High dynamic range (HDR) is a

dynamic range Dynamic range (abbreviated DR, DNR, or DYR) is the ratio between the largest and smallest values that a certain quantity can assume. It is often used in the context of signals, like sound and light. It is measured either as a ratio or as a base ...

higher than usual, synonyms are wide dynamic range, extended dynamic range, expanded dynamic range. The term is often used in discussing the dynamic range of various

signal In signal processing, a signal is a function that conveys information about a phenomenon. Any quantity that can vary over space or time can be used as a signal to share messages between observers. The '' IEEE Transactions on Signal Processing' ...

s such as

image An image is a visual representation of something. It can be two-dimensional, three-dimensional, or somehow otherwise feed into the visual system to convey information. An image can be an artifact, such as a photograph or other two-dimensio ...

video Video is an electronic medium for the recording, copying, playback, broadcasting, and display of moving visual media. Video was first developed for mechanical television systems, which were quickly replaced by cathode-ray tube (CRT) sy ...

audio Audio most commonly refers to sound, as it is transmitted in signal form. It may also refer to: Sound *Audio signal, an electrical representation of sound *Audio frequency, a frequency in the audio spectrum * Digital audio, representation of sou ...

radio Radio is the technology of signaling and communicating using radio waves. Radio waves are electromagnetic waves of frequency between 30 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a tr ...

. It may apply to the means of recording, processing, and reproducing such signals including analog and digitized signals. The term is also the name of some of the technologies or techniques allowing to achieve high dynamic range images, videos, or audio.

Imaging

In this context, the term ''high dynamic range'' means there is a lot of variation in light levels within a scene or an image. The ''

'' refers to the range of

luminosity Luminosity is an absolute measure of radiated electromagnetic power (light), the radiant power emitted by a light-emitting object over time. In astronomy, luminosity is the total amount of electromagnetic energy emitted per unit of time by a st ...

between the brightest area and the darkest area of that scene or image. (HDRI) refers to the set of imaging technologies and techniques that allow to increase the dynamic range of images or videos. It covers the acquisition, creation, storage, distribution and display of images and videos. Modern movies have often been filmed with cameras featuring a higher dynamic range, and

legacy In law, a legacy is something held and transferred to someone as their inheritance, as by will and testament. Personal effects, family property, marriage property or collective property gained by will of real property. Legacy or legacies may refer ...

movies can be converted even if manual intervention would 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 Closed-circuit television (CCTV), also known as video surveillance, is the use of video cameras to transmit a signal to a specific place, on a limited set of monitors. It differs from broadcast television in that the signal is not openly tr ...

systems, and other applications.

Capture

photography Photography is the art, application, and practice of creating durable images by recording light, either electronically by means of an image sensor, or chemically by means of a light-sensitive material such as photographic film. It is emplo ...

and

videography Videography is the process of capturing moving images on electronic media (e.g., videotape, direct to disk recording, or solid state storage) and even streaming media. The term includes methods of video production and post-production. It used ...

, a technique, commonly named ''

high dynamic range High dynamic range (HDR) is a dynamic range higher than usual, synonyms are wide dynamic range, extended dynamic range, expanded dynamic range. The term is often used in discussing the dynamic range of various signals such as images, videos, au ...

'' (''HDR''), allows to increase the dynamic range of captured photos and videos 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 into an image with a dynamic range higher than those of individually captured frames."Compositing Multiple Pictures of the Same Scene", by Steve Mann, in IS&T's 46th Annual Conference, Cambridge, Massachusetts, May 9–14, 1993 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 Complementary metal–oxide–semiconductor (CMOS, pronounced "sea-moss", ) is a type of metal–oxide–semiconductor field-effect transistor (MOSFET) fabrication process that uses complementary and symmetrical pairs of p-type and n-type MOSF ...

image sensor An image sensor or imager is a sensor that detects and conveys information used to make an image. It does so by converting the variable attenuation of light waves (as they pass through or reflect off objects) into signals, small bursts of c ...

s can often capture a high dynamic range images from a single exposure. This reduces the need to use the multi-exposure HDR capture technique. High dynamic range captured 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 High-dynamic-range rendering (HDRR or HDR rendering), also known as high-dynamic-range lighting, is the rendering of computer graphics scenes by using lighting calculations done in high dynamic range (HDR). This allows preservation of details tha ...

