Background neutralization

[CharlesW]

I began work on an HDR version of M42 yesterday. After cropping I found that there was no area of the images that were free of nebulosity. Most of the BN tutorials I've seen use a galaxy with lots of clear space around them. How does one handle BN with a gassy, dusty image? Thanks

[Harry page]

Hi

Bn can manage with very small sample say 10 pix square or try a dark part of the nebula , that works well sometimes

Harry