getting rid of localised reflection and using Ha as Lum for background?

[troypiggo]

Hi there.  Lights from the neighbours place caused a bit of a problem with these images captured the other night.  Unfortunately I didn't notice until too late.  Only seems to have affected the luminance and blue filters.  First image is just the RGB, no background extraction or anything.

Second image is the best I could achieve with DBE, background neutralisation, colour calibration, etc.  Got rid of the green at bottom right, but see the blue patch top right?  The red is some Ha nebulosity.

Final is Ha.  I think the background in this image is what I'd like the final image to be.

So, how can I get rid of that brighter blue patch?  And is it possible to use the background of the Ha as luminance for the overall image?  If so, how?

[oldwexi]

Hi Troypiggo!
Would not use the Ha for reducing the blue shade.
Green and Blue ar very similar especially on the background.
Ha differs to much!
Therefore the solution:
Extract R,G,B from the DBE image.
discard R
PixelMath B - G gets you DIFF
Use the process
Range Selection on the DIFF
   this gets you a nice mask for this blue patch (dont forget to soften it )
Finally use
Curves on the masked DBE image and reduce the blue shade carefully.

Aloha
Gerald

[troypiggo]

Thanks mate.  I had a quick run through you're suggested method this morning.  Makes sense.  Created the mask fine, and can see the curves helping, but will need some time to get it right.  Bit of trial and error.