At times, you will want to lighten or darken an image only in selected areas. Although you could select an area and make changes only to that area (see Part 3, "Selection Techniques"), you may find the Dodge, Burn, and Sponge tools more effective. These tools allow you to brush your corrections onto an image: The Dodge tool lightens the image, the Burn tool darkens it, and the Sponge tool lets you saturate or desaturate the color intensity.
Select the Proper Tool
Open the image you want to affect. Click and hold the Dodge tool in the toolbox. A pop-out menu appears from which you can select the Dodge, Burn, or Sponge tool. Point to the desired tool and release the mouse button to select it.
Set the Options Palette
From the Options bar, select Shadows, Midtones, or Highlights from the Range menu, depending on the tonal area of the image you want to modify. For the Sponge tool, select Saturate or Desaturate to increase or decrease the color intensity.
Set the Exposure
Exposure refers to the degree of effect applied to the image as you use the selected tool. You also can think of it as intensity or pressure. In the Options bar, click and drag to adjust the Exposure slider. Select a higher percentage number for a dramatic effect; select a lower number for subtle changes.
Select a Brush
From the Brushes palette (located in the palette well on the right end of the Options bar), select a suitable brush size for the tool you're working with and the image you're editing. To avoid hard-edged brushstrokes, select a feathered brush.
Begin Brushing in the Effect
Begin with a very low exposure and a feathered brush that is large enough to cover the desired area in just a few strokes. Repeatedly brush over the area, building up the effect as you go. If a pronounced brushstroke appears, undo the stroke (choose Edit, Undo) and lower the exposure. Click and drag lightly to apply the effect, instead of dragging back and forth.
Change Brush Size and Exposure
As you work, select a smaller brush size as needed to work into smaller areas. If you change the brush size, consider decreasing the exposure to hide the brushstrokes. This may be necessary because smaller brushstrokes are more visible when repeatedly applied.
To Undo the Effect
Because these effects are applied with repeated brushstrokes, choosing Edit, Undo does not revert the image to its appearance before you began. Give yourself a safety net by opening the History palette and creating a snapshot before you begin. (See Part 2, Task 5, "How to Undo with the History Palette," for more information.) After the effect is applied, click the snapshot to revert to the previous state or to compare the result.
Brushing in a Straight Line
To brush the effect along a straight line, click once at the start of the line, press and hold the Shift key, and click at the end of the line. Photoshop applies the effect in a straight line between the two points.