RAW16 (monochrome) set but images saved as 8 bit RGB

[simonleeADL]

Hi there!

I've got a ZWO ASI533MM Pro set up (working at a University) and in the allsky setting I've chosen "RAW16" as the "Image Type" to capture the full 14 bits from the sensor. I've changed the "Filename" to "image.png", set the Quality / Compression to 9, but the output seems to be an RGB image with 8 bits per channel rather than a 16 bit monochrome image.

Have I missed something?

I've included an example image and part of the Level 4 debug below. It even says BIT_DEPTH=16 in the log output so, I guess it's trying?

(I'm using the legacy overlay because I thought the modern overlay may be affecting the output format, but seemingly not)

2024-06-05T01:05:08.469757+09:30 allsky allsky[26597]:   > *****
2024-06-05T01:05:08.469972+09:30 allsky allsky[26597]:   > Image took 6,212.0 ms to save (average 5,667.3 ms).
2024-06-05T01:05:08.470035+09:30 allsky allsky[26597]:   > *****
2024-06-05T01:05:08.475060+09:30 allsky allsky[67197]: saveImage.sh NIGHT /home/allskycam/allsky/tmp/image-20240605010404.png DATE=20240605 TIME=010404 AUTOEXPOSURE=0 sAUTOEXPOSURE= EXPOSURE_US=1075613 sEXPOSURE=1.1 sec AUTOGAIN=1 sAUTOGAIN=(auto) GAIN=200 AUTOWB=0 sAUTOAWB= WBR=0 WBB=0 BRIGHTNESS=100 MEAN=86 FULLMEAN=30 TEMPERATURE_C=6 TEMPERATURE_F=43 BIN=1 FLIP=both BIT_DEPTH=16 DARKFRAME=0 eOVERLAY=0 AUTOUSB=1 USB=50
2024-06-05T01:05:46.924230+09:30 allsky allsky[67258]: INFO: Loading config /home/allskycam/allsky/config/settings.json
2024-06-05T01:05:46.925213+09:30 allsky allsky[67258]: INFO: Running night flow...
2024-06-05T01:05:46.925485+09:30 allsky allsky[67258]: INFO: ----------------------- Running Module allsky_loadimage.py -----------------------
2024-06-05T01:05:46.925564+09:30 allsky allsky[67258]: INFO: Attempting to load allsky_loadimage
2024-06-05T01:05:46.925621+09:30 allsky allsky[67258]: INFO: Image /home/allskycam/allsky/tmp/image-20240605010404.png Loaded
2024-06-05T01:05:46.925689+09:30 allsky allsky[67258]: INFO: Ignoring watchdog for module loadimage
2024-06-05T01:05:46.925753+09:30 allsky allsky[67258]: INFO: ----------------------- Running Module allsky_overlay.py -----------------------
2024-06-05T01:05:46.925799+09:30 allsky allsky[67258]: INFO: Attempting to load allsky_overlay
2024-06-05T01:05:46.925852+09:30 allsky allsky[67258]: INFO: External Overlay Disabled.
2024-06-05T01:05:46.925911+09:30 allsky allsky[67258]: INFO: Module allsky_overlay.py ran ok in 0.00s
2024-06-05T01:05:46.926007+09:30 allsky allsky[67258]: INFO: ----------------------- Running Module allsky_saveimage.py -----------------------
2024-06-05T01:05:46.926070+09:30 allsky allsky[67258]: INFO: Attempting to load allsky_saveimage
2024-06-05T01:05:46.926127+09:30 allsky allsky[67258]: INFO: Image /home/allskycam/allsky/tmp/image-20240605010404.png Saved, quality 9
2024-06-05T01:05:46.926183+09:30 allsky allsky[67258]: INFO: Ignoring watchdog for module saveimage
2024-06-05T01:05:46.926226+09:30 allsky allsky[67258]: INFO: night flow Complete...
2024-06-05T01:06:02.256361+09:30 allsky allsky[26597]: Executing sunwait poll exit angle -6.0000 34.9195S 138.60298E > /dev/null
2024-06-05T01:06:02.263150+09:30 allsky allsky[26597]: -----```

[EricClaeys]

@simonleeADL, Simon, sorry for the slow response. I've been out of town and haven't had a chance to look into this. I believe you've done everything correctly. Please do this:

sudo systemctl stop allsky
sudo truncate -s 0 /var/log/allsky.log
# Set Debug Level to 3 (4 only adds the overlay INFO lines which aren't relevant).

after you get an image in Live View, attach (don't copy/paste) /var/log/allsky.log and I'll take a look. I'll also try 16 bit on my ZWO camera.

Just curious - is there a reason you aren't using auto-exposure? If you do use it, I suggest NOT using auto-gain at the same time.

I like your image with all the buildings and clouds!
It looks like a mono image, not RGB. Which is it?

@Alex-developer, does the Overlay system support 16-bit mono images?

[simonleeADL]

Hi Eric!

Here's the log file you've requested:

allsky.log

I believe I'm using auto-exposure? But that's a good point, I could probably set the gain to a fixed value.

The image is monochrome, but it's being saved as an RGB PNG (where every R, G, and B value is the same per pixel) with 8 bits per channel.

Thanks!

[simonleeADL]

@EricClaeys

I figured it out!

In this line here (in allsky_loadimage.py), cv2.imread(s.CURRENTIMAGEPATH) should be cv2.imread(s.CURRENTIMAGEPATH,cv2.IMREAD_UNCHANGED) (which is appropriately done in allsky_overlay.py).

This succeeds in outputting a 16 bit monochrome PNG when asked. The legacy overlay does not interfere with this, however (unless I've done something wrong) the modern overlay simply does not show up.

[Alex-developer]

@EricClaeys

I figured it out!

In this line here (in allsky_loadimage.py), cv2.imread(s.CURRENTIMAGEPATH) should be cv2.imread(s.CURRENTIMAGEPATH,cv2.IMREAD_UNCHANGED) (which is appropriately done in allsky_overlay.py).

This succeeds in outputting a 16 bit monochrome PNG when asked. The legacy overlay does not interfere with this, however (unless I've done something wrong) the modern overlay simply does not show up.

Thanks for the fix.

I have added a fix to the current release, its awaiting merge and also to the upcoming release

Cheers

Alex

[EricClaeys]

@Alex-developer, FYI