Ha-ha!
If you're using Photoshop - for a quick fix, 'colour balance' is pretty good. But if you're after something a little more precise, I tend to use 'hue and saturation' to get an overall match, then play around with 'selective colour' for the fine tuning.
(
Captain Howdy,
Tue 26 Jun 2012, 9:57,
archived)