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ITU-R BT.709
ITU-R Recommendation 709, usually abbreviated Rec. 709, BT.709, or ITU-R 709, is a standard developed by the Radiocommunication Sector of the International Telecommunication Union (ITU-R) for image encoding and signal characteristics of high-definition television (HDTV). The standard specifies a scheme for digital encoding of colors as triplets of small integers, a widescreen format with 1080 active lines per picture and 1920 square pixels per line (a 16:9 aspect ratio), as well as several details of signal capture, transmission, and display. While directed to HDTV, some of its specifications (such as the color encoding) have also been adopted for other uses. Technical details The standard is freely available at the ITU website, and that document should be used as the authoritative reference. The essentials are summarized below. Image format and definition Recommendation ITU-R BT.709-6 defines a common image format (CIF) where picture characteristics are independ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CIE 1931 Color Space
In 1931, the International Commission on Illumination (CIE) published the CIE 1931 color spaces which define the relationship between the visible spectrum and human color vision. The CIE color spaces are mathematical models that comprise a "standard observer", which is a static idealization of the color vision of a normal human. A useful application of the CIEXYZ colorspace is that a mixture of two colors in some proportion lies on the straight line between those two colors. One disadvantage is that it is not perceptually uniform. This disadvantage is remedied in subsequent color models such as CIELUV and CIELAB, but these and modern color models still use the CIE 1931 color spaces as a foundation. The CIE (from the French name " Commission Internationale de l'éclairage" - International Commission on Illumination) developed and maintains many of the standards in use today relating to colorimetry. The CIE color spaces were created using data from a series of experiments, where ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Primary Color
Primary colors are colorants or colored lights that can be mixed in varying amounts to produce a gamut of colors. This is the essential method used to create the perception of a broad range of colors in, e.g., electronic displays, color printing, and paintings. Perceptions associated with a given combination of primary colors can be predicted by an appropriate mixing model (e.g., additive, subtractive) that uses the physics of how light interacts with physical media, and ultimately the retina to be able to accurately display the intended colors. The most common color mixing models are the additive primary colors (red, green, blue) and the subtractive primary colors (cyan, magenta, yellow). Red, yellow and blue are also commonly taught as primary colors (usually in the context of subtractive color mixing as opposed to additive color mixing), despite some criticism due to its lack of scientific basis. Primary colors can also be conceptual (not necessarily real), either as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HD-MAC
HD-MAC (High Definition Multiplexed Analogue Components) was a broadcast television systems, broadcast television standard proposed by the European Commission in 1986, as part of Eureka (organisation), Eureka 95 project. It belongs to the Multiplexed Analogue Components, MAC - Multiplexed Analogue Components standard family. It is an early attempt by the European Economic Community, EEC to provide High-definition television (HDTV) in Europe. It is a complex mix of Analog signal, analogue signal (based on the Multiplexed Analogue Components standard), multiplexed with digital sound, and assistance data for decoding (DATV). The video signal (1250 lines/50 fields per second in 16:9 aspect ratio, with 1152 visible lines) was encoded with a modified D2-MAC encoder. HD-MAC could be decoded by normal D2-MAC Standard-definition television, standard definition receivers, but no extra resolution was obtained and certain artifacts were visible. To decode the signal in full resolution a specifi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Multiple Sub-Nyquist Sampling Encoding
MUSE (Multiple sub-Nyquist Sampling Encoding), commercially known as Hi-Vision (a contraction of HIgh-definition teleVISION) was a Japanese analog high-definition television system, with design efforts going back to 1979. Traditional interlaced video shows either odd or even lines of video at any one time, but MUSE required four fields of video to complete a single video frame. Hi-Vision also refers to a closely related Japanese television system capable of transmitting video with 1035i resolution, in other words 1035 interlaced lines. MUSE was used as a compression scheme for Hi-Vision signals. Overview It used dot-interlacing and digital video compression to deliver 1125 line, 60 field-per-second (1125i60) signals to the home. The system was standardized as ITU-R recommendation BO.786 and specified by SMPTE 260M, using a colorimetry matrix specified by SMPTE 240M. As with other analog systems, not all lines carry visible information. On MUSE there are 1035 active interlac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
XvYCC
xvYCC or extended-gamut YCbCr is a color space that can be used in the video electronics of television sets to support a gamut 1.8 times as large as that of the sRGB color space. xvYCC was proposed by Sony, specified by the IEC in October 2005 and published in January 2006 as IEC 61966-2-4. xvYCC extends the ITU-R BT.709 tone curve by defining over-ranged values. xvYCC-encoded video retains the same color primaries and white point as BT.709, and uses either a BT.601 or BT.709 RGB-to-YCC conversion matrix and encoding. This allows it to travel through existing digital limited range YCC data paths, and any colors within the normal gamut will be compatible. It works by allowing negative RGB inputs and expanding the output chroma. These are used to encode more saturated colors by using a greater part of the RGB values that can be encoded in the YCbCr signal compared with those used in Broadcast Safe Level. The extra-gamut colors can then be displayed by a device whose underlying t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Highlight Headroom
