HDR Display Test
See what your browser reports about HDR and color-gamut support, then run a shadow-detail and highlight-detail step test to gauge how much near-black and near-white detail your display and eyes can actually resolve.
What this page can and can't tell you
A web page cannot honestly claim to measure or display true HDR. Real HDR requires a PQ or HLG transfer function, a display actually driven at high peak nits, and an OS/browser pipeline that hands untouched HDR data to the panel — and in most browsers today (2026), ordinary CSS and canvas content is still composited as standard dynamic range (SDR), even on HDR-capable hardware. Nothing on this page measures nits, contrast ratio, or actual HDR output.
What is genuinely useful without a real HDR pipeline: your ability to distinguish very close shades near black and near white. That's a real, meaningful check of your display's tone-mapping and your own perception — it just isn't "HDR" in the marketing sense. Treat everything below as a best-effort approximation, not a certified measurement.
Browser-reported signal (estimated)
This reads the CSS media features (dynamic-range: high) and
(color-gamut: …). These are signals your browser reports about
its own rendering pipeline — they are not proof that your OS is currently
feeding HDR data to the physical panel, and a "yes" here can still mean the
content you see is tone-mapped down to SDR.
Shadow detail self-test (near-black steps)
Each swatch below steps from pure black toward a very dark gray
(rgb(0,0,0) to rgb(30,30,30)). In a dim room, count how
many distinct steps you can actually tell apart from their neighbors — on a
weak panel or in a bright room, several steps may look identical.
Highlight detail self-test (near-white steps)
Same idea, inverted: these swatches step from a light gray up to pure white
(rgb(225,225,225) to rgb(255,255,255)). Bright glare or
an aggressive display "boost" mode can crush the top steps together.
Wide-gamut sample experimental
If your browser supports the CSS color(display-p3 …) function, a
second near-white strip below is drawn using wide-gamut color values instead of
plain sRGB. This is a wide-gamut sample — it only renders
distinctly on a compatible wide-gamut/HDR display and browser combination. On a
standard sRGB screen, or a browser without support, it will look identical (or
very close) to the sRGB strip above, which is expected and not a bug.
None of the counts above are saved, sent anywhere, or scored — they're for your own reference only. Nothing on this page is stored after you leave.