Astronomy Home Page

If you have 3 monochrome FITS files properly representing R,G,B filtered
data, then you can use standard (L)RGB techniques to reconstruct a proper
color image. See below for 3 methods:

Photo shop Tutorial URL:
http://www.autostarsuite.net/DonWaid/lrgb/lrgb.html

Other software can be used also. The essential thing is to align the colour
channels and scale them properly. See also
http://nightskypictures.com/lrgb.htm

For astronomical images, IRIS for example can do an excellent job with this,
see tutorial at :
http://arnholm.org/astro/software/iris/

To make it even better, you can also consider using Robert Gendlers technique.
Multiple Luminance Layering (LLRGB)