Alpha channels grew out of work done at the New York Institute of Technology in 1977. The goal was to embed transparency data directly into each file to cut down on rendering. The name alpha was chosen because it’s the part of a mathematical equation that represents blend-ing between composited images. The embedded alpha channel eliminated the need for a separate traveling matte. After Effects users should consider embedding alpha channels as Photoshop users do. Embedded mattes reduce the need for two-step rendering and eliminate the possibility of a misaligned matte.
This post sponsored by iStockphoto – Save 10% – Get a Free Audio Track