Auto Stretch issues - can't see any difference in the image

[Domain105]

Hello. I've been trying to get the AUTO_STRETCH option to work with the Allsky software on my Raspberry PI to work but don't seem to be making progress.
I've updated line 106 in scripts/saveImage.sh to an x due to there being a comma in there which I've been told is an error. I've set Auto Stretch to true and have tried the following settings in config.sh
AUTO_STRETCH="true"
AUTO_STRETCH_AMOUNT=5
AUTO_STRETCH_MID_POINT="30%"
I've tried various different amounts from 1 through to 1500
I've tried different midpoints from 0% to 80% and restarted the service after each change but I do not see any difference at all in the images.
Should the stretch be very subtle and I am missing it or is there something else I have missed?

Camera is a PiHQ on Bullseye. With debugging to 4, I can see in the log that that it is stretching but I see no difference in the image
Any help or guidance will be very much appreciated.

Jan 21 22:12:21 raspberrypi allsky.sh[5287]: STARTING EXPOSURE at: 2023-01-21 22:12:21 @ 50.0 sec
Jan 21 22:12:21 raspberrypi allsky.sh[5287]: > Kill command: pgrep 'libcamera-still' | xargs kill -9 2> /dev/null
Jan 21 22:12:21 raspberrypi allsky.sh[5287]: > Capture command: libcamera-still --output '/home/pi/allsky/tmp/image-20230121221221.jpg' --timeout 10 --nopreview --width 4056 --height 3040 --shutter 50000000 --gain 2 --awbgains 3.24,1.47 --saturation 1 --brightness 0.5 --quality 100 > /tmp/capture_RPiHQ_debug.txt 2>&1
Jan 21 22:12:22 raspberrypi allsky.sh[7935]: saveImage.sh: Stretching '/home/pi/allsky/tmp/image-20230121221126.jpg' by 50
Jan 21 22:13:15 raspberrypi allsky.sh[5287]: > Focus: 67.490274
Jan 21 22:13:15 raspberrypi allsky.sh[5287]: > Saving NIGHT image 'image-20230121221221.jpg'
Jan 21 22:13:15 raspberrypi allsky.sh[5287]: Sleeping 0.1 seconds...

[EricClaeys]

@Domain105 I just started using it a few weeks ago and had the same experience. I am using AMOUNT=30 and MID_POINT=10%.
What I did to determine my settings was to take an unstretched image, then manually ran the convert command on it with different settings and saved those files using the settings as the file names. That made it really easy to compare.
If you are good with shell scripts you could write a few line script to vary both settings and create the filenames automatically.

I found that increasing the MID_POINT very much made the light parts too bright without changing the dark parts.

Let me know how it goes. If you still don't see a change, attach a picture. Add a .txt to the filename first.

[EricClaeys]

You can look at line 106 in the saveImage.sh script to get the "convert" command line. It's pretty easy. You'll want a DIFFERENT output file name (the last parameter) than the input file.

[Domain105]

Thanks for the prompt reply Eric. At least I know it is not something I am doing wrong if you have expereinced the same. I'll try the separate convert command as you suggest.

[Domain105]

Hi, just tried the concert command separately and it worked. I just need to work out the best settings now. I'm not great with shell scripts but have dabbled in Python, .Net etc so should be able to work it out. Thanks for your help.

I'm not sure why the same command in saveimage.sh fails to run but atleast i can now see if stetching improved my images or now.

[EricClaeys]

@Domain105 I added an entry to the "to do" list to add some text and an example of using AUTO_STRETCH. Basically what I told you but more details.
I don't know why convert wouldn't work in saveImage.sh. There's a check after it executes to see if it failed and if so, display a message in the log. Can you check in the log? Look for AUTO_STRETCH.

[Domain105]

Hi @EricClaeys, I'm away from hiome for a bit I did did extend the logging level to 4 and check for anything relating to Auto_Stretch but there was nothing I could see. The log output in my original post if all I get before it loops to the next image