Chapter 4. Creating Transparent Video with After Effects
Transparency plays a key role in the success of animation and interactivity. By embedding transparency into graphic elements, you can composite together different elements created at different times, allowing for true flexibility.
The alpha channel is the technology behind transparency in computer graphics. It first evolved in the late 1970s at the New York Institute of Technology and then continued to be refined at Lucasfilm and at Pixar. When you employ alpha channels embedded into footage layers, transparency data can travel seamlessly between After Effects and Flash.