HDR Highlight Clipping Test
Tests whether your display and OS tone-mapping clip near-white specular highlights. Patches are strictly labeled with digital values (Level 240..255) rather than fabricated nit values.
Technical Scope & Limitations
Clipping may originate from OS HDR sliders, monitor tone-mapping, browser compositing, or hardware peak limits.
Browser rendering output can be influenced by OS display scaling, GPU driver color settings, and active HDR profiles.
- Look at the grid of 10 bright patches (Digital Levels 240 to 255).
- Check if Level 253, 254, and 255 remain visually distinguishable from one another.
- If levels 248–255 appear identical as a single flat white mass, highlight clipping is occurring.
What to inspect:
If Digital Levels 251–255 merge completely into a single uniform white block with no visible borders, specular highlight clipping is occurring. Adjust OS HDR brightness or monitor tone-mapping.
What This Test Checks
- Specular highlight separation across the brightest digital levels (240 to 255 out of 255).
- Tone-mapping roll-off behavior near peak white.
- Highlight crush caused by aggressive Windows HDR SDR-content brightness sliders or excessive monitor contrast.
How to Perform the Test
- Enter fullscreen mode and look at the array of 10 highlight patches.
- Observe whether Digital Level 253, 254, and 255 remain visually distinct.
- Click on individual patches to compare them side-by-side with peak reference white.
What to Look For
- If levels 248–255 merge completely into a single solid white patch without visible borders, specular highlight clipping is occurring.
Common Display Problems & Diagnostic Guidance
Windows HDR SDR Content Brightness
In Windows Settings → System → Display → HDR, setting the "SDR content brightness" slider too high can cause white clipping in desktop browser windows.
Frequently Asked Questions
Why does this test use digital levels instead of nit values?
Browsers encode content digitally in standard code values. True physical luminance in nits depends on your monitor backlight, tone-mapping algorithm, and calibration, which cannot be measured without an external meter.