This excerpt is from The Photoshop CS4 Companion for Photographers . Many photographers, including the pros, feel overwhelmed by all the editing options Photoshop provides. The Photoshop CS4 Companion for Photographers not only shows you which tools you'll need most often and how to use them, the book walks you though an enjoyable and efficient workflow that makes it easy to process your images using new user-friendly features that come with Photoshop CS4.
Most subjects will have some darkening under the eyes. Generally speaking, I think it looks unnatural to remove this characteristic completely. But you can do your subject a great service by softening those "bags under the eyes."

Select the Patch tool.

Select the area you want to adjust.

Click and drag to an area that will serve as the source
for the adjustment.
This technique doesn't completely remove dark circles under the eyes, but it does soften them dramatically. You can also use this recipe to correct hot areas on the forehead, and a variety of other imperfections.
If you want to see how your correction looks without the marching ants but without getting rid of your selection, press ⌘-H (Ctrl-H) to hide the selection outline. Press the keystroke again to bring it back.
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