Screen Color Test

Display full-screen red, green, blue, white, and black reference screens.

No accountLocal where possibleRetest anytime

White

CSS screen—

Viewport—

Pixel ratio—

Refresh estimate—

DeviceOK can display patterns and estimate browser frame timing, but visual panel defects still require your inspection and professional measurements require dedicated hardware.

Private by design

Test input is processed in your browser where possible.

What this tells you

Use the result as evidence, not a guess.

This test checks

Primary colors
Black
White

How to read it

A passing browser test confirms that the browser can observe this input/output path.

A failing test narrows the issue but does not by itself prove physical hardware failure.