Image An image or picture is a visual representation. An image can be Two-dimensional space, two-dimensional, such as a drawing, painting, or photograph, or Three-dimensional space, three-dimensional, such as a carving or sculpture. Images may be di ...

s and

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 ...

s use specific

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, models the system's output for each possible ...

s to describe the relationship between

electrical signal A signal is both the process and the result of transmission of data over some media accomplished by embedding some variation. Signals are important in multiple subject fields including signal processing, information theory and biology. In ...

, scene light and displayed light.

Definition

The opto-electronic transfer function (OETF) is the

having the scene light as input and converting into the picture or video signal as output. This is typically done within a

camera A camera is an instrument used to capture and store images and videos, either digitally via an electronic image sensor, or chemically via a light-sensitive material such as photographic film. As a pivotal technology in the fields of photograp ...

. The electro-optical transfer function (EOTF) is the

having the picture or video signal as input and converting it into the linear light output of the display. This is done within a

display device A display device is an output device for presentation of information in visual or tactile form (the latter used for example in tactile electronic displays for blind people). When the input information that is supplied has an electrical signa ...

. The opto-optical transfer function (OOTF) is the

having the scene light as input and the displayed light as output. The OOTF is the composition of the OETF and the EOTF and is usually

non-linear In mathematics and science, a nonlinear system (or a non-linear system) is a system in which the change of the output is not proportional to the change of the input. Nonlinear problems are of interest to engineers, biologists, physicists, mathe ...

List of transfer functions

Linear In mathematics, the term ''linear'' is used in two distinct senses for two different properties: * linearity of a '' function'' (or '' mapping''); * linearity of a '' polynomial''. An example of a linear function is the function defined by f(x) ...

* Raw formats *Some OETF and EOTF have an initial

linear In mathematics, the term ''linear'' is used in two distinct senses for two different properties: * linearity of a '' function'' (or '' mapping''); * linearity of a '' polynomial''. An example of a linear function is the function defined by f(x) ...

portion followed by a non-linear part (e.g. sRGB and Rec.709).

Gamma Gamma (; uppercase , lowercase ; ) 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 normally repr ...

* Rec. 601, Rec. 709 and Rec. 2020: The ITU-R recommendations BT.601, BT.709 and BT.2020 describe the reference OETF of respectively SD-TV, HD-TV and UHD-TV. They are identical OETF based on a gamma curve and used for SDR-TV. * BT.1886: The ITU-R Recommendation BT.1886 is the reference EOTF of Standard Dynamic Range TV (SDR). * sRGB: sRGB defines a transfer function based on a gamma curve and used for monitors, printers and the

Web Web most often refers to: * Spider web, a silken structure created by the animal * World Wide Web or the Web, an Internet-based hypertext system Web, WEB, or the Web may also refer to: Computing * WEB, a literate programming system created by ...

. sRGB is standardized as IEC 61966-2-1:1999

Logarithm In mathematics, the logarithm of a number is the exponent by which another fixed value, the base, must be raised to produce that number. For example, the logarithm of to base is , because is to the rd power: . More generally, if , the ...
ic

* S-Log: Developed by

Sony is a Japanese multinational conglomerate (company), conglomerate headquartered at Sony City in Minato, Tokyo, Japan. The Sony Group encompasses various businesses, including Sony Corporation (electronics), Sony Semiconductor Solutions (i ...

for

digital camera A digital camera, also called a digicam, is a camera that captures photographs in Digital data storage, digital memory. Most cameras produced today are digital, largely replacing those that capture images on photographic film or film stock. Dig ...

s in order to increase captured

dynamic range Dynamics (from Greek δυναμικός ''dynamikos'' "powerful", from δύναμις ''dynamis'' " power") or dynamic may refer to: Physics and engineering * Dynamics (mechanics), the study of forces and their effect on motion Brands and ent ...

* Canon Log: Developed by Canon for

s in order to increase captured

*Arri Log C: Developed by Arri for

s in order to increase captured

HDR

These transfer functions have been developed to allow HDR display: * Perceptual quantizer: PQ is a transfer function developed by Dolby for HDR and allowing a

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 wit ...

level of up to 10,000 cd/m². It is standardized in Rec. 2100 and also as SMPTE ST 2084. * Hybrid log–gamma: HLG is a transfer function developed by

NHK , also known by its Romanization of Japanese, romanized initialism NHK, is a Japanese public broadcasting, public broadcaster. It is a statutory corporation funded by viewers' payments of a television licence, television license fee. NHK ope ...

and

BBC The British Broadcasting Corporation (BBC) is a British public service broadcaster headquartered at Broadcasting House in London, England. Originally established in 1922 as the British Broadcasting Company, it evolved into its current sta ...

for HDR and offering some

backward compatibility In telecommunications and computing, backward compatibility (or backwards compatibility) is a property of an operating system, software, real-world product, or technology that allows for interoperability with an older legacy system, or with Input ...

on SDR displays. HLG is a hybrid transfer function in which the lower half of the signal values use a gamma curve and the upper half of the signal values use a

logarithmic curve In mathematics, logarithmic growth describes a phenomenon whose size or cost can be described as a logarithm function of some input. e.g. ''y'' = ''C'' log (''x''). Any logarithm base can be used, since one can be converted to anot ...

. It is standardized in Rec. 2100.

References

{{Reflist Transfer functions Video Imaging

Definition

List of transfer functions

Linear In mathematics, the term ''linear'' is used in two distinct senses for two different properties: * linearity of a '' function'' (or '' mapping''); * linearity of a '' polynomial''. An example of a linear function is the function defined by f(x) ...

Gamma Gamma (; uppercase , lowercase ; ) 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 normally repr ...

Logarithm In mathematics, the logarithm of a number is the exponent by which another fixed value, the base, must be raised to produce that number. For example, the logarithm of to base is , because is to the rd power: . More generally, if , the ...ic

HDR

References

Logarithm In mathematics, the logarithm of a number is the exponent by which another fixed value, the base, must be raised to produce that number. For example, the logarithm of to base is , because is to the rd power: . More generally, if , the ...
ic