Remove a color cast

On the main site you find two different Photoshop tutorials about removing a color cast, which are quite popular. Today I published a third method, which works for a slightly different problem. Sometimes you get a color cast that is not present in the entire photo, but for example only in the shadows. Pictures of snow are notorious for that. The shadows become very blue, while the snow is perfectly white, or even a bit yellow because of the late evening light. If you would correct the blue shadows using one of the two previously published methods, the snow would become very yellow. You would also lose the blue color of the sky. That’ why I published this alternative method, and why I published it today…

Update 8th January 2011: Direct link added.