(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).

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 Gamma (uppercase , lowercase ; ''gámma'') is the third letter of the Greek alphabet. In the system of Greek numerals it has a value of 3. In Ancient Greek, the letter gamma represented a voiced velar stop . In Modern Greek, this letter r ...

formats. These formats include: * Formats that are only used for storage purpose, such as: **

Raw image format A camera raw image file contains unprocessed or minimally processed data from the image sensor of either a digital camera, a motion picture film scanner, or other image scanner. Raw files are named so because they are not yet processed and ...

s **Formats that use a

linear Linearity is the property of a mathematical relationship ('' function'') that can be graphically represented as a straight line. Linearity is closely related to '' proportionality''. Examples in physics include rectilinear motion, the linear ...

transfer function In engineering, a transfer function (also known as system function or network function) of a system, sub-system, or component is a mathematical function that theoretically models the system's output for each possible input. They are widely used ...

with high bit-depth **Formats that use a logarithmic transfer function ** OpenEXR **

ACES ACeS (PT Asia Cellular Satellite) was a regional satellite telecommunications company based in Jakarta, Indonesia. It offered GSM-like satellite telephony services to Asian market. The coverage area included Indonesia, Malaysia, Thailand, Philip ...

* HDR formats that can be used for both storage and transmission to displays, such as: **

HDR10 HDR10 Media Profile, more commonly known as HDR10, is an open high-dynamic-range video (HDR) standard announced on 27 August 2015 by the Consumer Technology Association. It is the most widespread of the HDR formats. HDR10 is not backward compat ...

HDR10+ HDR10+ is a high dynamic range (HDR) video technology that adds dynamic metadata to HDR10 source files. The dynamic metadata are used to adjust and optimize each frame of the HDR video to the consumer display's capabilities in a way based on the ...

Dolby Vision Dolby Vision is a set of technologies developed by Dolby Laboratories for high dynamic range (HDR) video. It covers content creation, distribution, and playback. It includes dynamic metadata that are used to adjust and optimize each frame of the ...

** HLG OpenEXR was created in 1999 by

Industrial Light & Magic Industrial Light & Magic (ILM) is an American motion picture visual effects company that was founded on May 26, 1975 by George Lucas. It is a division of the film production company Lucasfilm, which Lucas founded, and was created when he began pr ...

(ILM) and released in 2003 as an

open source Open source is source code that is made freely available for possible modification and redistribution. Products include permission to use the source code, design documents, or content of the product. The open-source model is a decentralized so ...

software library In computer science, a library is a collection of non-volatile resources used by computer programs, often for software development. These may include configuration data, documentation, help data, message templates, pre-written code and sub ...

. OpenEXR is used for

film A film also called a movie, motion picture, moving picture, picture, photoplay or (slang) flick is a work of visual art that simulates experiences and otherwise communicates ideas, stories, perceptions, feelings, beauty, or atmospher ...

and

television Television, sometimes shortened to TV, is a telecommunication medium for transmitting moving images and sound. The term can refer to a television set, or the medium of television transmission. Television is a mass medium for advertising, ...

production.

Academy Color Encoding System The Academy Color Encoding System (ACES) is a color image encoding system created under the auspices of the Academy of Motion Picture Arts and Sciences. ACES allows for a fully encompassing color accurate workflow, with "seamless interchange of ...

