I was somewhat disappointed with my M31 efforts when I compared my results with the excellent images presented by other members and I thought I would have a final attempt to try and bring out more data and push all the processing.
Besides the difficulties my ankle presented which put me off my game a bit I feel I do think certain factors worked against me which I believe was probably due to not using a mask to focus and I do think the smoke haze perhaps played a role in making collection of sharp data perhaps came into play as well. Also I really donot have a clue when it comes to merging the various channels and perhaps I have still turned out purple where the blue should be.
This is how I approached trying to do better.
First I stacked every image I had to create a master luminance which met I had to abandon the 3 times drizzle and opted for no drizzle so I could stack a huge luminance.
I don't know if it had any effect but I loaded my blue subs and after those were in DSS went into the folder and renamed all the blue subs so I could load two sets of blue, so double subs. I also did this for green...I really don't no if that had the effect of increasing exposure time or the quality of the stack.
I estimate that all up I took my exposure time up to maybe 7 hours both by creating a luminance using everything and the blue and green double up.
Processed each stack in Startools and merged the 4 in photo shop.
I merged the red and the green first rationalising that would be brownish and less likely to go purple when I added the blue...I did this in the van so I have not showed my daughter for a comment if I have a blue or purple outcome...
I worked hard when all were merged with the dodge and burn tools in photoshop to maximise detail contrast.. In GIMP I blew the image up to maximum and applied the erode filter in the hope that the stars would seem a little smaller and coloured in a few in photo shop using a solid layer colour and the rubber tool to give a hint of colour to some stars as they just seemed colourless and I hoped that it would not be too noticeable but if you look I may have created some red giants out of some main sequence stars
.
And I rotated the image until I was happy with the presentation I feel it just looked better from an artistic point of view...I anyone asks I will blame the optics inverting etc...and it is only a pretty picture approach after all.
I also took some time with the haze removal tool in photo shop..usually I just run the image thru of the standard setting but with a little care one adjustement seemed the best.
So how purple is it
Edit...second final attempt added
alex