Green Screen Display

Chroma keying replaces a single colour in a picture with another image, which is how weather presenters stand in front of a map and how a YouTuber appears on a beach. All it needs is a flat, evenly lit area of a colour that the subject does not contain. This page turns any screen into such an area: a monitor, a tablet or a phone placed behind the subject, or a full-screen colour for testing how a camera and keying software respond to it.

Why green, blue or magenta

The keying software removes pixels near the chosen colour, so the colour must be far from skin and hair. Green is the usual choice: most camera sensors have twice as many green photosites as red or blue, so the green channel is the cleanest, and skin contains little green. Blue is better when the subject wears green or has green hair, and the page’s note also suggests it for night and low-light scenes. Magenta is used when both green and blue appear in the subject. The page offers #00b140, a common chroma green, and #0047bb, a chroma blue.

A worked example

Press Sample to select Chroma green at full brightness with the solid pattern. The preview fills with #00b140, and the note says that green is the default for most video because cameras are most sensitive to it. Press Show full screen, or double-click the colour, to fill your display; press Escape to leave. Switch to Tone steps and the area splits into four bands, from the colour to darker and lighter versions, which makes uneven brightness easy to see through a camera.

Using the patterns

The solid pattern is for the real shot. Tone steps help you compare how the camera exposes the colour: the bands should be clearly separate in the monitor, and none should clip to a flat saturated block. The grid draws faint lines across the colour so you can check lens distortion and line up a tracked background. Neither pattern is meant to stay in a finished shot.

Lighting and distance

Light the subject separately from the backdrop, and keep the subject at least a metre or two in front of it. A screen already glows, so do not point more light at it than needed. Check the key in your software with a few seconds of footage before you commit. Wrinkles in a cloth are a common problem, and a screen avoids them, which is its chief advantage.

Edge cases

A screen shows a pixel grid and has a limited viewing angle, so the colour can shift near the edges when seen from the side. A small screen covers only a small area behind the subject, so it suits close-ups and product shots. Some screens or modes dim or sleep; keep the device awake. Brightness is applied with a CSS filter, so the colour remains the same hue.

Limits

The page displays colours only. It does not key or process video, and the colours are not matched to a paint or fabric standard. It does not guarantee a clean key, which depends on lighting, camera and software. Nothing is stored or sent.

Related tools

• Webcam Test checks how your camera sees the backdrop.
• Screen Recorder records the finished composition.
• Dead Pixel Test uses full-screen colours to check the display itself.
• Digital Clapperboard marks takes and sync for the shoot.