How to Use Foreground and Background Colors in Photoshop CS6
Photoshop CS 6 has two categories of color — a foreground color and a background color. You apply the foreground color when you use the type tools, the painting tools, or the shape tools. The foreground color is also the beginning color of a default gradient applied by the Gradient tool. The background color is the color you apply with the Eraser tool and is the ending color of the default gradient.
When you increase the size of your canvas, you fill the additional canvas with the background color (also assuming you don’t have layers). You can find the swatches that represent the two color categories in the lower part of the Tools panel.
The default color for the foreground is black; for the background is white. Click the small icon labeled or simply press the D key to return the colors to the defaults. To switch the foreground and background colors, click the curved arrow in the Tools panel or press the X key.
Here are a few tips to help you get a handle on using tools with foreground and background colors:
Blend the foreground and background by using the Gradient tool. When you drag with the Gradient tool across the canvas and the gradient is set to the default, you get a blending of the foreground and background colors.
Fill selected areas with the foreground color. Just click your canvas with the Paint Bucket tool to select areas based on a Tolerance setting and fill those areas with the foreground color.
Apply the background color by erasing. If you’re working on a background, rather than a layer, you can use the Eraser tool to apply the background color. Some people prefer to say you’re erasing to the background or canvas color.
If you use the Eraser tool on a layer, you erase to transparency.
Add more background to your canvas and fill it with the background color. When you enlarge your canvas size, Photoshop, by default, automatically fills the added canvas with the background color.
If you enlarge a layer, the extra canvas is transparent.