A comment on NB colors – targets normally imaged in RGB can sometimes appear strangely colored when imaged in SHO; that is, more strange than usual. A while back one of the PixInsight team suggested an alternate blending formula to use in Pixel Math when combining the individual NB masters:
My recent NB image of the Cone Nebula (another target often imaged in RGB) produced a color balance with normal SHO processing that I did not particularly like, so I tried the alternate mixing. I was much happier with the results, as it looked more “natural.”
The resulting image:
Cone Nebula - Alt mix
The result of this mixing will vary greatly depending on the relative strengths of the Ha, SII and OII data in your target but you can get creative with final mix used.