If you need to lighten (dodge) or darken (burn) parts of you image or photograph, here's how you do it. No dark room needed. Be easy with this one, as well, folks.
- Create a new layer via Layer > New... > Layer. Name that layer Dodge/Burn. Change the blending mode to Overlay, and again make sure that “Fill with 50% gray” is checked.
- Select the brush tool and reset your foreground/background colors to black/white by pressing D. Change the opacity of the brush at the top of the screen; 5% is a pretty good start, but anywhere above that can be too strong.
- Brighten highlights by painting in white on the Dodge/Burn layer. Darken shadows by doing the same. It is possible to darken highlights by painting them black, but it tends to turn out pretty bad. Better to use it to accentuate things such as highlights in hair, or wrinkles in hands. It’s most effective on black/white images.