Background Equalization

[Radar]

With PI having so many functions and features and still working my way through them, what is the best way to equalise the background so that it is consistent? I seem to get a greenish circular band inside some of my images (mostly galaxies). Flat frames don't fix this. I've attached an image of Centaurus A, as you can see, just around the galaxy there is a greenish band. There are probably a myriad of ways to solve this problem, just interested in what others here would use?

Thanks

Ray

[eganz]

Try automatic background extraction, or dynamic background extraction.
DBE is more versatile, but takes more effort to learn and set up.
E

[Radar]

Thanks Eganz. I've tried those but my settings may be wrong. I used 100 background sample points, and background certainly changes colour but the green rings are still visible. The image on the left in the image I've just attached is after DBE and ABE and setting the white and black points in Colour Calibration via preview samples.

Cheers

Ray