Browser HDR capability and highlight test.

How this test works

Review browser-reported dynamic-range support alongside controlled highlight and grayscale patterns.

1. Prepare the display using the checklist below.
2. Select Start test and allow fullscreen mode if your browser asks.
3. Use the arrow keys, on-screen controls, or click the pattern to move through the test.
4. 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

Read the capability report as a software-path clue

The HDR runner checks what the active browser reports about dynamic-range and wide-gamut support, then presents a highlight-separation pattern. A reported capability is not a luminance reading, certification, or proof that the panel is currently showing calibrated HDR. The browser, operating system, graphics hardware, output mode, cable, input, and display must cooperate. If a capability is unavailable, confirm system HDR settings and the maker’s supported port and mode combinations before concluding that the monitor itself lacks HDR.

The same visible highlight pattern can appear in an SDR browser path. Look for whether nearby bright steps remain distinguishable, but do not infer peak nits from how bright the page feels. Your room, brightness control, tone mapping, and display processing all affect the impression. The page’s strongest factual signal is the browser capability report, which is still only about the active software path. The visual field is a comparison aid for clipping or abrupt tone transitions, not an instrument trace.

Check the full setup when HDR looks wrong

Enable HDR in the operating system if your setup requires it and make sure the window is on the intended display. Check the graphics output, cable, and monitor input against official specifications for that model. Battery-saving modes and night light can alter the path. If colors or highlights look unusual, compare the same setting with known HDR content in an app that you trust, while remembering that different apps may use different rendering routes. Do not repeatedly toggle many settings at once; keep a note of which change affected the result.

A monitor can advertise HDR while offering limited contrast or highlight headroom. This page cannot test that objectively. Likewise, a browser that reports wide-gamut CSS support does not prove the panel covers Display P3. If color-space behavior is the main question, use the focused P3 page. If bright SDR patches disappear, use the white saturation page. These related pages separate capability, visual clipping, and color handling so one broad label does not obscure the actual symptom.

Avoid turning an impression into a specification

Objective HDR evaluation needs a suitable luminance meter and controlled stimulus, plus a method for evaluating tone mapping and contrast. A phone photo cannot supply those measurements because exposure and image processing change the recorded highlight. This browser test does not calculate nits, contrast ratio, color volume, or certification level. Use it to report facts such as “the browser does not report HDR on this output” or “two bright patches appear merged under this mode,” with the settings and equipment noted.

If an HDR-capable monitor seems to show no difference, verify the mode in the system and the display menu, then compare under normal content. Some browsers may render the page through SDR even when the hardware is capable of HDR. Keep brightness comfortable during inspection and avoid leaving a bright static field on OLED. The final decision about whether a display performs well for HDR should combine correct configuration, everyday content, and independent instrument-based evidence when quantitative claims are important.

Frequently asked questions