The geniuses at Digital Photography School show how to create some pizzazz by adding a small area of color to a black-and-white photo.
The process involves “desaturating” the color from an image and then using the History Brush to “paint in” the desired area. It’s pretty simple overall, though you’ll need to go slowly and exercise care around the edges. This tutorial leverages Photoshop, though it should work similarly in any image editor that has the same desaturate and history-brush tools.
Originally from Lifehacker