Standard-dynamic-range (SDR) video is a
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 ...
technology which represents light intensity based on the
brightness
Brightness is an attribute of visual perception in which a source appears to be radiating or reflecting light. In other words, brightness is the perception elicited by the luminance of a visual target. The perception is not linear to luminance, ...
,
contrast and
color
Color (American English) or colour (British English) is the visual perceptual property deriving from the spectrum of light interacting with the photoreceptor cells of the eyes. Color categories and physical specifications of color are associ ...
characteristics and limitations of a
cathode ray tube
A cathode-ray tube (CRT) is a vacuum tube containing one or more electron guns, which emit electron beams that are manipulated to display images on a phosphorescent screen. The images may represent electrical waveforms ( oscilloscope), ...
(CRT) display.
SDR video is able to represent a video or picture's colors with a maximum
luminance
Luminance is a photometric measure of the luminous intensity per unit area of light travelling in a given direction. It describes the amount of light that passes through, is emitted from, or is reflected from a particular area, and falls with ...
around 100
cd/m2, a black level around 0.1
cd/m2 and
Rec.709 /
sRGB
sRGB is a standard RGB (red, green, blue) color space that HP and Microsoft created cooperatively in 1996 to use on monitors, printers, and the World Wide Web. It was subsequently standardized by the International Electrotechnical Commission ...
color gamut.
It uses the
gamma curve as its
electro-optical transfer function This article is about the transfer functions used in pictures and videos and describing the relationship between electrical signal, scene light and displayed light.
Definition
The opto-electronic transfer function (OETF) is the transfer functio ...
.
The first CRT
television set
A television set or television receiver, more commonly called the television, TV, TV set, telly, tele, or tube, is a device that combines a tuner, display, and loudspeakers, for the purpose of viewing and hearing television broadcasts, or using ...
s were manufactured in 1934 and the first color CRT television sets were manufactured in 1954.
The term "standard-dynamic-range video" was adopted to distinguish SDR video from
high-dynamic-range 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 ...
, a new technology that was developed in the 2010s to overcome SDR's limits.
Technical details
Transfer function
Conventional
gamma curves:
*
Opto-electronic transfer function (OETF):
**
Rec. 601
ITU-R Recommendation BT.601, more commonly known by the abbreviations Rec. 601 or BT.601 (or its former name CCIR 601) is a standard originally issued in 1982 by the CCIR (an organization, which has since been renamed as the Internatio ...
(
analog video
Video is an electronic medium for the recording, copying
Copying is the duplication of information or an artifact based on an instance of that information or artifact, and not using the process that originally generated it. With analog f ...
signals in
SD-TV digital video
Digital video is an electronic representation of moving visual images (video) in the form of encoded digital data
Digital data, in information theory and information systems, is information represented as a string of discrete symbols eac ...
form)
**
Rec. 709 (
HD-TV)
**
Rec. 2020
ITU-R Recommendation BT.2020, more commonly known by the abbreviations Rec. 2020 or BT.2020, defines various aspects of ultra-high-definition television (UHDTV) with standard dynamic range (SDR) and wide color gamut (WCG), including picture ...
(
UHD-TV)
**
sRGB
sRGB is a standard RGB (red, green, blue) color space that HP and Microsoft created cooperatively in 1996 to use on monitors, printers, and the World Wide Web. It was subsequently standardized by the International Electrotechnical Commission ...
*
Electro-optical transfer function This article is about the transfer functions used in pictures and videos and describing the relationship between electrical signal, scene light and displayed light.
Definition
The opto-electronic transfer function (OETF) is the transfer functio ...
(EOTF):
**
ITU-R BT.1886
ITU-R BT.1886 is the reference EOTF of SDR-TV. It is a gamma 2.4 transfer function (a power law with a 2.4 exponent) considered as a satisfactory approximation of the response characteristic of CRT to electrical signal. It has been standardize ...
(SDR-TV)
**
sRGB
sRGB is a standard RGB (red, green, blue) color space that HP and Microsoft created cooperatively in 1996 to use on monitors, printers, and the World Wide Web. It was subsequently standardized by the International Electrotechnical Commission ...
