Compress the output DICOM files (lossless)

[howff]

The output files should be compressed losslessly, although

• need to ensure either pyjpegls or pylibjpeg_openjpeg package is available for Python 3.6 (or use a newer Python inside the NSH)
• need to check the UID for JPEGLossless (it's changed, see below)
• need to ensure that IsIdentifiable can handle the compression scheme
• need to ensure that all kinds of overlay and frame are handled (as well as mono, colour, etc)
• need to check that PhotometricInterpretation is handled properly
• need to check that PlanarConfiguration is handled properly
• need to ensure that it doesn't break any of the different types of images we hold in the archive
• need to check that the viewers which eDRIS use can handle it (surely, it's been in the standard for a long time)

See https://pydicom.github.io/pydicom/stable/guides/encoding/jpeg_ls.html
and https://pydicom.github.io/pydicom/stable/guides/encoding/jpeg_2k.html

[howff]

Python 3.6 doesn't have jpegls but does have openjpeg, so use JPEG2000 compression (although check its support for various image types). The NSH-2.0 environment isn't limited to Python 3.6 so can use either compression scheme.

[rkm]

Python 3.10 is now our current minimum version in the NSH

[howff]

See breaking changes in pydicom v3:
https://pydicom.github.io/pydicom/dev/release_notes/index.html#version-3-0-0
in particular:

• The value for JPEGLossless has changed to 1.2.840.10008.1.2.4.57.

• The encoding used when saving datasets defaults to the set Transfer Syntax UID.

• Dataset.pixel_array will convert YCbCr Pixel Data to RGB by default when possible.