What does chroma key refer to in video production?

• A. A method of adjusting exposure
• B. A technique to superimpose images based on color hues
• C. A workflow for editing audio
• D. A camera lens calibration method

Answer: (B)

Chroma key is the technique of removing a specific color from a video so you can place another image or video behind it. In practice, you film against a solid green or blue screen, and the keying software analyzes the color hues in that range, making those pixels transparent. That lets the foreground footage sit on top of a different background, creating the composite shot. Good lighting and color separation are important to avoid spill and to get clean edges.

This isn’t about changing exposure, editing audio, or calibrating a lens. Exposure affects brightness, audio workflows handle sound, and lens calibration deals with sharpness and distortion—none of those directly accomplish background removal for compositing.