In this context, the term
high dynamic range means there is a large amount of variation in light levels within a scene or an image. The
dynamic range refers to the range of
luminosity between the brightest area and the darkest area of that scene or image.
High-dynamic-range imaging (
HDRI) refers to the set of imaging technologies and techniques that allow the dynamic range of images or videos to be increased. It covers the acquisition, creation, storage, distribution and display of images and videos. Modern films have often been shot with cameras featuring a higher dynamic range, and legacy films can be post-converted even if manual intervention will be needed for some frames (as when black-and-white films are converted to color). Also, special effects, especially those that mix real and synthetic footage, require both HDR shooting and
rendering. HDR video is also needed in applications that demand high accuracy for capturing temporal aspects of changes in the scene. This is important in monitoring of some industrial processes such as welding, in predictive driver assistance systems in automotive industry, in
surveillance video systems, and other applications.
Capture In
photography and
videography, a technique, commonly named
high dynamic range (
HDR) allows the dynamic range of photos and videos to be captured beyond the native capability of the camera. It consists of capturing multiple frames of the same scene but with different
exposures and then combining them into one, resulting in an image with a dynamic range higher than the individually captured frames. Some of the sensors on modern phones and cameras may even combine the two images on-chip. This also allows a wider dynamic range being directly available to the user for display or processing without in-pixel compression. Some cameras designed for use in security applications can capture HDR videos by automatically providing two or more images for each frame, with changing exposure. For example, a sensor for 30fps video will give out 60fps with the odd frames at a short exposure time and the even frames at a longer exposure time. Modern
CMOS image sensors can often capture high dynamic range images from a single exposure. This reduces the need to use the multi-exposure HDR capture technique. High dynamic range images are used in extreme dynamic range applications like welding or automotive work. In security cameras the term used instead of HDR is "wide dynamic range". Because of the nonlinearity of some sensors image artifacts can be common.
Rendering High-dynamic-range rendering (HDRR) is the real-time rendering and display of virtual environments using a dynamic range of 65,535:1 or higher (used in computer, gaming, and entertainment technology). HDRR does not require a
HDR display and originally used
tone mapping to display the rendering on a
standard dynamic range display.
Dynamic range compression or expansion The technologies used to store, transmit, display and print images have limited dynamic range. When captured or created images have a higher dynamic range, they must be
tone mapped in order to reduce that dynamic range.
Storage High-dynamic-range formats for image and video files are able to store more dynamic range than traditional 8-bit
gamma formats. These formats include: •
HDR formats that can be used for both storage and transmission to HDR displays, such as: • For video: •
HDR10 •
HDR10+ •
Dolby Vision •
HLG (backwards compatible with SDR displays) • For images: •
Gain map approaches, which adds a conversion layer on top of SDR data. The result is backwards compatible with SDR displays and storage. •
ISO 21496-1 Gain Map, evolved from a unification of Apple and Adobe's proposals. Used by Apple under the name
Adaptive HDR, ISO 21496-1 supports major file types like JPEG, HEIC, AVIF, JXL, etc. It is supported starting with
macOS 15,
iOS 18,
iPadOS 18,
Android 15, and
Chromium based browsers. • Adobe
Gain Map, a gain map image in a
JPEG image file; used by Google under the name
Ultra HDR and by Samsung under the name
Super HDR. Supports gain on 1 or 3 channels. • Apple
EDR (Extreme Dynamic Range), used in macOS and iOS. Apple refers to EDR as the combination of hardware and software that allows displaying SDR and HDR content on the same screen. •
HEIC (
HEVC codec in
HEIF file format) •
AVIF (
AV1 codec in HEIF file format) •
JPEG XR •
JPEG XL • HSP, CTA 2072 HDR Still Photo Interface (a format used by
Panasonic cameras for photo capture in HDR with the HLG
transfer function) • Formats that are only used for storage purpose, such as: •
Raw image formats • Formats that use a
linear transfer function with high
bit-depth • Formats that use a
logarithmic transfer function •
OpenEXR was created in 1999 by
Industrial Light & Magic (ILM) and released in 2003 as an
open source software library. OpenEXR is used for
film and
television production. ACES is a complete color and file management system that works with almost any professional workflow and it supports both HDR and
wide color gamut. On January 4, 2016, the Ultra HD Alliance announced their certification requirements for an HDR display. The HDR display must have either a peak brightness of over 1000
cd/m2 and a black level less than 0.05 cd/m2 (a
contrast ratio of at least 20,000:1) or a peak brightness of over 540 cd/m2 and a black level less than 0.0005 cd/m2 (a contrast ratio of at least 1,080,000:1). HLG and PQ require a
bit depth of 10-bits per sample. Multiple technologies allowed to increase the dynamic range of displays. In May 2003,
BrightSide Technologies demonstrated the first HDR display at the Display Week Symposium of the
Society for Information Display. The display used an array of individually-controlled LEDs behind a conventional LCD panel in a configuration known as "
local dimming". BrightSide later introduced a variety of related display and video technologies enabling visualization of HDR content. In April 2007,
BrightSide Technologies was acquired by
Dolby Laboratories.
OLED displays have high contrast.
MiniLED improves contrast.
Realtime HDR vision . In the 1970s and 1980s,
Steve Mann invented the Generation-1 and Generation-2 "Digital Eye Glass" as a vision aid to help people see better with some versions being built into welding helmets for HDR vision. ==Non-imaging==