xcalib is a program that allows you to use ICC profiles (to load its
'vcgt'-tag) for display calibration on X11-Servers with XVidModeExtension
supported (like X.org or XFree86 4.x.x). It can't create the profiles
so you need to acquire them elsewhere (e.g. from some commercial
program or from your display vendor).
New port added, thank you!