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.
You can create alpha channels in several ways. One common technique you can use for video footage is chroma key technology. By shooting elements against a blue or green screen, you can easily remove the background. This technology is hardly new, making its first appearance at RKO Radio Pictures in the 1930s. The popularity of chroma key technology has grown immensely, bringing the technology and tools within reach of most content creators.
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