Filling color to canvas background

The workspace surrounding the visible image area is commonly referred to as the canvas. This canvas area is filled with a gray color by default (equal amounts of RGB 192), which is a good, neutral choice suitable for optimizing images. However, you are not restricted to this color. You can change it to a custom color if you wish. Changing the color could help contrasting to the image to simulate the environment in which the image may be eventually presented.

To change the canvas area color, just choose the right color you wish to fill to the background canvas, then by selecting the paint bucket, hold down the Shift key and click in the canvas area.