Hi all
many thanks.
Yes I am having fun
especially since mastering this gamma select function in Iris, its sorta like a more manual version of the "Digital Development" function in Images Plus. Iris also has this handy function Paul "Photoncollector" put me onto called "black". To use, draw a small box on a black area of sky, then open the command window and type "black" then hit enter. It will set the background black. Then type "offset 500" hit enter, that will lighten the background a bit, only now it will be a nice neutral greay, in other words any colour cast is removed, effectively giving an instant correct colour balance. Its a VERY handy function.
Scott