No matter how great digital cameras are, inevitably, you end up with a photo now and then that has a rather unpleasant color cast to it. You can use Levels, Curves, Selective Color or any number of other color correction tools found in Photoshop to fix it – but there is a quick one-click way that works fairly well.
Take the image below left. The photo turned out fairly decent, but had a nasty yellowish tint to it.
Simply selecting Image>Auto Color or hitting Command + Shift + B tells Photoshop to automatically adjust the colors in your image based on the hidden colors it finds in the photo. As you can see on the image above right, the correction worked perfectly.
Of course you could use a plethora of tools to do the job, and you might even get better results. But for a quick fix, Auto Color works pretty darn well.