High Dynamic Range
Representing and displaying brightness over a much wider range than the conventional 0–1 signal, so highlights can be brighter without the rest getting darker.
High dynamic range (HDR) is the representation and display of brightness across a range far wider than the conventional standard-dynamic-range (SDR) signal. SDR encodes brightness as relative values between black and "white", and whatever white the display chooses (often around 100–300 nits) becomes the brightest thing on screen. HDR encodes absolute luminance, up to thousands of nits, so a sunlit window or a specular glint can be much brighter than a white sheet of paper in the same scene instead of being clipped to the same white.
The term covers two different things that are easy to confuse:
- HDR rendering means computing light internally in floating-point, unbounded values. Every modern renderer does this because Physically Based Rendering and Ray Tracing produce physically meaningful intensities that do not stop at 1.0. This has been standard for nearly two decades.
- HDR output means sending a signal to a display that can show more than SDR's range. It needs a capable panel, a wide-gamut color space, a perceptual transfer curve (PQ), 10-bit or deeper color to avoid banding, and every layer of the stack agreeing on all of it.
Between the two sits Tone Mapping, which compresses the renderer's unbounded values into whatever the display can show. An SDR game still renders HDR internally and tone-maps aggressively. An HDR game tone-maps less, to a target set by the display's measured peak.
The output path fails in many places, because each layer has to pass metadata through unchanged: the game, the graphics API, the API Translation Layer if there is one, the compositor, the driver, the cable, and the display's own processing. One layer that strips or misreads it gives washed-out greys, crushed blacks, or highlights clipped at SDR white, and from the couch these look like a "bad HDR implementation". Calibration tools that ask the player to tune paper white and peak brightness exist because the game cannot rely on the display reporting itself honestly.
HDR also changes how UI is designed. Interface elements need a fixed paper-white level, or menus become uncomfortably bright next to dark scenes. That is a Color Contrast problem in absolute units rather than relative ones.
See also3
Graphics Driver
The software that translates a program's drawing commands into instructions a particular graphics card can execute, split between a kernel part that manages memory and displays and a large user-space part that compiles shaders and implements graphics interfaces.
Systems & Tooling17 connections
OLED
A display in which every pixel makes its own light from thin layers of organic compounds, giving true blacks and near-instant response, at the cost of limited full-screen brightness and gradual burn-in.
Graphics & Rendering5 connections
Image Format
The file formats the web uses for pictures, from the GIF, JPEG, and PNG generation to newer formats derived from video codecs, and the slow, politics-laden process by which a new one becomes safe to use.
Web Platform9 connections
Linked from3
- Color GamutGraphics & Rendering
The range of colors a device or color space can represent, drawn as a triangle of primaries inside the larger region of colors humans can see.
- Image FormatWeb Platform
The file formats the web uses for pictures, from the GIF, JPEG, and PNG generation to newer formats derived from video codecs, and the slow, politics-laden process by which a new one becomes safe to use.
- OLEDGraphics & Rendering
A display in which every pixel makes its own light from thin layers of organic compounds, giving true blacks and near-instant response, at the cost of limited full-screen brightness and gradual burn-in.