HDR

Our eye can see a room and the bright window in it at the same time. A normal camera can’t do that. It either shows the window correctly and the room as a black area, or the other way around. HDR is the abbreviation for “High Dynamic Range,” meaning “a large span between dark and bright.” This refers to photos, videos, and screens that make the gap between the darkest and the brightest point noticeably larger than was previously the norm. The result doesn’t simply look brighter, but richer in detail: in the sun, clouds remain recognizable, and in the shade, contours stay visible.

Why sunlight and shadow overwhelm screens

The world has an enormous range of brightness. Direct sunlight is millions of times brighter than a street at night. Classic technology could only capture and display a narrow slice of that. Everything above it became pure white, everything below it pure black. These exact losses are called blown-out highlights and crushed shadows.

For phone photos, this is the most common reason for failed shots. A backlit portrait without HDR shows only a dark silhouette. With HDR, both the face and the background are recognizable at the same time. That’s why almost all smartphones switch on the process automatically, without anyone having to request it.

The topic is also economically relevant. TVs, monitors, and streaming services advertise HDR support as a selling point. There’s an important misconception here: a device with an HDR logo may be able to process the format, but it can still be too dim to actually show the benefit. What matters is the screen’s actual peak brightness, not the logo.

Multiple exposures, more bits, brighter panels

When capturing, HDR usually works with multiple images. In a fraction of a second, the camera takes a bright, a medium, and a dark shot. The shadow details come from the bright version, and the details in the bright areas come from the dark one. Software then computes a single image from these. Modern smartphones do this for every photo, often with AI support that compensates for movement between the individual frames.

When saving, such an image needs finer gradations. A classic photo uses 8 bits per color channel, meaning 256 brightness levels. HDR formats use 10 or 12 bits, giving over a thousand levels. Without these additional intermediate values, visible banding would appear in the sky instead of a smooth gradient.

The final step is display. An HDR screen must be able to make individual spots glow very brightly while others remain nearly black. OLED panels achieve this by switching off each pixel individually. LCD devices use many separately controllable backlight zones. If the image is brighter than the screen can handle, it gets converted. This adaptation to the device’s capabilities is called tone mapping.

HDR on the phone, on Netflix, and in games

Most commonly, one encounters HDR in the camera app. There, a corresponding abbreviation appears on the screen, or the process runs invisibly in the background. On streaming services, HDR appears alongside the resolution in the title description. Common variants are called HDR10, HDR10+, and Dolby Vision. The latter two provide additional control data for each scene, allowing the display to be adjusted more precisely.

In games, HDR is a menu item in the graphics settings. Consoles like PlayStation and Xbox have supported it for years. The difference is especially visible with explosions, sunsets, or dark caves with individual light sources.

In tech news, the term usually comes up in connection with new displays, often together with a brightness figure given in nits. Values of 1000 nits or more are considered adequate for HDR, while simple office screens tend to sit around 300. HDR should not be confused with resolution: 4K describes the number of pixels, while HDR describes the range of brightness and color. The two are independent of each other, but are often advertised together.