Beginning with a brief explanation of the keying process, Mark takes you through the steps involved in creating a perfect green-screen key: generating a rough matte, eliminating color spill and matte lines, and refining problematic edges. He shows how to work with Keylight and Primatte—two indispensable keying tools in After Effects—and explains when to use one over the other. And for times when green screen won’t work, he shows how to generate high-contrast mattes, or luma keys, based on the luminance data in your footage. Last, learn about compression and how to prep a shot for keying.