Sometimes a photo cannot be used because of a color cast. Color cast can be very easily removed in Photoshop CS4. It has three powerful tools that can be used very effectively and with ease.
Take this free stock 
image for example. The reds dominate. How can you remove them with the least amount
image for example. The reds dominate. How can you remove them with the least amount of bother?
Step 1 : Go to Image. You will find three options -- Auto Tone, Auto Contrast and Auto Color. These are the three powerful tools that can be used to fix color casts.
Step 2 : First I am clicking on Auto Tone.
This provides an improvement to the image, but not quite enough. Press CTRL+Z to undo Auto Tone.
Step 3 : I have clicked on Auto contrast.
This is the result. It is not satisfactory at all. Press CTRL+Z to undo Auto Contrast.
Step 4 : I have now clicked on Auto Color.
Step 5 : Look at this. The color cast has gone. The point is sometimes Auto Tone will work, sometimes Auto Contrast and sometimes Auto Color. See which suits your image. You should apply any one of these just once. You should not use them in combination.That is all.
There is a followup tutorial here
Other photoshop tutorials are here
