Thanks for comments, Russel and Cam
Cam, at the bottom of
http://www.astrosurf.com/buil/us/iris/iris.htm you have the complete tutorial for IRIS.
IRIS is a little difficult to work. It has many ressources, filters and tools for adjustment and enhancement of a photo. It isn't easy to choice the better tool, group of tools and theirs values. Small difference of values can change very much the result.
You must some time of using and some experiments to know how the ressources work and how they can change an image.
I posted these images here because they show areas and colors that I couldn't bring out with Photoshop. And I worked with the JPG, first photo, a result of Photoshop.
The first photo is more natural. But I feel I can let this natural appearance with the enhancements from IRIS: color and faint nebula area. It was an essay... of who is trying the first time with IRIS.
I returned to this software because I wish to do some photometries. And IRIS is a free software with some ressources in this area. And to use well these ressources ... you need know to use IRIS. You don't need to be an expert in it, but need to feel comfortable with it.
