Green Screen

How to use a green screen

Each pixel of a typical LCD or OLED display is made of red, green, and blue subpixels. A pure green field, #00FF00, turns the green subpixels fully on and leaves the red and blue ones off. That isolates one color channel, so a fault in it stands out.

1. 1

   Open it full screen. Browser toolbars around the field hide the edges and corners, where faults often sit.

2. 2

   Turn off color filters. Night mode, blue-light filters, and automatic color adjustment change how the green looks.

3. 3

   Clean the display first. A speck of dust can look like a dark pixel. If it wipes away, it was not a fault.

4. 4

   Scan slowly. Work across the screen one section at a time from your usual distance, then look closer at anything that stands out.

What a green screen can reveal

A dark dot is a pixel whose green subpixel does not light. Green is the brightest of the three primaries to the eye, so a missing green subpixel is especially easy to spot here.

A red, blue, or other colored dot is a pixel with a subpixel stuck on, lighting a color that should be off.

Uneven color, such as areas that look darker or more yellow than the rest, can point to uneven backlighting or panel variation. A small amount is normal on many displays, so check the manufacturer's warranty terms before deciding a panel is faulty.

Repeat the check with the Red Screen and the Blue Screen, and confirm any dot that stays put with the Dead Pixel Test.

As a small chroma-key backdrop

For close-up shots of small objects, a display showing pure green can stand in for a green backdrop that video software removes and replaces. Keep the subject a little in front of the screen, and light it separately. The display casts green light onto the subject, which can leave green edges after keying, and it is usually too small to sit behind a person.

This screen's exact value has its own #00FF00 color page, with its RGB and HSL values and its contrast against black and white.