Define chroma keying and name two common colors used as backgrounds.

Define chroma keying and name two common colors used as backgrounds.

• A. A technique to track motion in 3D; colors cyan and magenta.
• B. Keying technique to remove a colored background; common colors: green and blue.
• C. A method for adjusting exposure; colors white and black.
• D. A process for stabilizing footage; colors yellow and orange.

Answer: (B)

Chroma keying is a technique in video production that removes a solid-colored background so you can replace it with a different image or scene. It works by isolating pixels that match the chosen background color and making them transparent in the final composite, letting the new background show through.

Two colors are commonly used for the backdrop: green and blue. Green is the most popular because camera sensors capture more information in the green channel, which helps create a cleaner key with less noise and less color spill onto the subject. Green screens also work well with a wide range of lighting and wardrobe choices.

Blue is used in situations where green would cause issues—such as if the subject wears green or if the scene lighting makes green difficult to key cleanly. Blue provides a reliable alternative that still gives a strong separation between subject and background.

Other colors like cyan, magenta, white, or yellow don’t offer the same clean separation for most subjects, so they’re not standard for chroma keying.