ABE generates gray background

[animan]

I can often get into situations where ABE generates a "Gray Background" with equal RGB values. Image inspection of generated background reveals RGB values of around 10.86 in 16-bit numbers on an unstretched image.  This is using a Function degree of 1. If I subtract this background and generate another one, it generates the same gray background again... I can keep going on and on with same result.

My images have a lot of gradients due to light pollution. ABE will initially generate backgrounds to match the gradients and then keeps on generating the Gray backgrounds if re-run. Why are the gray backgrounds being generated and should the gray correction be indeed applied to the image?

Thanks.

[RickS]

You would get a grey background when there's no colour cast left.  That would be time to stop...

[animan]

Thanks for the response.

Yes, the normal thing would be to stop after ABE starts generating grey background, however, I have noticed that if I continue applying ABE with grey backgrounds, I gradually start to reveal coloration in stars and other subtle detail, it's like peeling layers of an onion. Do you know why this would be?

Also, is there a way I can run a Pixinsight process like ABE in a loop, I would like to experiment to see what I end up with after 500 to 1000 iterations.

Thanks.

[RickS]

Yes, the normal thing would be to stop after ABE starts generating grey background, however, I have noticed that if I continue applying ABE with grey backgrounds, I gradually start to reveal coloration in stars and other subtle detail, it's like peeling layers of an onion. Do you know why this would be?

If you keep removing a pedestal with R=G=B then any differences between the channels would be exaggerated, so I guess that would explain increased coloration.  I have a collection of techniques for increasing colour already so I've never felt the need to do this.

Also, is there a way I can run a Pixinsight process like ABE in a loop, I would like to experiment to see what I end up with after 500 to 1000 iterations.

You can write a script but I don't know of any simpler automated way for that many iterations.

Cheers,
Rick.

[animan]

Thank you Rick.