Red-subpixel check
Find points that look black, blue, green or unusually dim on red.
Red Screen
Use a full-screen red background to inspect red subpixels, color uniformity and pixels that stay green, blue, black or white.
What is a red screen used for?
A red screen activates the red component of the display and makes missing, dim or incorrectly colored pixels easier to spot. Compare the whole panel from your normal viewing position.
✓ No installation✓ Full-screen support✓ Works on compatible devices
Useful checks with a red screen
Color uniformity
Compare red saturation across the center, corners and edges.
Stuck-pixel confirmation
Retest a suspicious point against red, green, blue, white and black.
Ambient red light
Use a red background for low-light setups without claiming calibrated color output.
How to use this screen safely
- Clean the display gently according to the manufacturer’s instructions.
- Use your normal viewing distance and brightness first.
- Open full screen and inspect the center, edges and corners.
- Repeat the check with black, white, red, green, blue and gray backgrounds.
- Do not stare at an uncomfortable brightness or color for a prolonged period.
Important: This is a visual browser test. It cannot certify a display, identify the exact hardware cause, or replace professional measurement equipment.
Frequently asked questions
What does a black point on red mean?
It may indicate a red subpixel that is not responding, but dust or screen damage can look similar. Compare other colors before drawing a conclusion.
Why does red look different near the edges?
Viewing angle, panel uniformity, brightness and screen coating can all affect perceived color.
Can browser color management change the result?
Yes. The browser, operating system, display profile and HDR settings can influence displayed color.
Try another screen color
Run several colors because different pixel and uniformity problems appear on different backgrounds.
Explore more diagnostics
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Move between screen, camera, audio and device checks without returning to the homepage.
Dead Pixel TestInspect solid colors for dead, stuck, bright or dark pixels.
Touch Screen TestCheck touch coverage, dragging continuity and dead zones.
Keyboard TesterTest a full-size keyboard and confirm every key press.
Mouse TesterTest buttons, wheel, movement, dragging and double-clicks.
Audio TesterCheck speakers, stereo channels, tones and microphone input.
Camera & WebcamTest built-in, USB, phone, tablet and compatible TV cameras.
Microphone TesterView microphone levels, waveform, recording and playback.
Pixel ExerciserExercise a suspected stuck-pixel area with changing colors.
Gradient TestInspect gradients, tonal transitions and visible banding.
Brightness & ContrastCheck black levels, white saturation and contrast separation.
Screen Size TestView viewport, resolution, pixel ratio and display data.
Text SharpnessInspect text rendering, browser scaling and clarity.
Motion & GhostingObserve motion blur, ghosting and response behavior.
Resolution & ScalingCheck screen resolution, CSS pixels and scaling.
Device InformationReview screen, browser, hardware and platform information.
Browser CapabilityCheck which browser APIs and hardware features are supported.
Network TestCheck connection status, latency and estimated download speed.
GPS & LocationTest browser geolocation, accuracy, altitude and speed.
Sensor TesterTest orientation, motion, acceleration and rotation sensors.
Multi-Touch TesterTrack multiple touch points, pinching and rotation gestures.Screen Color ToolsOpen exact full-screen color pages for pixel, uniformity and lighting checks.Response Time TestObserve ghosting, blur and pixel-transition behavior at several speeds.Stylus Drawing TestCheck pen, touch, pressure, tilt and drawing continuity in your browser.
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