how would you go about processing a huge neb field?

[Carlos Milovic]

No no, what I meant was that once you calibrate the filter factors, then substract the LP, and after that all the colors should will be fine (and add a "background sky bias"... the median of the model works fine)... The problem, of course, is finding the LP gradient.

[Silvercup]

Hi:

I tried new background correction procedure with your image and this is the result:



Has background correction "eaten" any nebulosity? What do you think?

Best, Silvercup.

[h0ughy]

Hi:

I tried new background correction procedure with your image and this is the result:



Has background correction "eaten" any nebulosity? What do you think?

Best, Silvercup.

pm me your email address and i will email you the full res original jpeg to have a play with.  looks promising what you have done

[Silvercup]

Hi:

Basically the procedure is similar to doing this:

Just extract background with AutomaticBackgroundExtractor with substraction in target image correction, but without applying to image.

Now you must apply this pixelmath expression with rescale result checked:

_MG_6698etaraw-_MG_6698etaraw_ABE_background/1.3

1.3 is a correction factor. It's easy to obtain this factor. Just do a preview on a zone you are relatively sure that is background. Apply a factor correction begining with 1. Inspect preview histogram. In your image you wil see that RGB channels don't match, the red is displaced. Increase factor till RGB channles match.

An image example:



That's all. I think this procedure do a great job.