ref/out-fmt6.txt
+++ b/testsuite/oiiotool-deep/ref/out-fmt6.txt
@@ -12,7 +12,6 @@ allhalf.exr          :  160 x  120, 2 channel, deep half openexr
     version: 1
     worldToCamera: 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, -1, 0, 1.5, 0, 4, 1
     worldToNDC: 2.41421, 0, 0, 0, 0, 3.21895, 0, 0, 0, 0, -1.00671, -1, 3.62132, 0, 3.92617, 4
-    oiio:ColorSpace: "Linear"
     oiio:subimages: 1
     openexr:chunkCount: 6
     Stats Min: 0.011902 3.031250 (float)
@@ -56,7 +55,6 @@ swaptypes.exr        :  160 x  120, 2 channel, deep float/half openexr
     version: 1
     worldToCamera: 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, -1, 0, 1.5, 0, 4, 1
     worldToNDC: 2.41421, 0, 0, 0, 0, 3.21895, 0, 0, 0, 0, -1.00671, -1, 3.62132, 0, 3.92617, 4
-    oiio:ColorSpace: "Linear"
     oiio:subimages: 1
     openexr:chunkCount: 6
     Stats Min: 0.011902 3.031250 (float)
@@ -95,7 +93,6 @@ tinydeep.exr         :    4 x    4, 2 channel, deep float openexr
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
     version: 1
-    oiio:ColorSpace: "Linear"
     oiio:subimages: 1
     openexr:chunkCount: 4
     Pixel (0, 0): 0 samples 
diff --git a/testsuite/oiiotool-deep/ref/out.txt b/testsuite/oiiotool-deep/ref/out.txt
index 10ba1bf4ec..e0c5543496 100644
--- a/testsuite/oiiotool-deep/ref/out.txt
+++ b/testsuite/oiiotool-deep/ref/out.txt
@@ -12,7 +12,6 @@ allhalf.exr          :  160 x  120, 2 channel, deep half openexr
     version: 1
     worldToCamera: 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, -1, 0, 1.5, 0, 4, 1
     worldToNDC: 2.41421, 0, 0, 0, 0, 3.21895, 0, 0, 0, 0, -1.00671, -1, 3.62132, 0, 3.92617, 4
-    oiio:ColorSpace: "Linear"
     oiio:subimages: 1
     openexr:chunkCount: 6
     Stats Min: 0.011902 3.031250 (float)
@@ -56,7 +55,6 @@ swaptypes.exr        :  160 x  120, 2 channel, deep float/half openexr
     version: 1
     worldToCamera: 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, -1, 0, 1.5, 0, 4, 1
     worldToNDC: 2.41421, 0, 0, 0, 0, 3.21895, 0, 0, 0, 0, -1.00671, -1, 3.62132, 0, 3.92617, 4
-    oiio:ColorSpace: "Linear"
     oiio:subimages: 1
     openexr:chunkCount: 6
     Stats Min: 0.011902 3.031250 (float)
@@ -95,7 +93,6 @@ tinydeep.exr         :    4 x    4, 2 channel, deep float openexr
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
     version: 1
-    oiio:ColorSpace: "Linear"
     oiio:subimages: 1
     openexr:chunkCount: 4
     Pixel (0, 0): 0 samples 
diff --git a/testsuite/oiiotool-fixnan/ref/out.txt b/testsuite/oiiotool-fixnan/ref/out.txt
index d75c493c2c..1a4d0dc83e 100644
--- a/testsuite/oiiotool-fixnan/ref/out.txt
+++ b/testsuite/oiiotool-fixnan/ref/out.txt
@@ -9,7 +9,7 @@ src/bad.exr          :   64 x   64, 3 channel, half openexr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
     Stats Min: 0.000000 0.000000 0.000000 (float)
     Stats Max: 1.000000 1.000000 1.000000 (float)
@@ -28,7 +28,7 @@ black.exr            :   64 x   64, 3 channel, half openexr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
     Stats Min: 0.000000 0.000000 0.000000 (float)
     Stats Max: 1.000000 1.000000 1.000000 (float)
@@ -47,7 +47,7 @@ box3.exr             :   64 x   64, 3 channel, half openexr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
     Stats Min: 0.000000 0.000000 0.000000 (float)
     Stats Max: 1.000000 1.000000 1.000000 (float)
diff --git a/testsuite/oiiotool-maketx/ref/out-macarm.txt b/testsuite/oiiotool-maketx/ref/out-macarm.txt
index bc82b491fc..a41942f18c 100644
--- a/testsuite/oiiotool-maketx/ref/out-macarm.txt
+++ b/testsuite/oiiotool-maketx/ref/out-macarm.txt
@@ -277,7 +277,7 @@ nan.exr              :   64 x   64, 3 channel, half openexr
     uvslopes_scale: 0
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5"
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:SHA-1: "44B96A7C3AFBF8D7621E7C6453266E5DD1962D36"
     oiio:subimages: 1
     openexr:levelmode: 0
@@ -306,7 +306,7 @@ bigval.exr           :    2 x    2, 3 channel, half openexr
     uvslopes_scale: 0
     wrapmodes: "black,black"
     oiio:AverageColor: "1e+06,1e+06,1e+06"
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:ConstantColor: "1e+06,1e+06,1e+06"
     oiio:SHA-1: "E3D97EED7EE68F1885685F312DDD7D8773C29862"
     oiio:subimages: 1
@@ -349,7 +349,7 @@ checker-exr.pdq      :  128 x  128, 4 channel, half openexr
     uvslopes_scale: 0
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     oiio:subimages: 1
     openexr:roundingmode: 0
@@ -598,7 +598,6 @@ bumpslope-cdf.exr    :   64 x   64, 6 channel, half openexr
     uvslopes_scale: 0
     wrapmodes: "black,black"
     oiio:AverageColor: "0.499779,-0.000457942,-4.17233e-05,0.00197116,0.00178894,3.45764e-05"
-    oiio:ColorSpace: "Linear"
     oiio:SHA-1: "49B533110A914CE89BE0B14753A6A4CC037C964F"
     oiio:subimages: 1
     openexr:roundingmode: 0
diff --git a/testsuite/oiiotool-maketx/ref/out-rhel7.txt b/testsuite/oiiotool-maketx/ref/out-rhel7.txt
index 4b26077a2d..c3d6e1505d 100644
--- a/testsuite/oiiotool-maketx/ref/out-rhel7.txt
+++ b/testsuite/oiiotool-maketx/ref/out-rhel7.txt
@@ -277,7 +277,7 @@ nan.exr              :   64 x   64, 3 channel, half openexr
     uvslopes_scale: 0
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5"
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:SHA-1: "44B96A7C3AFBF8D7621E7C6453266E5DD1962D36"
     openexr:levelmode: 0
     Stats Min: 0.000000 0.000000 0.000000 (float)
@@ -305,7 +305,7 @@ checker-exr.pdq      :  128 x  128, 4 channel, half openexr
     uvslopes_scale: 0
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     openexr:roundingmode: 0
 Reading grid.tx
@@ -553,7 +553,6 @@ bumpslope-cdf.exr    :   64 x   64, 6 channel, half openexr
     uvslopes_scale: 0
     wrapmodes: "black,black"
     oiio:AverageColor: "0.499779,-0.000457942,-4.17233e-05,0.00197116,0.00178894,3.45764e-05"
-    oiio:ColorSpace: "Linear"
     oiio:SHA-1: "49B533110A914CE89BE0B14753A6A4CC037C964F"
     oiio:subimages: 1
     openexr:roundingmode: 0
diff --git a/testsuite/oiiotool-maketx/ref/out-win.txt b/testsuite/oiiotool-maketx/ref/out-win.txt
index 206280cfab..aac3f40417 100644
--- a/testsuite/oiiotool-maketx/ref/out-win.txt
+++ b/testsuite/oiiotool-maketx/ref/out-win.txt
@@ -277,7 +277,7 @@ nan.exr              :   64 x   64, 3 channel, half openexr
     uvslopes_scale: 0
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5"
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:SHA-1: "44B96A7C3AFBF8D7621E7C6453266E5DD1962D36"
     oiio:subimages: 1
     openexr:levelmode: 0
@@ -306,7 +306,7 @@ bigval.exr           :    2 x    2, 3 channel, half openexr
     uvslopes_scale: 0
     wrapmodes: "black,black"
     oiio:AverageColor: "1e+06,1e+06,1e+06"
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:ConstantColor: "1e+06,1e+06,1e+06"
     oiio:SHA-1: "E3D97EED7EE68F1885685F312DDD7D8773C29862"
     oiio:subimages: 1
@@ -349,7 +349,7 @@ checker-exr.pdq      :  128 x  128, 4 channel, half openexr
     uvslopes_scale: 0
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     oiio:subimages: 1
     openexr:roundingmode: 0
@@ -598,7 +598,6 @@ bumpslope-cdf.exr    :   64 x   64, 6 channel, half openexr
     uvslopes_scale: 0
     wrapmodes: "black,black"
     oiio:AverageColor: "0.499779,-0.000457942,-4.17233e-05,0.00197116,0.00178894,3.45764e-05"
-    oiio:ColorSpace: "Linear"
     oiio:SHA-1: "49B533110A914CE89BE0B14753A6A4CC037C964F"
     oiio:subimages: 1
     openexr:roundingmode: 0
diff --git a/testsuite/oiiotool-maketx/ref/out.txt b/testsuite/oiiotool-maketx/ref/out.txt
index 6434a8db4c..2b2884e703 100644
--- a/testsuite/oiiotool-maketx/ref/out.txt
+++ b/testsuite/oiiotool-maketx/ref/out.txt
@@ -277,7 +277,7 @@ nan.exr              :   64 x   64, 3 channel, half openexr
     uvslopes_scale: 0
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5"
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:SHA-1: "44B96A7C3AFBF8D7621E7C6453266E5DD1962D36"
     oiio:subimages: 1
