Red Screen

How to use a red screen

Each pixel of a typical LCD or OLED display is made of red, green, and blue subpixels. A pure red field, #FF0000, turns the red subpixels fully on and leaves the green and blue ones off. That isolates one color channel, so a fault in it has nowhere to hide.

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 red looks and can hide or imitate a fault.

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 red screen can reveal

A dark dot is a pixel whose red subpixel does not light. On a white screen the same pixel would show only as a faint cyan dot, which is easy to miss; on red it shows as black.

A green, 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, more orange, or more pink than the rest, can point to uneven backlighting or panel variation. A small amount is normal on many displays, so compare what you see with the manufacturer's warranty terms before deciding a panel is faulty.

Check all three channels

A fault can affect one color channel and not the others, so test each of them. After red, repeat the check with the Green Screen and the Blue Screen. If you find a dot that stays put, confirm it with the Dead Pixel Test.

This screen's exact value has its own #FF0000 color page, with its RGB and HSL values and its contrast against black and white.