What is the purpose of a chroma key in digital video production?

• A. To superimpose images or video onto a different background.
• B. To adjust the lighting in the scene.
• C. To remove background noise.
• D. To color-correct skin tones.

Answer: (A)

Chroma keying lets you remove a solid colored backdrop and replace it with a different background. This technique works by selecting a uniform color (commonly green or blue) in the shot and making that color transparent so the foreground subject can sit in front of any other image or video. In practice, you shoot the subject against a clean, evenly lit background, then use the keying software to strip out that color and composite in the new background. The goal isn’t to adjust lighting, reduce background noise, or color-correct skin tones—those are separate tasks—it's specifically about creating a seamless composite by swapping the background. Green is often preferred because it separates well from skin tones and clothing and responds better to lighting, which helps produce a cleaner key.