     openexr:levelmode: 0
@@ -306,7 +306,7 @@ bigval.exr           :    2 x    2, 3 channel, half openexr
     uvslopes_scale: 0
     wrapmodes: "black,black"
     oiio:AverageColor: "1e+06,1e+06,1e+06"
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:ConstantColor: "1e+06,1e+06,1e+06"
     oiio:SHA-1: "E3D97EED7EE68F1885685F312DDD7D8773C29862"
     oiio:subimages: 1
@@ -349,7 +349,7 @@ checker-exr.pdq      :  128 x  128, 4 channel, half openexr
     uvslopes_scale: 0
     wrapmodes: "black,black"
     oiio:AverageColor: "0.5,0.5,0.5,1"
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:SHA-1: "D924CA144A02479D1507F5910F5FC8F51EF78765"
     oiio:subimages: 1
     openexr:roundingmode: 0
@@ -598,7 +598,6 @@ bumpslope-cdf.exr    :   64 x   64, 6 channel, half openexr
     uvslopes_scale: 0
     wrapmodes: "black,black"
     oiio:AverageColor: "0.499779,-0.000457942,-4.17233e-05,0.00197116,0.00178894,3.45764e-05"
-    oiio:ColorSpace: "Linear"
     oiio:SHA-1: "49B533110A914CE89BE0B14753A6A4CC037C964F"
     oiio:subimages: 1
     openexr:roundingmode: 0
diff --git a/testsuite/oiiotool-subimage/ref/out.txt b/testsuite/oiiotool-subimage/ref/out.txt
index 2964d720c5..773bdac31f 100644
--- a/testsuite/oiiotool-subimage/ref/out.txt
+++ b/testsuite/oiiotool-subimage/ref/out.txt
@@ -10,7 +10,7 @@ gpgr.exr             :   64 x   64, 3 channel, half openexr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimagename: "layerA"
     oiio:subimages: 4
     openexr:chunkCount: 4
@@ -23,7 +23,7 @@ gpgr.exr             :   64 x   64, 3 channel, half openexr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimagename: "layerB"
     oiio:subimages: 4
     openexr:chunkCount: 4
@@ -36,7 +36,7 @@ gpgr.exr             :   64 x   64, 3 channel, half openexr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimagename: "layerC"
     oiio:subimages: 4
     openexr:chunkCount: 4
@@ -49,7 +49,7 @@ gpgr.exr             :   64 x   64, 3 channel, half openexr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimagename: "layerD"
     oiio:subimages: 4
     openexr:chunkCount: 4
diff --git a/testsuite/oiiotool/ref/out.txt b/testsuite/oiiotool/ref/out.txt
index e5532a1f56..9e23ae30c9 100644
--- a/testsuite/oiiotool/ref/out.txt
+++ b/testsuite/oiiotool/ref/out.txt
@@ -40,7 +40,7 @@ add_rgb_rgba.exr     :   64 x   64, 4 channel, float openexr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 dumpdata:
 dump.exr             :    2 x    2, 3 channel, half openexr
diff --git a/testsuite/openexr-chroma/ref/out.txt b/testsuite/openexr-chroma/ref/out.txt
index 1a7b552c71..bb656fa2d1 100644
--- a/testsuite/openexr-chroma/ref/out.txt
+++ b/testsuite/openexr-chroma/ref/out.txt
@@ -7,7 +7,7 @@ Reading ../openexr-images/Chromaticities/Rec709.exr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Comparing "../openexr-images/Chromaticities/Rec709.exr" and "Rec709.exr"
 PASS
@@ -21,7 +21,7 @@ Reading ../openexr-images/Chromaticities/XYZ.exr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Comparing "../openexr-images/Chromaticities/XYZ.exr" and "XYZ.exr"
 PASS
@@ -35,7 +35,6 @@ Reading ../openexr-images/LuminanceChroma/Garden.exr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
     oiio:subimages: 1
 Comparing "../openexr-images/LuminanceChroma/Garden.exr" and "Garden.exr"
 PASS
diff --git a/testsuite/openexr-decreasingy/ref/out.txt b/testsuite/openexr-decreasingy/ref/out.txt
index 22f8254a91..145bb58c03 100644
--- a/testsuite/openexr-decreasingy/ref/out.txt
+++ b/testsuite/openexr-decreasingy/ref/out.txt
@@ -9,7 +9,7 @@ increasingY-resize.exr : 4080 x 3072, 3 channel, half openexr
     screenWindowWidth: 1
     XResolution: 72
     YResolution: 72
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Reading increasingY-copy.exr
 increasingY-copy.exr : 4080 x 3072, 3 channel, half openexr
@@ -22,7 +22,7 @@ increasingY-copy.exr : 4080 x 3072, 3 channel, half openexr
     screenWindowWidth: 1
     XResolution: 72
     YResolution: 72
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Reading decreasingY-resize.exr
 decreasingY-resize.exr : 4080 x 3072, 3 channel, half openexr
@@ -35,7 +35,7 @@ decreasingY-resize.exr : 4080 x 3072, 3 channel, half openexr
     screenWindowWidth: 1
     XResolution: 72
     YResolution: 72
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Reading decreasingY-copy.exr
 decreasingY-copy.exr : 4080 x 3072, 3 channel, half openexr
@@ -48,7 +48,7 @@ decreasingY-copy.exr : 4080 x 3072, 3 channel, half openexr
     screenWindowWidth: 1
     XResolution: 72
     YResolution: 72
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Comparing "increasingY-copy.exr" and "decreasingY-copy.exr"
 PASS
diff --git a/testsuite/openexr-luminance-chroma/ref/out-macarm.txt b/testsuite/openexr-luminance-chroma/ref/out-macarm.txt
index f192fc5a19..4bac7d872a 100644
--- a/testsuite/openexr-luminance-chroma/ref/out-macarm.txt
+++ b/testsuite/openexr-luminance-chroma/ref/out-macarm.txt
@@ -7,7 +7,7 @@ Reading ../openexr-images/Chromaticities/Rec709_YC.exr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
     openexr:luminancechroma: 1
 Comparing "../openexr-images/Chromaticities/Rec709_YC.exr" and "Rec709_YC.exr"
@@ -22,7 +22,7 @@ Reading ../openexr-images/Chromaticities/XYZ_YC.exr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
     openexr:luminancechroma: 1
 Comparing "../openexr-images/Chromaticities/XYZ_YC.exr" and "XYZ_YC.exr"
@@ -37,7 +37,7 @@ Reading ../openexr-images/LuminanceChroma/CrissyField.exr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
     openexr:luminancechroma: 1
 Comparing "../openexr-images/LuminanceChroma/CrissyField.exr" and "CrissyField.exr"
@@ -51,7 +51,7 @@ Reading ../openexr-images/LuminanceChroma/Flowers.exr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
     openexr:luminancechroma: 1
 Comparing "../openexr-images/LuminanceChroma/Flowers.exr" and "Flowers.exr"
@@ -65,7 +65,7 @@ Reading ../openexr-images/LuminanceChroma/MtTamNorth.exr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
     openexr:luminancechroma: 1
 Comparing "../openexr-images/LuminanceChroma/MtTamNorth.exr" and "MtTamNorth.exr"
@@ -79,7 +79,7 @@ Reading ../openexr-images/LuminanceChroma/StarField.exr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
     openexr:luminancechroma: 1
 Comparing "../openexr-images/LuminanceChroma/StarField.exr" and "StarField.exr"
diff --git a/testsuite/openexr-luminance-chroma/ref/out.txt b/testsuite/openexr-luminance-chroma/ref/out.txt
index 90406fb308..9bb6630d48 100644
--- a/testsuite/openexr-luminance-chroma/ref/out.txt
+++ b/testsuite/openexr-luminance-chroma/ref/out.txt
@@ -7,7 +7,7 @@ Reading ../openexr-images/Chromaticities/Rec709_YC.exr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
     openexr:luminancechroma: 1
 Comparing "../openexr-images/Chromaticities/Rec709_YC.exr" and "Rec709_YC.exr"
@@ -22,7 +22,7 @@ Reading ../openexr-images/Chromaticities/XYZ_YC.exr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
     openexr:luminancechroma: 1
 Comparing "../openexr-images/Chromaticities/XYZ_YC.exr" and "XYZ_YC.exr"
@@ -37,7 +37,7 @@ Reading ../openexr-images/LuminanceChroma/CrissyField.exr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
     openexr:luminancechroma: 1
 Comparing "../openexr-images/LuminanceChroma/CrissyField.exr" and "CrissyField.exr"
@@ -51,7 +51,7 @@ Reading ../openexr-images/LuminanceChroma/Flowers.exr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
     openexr:luminancechroma: 1
 Comparing "../openexr-images/LuminanceChroma/Flowers.exr" and "Flowers.exr"
@@ -65,7 +65,7 @@ Reading ../openexr-images/LuminanceChroma/MtTamNorth.exr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
     openexr:luminancechroma: 1
 Comparing "../openexr-images/LuminanceChroma/MtTamNorth.exr" and "MtTamNorth.exr"
@@ -79,7 +79,7 @@ Reading ../openexr-images/LuminanceChroma/StarField.exr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
     openexr:luminancechroma: 1