(ACES) was created by the

Academy of Motion Picture Arts and Sciences The Academy of Motion Picture Arts and Sciences (AMPAS, often pronounced ; also known as simply the Academy or the Motion Picture Academy) is a professional honorary organization with the stated goal of advancing the arts and sciences of motio ...

and released in December 2014. 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 In color reproduction, including computer graphics and photography, the gamut, or color gamut , is a certain ''complete subset'' of colors. The most common usage refers to the subset of colors which can be accurately represented in a given cir ...

. More information can be found a
https://www.ACESCentral.com
(WCG).

Transmission to displays

High dynamic range High dynamic range (HDR) is a dynamic range higher than usual, synonyms are wide dynamic range, extended dynamic range, expanded dynamic range. The term is often used in discussing the dynamic range of various signals such as images, videos, au ...

(HDR) is also the common name of a technology allowing to transmit high dynamic range videos and images to compatible displays. That technology also improves other aspects of transmitted images, such as

color gamut In color reproduction, including computer graphics and photography, the gamut, or color gamut , is a certain ''complete subset'' of colors. The most common usage refers to the subset of colors which can be accurately represented in a given ci ...

. In this context, * HDR displays refers to displays compatible with that technology. * HDR formats refers to formats such as

and HLG. *

HDR video High-dynamic-range television (HDR or HDR-TV) is a technology that improves the quality of display signals. It is contrasted with the retroactively-named standard dynamic range (SDR). HDR changes the way the luminance and colors of videos and ...

refers to a video encoded in an HDR format. Thoses HDR video have a greater bit depth, luminance and color volume than standard dynamic range (SDR) video which uses a conventional

gamma curve Gamma correction or gamma is a nonlinear operation used to encode and decode luminance or tristimulus values in video or still image systems. Gamma correction is, in the simplest cases, defined by the following power-law expression: : V_\text = ...

. On January 4, 2016, the Ultra HD Alliance announced their certification requirements for a 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 The contrast ratio (CR) is a property of a display system, defined as the ratio of the luminance of the brightest shade (white) to that of the darkest shade (black) that the system is capable of producing. A high contrast ratio is a desired aspec ...

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). The two options allow for different types of HDR displays such as LCD and

OLED An organic light-emitting diode (OLED or organic LED), also known as organic electroluminescent (organic EL) diode, is a light-emitting diode (LED) in which the emissive electroluminescent layer is a film of organic compound that emits light i ...

. Some options to use HDR

transfer function In engineering, a transfer function (also known as system function or network function) of a system, sub-system, or component is a function (mathematics), mathematical function that mathematical model, theoretically models the system's output for ...

s that better match the human

visual system The visual system comprises the sensory organ (the eye) and parts of the central nervous system (the retina containing photoreceptor cells, the optic nerve, the optic tract and the visual cortex) which gives organisms the sense of sight (the a ...

other than a conventional gamma curve include the HLG and perceptual quantizer (PQ). HLG and PQ require a bit depth of 10-bits per sample.

Display

The dynamic range of a display refers to range of

the display can reproduce, from the black level to its peak brightness. The contrast of a display refers to the

ratio In mathematics, a ratio shows how many times one number contains another. For example, if there are eight oranges and six lemons in a bowl of fruit, then the ratio of oranges to lemons is eight to six (that is, 8:6, which is equivalent to the ...

between the luminance of the brightest white and the darkest black that a monitor can produce. Multiple technologies allowed to increase the dynamic range of displays. In May 2003,

BrightSide Technologies BrightSide Technologies Inc. (formerly ''Sunnybrook Technologies'') was a firm spun-out from the Structured Surface Physics Laboratory of the University of British Columbia, developing and commercializing electronic display technologies, speci ...

demonstrated the first HDR display at the Display Week Symposium of the

Society for Information Display The Society for Information Display (SID) is an industry organization for displays, generally electronic displays such as televisions and computer monitors. SID was founded in September 1962. Its main activities are publishing technical journals ...

