A Quick demonstration of the Nuke gizmo "mmColorTarget" that i've been working on recently:
It matches colors of two input images using the MacBeth ColorChecker.
This can be useful especially if you need to match footage from different cameras with different color settings. The resulting ColorMatrix Node does a linear color transformation that approximates the source to the target values. Also there's an option to use reference Values to approximate neutral sRGB Values instead of a target image.
Available on nukepedia, check my blogpost for further information.