 Comparing "../openexr-images/LuminanceChroma/StarField.exr" and "StarField.exr"
diff --git a/testsuite/openexr-multires/ref/out.txt b/testsuite/openexr-multires/ref/out.txt
index 5e25a0e7bd..b891b21044 100644
--- a/testsuite/openexr-multires/ref/out.txt
+++ b/testsuite/openexr-multires/ref/out.txt
@@ -12,7 +12,7 @@ Reading ../openexr-images/MultiResolution/Bonita.exr
     screenWindowWidth: 1
     textureformat: "Plain Texture"
     wrapmodes: "clamp,clamp"
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
     openexr:roundingmode: 0
 Comparing "../openexr-images/MultiResolution/Bonita.exr" and "Bonita.exr"
@@ -31,7 +31,7 @@ Reading ../openexr-images/MultiResolution/ColorCodedLevels.exr
     screenWindowWidth: 1
     textureformat: "Plain Texture"
     wrapmodes: "periodic,periodic"
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
     openexr:roundingmode: 0
 Comparing "../openexr-images/MultiResolution/ColorCodedLevels.exr" and "ColorCodedLevels.exr"
@@ -50,7 +50,7 @@ Reading ../openexr-images/MultiResolution/KernerEnvCube.exr
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
     textureformat: "CubeFace Environment"
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:sampleborder: 1
     oiio:subimages: 1
     openexr:roundingmode: 0
@@ -68,7 +68,7 @@ Reading ../openexr-images/MultiResolution/KernerEnvLatLong.exr
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
     textureformat: "LatLong Environment"
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:sampleborder: 1
     oiio:subimages: 1
     oiio:updirection: "y"
@@ -88,7 +88,7 @@ Reading ../openexr-images/MultiResolution/MirrorPattern.exr
     screenWindowWidth: 1
     textureformat: "Plain Texture"
     wrapmodes: "mirror,mirror"
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
     openexr:roundingmode: 0
 Comparing "../openexr-images/MultiResolution/MirrorPattern.exr" and "MirrorPattern.exr"
@@ -107,7 +107,7 @@ Reading ../openexr-images/MultiResolution/OrientationCube.exr
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
     textureformat: "CubeFace Environment"
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:sampleborder: 1
     oiio:subimages: 1
     openexr:roundingmode: 0
@@ -125,7 +125,7 @@ Reading ../openexr-images/MultiResolution/OrientationLatLong.exr
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
     textureformat: "LatLong Environment"
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:sampleborder: 1
     oiio:subimages: 1
     oiio:updirection: "y"
@@ -145,7 +145,7 @@ Reading ../openexr-images/MultiResolution/PeriodicPattern.exr
     screenWindowWidth: 1
     textureformat: "Plain Texture"
     wrapmodes: "periodic,periodic"
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
     openexr:roundingmode: 0
 Comparing "../openexr-images/MultiResolution/PeriodicPattern.exr" and "PeriodicPattern.exr"
@@ -164,7 +164,7 @@ Reading ../openexr-images/MultiResolution/StageEnvCube.exr
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
     textureformat: "CubeFace Environment"
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:sampleborder: 1
     oiio:subimages: 1
     openexr:roundingmode: 0
@@ -182,7 +182,7 @@ Reading ../openexr-images/MultiResolution/StageEnvLatLong.exr
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
     textureformat: "LatLong Environment"
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:sampleborder: 1
     oiio:subimages: 1
     oiio:updirection: "y"
@@ -203,7 +203,7 @@ Reading ../openexr-images/MultiResolution/WavyLinesCube.exr
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
     textureformat: "CubeFace Environment"
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:sampleborder: 1
     oiio:subimages: 1
     openexr:roundingmode: 0
@@ -221,7 +221,7 @@ Reading ../openexr-images/MultiResolution/WavyLinesLatLong.exr
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
     textureformat: "LatLong Environment"
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:sampleborder: 1
     oiio:subimages: 1
     oiio:updirection: "y"
@@ -237,7 +237,7 @@ Reading ../openexr-images/MultiResolution/WavyLinesSphere.exr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Comparing "../openexr-images/MultiResolution/WavyLinesSphere.exr" and "WavyLinesSphere.exr"
 PASS
@@ -254,7 +254,7 @@ Reading ../openexr-images/MultiView/Adjuster.exr
     screenWindowWidth: 1
     XResolution: 100
     YResolution: 100
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Comparing "../openexr-images/MultiView/Adjuster.exr" and "Adjuster.exr"
 PASS
@@ -270,7 +270,7 @@ Reading ../openexr-images/MultiView/Balls.exr
     screenWindowWidth: 1
     XResolution: 100
     YResolution: 100
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Comparing "../openexr-images/MultiView/Balls.exr" and "Balls.exr"
 PASS
@@ -290,7 +290,6 @@ Reading ../openexr-images/MultiView/Fog.exr
     screenWindowWidth: 1
     XResolution: 100
     YResolution: 100
-    oiio:ColorSpace: "Linear"
     oiio:subimages: 1
 Comparing "../openexr-images/MultiView/Fog.exr" and "Fog.exr"
 PASS
@@ -312,7 +311,7 @@ Reading ../openexr-images/MultiView/Impact.exr
     wrapmodes: "clamp,clamp"
     XResolution: 100
     YResolution: 100
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
     openexr:roundingmode: 0
 Comparing "../openexr-images/MultiView/Impact.exr" and "Impact.exr"
@@ -332,7 +331,7 @@ Reading ../openexr-images/MultiView/LosPadres.exr
     screenWindowWidth: 1
     XResolution: 100
     YResolution: 100
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Comparing "../openexr-images/MultiView/LosPadres.exr" and "LosPadres.exr"
 PASS
diff --git a/testsuite/openexr-suite/ref/out.txt b/testsuite/openexr-suite/ref/out.txt
index 95bb532cd8..c8650e6801 100644
--- a/testsuite/openexr-suite/ref/out.txt
+++ b/testsuite/openexr-suite/ref/out.txt
@@ -14,7 +14,7 @@ Reading ../openexr-images/ScanLines/Blobbies.exr
     screenWindowWidth: 1
     utcOffset: 28800
     whiteLuminance: 50
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Comparing "../openexr-images/ScanLines/Blobbies.exr" and "Blobbies.exr"
 PASS
@@ -31,7 +31,7 @@ Reading ../openexr-images/ScanLines/CandleGlass.exr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Comparing "../openexr-images/ScanLines/CandleGlass.exr" and "CandleGlass.exr"
 PASS
@@ -44,7 +44,7 @@ Reading ../openexr-images/ScanLines/Cannon.exr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Comparing "../openexr-images/ScanLines/Cannon.exr" and "Cannon.exr"
 PASS
@@ -56,7 +56,7 @@ Reading ../openexr-images/ScanLines/Desk.exr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Comparing "../openexr-images/ScanLines/Desk.exr" and "Desk.exr"
 PASS
@@ -75,7 +75,7 @@ Reading ../openexr-images/ScanLines/MtTamWest.exr
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
     utcOffset: 25200
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Comparing "../openexr-images/ScanLines/MtTamWest.exr" and "MtTamWest.exr"
 PASS
@@ -92,7 +92,7 @@ Reading ../openexr-images/ScanLines/PrismsLenses.exr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Comparing "../openexr-images/ScanLines/PrismsLenses.exr" and "PrismsLenses.exr"
 PASS
@@ -107,7 +107,7 @@ Reading ../openexr-images/ScanLines/StillLife.exr
     screenWindowCenter: 0, 0
     screenWindowWidth: 0.45
     utcOffset: 25200
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Comparing "../openexr-images/ScanLines/StillLife.exr" and "StillLife.exr"
 PASS
@@ -125,7 +125,7 @@ Reading ../openexr-images/ScanLines/Tree.exr
     screenWindowWidth: 0.48
     utcOffset: 25200
     whiteLuminance: 621
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Comparing "../openexr-images/ScanLines/Tree.exr" and "Tree.exr"
 PASS
@@ -137,7 +137,7 @@ Reading ../openexr-images/TestImages/AllHalfValues.exr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Comparing "../openexr-images/TestImages/AllHalfValues.exr" and "AllHalfValues.exr"
 PASS