. The display used an array of individually-controlled LEDs behind a conventional LCD panel in a configuration known as "

local dimming A backlight is a form of illumination used in liquid crystal displays (LCDs). As LCDs do not produce light by themselves—unlike, for example, cathode ray tube (CRT), plasma (PDP) or OLED displays—they need illumination (available light, ambie ...

" today. BrightSide later introduced a variety of related display and video technologies enabling visualization of HDR content. In April 2007,

was acquired by

Dolby Laboratories Dolby Laboratories, Inc. (often shortened to Dolby Labs and known simply as Dolby) is an American company specializing in Noise reduction#In audio, audio noise reduction, Audio data compression, audio encoding/compression, spatial audio, and ...

displays have high contrast. MiniLED improves contrast.

Audio

In Audio, the term ''high dynamic range'' means there is a lot of variation in the levels of the sound. Here, the ''

'' refers to the range between the highest volume and lowest volume of the sound.

XDR (audio) XDR (expanded dynamic range), also known as SDR (super dynamic range) is a quality-control and duplication process for the mass-production of pre-recorded audio cassettes. It is a process designed to provide higher quality audio on pre-recorded ...

is used to provide higher-quality audio when using microphone sound systems or recording onto cassette tapes. HDR Audio is a dynamic mixing technique used in

EA Digital Illusions CE EA Digital Illusions CE AB (trade name: DICE) is a Swedish video game developer based in Stockholm. The company was founded in 1992 and has been a subsidiary of Electronic Arts since 2006. Its releases include the ''Battlefield'', '' Mirror's ...

Frostbite Engine Frostbite is a game engine developed by DICE (company), DICE, designed for cross-platform use on Microsoft Windows, Seventh generation of video game consoles, seventh generation game consoles PlayStation 3 and Xbox 360, Eighth generation of video ...

to allow relatively louder sounds to drown out softer sounds.

Dynamic range compression Dynamic range compression (DRC) or simply compression is an audio signal processing operation that reduces the volume of loud sounds or amplifies quiet sounds, thus reducing or ''compressing'' an audio signal's dynamic range. Compression is ...

is a set of techniques used in audio recording and communication to put high-dynamic-range material through channels or media of lower dynamic range. Optionally,

dynamic range expansion Dynamic range compression (DRC) or simply compression is an audio signal processing operation that reduces the volume of loud sounds or amplifies quiet sounds, thus reducing or ''compressing'' an audio signal's dynamic range. Compression is ...

is used to restore the original high dynamic range on playback.

Radio

In radio, high dynamic range is important especially when there are potentially interfering signals. Measures such as

spurious-free dynamic range Spurious-free dynamic range (SFDR) is the strength ratio of the fundamental signal to the strongest spurious signal in the output. It is also defined as a measure used to specify analog-to-digital and digital-to-analog converters (ADCs and DACs, res ...

are used to quantify the dynamic range of various system components such as frequency synthesizers. HDR concepts are important in both conventional and

software-defined radio Software-defined radio (SDR) is a radio communication system where components that have been traditionally implemented in analog hardware (e.g. mixers, filters, amplifiers, modulators/demodulators, detectors, etc.) are instead implemented by me ...

design.

Instrumentation

In many fields, instruments need to have a very high dynamic range. For example, in

seismology Seismology (; from Ancient Greek σεισμός (''seismós'') meaning "earthquake" and -λογία (''-logía'') meaning "study of") is the scientific study of earthquakes and the propagation of elastic waves through the Earth or through other ...

, HDR accelerometers are needed, as in the ICEARRAY instruments.

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 See also, IEEE Technology and Society Magazine 31(3) and the supplemental material entitled "GlassEyes".

References

External links

*{{cite web , title=High Dynamic Range (HDR) on Intel Graphics , publisher=Intel Corporation , url=https://www.intel.com/content/dam/support/us/en/documents/graphics/HDR_Intel_Graphics_TechWhitePaper.pdf , date= November 2017 Broad-concept articles Display technology Electrical engineering Film and video technology Television technology