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46-632: On July 21, 2015, the Ultra HD Forum announced that they had over 20 member companies after incorporating as a US-based non-profit a month earlier. On April 18, 2016, the Ultra HD Forum announced industry guidelines for UHD Phase A content. The Ultra HD Forum also announced that it had increased to 46 member companies. On January 5, 2017, the Ultra HD Forum announced that their guidelines had been updated to version 1.2 (including things like immersive audio, BT.2100 , etc.) and that additional companies have joined which includes Google . On September 14, 2017

92-435: A Wide Color Gamut . Rec. 2100 specifies three resolutions of 1920 × 1080 ("Full HD"), 3840 × 2160 ("4K UHD"), and 7680 × 4320 ("8K UHD"). These resolutions have an aspect ratio of 16:9 and use square pixels . Rec. 2100 specifies the following frame rates: 120p, 119.88p, 100p, 60p, 59.94p, 50p, 30p, 29.97p, 25p, 24p, 23.976p. Only progressive scan frame rates are allowed. Rec. 2100 specifies

138-433: A black body follows Planck's law : At the time of standardizing illuminant A, both c 1 = 2 π ⋅ h ⋅ c 2 {\displaystyle c_{1}=2\pi \cdot h\cdot c^{2}} (which does not affect the relative SPD) and c 2 = h ⋅ c / k {\displaystyle c_{2}=h\cdot c/k} were different. In 1968,

184-531: A white point , corresponding to a correlated color temperature of 6504 K. Rec. 709 , used in HDTV systems, truncates the CIE 1931 coordinates to x=0.3127, y=0.329. There are no actual daylight light sources, only simulators. Constructing a practical light source that emulates a D-series illuminant is a difficult problem. The chromaticity can be replicated simply by taking a well known light source and applying filters, such as

230-445: A CIE recommendation. Nevertheless, they do provide a measure, called the metamerism index , to assess the quality of daylight simulators. The Metamerism Index tests how well five sets of metameric samples match under the test and reference illuminant. In a manner similar to the color rendering index , the average difference between the metamers is calculated. The CIE defines illuminant A in these terms: CIE standard illuminant A

276-629: A bit depth of either 10-bits per sample or 12-bits per sample, with either narrow range or full range color values. A future-use and intermediate linear RGB format using IEEE 16 bit floating point representation for each channel is also specified. For narrow range color, 10-bit per sample signals use video levels where the black level is defined as 64, achromatic gray level as 512 and the nominal peak as 940 in RGB, Y, and I encoding and 960 in Cb/Cr, and Ct/Cp component encoding. 12-bit per sample signals define 256 as

322-504: A color temperature, but it can be approximated by a D series illuminant with a CCT of 5455 K. (Of the canonical illuminants, D 55 is the closest.) Manufacturers sometimes compare light sources against illuminant E to calculate the excitation purity . The F series of illuminants represent various types of fluorescent lighting . F1–F6 "standard" fluorescent lamps consist of two semi-broadband emissions of antimony and manganese activations in calcium halophosphate phosphor . F4

368-498: A letter or by a letter-number combination. Illuminants A, B, and C were introduced in 1931, with the intention of respectively representing average incandescent light, direct sunlight, and average daylight. Illuminants D (1967) represent variations of daylight, illuminant E is the equal-energy illuminant, while illuminants F (2004) represent fluorescent lamps of various composition. There are instructions on how to experimentally produce light sources ("standard sources") corresponding to

414-400: A pair of chromaticity coordinates . If an image is recorded in tristimulus coordinates (or in values which can be converted to and from them), then the white point of the illuminant used gives the maximum value of the tristimulus coordinates that will be recorded at any point in the image, in the absence of fluorescence . It is called the white point of the image. The process of calculating

460-428: A red LED. LED-RGB1 defines the white light produced by a tricolor LED mix. LED-V1 and V2 define LEDs with phosphor-converted violet light. The spectrum of a standard illuminant, like any other profile of light, can be converted into tristimulus values . The set of three tristimulus coordinates of an illuminant is called a white point . If the profile is normalized , then the white point can equivalently be expressed as

506-400: A reference viewing environment the peak luminance of display should be 1000 cd/m or more for small area highlights and the black level should be 0.005 cd/m or less. The surround light should be 5 cd/m and be neutral grey at standard illuminant D 65 . Within each set, the documented transfer functions include an: Rec. 2100 uses the same color primaries as Rec. 2020 which is