@@ -149,7 +149,7 @@ Reading ../openexr-images/TestImages/BrightRings.exr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Comparing "../openexr-images/TestImages/BrightRings.exr" and "BrightRings.exr"
 PASS
@@ -161,7 +161,7 @@ Reading ../openexr-images/TestImages/BrightRingsNanInf.exr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Comparing "../openexr-images/TestImages/BrightRingsNanInf.exr" and "BrightRingsNanInf.exr"
 PASS
@@ -173,7 +173,7 @@ Reading ../openexr-images/TestImages/GammaChart.exr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Comparing "../openexr-images/TestImages/GammaChart.exr" and "GammaChart.exr"
 PASS
@@ -185,7 +185,6 @@ Reading ../openexr-images/TestImages/GrayRampsDiagonal.exr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
     oiio:subimages: 1
 Comparing "../openexr-images/TestImages/GrayRampsDiagonal.exr" and "GrayRampsDiagonal.exr"
 PASS
@@ -197,7 +196,6 @@ Reading ../openexr-images/TestImages/GrayRampsHorizontal.exr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
     oiio:subimages: 1
 Comparing "../openexr-images/TestImages/GrayRampsHorizontal.exr" and "GrayRampsHorizontal.exr"
 PASS
@@ -209,7 +207,7 @@ Reading ../openexr-images/TestImages/RgbRampsDiagonal.exr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Comparing "../openexr-images/TestImages/RgbRampsDiagonal.exr" and "RgbRampsDiagonal.exr"
 PASS
@@ -221,7 +219,7 @@ Reading ../openexr-images/TestImages/SquaresSwirls.exr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Comparing "../openexr-images/TestImages/SquaresSwirls.exr" and "SquaresSwirls.exr"
 PASS
@@ -234,7 +232,7 @@ Reading ../openexr-images/TestImages/WideColorGamut.exr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Comparing "../openexr-images/TestImages/WideColorGamut.exr" and "WideColorGamut.exr"
 PASS
@@ -246,7 +244,6 @@ Reading ../openexr-images/TestImages/WideFloatRange.exr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
     oiio:subimages: 1
 Comparing "../openexr-images/TestImages/WideFloatRange.exr" and "WideFloatRange.exr"
 PASS
@@ -270,7 +267,7 @@ Reading ../openexr-images/Tiles/GoldenGate.exr
     screenWindowCenter: 0, 0
     screenWindowWidth: 1.15
     utcOffset: 28800
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Comparing "../openexr-images/Tiles/GoldenGate.exr" and "GoldenGate.exr"
 PASS
@@ -285,7 +282,7 @@ Reading ../openexr-images/Tiles/Ocean.exr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Comparing "../openexr-images/Tiles/Ocean.exr" and "Ocean.exr"
 PASS
@@ -306,7 +303,7 @@ Reading ../openexr-images/Tiles/Spirals.exr
     screenWindowWidth: 1
     utcOffset: 28800
     whiteLuminance: 90
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Comparing "../openexr-images/Tiles/Spirals.exr" and "Spirals.exr"
 PASS
@@ -323,7 +320,7 @@ Reading ../openexr-images/Beachball/singlepart.0001.exr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimagename: "rgba"
     oiio:subimages: 1
 Comparing "../openexr-images/Beachball/singlepart.0001.exr" and "singlepart.0001.exr"
diff --git a/testsuite/openexr-v2/ref/out.txt b/testsuite/openexr-v2/ref/out.txt
index a2c3ed96b4..2e9772be95 100644
--- a/testsuite/openexr-v2/ref/out.txt
+++ b/testsuite/openexr-v2/ref/out.txt
@@ -15,7 +15,7 @@ Reading ../openexr-images/v2/Stereo/composited.exr
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
     view: "left"
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimagename: "rgba.left"
     oiio:subimages: 4
     openexr:chunkCount: 1078
@@ -32,7 +32,6 @@ Reading ../openexr-images/v2/Stereo/composited.exr
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
     view: "left"
-    oiio:ColorSpace: "Linear"
     oiio:subimagename: "depth.left"
     oiio:subimages: 4
     openexr:chunkCount: 1078
@@ -49,7 +48,7 @@ Reading ../openexr-images/v2/Stereo/composited.exr
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
     view: "right"
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimagename: "rgba.right"
     oiio:subimages: 4
     openexr:chunkCount: 1078
@@ -66,7 +65,6 @@ Reading ../openexr-images/v2/Stereo/composited.exr
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
     view: "right"
-    oiio:ColorSpace: "Linear"
     oiio:subimagename: "depth.right"
     oiio:subimages: 4
     openexr:chunkCount: 1078
@@ -99,7 +97,7 @@ Reading ../openexr-images/v2/Stereo/Balls.exr
     screenWindowWidth: 1
     version: 1
     view: "left"
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimagename: "rgba.left"
     oiio:subimages: 2
     openexr:chunkCount: 761
@@ -117,7 +115,7 @@ Reading ../openexr-images/v2/Stereo/Balls.exr
     screenWindowWidth: 1
     version: 1
     view: "right"
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimagename: "rgba.right"
     oiio:subimages: 2
     openexr:chunkCount: 761
@@ -158,7 +156,7 @@ Reading ../openexr-images/v2/Stereo/Leaves.exr
     screenWindowWidth: 1
     version: 1
     view: "left"
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimagename: "rgba.left"
     oiio:subimages: 2
     openexr:chunkCount: 1080
@@ -173,7 +171,7 @@ Reading ../openexr-images/v2/Stereo/Leaves.exr
     screenWindowWidth: 1
     version: 1
     view: "right"
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimagename: "rgba.right"
     oiio:subimages: 2
     openexr:chunkCount: 1080
@@ -215,7 +213,7 @@ Reading ../openexr-images/Beachball/multipart.0001.exr
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
     view: "right"
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimagename: "rgba_right"
     oiio:subimages: 10
     openexr:chunkCount: 876
@@ -231,7 +229,6 @@ Reading ../openexr-images/Beachball/multipart.0001.exr
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
     view: "left"
-    oiio:ColorSpace: "Linear"
     oiio:subimagename: "depth_left"
     oiio:subimages: 10
     openexr:chunkCount: 876
@@ -247,7 +244,6 @@ Reading ../openexr-images/Beachball/multipart.0001.exr
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
     view: "left"
-    oiio:ColorSpace: "Linear"
     oiio:subimagename: "forward_left"
     oiio:subimages: 10
     openexr:chunkCount: 876
@@ -263,7 +259,6 @@ Reading ../openexr-images/Beachball/multipart.0001.exr
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
     view: "left"
-    oiio:ColorSpace: "Linear"
     oiio:subimagename: "whitebarmask_left"
     oiio:subimages: 10
     openexr:chunkCount: 769
@@ -279,7 +274,7 @@ Reading ../openexr-images/Beachball/multipart.0001.exr
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
     view: "left"
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimagename: "rgba_left"
     oiio:subimages: 10
     openexr:chunkCount: 876
@@ -295,7 +290,6 @@ Reading ../openexr-images/Beachball/multipart.0001.exr
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
     view: "right"
-    oiio:ColorSpace: "Linear"
     oiio:subimagename: "depth_right"
     oiio:subimages: 10
     openexr:chunkCount: 876
@@ -311,7 +305,6 @@ Reading ../openexr-images/Beachball/multipart.0001.exr
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
     view: "right"
-    oiio:ColorSpace: "Linear"
     oiio:subimagename: "forward_right"
     oiio:subimages: 10
     openexr:chunkCount: 876
@@ -326,7 +319,6 @@ Reading ../openexr-images/Beachball/multipart.0001.exr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
     oiio:subimagename: "disparityL"
     oiio:subimages: 10
     openexr:chunkCount: 876
@@ -341,7 +333,6 @@ Reading ../openexr-images/Beachball/multipart.0001.exr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
     oiio:subimagename: "disparityR"
     oiio:subimages: 10
     openexr:chunkCount: 876
@@ -357,7 +348,6 @@ Reading ../openexr-images/Beachball/multipart.0001.exr
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
     view: "right"
-    oiio:ColorSpace: "Linear"
     oiio:subimagename: "whitebarmask_right"
     oiio:subimages: 10
     openexr:chunkCount: 769
diff --git a/testsuite/openexr-window/ref/out.txt b/testsuite/openexr-window/ref/out.txt
