Standard-dynamic-range (SDR) video is a
video
Video is an Electronics, electronic medium for the recording, copying, playback, broadcasting, and display of moving picture, moving image, visual Media (communication), media. Video was first developed for mechanical television systems, whi ...
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 assoc ...
characteristics and limitations of a
cathode ray tube (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 withi ...
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
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 circ ...
.
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 functi ...
.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.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 i ...
, 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 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 ...
(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, 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) syst ...
signals in SD-TV digital video form)[
** Rec. 2020 ( 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 functi ...
(EOTF):
** ITU-R BT.1886 (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 se ...
)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, ...
(HDR) cameras.[ An example of a conventional gamma curve would be Rec. 601:
ITU-R Recommendation BT.1886 describe the reference EOTF of SDR.][ It's a gamma curve representing the response of ]CRT
CRT or Crt may refer to:
Science, technology, and mathematics Medicine and biology
* Calreticulin, a protein
*Capillary refill time, for blood to refill capillaries
*Cardiac resynchronization therapy and CRT defibrillator (CRT-D)
* Catheter-re ...
to video signal.[ It has been published by ITU 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.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 ...
.[ HLG is compatible with SDR displays.]
Color gamut
In some cases the term SDR is also used with a meaning including the standard 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 circ ...
(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).[ HDR 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 circ ...
(WCG) such as Rec. 2020 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 stan ...
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 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
CRT or Crt may refer to:
Science, technology, and mathematics Medicine and biology
* Calreticulin, a protein
*Capillary refill time, for blood to refill capillaries
*Cardiac resynchronization therapy and CRT defibrillator (CRT-D)
* Catheter-re ...
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).[ However, current displays are often far more capable than CRT's limits.][ On such displays, higher brightness and wider color gamut can be displayed by adjusting and trying to enhance the SDR picture.][ HDR is however required for the creative intents to be preserved.][
]
See also
*