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02.01 Introduction

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In any “digital workflow” to make any changes or creative decisions, you “need to select it to affect it.” The computer just has a pile of information that represents your content. If you want to add more flowing abstract colors to a background of a video, then some way of telling the computer what is background and not background is required. In early film production, physical masks were used to only allow a certain portion of a film frame to be exposed to light. Then this “mask” shape was reversed so the previously unexposed portion of the film could capture information. Masking tools still remain in digital video software editors, just like the terms “burn” and “dodge” remain in the tools of digital photo editors. In addition to simple masks, luma keys, chroma keys, rotoscoping, track mattes, blending modes, overlays and many other tools allow you to select portions of your video content and make changes. This allows you to make more deliberate creative decisions and more complex video compositing.

Learning Objectives

  • Use masks to modify and combine videos
  • Shoot video with green screen using proper camera settings
  • Key out green screen with Premiere Pro
  • Key out green screen with After Effects
  • Use rotoscoping to select the subject of a video not in front of a green screen
  • Use basic compositing techniques to combine video with an alpha channel with other content

Key Terms

  • Alpha Channel
  • Green Screen
  • Mask
  • Track Matte
  • Rotoscoping
  • Luma Key
  • Abstract Video
  • Public Domain
  • Fair Use