Can your screen show HDR?

Find out what your device can do, and see why HDR is not simply making everything brighter. Your own screen does the demonstrating.

Start the HDR test

What your device reports

Your browser: Detecting…
Your display: Detecting…
HDR capability: Detecting…

The tests

Two short tests. In each one you will see a list of bars and click the bar where something changes — you do not need to be exact, and if two bars next to each other look the same, either is a fine answer. The first test asks whether your screen can show anything brighter than an ordinary white background. The second asks how much further above that it can still show a real difference in brightness. Neither test depends on telling colours apart. Neither gives you a percentage, either: you get a plain number in stops above reference white (and what that is in nits), not a claim about your screen's spec-sheet peak brightness.

Checking what this browser can send…

Your result

Checking what this browser can send…

See HDR

A workshop with a window, rendered rather than photographed, so every value in it is a stated quantity of light rather than whatever a camera happened to record.

Rendering the scene…

Only one version is shown here

This browser has no way to put HDR on the page, so there is no HDR half to compare against. What is above is the tone-mapped SDR version on its own. Showing it twice and labelling one of them HDR is exactly the misleading comparison this page is about, so it is not done.

The highlight map still works: it is an ordinary image, and it shows which parts of the scene an HDR display would have put above white.

Both versions are the same scene, rendered from the same light. The SDR version is not darkened, desaturated or flattened: everything below 183 cd/m² is untouched, and only the highlights above it are compressed to fit. Colour is preserved exactly — the curve is applied to all three channels together.

What the scene is made of
Part of the scene	Luminance	Relative to white
Shadow under the bench	0.2 cd/m²	1/1015
Workshop wall	6 cd/m²	1/34
Sheet of paper	203 cd/m²	1.0x
Sunlit bench	320 cd/m²	1.6x
Sky through the window	1600 cd/m²	7.9x
Chrome highlight	2500 cd/m²	12x
Edge of the sun	7000 cd/m²	34x

The same comparison, on a real photograph

A rendered scene can state its own light exactly, which is why the comparison above uses one. This is the trade for a genuine photograph instead: real, extreme contrast, put through the same tone-map and encoder, but honest that its brightness is recovered rather than stated.

Only one version is shown here

This browser has no way to put HDR on the page, so there is no HDR half to compare against. What is above is the tone-mapped SDR version on its own.

Both halves are the same photograph, put through this page's own tone-map — the same code the rendered scene above uses, not a separate demonstration.

Mount Tamalpais, from the OpenEXR project's sample images (ScanLines/MtTamWest.exr, © Industrial Light & Magic, BSD-3-Clause licence). Roughly 26.5% of the frame sits above reference white, peaking around 2.1 stops above it — an exposure choice made when preparing this page, not a value the photograph states on its own. See scripts/generate-hdr-photo.mts for exactly how.

Understand HDR

HDR gives a picture more room between its darkest part and its brightest part. It does not make everything brighter.

SDR: white is the ceiling

Paper

Cloud

Sun

white — nothing can go past it

A sheet of paper, a cloud and the sun all end up at the same value, because there is nothing above white to put them at. Whatever the difference was in the original scene is gone by the time it reaches you.

HDR: white is not the top

Paper

Cloud

Sun

reference white — 203 cd/m²

Ordinary white stays at a normal, comfortable brightness. The room above it is for things that are actually very bright, like the sun. The paper stays where it was. The sun does not.

That is why turning the brightness up is not the same thing. Brightness moves the whole picture, including the shadows. Range moves only the top.

The vocabulary

Brightness, and the unit it is measured in

Luminance is measured in cd/m², candelas per square metre, usually called nits. It is an amount of light coming off a surface, so it is a physical quantity rather than a setting.

A typical laptop in a room might put white at 100 to 300 cd/m². HDR content is normally mastered with reference white at 203 and highlights reaching 1,000 or more.

Dynamic range

The ratio between the darkest thing a display can show and the brightest. Both ends count: a display that reaches 1,500 cd/m² but cannot render a dark grey has a worse range than the number suggests, which is most of why OLED and Mini-LED sets look different from each other on the same content.

A set with the bigger number

1,500 cd/m² peak

A set with the smaller number

800 cd/m² peak

The pale segment is the black level — how far off true black the darkest pixel actually sits. The second set has a lower peak and a longer usable range above its own floor, which is why the bigger number does not automatically win.

Stops

One stop is a doubling of light. It is the unit photographers already think in, and it makes headroom legible: 100, 200, 400, 800, 1,600 is four stops.

100

200

400

800

1600

Each bar is the last one doubled — equal steps in stops, not equal steps in cd/m².

Reference white to a 1,600 cd/m² highlight is about three stops. That sounds small and is not: it is eight times the light.

Tone mapping

Fitting content into a display with less range than the content has. Every HDR display does it, because content is routinely mastered brighter than anything can show, and how well it is done is much of what separates two sets showing the same film.