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552-524: A relatively high absorbance at the red end of the spectrum, effectively increasing the CCT of the incandescent lamp to daylight levels. This is similar in function to a CTB color gel that photographers and cinematographers use today, albeit much less convenient. Each filter uses a pair of solutions, comprising specific amounts of distilled water, copper sulfate , mannite , pyridine , sulfuric acid , cobalt , and ammonium sulfate . The solutions are separated by

598-413: A representative of noon sunlight, with a correlated color temperature (CCT) of 4874 K, while C represented average day light with a CCT of 6774 K. Unfortunately, they are poor approximations of any phase of natural daylight, particularly in the short-wave visible and in the ultraviolet spectral ranges. Once more realistic simulations were achievable, illuminants B and C were deprecated in favor of

644-513: A sheet of uncolored glass. The amounts of the ingredients are carefully chosen so that their combination yields a color temperature conversion filter; that is, the filtered light is still white. The D series of illuminants are designed to represent natural daylight and lie along the daylight locus. They are difficult to produce artificially, but are easy to characterize mathematically. By 1964, several spectral power distributions (SPDs) of daylight had been measured independently by H. W. Budde of

690-495: A simple, quadratic relation, later known as the daylight locus: Characteristic vector analysis revealed that the SPDs could be satisfactorily approximated by using the mean (S 0 ) and first two characteristic vectors (S 1 and S 2 ): In simpler terms, the SPD of the studied daylight samples can be expressed as the linear combination of three, fixed SPDs. The first vector (S 0 )

736-623: A zero at 560 nm , since all the relative SPDs have been normalized about this point. In order to match all significant digits of the published data of the canonical illuminants the values of M 1 and M 2 have to be rounded to three decimal places before calculation of S D . Using the standard 2° observer , the CIE 1931 color space chromaticity coordinates of D65 are x = 0.31272 y = 0.32903 {\displaystyle {\begin{aligned}x&=0.31272\\y&=0.32903\end{aligned}}} and

782-407: Is a theoretical source of visible light with a spectral power distribution that is published. Standard illuminants provide a basis for comparing images or colors recorded under different lighting. The International Commission on Illumination (usually abbreviated CIE for its French name) is the body responsible for publishing all of the well-known standard illuminants. Each of these is known by

828-446: Is designed for high dynamic range (HDR) and wide color gamut signals (WCG). Rec. 2100 allows for RGB , YCbCr , and ICtCp signal formats with 4:4:4, 4:2:2, and 4:2:0 chroma subsampling . Rec. 2100 specifies that if a luma (Y') signal is made that it use the same matrix coefficients as Rec. 2020 : 0.2627 for red, 0.678 for green, and 0.0593 for blue (derived from BT.2020 primaries and white point). Before Rec. BT.2020

874-415: Is intended to represent typical, domestic, tungsten-filament lighting. Its relative spectral power distribution is that of a Planckian radiator at a temperature of approximately 2856 K. CIE standard illuminant A should be used in all applications of colorimetry involving the use of incandescent lighting, unless there are specific reasons for using a different illuminant. The spectral radiant exitance of

920-460: Is of particular interest since it was used for calibrating the CIE color rendering index (the CRI formula was chosen such that F4 would have a CRI of 51). F7–F9 are "broadband" ( full-spectrum light ) fluorescent lamps with multiple phosphors, and higher CRIs. Finally, F10–F12 are narrow triband illuminants consisting of three "narrowband" emissions (caused by ternary compositions of rare-earth phosphors) in

966-402: Is the mean of all the SPD samples, which is the best reconstituted SPD that can be formed with only a fixed vector. The second vector (S 1 ) corresponds to yellow–blue variation (along the locus), accounting for changes in the correlated color temperature due to proportion of indirect to direct sunlight. The third vector (S 2 ) corresponds to pink–green variation (across the locus) caused by

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1012-472: The High Efficiency Video Coding (HEVC) Main 10 profile Level 5.1 and process Hybrid log–gamma (HLG10) or Perceptual quantizer ( PQ10 )/ HDR10 content using Rec. 2020 color primaries. The guidelines consider Rec. 2100 1080p content with Wide Color Gamut ( BT.2020 ) and High Dynamic Range as Ultra HD service. The guidelines also document live and pre-recorded production, as well as

1058-692: The National Research Council of Canada in Ottawa , H. R. Condit and F. Grum of the Eastman Kodak Company in Rochester, New York , and S. T. Henderson and D. Hodgkiss of Thorn Electrical Industries in Enfield (north London) , totaling among them 622 samples. Deane B. Judd , David MacAdam , and Günter Wyszecki analyzed these samples and found that the ( x , y ) chromaticity coordinates followed

