When a color is keyed out and replaced with video footage, this technique is known as what?

The technique of replacing a color in a video with another image or video footage is known as chroma key. This process typically involves using a specific color, often green or blue, as a backdrop, which is then digitally removed to allow for other visuals to be placed in its place. This is widely utilized in film and video production to create seamless integrations of live-action footage with different backgrounds or special effects.

Chroma keying is distinct because it relies on the color-based removal and requires specific lighting and camera settings to effectively isolate the color. The precision in selecting the color to be keyed out is essential for achieving clean edges and blending the inserted footage seamlessly with the original scene. This method is foundational in creating immersive environments in filmmaking and live broadcasting, where the subject can interact with a completely different background.

While digital compositing also deals with layering video images, chroma keying specifically focuses on the process of removing a uniformly colored background, making it the most accurate term for the described technique. Color grading pertains to adjusting the colors of footage, and frame blending is related to smoothing out transitions between frames rather than replacing parts of the video.