index 664d71e8a3..628bf69bbb 100644
--- a/testsuite/openexr-window/ref/out.txt
+++ b/testsuite/openexr-window/ref/out.txt
@@ -6,7 +6,7 @@ Reading ../openexr-images/DisplayWindow/t01.exr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Comparing "../openexr-images/DisplayWindow/t01.exr" and "t01.exr"
 PASS
@@ -20,7 +20,7 @@ Reading ../openexr-images/DisplayWindow/t02.exr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Comparing "../openexr-images/DisplayWindow/t02.exr" and "t02.exr"
 PASS
@@ -34,7 +34,7 @@ Reading ../openexr-images/DisplayWindow/t03.exr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Comparing "../openexr-images/DisplayWindow/t03.exr" and "t03.exr"
 PASS
@@ -48,7 +48,7 @@ Reading ../openexr-images/DisplayWindow/t04.exr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Comparing "../openexr-images/DisplayWindow/t04.exr" and "t04.exr"
 PASS
@@ -62,7 +62,7 @@ Reading ../openexr-images/DisplayWindow/t05.exr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Comparing "../openexr-images/DisplayWindow/t05.exr" and "t05.exr"
 PASS
@@ -76,7 +76,7 @@ Reading ../openexr-images/DisplayWindow/t06.exr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Comparing "../openexr-images/DisplayWindow/t06.exr" and "t06.exr"
 PASS
@@ -90,7 +90,7 @@ Reading ../openexr-images/DisplayWindow/t07.exr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Comparing "../openexr-images/DisplayWindow/t07.exr" and "t07.exr"
 PASS
@@ -105,7 +105,7 @@ Reading ../openexr-images/DisplayWindow/t08.exr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Comparing "../openexr-images/DisplayWindow/t08.exr" and "t08.exr"
 PASS
@@ -119,7 +119,7 @@ Reading ../openexr-images/DisplayWindow/t09.exr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Comparing "../openexr-images/DisplayWindow/t09.exr" and "t09.exr"
 PASS
@@ -133,7 +133,7 @@ Reading ../openexr-images/DisplayWindow/t10.exr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Comparing "../openexr-images/DisplayWindow/t10.exr" and "t10.exr"
 PASS
@@ -147,7 +147,7 @@ Reading ../openexr-images/DisplayWindow/t11.exr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Comparing "../openexr-images/DisplayWindow/t11.exr" and "t11.exr"
 PASS
@@ -161,7 +161,7 @@ Reading ../openexr-images/DisplayWindow/t12.exr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Comparing "../openexr-images/DisplayWindow/t12.exr" and "t12.exr"
 PASS
@@ -175,7 +175,7 @@ Reading ../openexr-images/DisplayWindow/t13.exr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Comparing "../openexr-images/DisplayWindow/t13.exr" and "t13.exr"
 PASS
@@ -189,7 +189,7 @@ Reading ../openexr-images/DisplayWindow/t14.exr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Comparing "../openexr-images/DisplayWindow/t14.exr" and "t14.exr"
 PASS
@@ -203,7 +203,7 @@ Reading ../openexr-images/DisplayWindow/t15.exr
     PixelAspectRatio: 1.5
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Comparing "../openexr-images/DisplayWindow/t15.exr" and "t15.exr"
 PASS
@@ -217,7 +217,7 @@ Reading ../openexr-images/DisplayWindow/t16.exr
     PixelAspectRatio: 0.666667
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
 Comparing "../openexr-images/DisplayWindow/t16.exr" and "t16.exr"
 PASS
diff --git a/testsuite/python-colorconfig/ref/out-ocio23.txt b/testsuite/python-colorconfig/ref/out-ocio23.txt
index ce01af5931..3c4903bb06 100644
--- a/testsuite/python-colorconfig/ref/out-ocio23.txt
+++ b/testsuite/python-colorconfig/ref/out-ocio23.txt
@@ -15,7 +15,7 @@ getNumRoles = 9
 getRoles = ['aces_interchange', 'cie_xyz_d65_interchange', 'color_picking', 'color_timing', 'compositing_log', 'data', 'matte_paint', 'scene_linear', 'texture_paint']
 aliases of 'scene_linear' are ['ACES - ACEScg', 'lin_ap1']
 resolve('foo'): foo
-resolve('linear'): ACEScg
+resolve('linear'): Linear Rec.709 (sRGB)
 resolve('scene_linear'): ACEScg
 resolve('lin_srgb'): Linear Rec.709 (sRGB)
 resolve('srgb'): sRGB - Texture
diff --git a/testsuite/python-colorconfig/ref/out-ocio24.txt b/testsuite/python-colorconfig/ref/out-ocio24.txt
index df805042c9..ba4d19225a 100644
--- a/testsuite/python-colorconfig/ref/out-ocio24.txt
+++ b/testsuite/python-colorconfig/ref/out-ocio24.txt
@@ -15,7 +15,7 @@ getNumRoles = 9
 getRoles = ['aces_interchange', 'cie_xyz_d65_interchange', 'color_picking', 'color_timing', 'compositing_log', 'data', 'matte_paint', 'scene_linear', 'texture_paint']
 aliases of 'scene_linear' are ['ACES - ACEScg', 'lin_ap1', 'lin_ap1_scene']
 resolve('foo'): foo
-resolve('linear'): ACEScg
+resolve('linear'): Linear Rec.709 (sRGB)
 resolve('scene_linear'): ACEScg
 resolve('lin_srgb'): Linear Rec.709 (sRGB)
 resolve('srgb'): sRGB Encoded Rec.709 (sRGB)
diff --git a/testsuite/python-colorconfig/ref/out.txt b/testsuite/python-colorconfig/ref/out.txt
index 1f9c18c8c7..b4d7580085 100644
--- a/testsuite/python-colorconfig/ref/out.txt
+++ b/testsuite/python-colorconfig/ref/out.txt
@@ -15,7 +15,7 @@ getNumRoles = 9
 getRoles = ['aces_interchange', 'cie_xyz_d65_interchange', 'color_picking', 'color_timing', 'compositing_log', 'data', 'matte_paint', 'scene_linear', 'texture_paint']
 aliases of 'scene_linear' are ['ACES - ACEScg', 'lin_ap1']
 resolve('foo'): foo
-resolve('linear'): ACEScg
+resolve('linear'): Linear Rec.709 (sRGB)
 resolve('scene_linear'): ACEScg
 resolve('lin_srgb'): Linear Rec.709 (sRGB)
 resolve('srgb'): sRGB - Texture
diff --git a/testsuite/rational/ref/out.txt b/testsuite/rational/ref/out.txt
index 45aa115b1e..7d3450ff38 100644
--- a/testsuite/rational/ref/out.txt
+++ b/testsuite/rational/ref/out.txt
@@ -62,7 +62,7 @@ src/test.exr         :   64 x   64, 3 channel, half openexr
     Software: "OpenImageIO 1.8.5dev : oiiotool cropped-stripped-Isabella.0.exr -cut 64x64+0+0 -o test.exr"
     timecodeRate: 24
     Exif:ImageHistory: "oiiotool cropped-stripped-Isabella.0.exr -cut 64x64+0+0 -o test.exr"
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
     smpte:TimeCode: 01:18:19:06
 Comparing "src/test.exr" and "test.exr"
@@ -76,5 +76,5 @@ rat2.exr             :   64 x   64, 3 channel, float openexr
     PixelAspectRatio: 1
     screenWindowCenter: 0, 0
     screenWindowWidth: 1
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:subimages: 1
diff --git a/testsuite/raw/ref/out-libraw-0.20.2-gh.txt b/testsuite/raw/ref/out-libraw-0.20.2-gh.txt
index 0848b7b29d..fda4b1757a 100644
--- a/testsuite/raw/ref/out-libraw-0.20.2-gh.txt
+++ b/testsuite/raw/ref/out-libraw-0.20.2-gh.txt
@@ -52,7 +52,6 @@
     Canon:SpecularWhiteLevel: 12749
     Canon:SpotMeteringMode: 0 (center)
     Exif:ApertureValue: 2.97085 (f/2.8)
-    Exif:ColorSpace: 1
     Exif:CustomRendered: 0 (no)
     Exif:DateTimeDigitized: "2009:10:09 14:18:45"
     Exif:DateTimeOriginal: "2009:10:09 14:18:45"
@@ -77,7 +76,7 @@
     Exif:SubsecTimeDigitized: "00"
     Exif:SubsecTimeOriginal: "00"
     Exif:WhiteBalance: 0 (auto)
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     raw:cam_mul: 2076, 1024, 1584, 1024
     raw:cam_xyz: 0.6844, -0.0996, -0.0856, -0.3876, 1.1761, 0.2396, -0.0593, 0.1772, 0.6198, 0, 0, 0
@@ -167,7 +166,7 @@
     Nikon:PhaseDetectAF: 0
     Nikon:ShootingMode: 0
     Nikon:VRMode: 0
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     raw:cam_mul: 463, 256, 396, 256
     raw:cam_xyz: 0.7171, -0.1986, -0.0648, -0.8085, 1.5555, 0.2718, -0.217, 0.2512, 0.7457, 0, 0, 0
@@ -188,7 +187,6 @@
     Software: "Digital Camera FinePix F700  Ver2.00"
     Exif:ApertureValue: 3.69599 (f/3.6)
     Exif:BrightnessValue: 773/100 (7.73)
-    Exif:ColorSpace: 1
     Exif:CompressedBitsPerPixel: 30/10 (3)
     Exif:CustomRendered: 0 (no)
     Exif:DateTimeDigitized: "2007:01:06 14:20:22"
@@ -241,7 +239,7 @@
     Fujifilm:Rating: 0
     Fujifilm:ShutterType: 0
     Fujifilm:WB_Preset: 0
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     raw:cam_mul: 131.532, 80, 97.3451, 80
     raw:cam_xyz: 1.0004, -0.3219, -0.1201, -0.7036, 1.5047, 0.2107, -0.1863, 0.2565, 0.7736, 0, 0, 0