The SDR half of the comparison above is tone-mapped, and how is stated there rather than left to be trusted.

Colour space, and why it is a separate question

Gamut is which colours a display can show; dynamic range is how much light. They travel together in practice — HDR formats specify wide-gamut primaries — but they are independent, and a wide-gamut display is not necessarily an HDR one. The capability table above reports them separately for that reason.

Simulated HDR, for a display without it

You cannot create HDR on an SDR display, and this does not try to. It is a drawing of the idea in ordinary greys: the slider changes how much room the simulated display has above white, and everything below white deliberately does not move.

Display rangeSDR — no headroom

Shadow behind the door0.3 cd/m²

The far wall8 cd/m²

A lit wall60 cd/m²

White paper203 cd/m²

A bare bulb900 cd/m²beyond this display

Sun through the window6000 cd/m²beyond this display

With no headroom, every highlight lands on exactly the same white as the paper. That is SDR: white is the ceiling, and a bulb and a sheet of paper are the same value.

The scale is logarithmic: each label is roughly ten times the light of the one before it. The marked band is what the simulated display can reach.

Why screenshots are not proof

A screenshot of an HDR image is not a reliable way to show someone HDR. It can work, and increasingly does — several platforms now capture, store and display HDR end to end. What it cannot do is work dependably, because it only survives if every stage of the chain preserves it.

01Camera or render
02Editing and grading
03Encoding
04Platform or service
05App
06Operating system
07Display

Any one of those can convert to SDR, and most do it silently. The person sharing the screenshot sees it correctly on the device that took it, which is exactly why the practice persists.

Try it on this page

Take a screenshot of the comparison above and open it beside the original. If your whole chain preserves HDR you will see no difference. If it does not, you have just demonstrated the point, and neither result tells you anything about the display — only about the pipeline between it and the file.

Three comparisons that mislead

The flattened SDR

A vivid HDR image beside a grey, washed-out one labelled SDR.

SDR does not look like that. A properly tone-mapped SDR version of the same picture keeps its contrast, its colour and its shadows, and gives up only the brightness of the highlights. The comparison on this page is generated that way, and says what it did.

The brightness comparison

Two versions of an image, one uniformly brighter than the other.

That is a demonstration of brightness, which is a setting, not a demonstration of dynamic range. HDR lets one part of a picture be far brighter while the rest stays where it was. If everything moved together, nothing has been shown.

The screenshot

A screenshot of an HDR image, posted as proof of what HDR looks like.

The picture has to survive capture, storage, upload, whatever the platform does to it, the viewing app, the operating system and finally the display. Any one of those stages can convert it to SDR, and most of them are invisible to the person posting it.

Formats

Metadata	Typical use	Strength	Weakness
Absolute	HEIC/HEIF photos, some AVIF, and this page’s own PNGs	A code value means a specific quantity of light, the same on every display.	Defined far past what any screen can show, so almost everything still needs mapping down.
Relative	HEIC photos from some cameras, alongside PQ	The bottom of its curve matches ordinary SDR, so a viewer that ignores it still shows something sensible.	Its brightness scales to the display, so the same file is not guaranteed to look the same on two HDR screens.
A second image, not a curve	Camera photos from Android and iPhone, in JPEG or HEIC	The file a plain viewer opens is an ordinary, correctly-exposed SDR photo — nothing breaks for anyone.	The extra brightness is relative to that SDR rendering and the viewer’s own headroom, not a stated amount of light.

Select a format for more on how it works.

What you are likely to meet, by device

Deliberately generic. Naming models and their capabilities means maintaining that list continuously, and a device table that is quietly two years out of date is worse than none — it is wrong with an air of authority.

iPhone and iPadHDR display and HDR photo support arrived over several generations, so it varies by age rather than by model name.
Android phonesEntirely manufacturer-dependent. Two phones sold in the same year and the same price bracket often differ.
OLED televisionsPer-pixel black, so the contrast is exceptional even where the peak brightness is moderate.
Mini-LED and full-array televisionsUsually the higher peak brightness, with blooming around small highlights on a dark field.
Computer monitorsThe most inconsistent category. Many that advertise HDR have neither the peak brightness nor the local dimming to show it.
Mac laptops and displaysRecent ones drive HDR consistently, and the operating system keeps it on rather than switching modes.
Windows PCsDepends on the display, the GPU, the cable and an operating system setting that is off by default on many machines.

Analyse an image

Drop in a file of your own and this reads its metadata for the formats above: whether it declares PQ, HLG or a gain map, its bit depth and dimensions, and anything else its container states. Then it puts the file's own bytes next to a version forced through a plain SDR canvas, so you can see what its declared HDR signal actually adds on this browser and this screen.

Read in this tab only. Nothing here is uploaded anywhere, and it is gone the moment you remove it, choose another file, or leave this page.