So here is my attempt at
@Juno16 Jims data. Thanks Jim!
M101 is much harder to do well than one would think. Thats from my own personal experience but I've seen lots of other imagers say the same. I'm not sure why - It has lots in its favour, size, location, details within the galaxy but I just struggle to do it well. This one is no exception - and its nothing to do with the data which is great.
I think its really useful to have some processing goals before you start a specific image otherwise its easy to meander along wherever the software decides to take you. So on this one my goals were; get some blue in the galaxy but without it being a deep blue (personal preference), incorporate Jims L-enhance data but shoot for magenta rather than deep red
Ha (personal preference again), since we have
RGB data get a nice range of star colour, get structure within the galaxy as far into the core as possible (accepting some noise in expense for detail), get some of the outer star clouds to show.
Processing was quite long winded and I took a few dead ends and had to backtrack several times to get what I wanted
In Pixinsight
Linear
Registered the two images
RGB and LE (L-enhance) and cropped each maintaining reg,
DBE on
RGB - I was seeing an axial gradient so did an axial pass then a normal pass which seemed to work well
DBE on LE
Colour correction - I tried PCC on
RGB but it was not doing a good job - really washing out the colour that was there - I processed the PCC output in parallel to the non-PCC but in the end scrapped it as rather insipid.
Deconvolution, EZ-denoise and StarXterminator on both
RGB and LE
Gently stretched starless files using HT
Non Linear
RGB - CT for contrast and saturation, LHE
LE - further tweaks in CT and LHE then I made a range mask and brightened up only the inner
Ha areas - this may have been a mistake. Removed R channel and called
Ha.
I tried several ways to get the
Ha into the
RGB (used NBRGB script, tried putting it in as a Lum layer - neither gave a good result and I think this is where I paid for my range mask mistake) but settled on blending it 50/50 (pixelmath) with the red channel from
RGB and recombining as HaR-GB
HaRGB - further adjustments with CT and a gentle LHE
Stretched the
RGB stars, increased the sat in CT then added the stars back to the starless HaRGB (Pixelmath).
I tried
@STEVE333 's "make it pop" routine which usually gives me good results but this time was not very pleasing so not used.
Exported as 16b tiff
In Photoshop
Balanced background and adjusted black point (I find this much easier to do in
PS)
Some minor tweaks on colour and sat in Camera raw filter
Tried my selective High Pass routine but like Steves "pop" it was not really giving a good result
Did a crop in and then exported both crop and uncropped as jpeg to give;
Its OK but honestly its not as good as it should be - the data is better than this. The Curse of M101 strikes again!!
Comments/suggestions on the process flow greatly appreciated