What is the primary use of a “chroma key” effect?

The chroma key effect is primarily used in video production to replace a solid color background with another image or video. This technique allows for the creation of composite images, where an actor or subject filmed in front of a uniformly colored background—typically green or blue—can be seamlessly placed into a different environment or scene. The reason this method is effective lies in its ability to isolate specific colors; once the chosen color is identified, it can be made transparent, allowing for the overlay of different visuals behind the subject. This is commonly applied in news broadcasts, film, and television to create special effects, virtual sets, or to superimpose graphics.

In contrast, the other options do not align with the function of a chroma key effect. The addition of sound effects pertains to audio editing, enhancing video brightness relates to color correction and grading, and editing audio tracks is a separate facet of video production focusing on sound rather than visuals.