Highlight headroom is the measure of how much additional dynamic range a given photographic medium (such as film or digital image sensors) has to record the detail within the brightest parts of a scene. As an example, consider a photograph of a white wedding dress against a white background. With limited highlight headroom, it will be hard to appreciate the intricate details within the fabric of the dress. The higher the available headroom, the more subtle shades of white will be captured. In practice, photographers are often faced with photographing outdoors on a cloudy day, but with the sun shining through a gap onto the subjects forehead. This can often lead to a bright reflection which records as bright white. If this bright spot (called a highlight) lies at the edge of the person's outline (from the camera's perspective) then it may end up blending into the cloudy sky if there is insufficient highlight headroom. This is a particular problem with digital cameras which of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
EBU Tech 3320
The European Broadcasting Union (EBU; , UER) is an alliance of Public broadcasting, public service media organisations in countries within the European Broadcasting Area (EBA) or who are member states of the Council of Europe, members of the Council of Europe. , it is made up of 123 member organisations from 56 countries, and 31 associate members from a further 20 countries. It was established in 1950, and has its administrative headquarters in Geneva. The EBU owns and operates the Eurovision (network), Eurovision and Euroradio telecommunications networks on which major television and radio broadcasts are distributed live to its members. It also operates the daily Eurovision news exchange in which members share breaking news footage. In 2017, the EBU launched the Eurovision Social Newswire, an eyewitness and video verification service. Led by Head of Social Newsgathering, Derek Bowler, the service provides members of the EBU with verified and cleared-for-use newsworthy eyewitn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ITU-R BT
The ITU Radiocommunication Sector (ITU-R) is one of the three sectors (divisions or units) of the International Telecommunication Union (ITU) and is responsible for radio communications. Its role is to manage the international radio-frequency spectrum and satellite orbit resources and to develop standards for radiocommunication systems with the objective of ensuring the effective use of the spectrum. ITU is required, according to its constitution, to allocate spectrum and register frequency allocation, orbital positions and other parameters of satellites, "in order to avoid harmful interference between radio stations of different countries". The international spectrum management system is therefore based on regulatory procedures for frequency coordination, notification and registration. ITU-R has a permanent secretariat, the Radiocommunication Bureau, based at the ITU HQ in Geneva, Switzerland. The elected Director of the Bureau is Mario Maniewicz; he was first elected by th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Colorfulness
Colorfulness, chroma and saturation are attributes of perceived color relating to chromatic intensity. As defined formally by the International Commission on Illumination (CIE) they respectively describe three different aspects of chromatic intensity, but the terms are often used loosely and interchangeably in contexts where these aspects are not clearly distinguished. The precise meanings of the terms vary by what other functions they are dependent on. * Colorfulness is the "attribute of a visual perception according to which the perceived color of an area appears to be more or less chromatic (Any color that is absent of white, grey, or black)"., page 87. The colorfulness evoked by an object depends not only on its spectral reflectance but also on the strength of the illumination, and increases with the latter unless the brightness is very high (Hunt effect (color), Hunt effect). * Chroma is the "colorfulness of an area judged as a proportion of the brightness of a similarl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Contrast (vision)
Contrast is the difference in luminance or color that makes an object (or its representation in an image or display) visible against a background of different luminance or color. The human visual system is more sensitive to contrast than to absolute luminance; thus, we can perceive the world similarly despite significant changes in illumination throughout the day or across different locations. The maximum contrast of an image is termed the contrast ratio or dynamic range. In images where the contrast ratio approaches the maximum possible for the medium, there is a ''conservation of contrast''. In such cases, increasing contrast in certain parts of the image will necessarily result in a decrease in contrast elsewhere. Brightening an image increases contrast in darker areas but decreases it in brighter areas; conversely, darkening the image will have the opposite effect. Bleach bypass reduces contrast in the darkest and brightest parts of an image while enhancing luminance contr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transfer Functions In Imaging
Images and videos use specific transfer functions to describe the relationship between electrical signal, scene light and displayed light. Definition The opto-electronic transfer function (OETF) is the transfer function having the scene light as input and converting into the picture or video signal as output. This is typically done within a camera. The electro-optical transfer function (EOTF) is the transfer function 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. The opto-optical transfer function (OOTF) is the transfer function 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. List of transfer functions Linear * Raw formats *Some OETF and EOTF have an initial linear portion followed by a non-linear part (e.g. sRGB and Rec.709). Gamma * Rec. 601, Rec. 709 and Rec. 2020: Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linear Function
In mathematics, the term linear function refers to two distinct but related notions: * In calculus and related areas, a linear function is a function whose graph is a straight line, that is, a polynomial function of degree zero or one. For distinguishing such a linear function from the other concept, the term ''affine function'' is often used. * In linear algebra, mathematical analysis, and functional analysis, a linear function is a linear map. As a polynomial function In calculus, analytic geometry and related areas, a linear function is a polynomial of degree one or less, including the zero polynomial (the latter not being considered to have degree zero). When the function is of only one variable, it is of the form :f(x)=ax+b, where and are constants, often real numbers. The graph of such a function of one variable is a nonvertical line. is frequently referred to as the slope of the line, and as the intercept. If ''a > 0'' then the gradient is positive an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
