Too much red with AWB in Live Stack

[admin]

Hi Don,

Thanks for the quick response. Unfortunately when I load the first image into the test camera and use it for live stacking I don't see the problem that you're describing – the AWB button actually gives a fairly good white balance for me when I try that out.

noadjust.PNG (751.7 KiB) Viewed 552 times

awb.PNG (717.58 KiB) Viewed 552 times

Maybe we'll get further by using testing with the raw frames saved during a live stack – if you can send me a couple of those after your next session along with any dark or flat frames used then I could try that approach. If you happen to have recorded the session online and can point me at the link then I can compare my experience to how the feature worked for you as well.

Cheers, Robin

[donboy]

Hi Robin,

When I used Fitswork to debayer the .fits files The first one was very bright red and the second .fits file was slightly green. The first few .fits files were collected without manual correction which was the fits 1 image and the fits 3 image was captured after manual correction by reducing the red slider.

I'll follow up this weekend with what you suggested.

Don

[donboy]

This is frame_3.fits before AWB and after AWB:

Screen Shot 2019-02-06 at 8.47.54 PM.jpg (218.18 KiB) Viewed 549 times

Typically what we see when AWB is pressed. The blue is inline with the green, but the red is too much and we have to manually reduce the red to line up with the blue and green in the Display histogram.

Screen Shot 2019-02-06 at 8.47.38 PM.jpg (231.17 KiB) Viewed 549 times

Don

[donboy]

Well I was hoping that the AWB in live stack would be able to handle the LPS filters like the Idas P2 or Idas D1. When using these filters with my ASI294 I am unable to get a white balance under Image Controls and end up with the Red channel set to 99 and still not getting the red to match the green channel.

When I stack and apply the AWB in live stack the red channel over compensates and sets the red channel very high. The amount of overshoot is tied into the level of the red channel when set up under Image Controls. If Red channel is almost equal with the green channel the over shoot for AWB in live stack is not as great, but if the red channel is low compared to the green channel the application of AWB in live stack results in a very large red channel overshoot.

It thus appears to me that the AWB algorithm is not working in a fashion I would expect. I would have thought that the AWB would track the Green channel's level and match the red channel to it. It appears to have a non linear response.

Don

[admin]

Hi Don,

To be able to improve the white balance calculations I need to collect more images that don't work well so that I can try and understand why.

To be really useful the images must be saved from live stacking with the 'Save as raw (32 bit) stack' option rather than any other save options. That gets me the images before the live stack colour adjustment and stretch adjustments are applied so that I can then process the images from scratch rather than trying to reprocess an already processed image which is usually not helpful. Along with the unprocessed stack image, it would be ideal if you could provide the settings of the R/G/B sliders that you feel give a good colour balance and also a rough idea of the positions of the live stacking stretching black/mid/white levels.

Cheers, Robin

[donboy]

Don't remember how to send larger files

Stack_32bits_20frames_300s.CameraSettings.txt

(1.06 KiB) Downloaded 15 times

[donboy]

Robin. here are files you requested

https://www.dropbox.com/s/j0v33stn0ois4 ... .fits?dl=0
https://www.dropbox.com/s/y7nylneidvy9s ... 4.PNG?dl=0

[admin]

Thank you Don

Cheers, Robin

[JimsShed]

Hi,
I've also seen the over-red issue discussed here, and at times over-blue. In fact if I live-stack "Test Camera 1(deep sky)" which shows the Orion Nebula and click "Auto colour balance from histogram peaks", then I get excessive over-blue and under-red at the same time. Not sure if this is exhibiting the issue or a quirk of the test image.

Moving on though, I just assumed the auto balance button to be an algorithmic guess and always deal with any over-under by manual adjustment, however I have on occasion had live stacking results where I just couldn't adjust to the colour quality I normally expect, and in those cases noticed that doing one of the following got everything happy again
1) Set both dark and flat files to "None"
2) Stop using the flat file, and subsequently create a new one
3) Recreate my dark file for the target exposure (this is my usual fix)

My camera is an ASI 294MCPro at -10c.

My 20 cents worth. May or may not be connected to the issue.
Jim

[donboy]

Hi Robin,

I was wondering if there was any advances in resolving the Auto Color Balance in Live Stack.

This may be naively oversimplified but could the ADU levels of the Red and Blue be servoed to the Green channel in Live Stack?

Don