@@ -331,7 +329,7 @@
     Nikon:PhaseDetectAF: 0
     Nikon:ShootingMode: 0
     Nikon:VRMode: 0
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     raw:cam_mul: 463, 256, 396, 256
     raw:cam_xyz: 0.7171, -0.1986, -0.0648, -0.8085, 1.5555, 0.2718, -0.217, 0.2512, 0.7457, 0, 0, 0
@@ -354,7 +352,6 @@
     PixelAspectRatio: 1
     Software: "Version 1.0                    "
     Exif:ApertureValue: 2 (f/2.0)
-    Exif:ColorSpace: 1
     Exif:Contrast: 0 (normal)
     Exif:CustomRendered: 1 (yes)
     Exif:DateTimeDigitized: "2008:12:19 12:29:40"
@@ -378,7 +375,7 @@
     Exif:Sharpness: 1 (soft)
     Exif:ShutterSpeedValue: 8.32193 (1/319 s)
     Exif:WhiteBalance: 1 (manual)
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     Olympus:AFFineTune: 0
     Olympus:AFPoint: 0
@@ -447,7 +444,7 @@
     Exif:ShutterSpeedValue: 7.96578 (1/249 s)
     Exif:SubjectDistanceRange: 3 (distant)
     Exif:WhiteBalance: 1 (manual)
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     Pentax:AFAdjustment: 0
     Pentax:AFPoint: -2
@@ -496,7 +493,6 @@
     Software: "DSLR-A300 v1.00"
     Exif:ApertureValue: 4.97085 (f/5.6)
     Exif:BrightnessValue: 137/100 (1.37)
-    Exif:ColorSpace: 1
     Exif:CompressedBitsPerPixel: 8/1 (8)
     Exif:Contrast: 0 (normal)
     Exif:CustomRendered: 0 (no)
@@ -522,7 +518,7 @@
     Exif:Sharpness: 0 (normal)
     Exif:ShutterSpeedValue: 5.90689 (1/59 s)
     Exif:WhiteBalance: 0 (auto)
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     raw:cam_mul: 1972, 1024, 1632, 1024
     raw:cam_xyz: 0.9847, -0.3091, -0.0928, -0.8485, 1.6345, 0.2225, -0.0715, 0.0595, 0.7103, 0, 0, 0
diff --git a/testsuite/raw/ref/out-libraw-0.20.2.txt b/testsuite/raw/ref/out-libraw-0.20.2.txt
index b2ebfb6784..94a5d7d541 100644
--- a/testsuite/raw/ref/out-libraw-0.20.2.txt
+++ b/testsuite/raw/ref/out-libraw-0.20.2.txt
@@ -52,7 +52,6 @@
     Canon:SpecularWhiteLevel: 12749
     Canon:SpotMeteringMode: 0 (center)
     Exif:ApertureValue: 2.97085 (f/2.8)
-    Exif:ColorSpace: 1
     Exif:CustomRendered: 0 (no)
     Exif:DateTimeDigitized: "2009:10:09 14:18:45"
     Exif:DateTimeOriginal: "2009:10:09 14:18:45"
@@ -77,7 +76,7 @@
     Exif:SubsecTimeDigitized: "00"
     Exif:SubsecTimeOriginal: "00"
     Exif:WhiteBalance: 0 (auto)
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     raw:cam_mul: 2076, 1024, 1584, 1024
     raw:cam_xyz: 0.6844, -0.0996, -0.0856, -0.3876, 1.1761, 0.2396, -0.0593, 0.1772, 0.6198, 0, 0, 0
@@ -167,7 +166,7 @@
     Nikon:PhaseDetectAF: 0
     Nikon:ShootingMode: 0
     Nikon:VRMode: 0
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     raw:cam_mul: 463, 256, 396, 256
     raw:cam_xyz: 0.7171, -0.1986, -0.0648, -0.8085, 1.5555, 0.2718, -0.217, 0.2512, 0.7457, 0, 0, 0
@@ -188,7 +187,6 @@
     Software: "Digital Camera FinePix F700  Ver2.00"
     Exif:ApertureValue: 3.69599 (f/3.6)
     Exif:BrightnessValue: 773/100 (7.73)
-    Exif:ColorSpace: 1
     Exif:CompressedBitsPerPixel: 30/10 (3)
     Exif:CustomRendered: 0 (no)
     Exif:DateTimeDigitized: "2007:01:06 14:20:22"
@@ -241,7 +239,7 @@
     Fujifilm:Rating: 0
     Fujifilm:ShutterType: 0
     Fujifilm:WB_Preset: 0
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     raw:cam_mul: 131.532, 80, 97.3451, 80
     raw:cam_xyz: 1.0004, -0.3219, -0.1201, -0.7036, 1.5047, 0.2107, -0.1863, 0.2565, 0.7736, 0, 0, 0
@@ -331,7 +329,7 @@
     Nikon:PhaseDetectAF: 0
     Nikon:ShootingMode: 0
     Nikon:VRMode: 0
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     raw:cam_mul: 463, 256, 396, 256
     raw:cam_xyz: 0.7171, -0.1986, -0.0648, -0.8085, 1.5555, 0.2718, -0.217, 0.2512, 0.7457, 0, 0, 0
@@ -354,7 +352,6 @@
     PixelAspectRatio: 1
     Software: "Version 1.0                    "
     Exif:ApertureValue: 2 (f/2.0)
-    Exif:ColorSpace: 1
     Exif:Contrast: 0 (normal)
     Exif:CustomRendered: 1 (yes)
     Exif:DateTimeDigitized: "2008:12:19 12:29:40"
@@ -378,7 +375,7 @@
     Exif:Sharpness: 1 (soft)
     Exif:ShutterSpeedValue: 8.32193 (1/319 s)
     Exif:WhiteBalance: 1 (manual)
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     Olympus:AFFineTune: 0
     Olympus:AFPoint: 0
@@ -437,7 +434,7 @@
     Exif:MaxApertureValue: 925/256 (3.61328)
     Exif:MeteringMode: 5 (pattern)
     Exif:ShutterSpeedValue: 8.64386 (1/399 s)
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     Panasonic:AFPoint: -1
     Panasonic:BlackLevel: 0, 0, 0, 0, 0, 0, 0, 0
     Panasonic:CameraFormat: 8
@@ -487,7 +484,7 @@
     Exif:ShutterSpeedValue: 7.96578 (1/249 s)
     Exif:SubjectDistanceRange: 3 (distant)
     Exif:WhiteBalance: 1 (manual)
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     Pentax:AFAdjustment: 0
     Pentax:AFPoint: -2
@@ -536,7 +533,6 @@
     Software: "DSLR-A300 v1.00"
     Exif:ApertureValue: 4.97085 (f/5.6)
     Exif:BrightnessValue: 137/100 (1.37)
-    Exif:ColorSpace: 1
     Exif:CompressedBitsPerPixel: 8/1 (8)
     Exif:Contrast: 0 (normal)
     Exif:CustomRendered: 0 (no)
@@ -562,7 +558,7 @@
     Exif:Sharpness: 0 (normal)
     Exif:ShutterSpeedValue: 5.90689 (1/59 s)
     Exif:WhiteBalance: 0 (auto)
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     raw:cam_mul: 1972, 1024, 1632, 1024
     raw:cam_xyz: 0.9847, -0.3091, -0.0928, -0.8485, 1.6345, 0.2225, -0.0715, 0.0595, 0.7103, 0, 0, 0
diff --git a/testsuite/raw/ref/out-libraw0.20.0-gh.txt b/testsuite/raw/ref/out-libraw0.20.0-gh.txt
index 5c962a14f8..7b80e3a174 100644
--- a/testsuite/raw/ref/out-libraw0.20.0-gh.txt
+++ b/testsuite/raw/ref/out-libraw0.20.0-gh.txt
@@ -77,7 +77,7 @@
     Exif:SubsecTimeDigitized: "00"
     Exif:SubsecTimeOriginal: "00"
     Exif:WhiteBalance: 0 (auto)
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     raw:cam_mul: 2076, 1024, 1584, 1024
     raw:cam_xyz: 0.6844, -0.0996, -0.0856, -0.3876, 1.1761, 0.2396, -0.0593, 0.1772, 0.6198, 0, 0, 0
@@ -167,7 +167,7 @@
     Nikon:PhaseDetectAF: 0
     Nikon:ShootingMode: 0
     Nikon:VRMode: 0
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     raw:cam_mul: 463, 256, 396, 256
     raw:cam_xyz: 0.7171, -0.1986, -0.0648, -0.8085, 1.5555, 0.2718, -0.217, 0.2512, 0.7457, 0, 0, 0
@@ -188,7 +188,6 @@
     Software: "Digital Camera FinePix F700  Ver2.00"
     Exif:ApertureValue: 3.69599 (f/3.6)
     Exif:BrightnessValue: 773/100 (7.73)
-    Exif:ColorSpace: 1
     Exif:CompressedBitsPerPixel: 30/10 (3)
     Exif:CustomRendered: 0 (no)
     Exif:DateTimeDigitized: "2007:01:06 14:20:22"
@@ -241,7 +240,7 @@
     Fujifilm:Rating: 0
     Fujifilm:ShutterType: 0
     Fujifilm:WB_Preset: 0
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     raw:cam_mul: 131.532, 80, 97.3451, 80
     raw:cam_xyz: 1.0004, -0.3219, -0.1201, -0.7036, 1.5047, 0.2107, -0.1863, 0.2565, 0.7736, 0, 0, 0
@@ -331,7 +330,7 @@
     Nikon:PhaseDetectAF: 0
     Nikon:ShootingMode: 0
     Nikon:VRMode: 0
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     raw:cam_mul: 463, 256, 396, 256
     raw:cam_xyz: 0.7171, -0.1986, -0.0648, -0.8085, 1.5555, 0.2718, -0.217, 0.2512, 0.7457, 0, 0, 0
@@ -354,7 +353,6 @@
     PixelAspectRatio: 1
     Software: "Version 1.0                    "
     Exif:ApertureValue: 2 (f/2.0)
-    Exif:ColorSpace: 1
     Exif:Contrast: 0 (normal)
     Exif:CustomRendered: 1 (yes)
     Exif:DateTimeDigitized: "2008:12:19 12:29:40"
@@ -378,7 +376,7 @@
     Exif:Sharpness: 1 (soft)
     Exif:ShutterSpeedValue: 8.32193 (1/319 s)
     Exif:WhiteBalance: 1 (manual)
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     Olympus:AFFineTune: 0
     Olympus:AFPoint: 0
@@ -447,7 +445,7 @@
     Exif:ShutterSpeedValue: 7.96578 (1/249 s)
     Exif:SubjectDistanceRange: 3 (distant)
     Exif:WhiteBalance: 1 (manual)
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     Pentax:AFAdjustment: 0
     Pentax:AFPoint: -2
@@ -496,7 +494,6 @@
     Software: "DSLR-A300 v1.00"
     Exif:ApertureValue: 4.97085 (f/5.6)
     Exif:BrightnessValue: 137/100 (1.37)
-    Exif:ColorSpace: 1
