Greg,
Quote:
I do some minor stretching in CCDstack (click auto) and process the callibration, the data rejection and the registering and combine into masters and the initial colour combine. I don't see much evidence of a dark ring around it on my monitor but I can a slight one in the thumbnail.
I don't use DDP for stretching of my images but rather curves and levels.
In Photoshop that is 16 bits. Do you think 32 bit files in Photoshop would help?
Unfortunately this was shot low in the sky where I have the most light pollution. I then use a few gradient handling techniques to get rid of that. That's probably some minor residual of that routine. If you saw the process along the way its a mile from where it started. Yes the background being a bit darker is part of that process as well. At a dark site I would allow the background to be a bit lighter like Mikes - a dark grey My image is also only 1/3rd of exposure time of his and he is now in a dark site area. If the object were higher or past the Meridian and I was imaging to the west where I have little light pollution it would be a nicer result.
So in summary I don't think it came from the stretching process but the gradient handling process - Gradient Xterminator requires you to lasso the object and invert the image before running.
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Hi Greg,
I am only a beginner compared to you so take all this with a grain of salt if you want.
I find that stretching in 32 bits is well worth the effort.
You have DDP in Maxim but I haven't tried that yet.
I now save my stacks from Deep Sky Stacker as 32 Bit FITS files
& stretch them using the free program
FITS Liberator.
I find that the compression stretch function x^1/5 works well.
It expands out the lower levels which allowed me to show
the halo of Centaurus A which was almost missing on previous
Photoshop 16 bit stretches. ( in my flickr photos )
I was surprised that I could get any halo at all as I took the image
from a semi light polluted location - outer suburb of Melbourne
& only 2 hours of integration time.
Yes - gradient handling can cause the darker area around a galaxy.
I use
Fitswork 4 & -
background flatten - variable flatten.
Yes it also requires a masking of the brighter areas which can
cause a dark band to form around a galaxy.
Whatever we do we are always limited by light pollution.
Mike had the luxury of more time & super dark skies.
Your image is remarkable given the conditions.
cheers
Allan
)
...we'll see, I have other options...it'll probably be something Rick's imaging I bet 
I'm playing around with the processing of my first Hubble Palette image tonight - trying to do J.P. Metsavainio style tone mapping in PixInsight.
