Hi Martin,
nice picture but there appears to be a problem with the black point.
Some parts are way down at 1 or 2 out of 255 bits.
Most people would aim for a black point of between 20 and 30 bits.
It appears that the black point has been clipped when the image was stretched.
I attach a picture of the Photoshop Histogram of your picture on the left of M20
and another of a random picture of M20 found on the internet on the right.
The Histograms shows the problem.
Louie Atalas gives some very good explanations of Histograms here:
https://www.youtube.com/watch?v=IllEy85eUWY
and here:
https://www.youtube.com/watch?v=fE2GS_87Ct8
Free programs like NASA FITS Liberator
https://esahubble.org/projects/fits_.../download_v30/
take all of the hard work out of stretching and when I was imaging
I used it all the time.
I found that the stretch function of x^(1/5) was very good
at getting high compression to cover the whole 255 bit range
once the picture ended up as a jpg.
I hope I have been of help to you?
cheers
Allan