Follow-on from the previous image with 4 hours of S-II data added for a first attempt at a Hubble palette image, followed by another SHO image which preserves the dominance of the green channel due to the brightness of the H-a image assigned to it. The second approach was easier and preserved more detail, and by avoiding the more dramatic colour changes I had less noise I to deal with.

I had no idea how difficult it was to produce these things! The 'natural' colour with this mapping is a rather spectacular emerald green due to the dominance of H-alpha in the green channel. It took me several tries and reading various tutorials before I managed to get something that looked about right.

It's not particularly good, in part due to the very aggressive noise reduction I ended up doing to stop colour noise being too dominant in the final image, and the overly dark background which is an attempt to mask some strong colour casts that were a bit too obvious otherwise. At least it works as a proof of concept and gave me useful experience with the technique.

I'll definitely have a few more goes and perhaps add some more captures to boost the SNR, especially for the O-III image which is a lot fainter than I expected.

The rather different revised version is far closer to the initial RGB combined image produced in Astro Pixel Processor and I think it's worked a lot better. It didn't need as much processing and stretching of channels so consequently there was much less noise, and it was much easier to get a reasonably neutral background and keep more of the stars. The green and blue of H-a and O-III stand out well so faint detail is more obvious and gives a better idea of the true size of these things. From an aesthetic POV I also prefer images like these to have the subject matter gradually blending into the rest of the starfield rather than being isolated against the background, which in extreme cases can look almost artificial.