Color Banding Test
The screen should render each gradient as a perfectly smooth sweep. Coarse stair-steps mean limited color depth, a weak panel driver, or aggressive compression from the source.
Each gradient should look perfectly smooth. Visible stair-steps = banding.
How to use this test
Click Start — the test opens fullscreen over this page (nothing is installed, nothing leaves your browser). A control bar at the bottom of the screen lets you switch colors and exit with one tap — touch screens included; the Esc key and your browser's back button work too. Judge the screen in the lighting the test asks for; judging bleed or uniformity in a bright room defeats the test.
Frequently asked questions
Why do gradients look stepped?
Either the panel is 6-bit (+FRC) instead of true 8-bit, or the source video driver is compressing the gradient.
Should I worry about mild banding?
On budget laptops it is common. On a monitor sold as "8-bit" or "HDR", it is a legitimate return reason.