Photoshop channels store color information about images. By default, grayscale and indexed color images have one channel, RGB images have three channels, and CMYK images have four channels. These are referred to collectively as the default channels. You can use the Channels pane of the PSD Import palette to show and hide all channels, to change the color and ink solidity of a selected spot-color channel or alpha channel, and to assign spot colors to selected indexed colors. For example, you might assign special effects such as varnishes, embossing, and die cuts to channels.

• Showing and hiding channels
• Modifying channel color and solidity
• Working with indexed color channels