(monitors, printers,
World Wide Web
The World Wide Web (WWW), commonly known as the Web, is an information system enabling documents and other web resources to be accessed over the Internet.
Documents and downloadable media are made available to the network through web ...
)
The linear part of the conventional gamma curve was used to limit camera noise in low light video but is no longer needed with
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) cameras.
An example of a conventional gamma curve would be Rec. 601:
ITU-R Recommendation BT.1886 describe the reference
EOTF This article is about the transfer functions used in pictures and videos and describing the relationship between electrical signal, scene light and displayed light.
Definition
The opto-electronic transfer function (OETF) is the transfer function ...
of SDR.
It's a
gamma curve representing the response of
CRT to video signal.
It has been published by
ITU
The International Telecommunication Union is a specialized agency of the United Nations responsible for many matters related to information and communication technologies. It was established on 17 May 1865 as the International Telegraph Union ...
in 2011.
A
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 ...
that is closer to
Weber's law allows for a larger dynamic range, at the same
bit depth, than a conventional gamma curve.
standards such as
hybrid log–gamma
The hybrid log–gamma (HLG) transfer function is a transfer function jointly developed by the BBC and NHK for high dynamic range (HDR) display. It's backward compatible with the transfer function of SDR (the gamma curve). It was approved as ARIB ...
(HLG) and
SMPTE ST 2084 allow for a larger dynamic range by using a different
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 ...
.
is compatible with SDR displays.
Color gamut
In some cases the term SDR is also used with a meaning including the standard
color gamut (i.e.
Rec.709 /
sRGB
sRGB is a standard RGB (red, green, blue) color space that HP and Microsoft created cooperatively in 1996 to use on monitors, printers, and the World Wide Web. It was subsequently standardized by the International Electrotechnical Commission ...
color primaries).
uses
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 ...
(WCG) such as
Rec. 2020
ITU-R Recommendation BT.2020, more commonly known by the abbreviations Rec. 2020 or BT.2020, defines various aspects of ultra-high-definition television (UHDTV) with standard dynamic range (SDR) and wide color gamut (WCG), including picture ...
or
DCI-P3
P3 is an RGB color space. DCI-P3 (Digital Cinema Initiative) is used with digital theatrical motion picture distribution (DCDM). Display P3 is a variant developed by Apple Inc. for wide-gamut displays.
__TOC__
History Development of the sta ...
color primaries.
Dynamic range
The
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 ...
that can be perceived by the
human eye
The human eye is a sensory organ, part of the sensory nervous system, that reacts to visible light and allows humans to use visual information for various purposes including seeing things, keeping balance, and maintaining circadian rhythm.
...
in a single image is around 14
stops.
SDR video with a conventional gamma curve and a
bit depth of 8-bits per sample has a dynamic range of about 6 stops, assuming a
luminance quantisation threshold of 5% is used.
A threshold of 5% is used in the paper (instead of the standard 2% threshold) to allow for the typical display being dimmer than ideal. Professional SDR video with a bit depth of 10-bits per sample has a dynamic range of about 10 stops.
Displaying SDR video on modern displays
While conventional
gamma curves are useful for low light and are compatible with
CRT displays, they can only represent a limited
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 ...
.
brightness
Brightness is an attribute of visual perception in which a source appears to be radiating or reflecting light. In other words, brightness is the perception elicited by the luminance of a visual target. The perception is not linear to luminance, ...
, gamma curve, Rec. 709 color primaries).
See also
* High-dynamic-range 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 ...
* 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 ...
* Gamma correction
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_\tex ...
* Rec. 601
ITU-R Recommendation BT.601, more commonly known by the abbreviations Rec. 601 or BT.601 (or its former name CCIR 601) is a standard originally issued in 1982 by the CCIR (an organization, which has since been renamed as the Internatio ...
* Rec. 709
* sRGB
sRGB is a standard RGB (red, green, blue) color space that HP and Microsoft created cooperatively in 1996 to use on monitors, printers, and the World Wide Web. It was subsequently standardized by the International Electrotechnical Commission ...
References
External links
ITU-R Recommendation BT.1886
{{Dynamic range color representation
Display technology
Film and video technology
Television technology
Color
High dynamic range