     Exif:CompressedBitsPerPixel: 8/1 (8)
     Exif:Contrast: 0 (normal)
     Exif:CustomRendered: 0 (no)
@@ -522,7 +519,7 @@
     Exif:Sharpness: 0 (normal)
     Exif:ShutterSpeedValue: 5.90689 (1/59 s)
     Exif:WhiteBalance: 0 (auto)
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     raw:cam_mul: 1972, 1024, 1632, 1024
     raw:cam_xyz: 0.9847, -0.3091, -0.0928, -0.8485, 1.6345, 0.2225, -0.0715, 0.0595, 0.7103, 0, 0, 0
diff --git a/testsuite/raw/ref/out-libraw0.20.0.txt b/testsuite/raw/ref/out-libraw0.20.0.txt
index 144dd0d478..0ef132cb8d 100644
--- a/testsuite/raw/ref/out-libraw0.20.0.txt
+++ b/testsuite/raw/ref/out-libraw0.20.0.txt
@@ -52,7 +52,6 @@
     Canon:SpecularWhiteLevel: 12749
     Canon:SpotMeteringMode: 0 (center)
     Exif:ApertureValue: 2.97085 (f/2.8)
-    Exif:ColorSpace: 1
     Exif:CustomRendered: 0 (no)
     Exif:DateTimeDigitized: "2009:10:09 14:18:45"
     Exif:DateTimeOriginal: "2009:10:09 14:18:45"
@@ -77,7 +76,7 @@
     Exif:SubsecTimeDigitized: "00"
     Exif:SubsecTimeOriginal: "00"
     Exif:WhiteBalance: 0 (auto)
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     raw:cam_mul: 2076, 1024, 1584, 1024
     raw:cam_xyz: 0.6844, -0.0996, -0.0856, -0.3876, 1.1761, 0.2396, -0.0593, 0.1772, 0.6198, 0, 0, 0
@@ -167,7 +166,7 @@
     Nikon:PhaseDetectAF: 0
     Nikon:ShootingMode: 0
     Nikon:VRMode: 0
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     raw:cam_mul: 463, 256, 396, 256
     raw:cam_xyz: 0.7171, -0.1986, -0.0648, -0.8085, 1.5555, 0.2718, -0.217, 0.2512, 0.7457, 0, 0, 0
@@ -188,7 +187,6 @@
     Software: "Digital Camera FinePix F700  Ver2.00"
     Exif:ApertureValue: 3.69599 (f/3.6)
     Exif:BrightnessValue: 773/100 (7.73)
-    Exif:ColorSpace: 1
     Exif:CompressedBitsPerPixel: 30/10 (3)
     Exif:CustomRendered: 0 (no)
     Exif:DateTimeDigitized: "2007:01:06 14:20:22"
@@ -241,7 +239,7 @@
     Fujifilm:Rating: 0
     Fujifilm:ShutterType: 0
     Fujifilm:WB_Preset: 0
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     raw:cam_mul: 131.532, 80, 97.3451, 80
     raw:cam_xyz: 1.0004, -0.3219, -0.1201, -0.7036, 1.5047, 0.2107, -0.1863, 0.2565, 0.7736, 0, 0, 0
@@ -331,7 +329,7 @@
     Nikon:PhaseDetectAF: 0
     Nikon:ShootingMode: 0
     Nikon:VRMode: 0
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     raw:cam_mul: 463, 256, 396, 256
     raw:cam_xyz: 0.7171, -0.1986, -0.0648, -0.8085, 1.5555, 0.2718, -0.217, 0.2512, 0.7457, 0, 0, 0
@@ -354,7 +352,6 @@
     PixelAspectRatio: 1
     Software: "Version 1.0                    "
     Exif:ApertureValue: 2 (f/2.0)
-    Exif:ColorSpace: 1
     Exif:Contrast: 0 (normal)
     Exif:CustomRendered: 1 (yes)
     Exif:DateTimeDigitized: "2008:12:19 12:29:40"
@@ -378,7 +375,7 @@
     Exif:Sharpness: 1 (soft)
     Exif:ShutterSpeedValue: 8.32193 (1/319 s)
     Exif:WhiteBalance: 1 (manual)
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     Olympus:AFFineTune: 0
     Olympus:AFPoint: 0
@@ -437,7 +434,7 @@
     Exif:MaxApertureValue: 925/256 (3.61328)
     Exif:MeteringMode: 5 (pattern)
     Exif:ShutterSpeedValue: 8.64386 (1/399 s)
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     Panasonic:AFPoint: -1
     Panasonic:BlackLevel: 0, 0, 0, 0, 0, 0, 0, 0
     Panasonic:CameraFormat: 8
@@ -487,7 +484,7 @@
     Exif:ShutterSpeedValue: 7.96578 (1/249 s)
     Exif:SubjectDistanceRange: 3 (distant)
     Exif:WhiteBalance: 1 (manual)
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     Pentax:AFAdjustment: 0
     Pentax:AFPoint: -2
@@ -536,7 +533,6 @@
     Software: "DSLR-A300 v1.00"
     Exif:ApertureValue: 4.97085 (f/5.6)
     Exif:BrightnessValue: 137/100 (1.37)
-    Exif:ColorSpace: 1
     Exif:CompressedBitsPerPixel: 8/1 (8)
     Exif:Contrast: 0 (normal)
     Exif:CustomRendered: 0 (no)
@@ -562,7 +558,7 @@
     Exif:Sharpness: 0 (normal)
     Exif:ShutterSpeedValue: 5.90689 (1/59 s)
     Exif:WhiteBalance: 0 (auto)
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     raw:cam_mul: 1972, 1024, 1632, 1024
     raw:cam_xyz: 0.9847, -0.3091, -0.0928, -0.8485, 1.6345, 0.2225, -0.0715, 0.0595, 0.7103, 0, 0, 0
diff --git a/testsuite/raw/ref/out-libraw0.21.0-gh.txt b/testsuite/raw/ref/out-libraw0.21.0-gh.txt
index 42f2621dc3..8136c0438a 100644
--- a/testsuite/raw/ref/out-libraw0.21.0-gh.txt
+++ b/testsuite/raw/ref/out-libraw0.21.0-gh.txt
@@ -49,7 +49,6 @@
     Canon:SpecularWhiteLevel: 12749
     Canon:SpotMeteringMode: 0 (center)
     Exif:ApertureValue: 2.97085 (f/2.8)
-    Exif:ColorSpace: 1
     Exif:CustomRendered: 0 (no)
     Exif:DateTimeDigitized: "2009:10:09 14:18:45"
     Exif:DateTimeOriginal: "2009:10:09 14:18:45"
@@ -74,7 +73,7 @@
     Exif:SubsecTimeDigitized: "00"
     Exif:SubsecTimeOriginal: "00"
     Exif:WhiteBalance: 0 (auto)
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     raw:cam_mul: 2076, 1024, 1584, 1024
     raw:cam_xyz: 0.6844, -0.0996, -0.0856, -0.3876, 1.1761, 0.2396, -0.0593, 0.1772, 0.6198, 0, 0, 0
@@ -161,7 +160,7 @@
     Nikon:NEFCompression: 3
     Nikon:ShootingMode: 0
     Nikon:VRMode: 0
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     raw:cam_mul: 463, 256, 396, 256
     raw:cam_xyz: 0.7171, -0.1986, -0.0648, -0.8085, 1.5555, 0.2718, -0.217, 0.2512, 0.7457, 0, 0, 0
@@ -182,7 +181,6 @@
     Software: "Digital Camera FinePix F700  Ver2.00"
     Exif:ApertureValue: 3.69599 (f/3.6)
     Exif:BrightnessValue: 773/100 (7.73)
-    Exif:ColorSpace: 1
     Exif:CompressedBitsPerPixel: 30/10 (3)
     Exif:CustomRendered: 0 (no)
     Exif:DateTimeDigitized: "2007:01:06 14:20:22"
@@ -233,7 +231,7 @@
     Fujifilm:Rating: 0
     Fujifilm:ShutterType: 0
     Fujifilm:WB_Preset: 0
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     raw:cam_mul: 131, 80, 97, 80
     raw:cam_xyz: 1.0004, -0.3219, -0.1201, -0.7036, 1.5047, 0.2107, -0.1863, 0.2565, 0.7736, 0, 0, 0
@@ -320,7 +318,7 @@
     Nikon:NEFCompression: 3
     Nikon:ShootingMode: 0
     Nikon:VRMode: 0
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     raw:cam_mul: 463, 256, 396, 256
     raw:cam_xyz: 0.7171, -0.1986, -0.0648, -0.8085, 1.5555, 0.2718, -0.217, 0.2512, 0.7457, 0, 0, 0
@@ -343,7 +341,6 @@
     PixelAspectRatio: 1
     Software: "Version 1.0                    "
     Exif:ApertureValue: 2 (f/2.0)
-    Exif:ColorSpace: 1
     Exif:Contrast: 0 (normal)
     Exif:CustomRendered: 1 (yes)
     Exif:DateTimeDigitized: "2008:12:19 12:29:40"
@@ -367,7 +364,7 @@
     Exif:Sharpness: 1 (soft)
     Exif:ShutterSpeedValue: 8.32193 (1/319 s)
     Exif:WhiteBalance: 1 (manual)
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     Olympus:AFFineTune: 255
     Olympus:AFFineTuneAdj: -32768, -32768, -32768
@@ -437,7 +434,7 @@
     Exif:ShutterSpeedValue: 7.96578 (1/249 s)
     Exif:SubjectDistanceRange: 3 (distant)
     Exif:WhiteBalance: 1 (manual)
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     Pentax:AFAdjustment: 0
     Pentax:AFPoint: -2
@@ -486,7 +483,6 @@
     Software: "DSLR-A300 v1.00"
     Exif:ApertureValue: 4.97085 (f/5.6)
     Exif:BrightnessValue: 137/100 (1.37)
-    Exif:ColorSpace: 1
     Exif:CompressedBitsPerPixel: 8/1 (8)
     Exif:Contrast: 0 (normal)
     Exif:CustomRendered: 0 (no)
@@ -512,7 +508,7 @@
     Exif:Sharpness: 0 (normal)
     Exif:ShutterSpeedValue: 5.90689 (1/59 s)
     Exif:WhiteBalance: 0 (auto)
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     raw:cam_mul: 1972, 1024, 1632, 1024
     raw:cam_xyz: 0.9847, -0.3091, -0.0928, -0.8485, 1.6345, 0.2225, -0.0715, 0.0595, 0.7103, 0, 0, 0
diff --git a/testsuite/raw/ref/out-libraw0.21.0-mac.txt b/testsuite/raw/ref/out-libraw0.21.0-mac.txt
index 9a829f8f7a..2ecf30bfb2 100644
--- a/testsuite/raw/ref/out-libraw0.21.0-mac.txt
+++ b/testsuite/raw/ref/out-libraw0.21.0-mac.txt
@@ -49,7 +49,6 @@
     Canon:SpecularWhiteLevel: 12749
     Canon:SpotMeteringMode: 0 (center)
     Exif:ApertureValue: 2.97085 (f/2.8)
-    Exif:ColorSpace: 1
     Exif:CustomRendered: 0 (no)
     Exif:DateTimeDigitized: "2009:10:09 14:18:45"
     Exif:DateTimeOriginal: "2009:10:09 14:18:45"
