How this test works
Review browser-reported dynamic-range support alongside controlled highlight and grayscale patterns.
- Prepare the display using the checklist below.
- Select Start test and allow fullscreen mode if your browser asks.
- Use the arrow keys, on-screen controls, or click the pattern to move through the test.
- Exit the runner and save a local observation if useful.
Before you begin
- Enable HDR in the operating system
- Use an HDR-capable cable and input
- Disable night light and battery saving
What to look for
- Whether the browser reports high dynamic range
- Separation between bright tone steps
- Clipping, tint, or abrupt tone changes
Important: Browser capability reporting does not measure peak brightness, contrast, tone mapping, or HDR certification. Some browsers render this page through an SDR path.
Frequently asked questions
Can a website measure HDR brightness?
No. Accurate luminance measurement requires a meter. This test reports browser capability and provides visual patterns.
Why does HDR support show unavailable?
The operating system, browser, GPU, cable, input, and display must all support an active HDR path.
Does a visible pattern prove HDR is working?
No. SDR displays can show the pattern too. Use system information and a meter for confirmation.