I am very concerned about color settings, and I have been very angry with GNU/Linux in that respect lately. When I get a new machine, one of the first things I do is set the gamma correction factor, in xorg.conf or with xgamma. It used to work perfectly 3 or 4 years ago, only Mozilla would do something strange to pictures and ruin it... But the colors in the window manager, for example (vtwm), or in other programs would look perfect. Now, there is something very strange going on in the machine I am working today. Although the colors look right if I display test images, all the chrome from the graphical program I use look bad. I don't know if they were set up for non-corrected monitors or what... I'm still trying to figure out what could be still wrong in my system. It looks like there is some "extra" gamma correction going on somewhere. And today people like these subtle shadings in the interface, and suing gray texts... That all just vanish! :( But anyway, what do you want to know if X can do? Dual screen or color correction? Why would both at same time be difficult if they are possible alone? As for using a camera to analyze colors, that might work somehow, but you must bear in mind there are imperfections in the moment you take the picture, and you must take that in consideration. But you might reach a set of parameters to help you make things look like you want them to. Last note: good thing you are using a CRT, because LCDs can be very bad for color. My monitor has only a very narrow strip I can actually make things look good there. The gamma varies very strongly with viewing angle, and I guess other parameters too. Good luck! :)