Greenscreens

Greenscreens are uniform green backdrops used in chroma key compositing to replace the background of a scene with a separate image or environment. They are commonly used in film, television, photography, and live streaming to allow different backgrounds to be added in post-production or in real time.

The technique, chroma keying, relies on separating a specific color from the foreground and making it transparent so a different image can show through. Green has become the standard due to practical advantages with digital cameras: the green channel typically captures the most luminance and offers strong contrast with human skin tones, making keys cleaner and easier to refine. While blue screens are still used in some cases, green is the prevalent choice for modern productions.

To achieve a clean key, greenscreens should be lit evenly and free of wrinkles or shadows. The subject should be positioned away from the screen to minimize color spill, where green light reflects onto the subject. Post-production tools look for areas that match the key color and remove them, often using garbage mattes, edge feathering, and spill suppression to improve realism.

Greenscreens are used across studios for feature films, TV shows, weather graphics, and virtual production with LED walls or backdrops, enabling real-time or later replacement with digital environments. They require compatible wardrobe choices, typically avoiding garments that match the screen color. Practical limitations include difficult keys with translucent or reflective materials, intricate hair details, or scenes requiring complex lighting that encroaches on the green surface.