Photoshop's Burn Tool paints in areas of darkness to an image. It can be used to burn in shadows of a portrait, darken the skin tones of a model, or increase the intensity in a stormy sky. Taking the form of a paintbrush, the Burn Tool can strengthen the tones of an image in a more artistic way than other methods, making fine, precision guided adjustments that add contrast and tonality to an otherwise flat image.