1104-651: The XYZ tristimulus values (normalized to Y = 100 ), are X = 95.047 Y = 100 .000 Z = 108.883 {\displaystyle {\begin{alignedat}{2}X&={}&95.047\\Y&={}&100{\phantom {.000}}\\Z&={}&108.883\end{alignedat}}} For the supplementary 10° observer , x = 0.31382 y = 0.33100 {\displaystyle {\begin{aligned}x&=0.31382\\y&=0.33100\end{aligned}}} and

1150-464: The chroma sample location that was in use was center left. But in H.265 (2018-02) top-left chroma siting was mandated for BT.2020-2 and BT.2100-1, that must be described in VUI (video usability information) as such. First value of VUI should be 2 for top-left chroma and 0 for center left. Blu-ray also uses top-left chroma for HDR, including for Dolby Vision. Standard illuminant A standard illuminant

1196-461: The visible spectrum . It is useful as a theoretical reference; an illuminant that gives equal weight to all wavelengths. It also has equal CIE XYZ tristimulus values, thus its chromaticity coordinates are (x,y)=(1/3,1/3). This is by design; the XYZ color matching functions are normalized such that their integrals over the visible spectrum are the same. Illuminant E is not a black body, so it does not have

1242-540: The CIE today are derived by linear interpolation of the 10 nm data set down to 5 nm . However, there is a proposal to use spline interpolation instead. Similar studies have been undertaken in other parts of the world, or repeating Judd et al.' s analysis with modern computational methods. In several of these studies, the daylight locus is notably closer to the Planckian locus than in Judd et al. The CIE positions D65 as

1288-475: The D series. Illuminant C does not have the status of CIE standard illuminants but its relative spectral power distribution, tristimulus values and chromaticity coordinates are given in Table T.1 and Table T.3, as many practical measurement instruments and calculations still use this illuminant. Illuminant B was not so honored in 2004. The liquid filters, designed by Raymond Davis and Kasson S. Gibson in 1931, have

1334-551: The D-series SPD (S D ) that corresponds to those coordinates, the coefficients M 1 and M 2 of the characteristic vectors S 1 and S 2 are determined: where S 0 ( λ ) , S 1 ( λ ) , S 2 ( λ ) {\displaystyle S_{0}(\lambda ),S_{1}(\lambda ),S_{2}(\lambda )} are the mean and first two eigenvector SPDs, depicted in figure. The characteristic vectors both have

1380-487: The R,G,B regions of the visible spectrum. The phosphor weights can be tuned to achieve the desired CCT. The spectra of these illuminants are published in Publication 15:2004. Publication 15:2018 introduces new illuminants for different white LED types with CCTs ranging from approx. 2700 K to 6600 K. LED-B1 through B5 defines LEDs with phosphor-converted blue light. LED-BH1 defines a blend of phosphor-converted blue and

1426-463: The Spectralight III, that used filtered incandescent lamps. However, the SPDs of these sources deviate from the D-series SPD, leading to bad performance on the CIE metamerism index . Better sources were achieved in the 2010s with phosphor-coated white LEDs that can easily emulate the A, D, and E illuminants with high CRI. Illuminant E is an equal-energy radiator; it has a constant SPD inside

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1472-512: The abbreviations Rec. 2100 or BT.2100 , introduced high-dynamic-range television (HDR-TV) by recommending the use of the perceptual quantizer (PQ [SMPTE ST 2084]) or hybrid log–gamma (HLG) transfer functions instead of the traditional " gamma " previously used for SDR -TV. It defines various aspects of HDR-TV such as display resolution ( HDTV and UHDTV ), frame rate , chroma subsampling , bit depth , color space , color primaries , white point , and transfer function . It

1518-487: The black level, 2048 as the gray level and the nominal peak is 3760 in RGB, Y, and I component encoding and 3840 in Cb/Cr, and Ct/Cp component encoding. Narrow range signals may extend below black or above peak white (super-black and super-white respectively), but must always be clipped to the signal range of 4-1019 for 10-bit signals or 16-4079 for 12-bit signals. Rec. 2100 specifies the use of RGB, YCbCr, and ICtCp. ICtCp provides an improved color representation that

1564-521: The chromaticity coordinates must be determined: where T is the illuminant's CCT. Note that the CCTs of the canonical illuminants, D 50 , D 55 , D 65 , and D 75 , differ slightly from what their names suggest. For example, D50 has a CCT of 5003 K ("horizon" light), while D65 has a CCT of 6504 K (noon light). This is because the value of the constants in Planck's law have been slightly changed since