@@ -74,7 +73,7 @@
     Exif:SubsecTimeDigitized: "00"
     Exif:SubsecTimeOriginal: "00"
     Exif:WhiteBalance: 0 (auto)
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     raw:cam_mul: 2076, 1024, 1584, 1024
     raw:cam_xyz: 0.6844, -0.0996, -0.0856, -0.3876, 1.1761, 0.2396, -0.0593, 0.1772, 0.6198, 0, 0, 0
@@ -161,7 +160,7 @@
     Nikon:NEFCompression: 3
     Nikon:ShootingMode: 0
     Nikon:VRMode: 0
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     raw:cam_mul: 463, 256, 396, 256
     raw:cam_xyz: 0.7171, -0.1986, -0.0648, -0.8085, 1.5555, 0.2718, -0.217, 0.2512, 0.7457, 0, 0, 0
@@ -182,7 +181,6 @@
     Software: "Digital Camera FinePix F700  Ver2.00"
     Exif:ApertureValue: 3.69599 (f/3.6)
     Exif:BrightnessValue: 773/100 (7.73)
-    Exif:ColorSpace: 1
     Exif:CompressedBitsPerPixel: 30/10 (3)
     Exif:CustomRendered: 0 (no)
     Exif:DateTimeDigitized: "2007:01:06 14:20:22"
@@ -233,7 +231,7 @@
     Fujifilm:Rating: 0
     Fujifilm:ShutterType: 0
     Fujifilm:WB_Preset: 0
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     raw:cam_mul: 131, 80, 97, 80
     raw:cam_xyz: 1.0004, -0.3219, -0.1201, -0.7036, 1.5047, 0.2107, -0.1863, 0.2565, 0.7736, 0, 0, 0
@@ -320,7 +318,7 @@
     Nikon:NEFCompression: 3
     Nikon:ShootingMode: 0
     Nikon:VRMode: 0
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     raw:cam_mul: 463, 256, 396, 256
     raw:cam_xyz: 0.7171, -0.1986, -0.0648, -0.8085, 1.5555, 0.2718, -0.217, 0.2512, 0.7457, 0, 0, 0
@@ -343,7 +341,6 @@
     PixelAspectRatio: 1
     Software: "Version 1.0                    "
     Exif:ApertureValue: 2 (f/2.0)
-    Exif:ColorSpace: 1
     Exif:Contrast: 0 (normal)
     Exif:CustomRendered: 1 (yes)
     Exif:DateTimeDigitized: "2008:12:19 12:29:40"
@@ -367,7 +364,7 @@
     Exif:Sharpness: 1 (soft)
     Exif:ShutterSpeedValue: 8.32193 (1/319 s)
     Exif:WhiteBalance: 1 (manual)
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     Olympus:AFFineTune: 255
     Olympus:AFFineTuneAdj: -32768, -32768, -32768
@@ -427,7 +424,7 @@
     Exif:MaxApertureValue: 925/256 (3.61328)
     Exif:MeteringMode: 5 (pattern)
     Exif:ShutterSpeedValue: 8.64386 (1/399 s)
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     Panasonic:AFPoint: -1
     Panasonic:BlackLevel: 0, 0, 0, 0, 0, 0, 0, 0
     Panasonic:CameraFormat: 8
@@ -477,7 +474,7 @@
     Exif:ShutterSpeedValue: 7.96578 (1/249 s)
     Exif:SubjectDistanceRange: 3 (distant)
     Exif:WhiteBalance: 1 (manual)
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     Pentax:AFAdjustment: 0
     Pentax:AFPoint: -2
@@ -526,7 +523,6 @@
     Software: "DSLR-A300 v1.00"
     Exif:ApertureValue: 4.97085 (f/5.6)
     Exif:BrightnessValue: 137/100 (1.37)
-    Exif:ColorSpace: 1
     Exif:CompressedBitsPerPixel: 8/1 (8)
     Exif:Contrast: 0 (normal)
     Exif:CustomRendered: 0 (no)
@@ -552,7 +548,7 @@
     Exif:Sharpness: 0 (normal)
     Exif:ShutterSpeedValue: 5.90689 (1/59 s)
     Exif:WhiteBalance: 0 (auto)
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     raw:cam_mul: 1972, 1024, 1632, 1024
     raw:cam_xyz: 0.9847, -0.3091, -0.0928, -0.8485, 1.6345, 0.2225, -0.0715, 0.0595, 0.7103, 0, 0, 0
diff --git a/testsuite/raw/ref/out.txt b/testsuite/raw/ref/out.txt
index 7532e6d87f..6db36bd127 100644
--- a/testsuite/raw/ref/out.txt
+++ b/testsuite/raw/ref/out.txt
@@ -51,7 +51,6 @@
     Canon:SpecularWhiteLevel: 12749
     Canon:SpotMeteringMode: 0 (center)
     Exif:ApertureValue: 2.97085 (f/2.8)
-    Exif:ColorSpace: 1
     Exif:CustomRendered: 0 (no)
     Exif:DateTimeDigitized: "2009:10:09 14:18:45"
     Exif:DateTimeOriginal: "2009:10:09 14:18:45"
@@ -76,7 +75,7 @@
     Exif:SubsecTimeDigitized: "00"
     Exif:SubsecTimeOriginal: "00"
     Exif:WhiteBalance: 0 (auto)
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     raw:cam_mul: 2076, 1024, 1584, 1024
     raw:cam_xyz: 0.6844, -0.0996, -0.0856, -0.3876, 1.1761, 0.2396, -0.0593, 0.1772, 0.6198, 0, 0, 0
@@ -166,7 +165,7 @@
     Nikon:PhaseDetectAF: 0
     Nikon:ShootingMode: 0
     Nikon:VRMode: 0
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     raw:cam_mul: 463, 256, 396, 256
     raw:cam_xyz: 0.7171, -0.1986, -0.0648, -0.8085, 1.5555, 0.2718, -0.217, 0.2512, 0.7457, 0, 0, 0
@@ -187,7 +186,6 @@
     Software: "Digital Camera FinePix F700  Ver2.00"
     Exif:ApertureValue: 3.69599 (f/3.6)
     Exif:BrightnessValue: 773/100 (7.73)
-    Exif:ColorSpace: 1
     Exif:CompressedBitsPerPixel: 30/10 (3)
     Exif:CustomRendered: 0 (no)
     Exif:DateTimeDigitized: "2007:01:06 14:20:22"
@@ -238,7 +236,7 @@
     Fujifilm:Rating: 0
     Fujifilm:ShutterType: 0
     Fujifilm:WB_Preset: 0
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     raw:cam_mul: 131.532, 80, 97.3451, 80
     raw:cam_xyz: 1.0004, -0.3219, -0.1201, -0.7036, 1.5047, 0.2107, -0.1863, 0.2565, 0.7736, 0, 0, 0
@@ -328,7 +326,7 @@
     Nikon:PhaseDetectAF: 0
     Nikon:ShootingMode: 0
     Nikon:VRMode: 0
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     raw:cam_mul: 463, 256, 396, 256
     raw:cam_xyz: 0.7171, -0.1986, -0.0648, -0.8085, 1.5555, 0.2718, -0.217, 0.2512, 0.7457, 0, 0, 0
@@ -351,7 +349,6 @@
     PixelAspectRatio: 1
     Software: "Version 1.0                    "
     Exif:ApertureValue: 2 (f/2.0)
-    Exif:ColorSpace: 1
     Exif:Contrast: 0 (normal)
     Exif:CustomRendered: 1 (yes)
     Exif:DateTimeDigitized: "2008:12:19 12:29:40"
@@ -375,7 +372,7 @@
     Exif:Sharpness: 1 (soft)
     Exif:ShutterSpeedValue: 8.32193 (1/319 s)
     Exif:WhiteBalance: 1 (manual)
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     Olympus:AFFineTune: 0
     Olympus:AFPoint: 0
@@ -433,7 +430,7 @@
     Exif:MaxApertureValue: 925/256 (3.61328)
     Exif:MeteringMode: 5 (pattern)
     Exif:ShutterSpeedValue: 8.64386 (1/399 s)
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     Panasonic:AFPoint: -1
     Panasonic:BlackLevel: 0, 0, 0, 0, 0, 0, 0, 0
     Panasonic:CanonFocalUnits: 1
@@ -478,7 +475,7 @@
     Exif:ShutterSpeedValue: 7.96578 (1/249 s)
     Exif:SubjectDistanceRange: 3 (distant)
     Exif:WhiteBalance: 1 (manual)
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     Pentax:AFAdjustment: 0
     Pentax:AFPoint: -1
@@ -527,7 +524,6 @@
     Software: "DSLR-A300 v1.00"
     Exif:ApertureValue: 4.97085 (f/5.6)
     Exif:BrightnessValue: 137/100 (1.37)
-    Exif:ColorSpace: 1
     Exif:CompressedBitsPerPixel: 8/1 (8)
     Exif:Contrast: 0 (normal)
     Exif:CustomRendered: 0 (no)
@@ -553,7 +549,7 @@
     Exif:Sharpness: 0 (normal)
     Exif:ShutterSpeedValue: 5.90689 (1/59 s)
     Exif:WhiteBalance: 0 (auto)
-    oiio:ColorSpace: "linear"
+    oiio:ColorSpace: "lin_rec709"
     oiio:MakerNoteOffset: 0
     raw:cam_mul: 1972, 1024, 1632, 1024
     raw:cam_xyz: 0.9847, -0.3091, -0.0928, -0.8485, 1.6345, 0.2225, -0.0715, 0.0595, 0.7103, 0, 0, 0
diff --git a/testsuite/rla/ref/out.txt b/testsuite/rla/ref/out.txt
index fa529c6850..b0cbdd1e01 100644
--- a/testsuite/rla/ref/out.txt
+++ b/testsuite/rla/ref/out.txt
@@ -90,7 +90,7 @@ Reading ../oiio-images/rla/imgmake_rgba_nc10.rla
     compression: "rle"
     HostComputer: "hawk073.spimageworks.com"
     oiio:BitsPerSample: 10
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_srgb"
     rla:Aspect: " 1.333"
     rla:BlueChroma: 0.14, 0.14, 0.08
     rla:ColorChannel: "rgb"
@@ -193,7 +193,7 @@ Reading ../oiio-images/rla/imgmake_rgba_nc16.rla
     compression: "rle"
     HostComputer: "hawk073.spimageworks.com"
     oiio:BitsPerSample: 16
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_srgb"
     rla:Aspect: " 1.333"
     rla:BlueChroma: 0.14, 0.14, 0.08
     rla:ColorChannel: "rgb"
@@ -296,7 +296,7 @@ Reading ../oiio-images/rla/imgmake_rgba_nc8.rla
     compression: "rle"
     HostComputer: "hawk073.spimageworks.com"
     oiio:BitsPerSample: 8
-    oiio:ColorSpace: "Linear"
+    oiio:ColorSpace: "lin_srgb"
     rla:Aspect: " 1.333"
     rla:BlueChroma: 0.14, 0.14, 0.08
     rla:ColorChannel: "rgb"