Screen Test Online — Dead Pixel & Monitor Test

功能特性

Eight solid color screens

Black, white, red, green, blue, cyan, magenta and yellow reveal dead or stuck pixels, dust, smudges and backlight bleed.

Gradient and banding check

A black-to-white ramp plus RGB ramps show whether your panel renders smooth gradients or breaks them into visible bands.

Shadow and highlight detail

A 32-step grayscale plus fine 0–15 and 240–255 steps expose crushed blacks and blown highlights from bad contrast or gamma.

Color cast and saturation

A hue wheel and a color chart with a neutral gray reference row make even a slight white balance shift easy to spot.

Pixel-perfect geometry patterns

A 1px checkerboard, a 1px grid with corner crosshairs and center circles, sharpness targets and a ghosting test, all drawn at true device pixels.

Live screen report

See your window size, device pixel ratio, real render resolution, measured refresh rate, color gamut and HDR capability at a glance.

使用方法

1

Pick a test

Open the page and tap any card. Each card shows a live thumbnail of the pattern, so you always know what you are about to see.

2

Go full screen

The pattern fills the whole screen with zero interface. Tap or press the arrow keys to move between tests, up and down to jump between groups.

3

Look for defects

An optional one-line hint tells you exactly what to look for on each pattern — an off-color dot means a dead pixel, glowing corners mean backlight bleed.

4

Or let it play itself

Hit Play all to cycle through every test hands-free, with 3, 5 or 10 seconds per screen. Press Escape to return to the menu.

常見問題

Is this screen test really free?

Yes. Every pattern is free to use, with no signup, no login, no ads and nothing to install. Just open the page.

How do I find dead pixels?

Run the solid color screens one by one. A pixel that stays black on a white screen is a dead pixel; one that stays lit on the black screen is a stuck or hot pixel. Cleaning the screen first helps rule out dust.

Does it work on a phone or tablet?

Yes. Patterns are drawn at your device's real pixel resolution, so 1px checkerboards and grids stay pixel accurate on high-DPI screens. Swipe left and right to change tests.

Why does my screen show bands in the gradient?

Visible steps in a smooth ramp usually mean limited color depth, aggressive display scaling, or an inaccurate panel. Comparing the gray ramp with the RGB ramps helps narrow it down.

Can I test refresh rate and HDR here?

The entry screen measures your actual refresh rate from animation frames and reports the color gamut and whether the browser sees a high dynamic range display. The ghosting pattern shows how cleanly moving edges are drawn.