Digital Media Technology

Softmasking (Alpha Channel)

Softmasking (Alpha Channel or Alpha Composting)

What is softmasking, alpha channel, or alpha composting? How does softmasking help in image processing? For what softmasking is used?

Softmasking, alpha channel, or alpha composting is a channel/process used in graphic software to combine an image with a background to create the appearance of partial transparency. It is very helpful in rendering different image elements in separate passes, and then combining the resulting multiple 2D images into a single, finished image. Softmasking is used widely for combining computer rendered images with live footage.

Photoshop allows us to save multiple alpha channels creating the appearance of partial transparency in one image. The darkest sectors of an alpha channel are transparent while white ones are lightproof and gray ones bring out different levels of transparency. In the majority of cases, alpha channels complement clipping paths to create soft edges for hairstyle.