Alpha channels, also referred to simply as channels, let you store and edit path-based and pixel-based selections in an active document. Corel Painter stores only the current selection by default, therefore, when you make a new selection, your previous selection is automatically lost. However, by saving the selection as an alpha channel, you can retain the selection information and load it in the image whenever you need it.
The alpha channel is a grayscale image that stores 8 bits of information per pixel, which means that each pixel can be assigned one of 256 levels of gray — from 0 (black) to 255 (white). White areas of the channel are selected, and black areas of the channel are protected. Intermediate levels of gray are partially protected. For example, areas that are 50% gray will allow 50% of the brushstroke or effect to get through the channel to the image.