1610-635: The combination of HDR and SDR video content and conversion between BT.709 and BT.2020 color spaces and different HDR metadata formats. Broadcasters are advised to provide backward compatibility by using HLG10 with BT.2020 color space, or simulcasting PQ10 or HDR10 streams (for example, using Scalable HEVC ). An April 7, 2018 Ultra HD Forum published UHD Guidelines for phase B. Technologies that have been included in UHD Phase B, which targets UHD services launching in 2018-2020, include: BT.2100 ITU-R Recommendation BT.2100 , more commonly known by

1656-423: The corresponding XYZ tristimulus values are X = 94.811 Y = 100 .000 Z = 107.304 {\displaystyle {\begin{alignedat}{2}X&={}&94.811\\Y&={}&100{\phantom {.000}}\\Z&={}&107.304\end{alignedat}}} Since D65 represents white light, its coordinates are also

1702-661: The definition of these canonical illuminants, whose SPDs are based on the original values in Planck's law. The same discrepancy applies to all illuminants in the D series—D 50 , D 55 , D 65 , D 75 —and can be "rectified" by multiplying the nominal color temperature by c 2 1.4380 {\displaystyle {\frac {c_{2}}{1.4380}}} ; for example 6500   K × 1.438776877 … 1.4380 = 6503.51   K {\displaystyle 6500\ {\text{K}}\times {\frac {1.438776877\dots }{1.4380}}=6503.51\ {\text{K}}} for D 65 . To determine

1748-463: The estimate of c 2 was revised from 0.01438 m·K to 0.014388 m·K (and before that, it was 0.01435 m·K when illuminant A was standardized). This difference shifted the Planckian locus , changing the color temperature of the illuminant from its nominal 2848 K to 2856 K: In order to avoid further possible changes in the color temperature, the CIE now specifies the SPD directly, based on

1794-503: The guidelines were updated to version 1.4 (including new definitions of PQ10 and HDR10 , a matrix receiver/decoder capability combinations, the receiver/decoders combinations to render different formats, statistical methods of deriving CLL values, "graphics white" level for HLG as recommended by BBC and NHK, etc.) UHD Phase A covers broadcasting services to be launched by end of 2016 or early 2017. The guidelines for UHD Phase A are: UHD Phase A consumer devices should be able to decode

1840-417: The older illuminants. For the relatively newer ones (such as series D), experimenters are left to measure to profiles of their sources and compare them to the published spectra: At present no artificial source is recommended to realize CIE standard illuminant D65 or any other illuminant D of different CCT. It is hoped that new developments in light sources and filters will eventually offer sufficient basis for

1886-424: The original (1931) value of c 2 : The coefficients have been selected to achieve a normalized SPD of 100 at 560 nm . The tristimulus values are ( X , Y , Z ) = (109.85, 100.00, 35.58) , and the chromaticity coordinates using the standard observer are ( x , y ) = (0.44758, 0.40745) . Illuminants B and C are easily achieved daylight simulations. They modify illuminant A by using liquid filters. B served as

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1932-547: The presence of water in the form of vapor and haze. By the time the D-series was formalized by the CIE, a computation of the chromaticity ( x , y ) {\displaystyle (x,y)} for a particular isotherm was included. Judd et al. then extended the reconstituted SPDs to 300 nm – 330 nm and 700 nm – 830 nm by using Moon's spectral absorbance data of the Earth's atmosphere. The tabulated SPDs presented by

1978-430: The standard daylight illuminant: [D65] is intended to represent average daylight and has a correlated colour temperature of approximately 6500 K. CIE standard illuminant D65 should be used in all colorimetric calculations requiring representative daylight, unless there are specific reasons for using a different illuminant. Variations in the relative spectral power distribution of daylight are known to occur, particularly in

2024-461: The ultraviolet spectral region, as a function of season, time of day, and geographic location. The relative spectral power distribution (SPD) S D ( λ ) {\displaystyle S_{D}(\lambda )} of a D series illuminant can be derived from its chromaticity coordinates in the CIE 1931 color space , ( x D , y D ) {\displaystyle (x_{D},y_{D})} . First,

2070-404: The white point discards a great deal of information about the profile of the illuminant, and so although it is true that for every illuminant the exact white point can be calculated, it is not the case that knowing the white point of an image alone tells you a great deal about the illuminant that was used to record it. A list of standardized illuminants, their CIE chromaticity coordinates (x,y) of

2116-593: Was posted on the International Telecommunication Union (ITU) website on July 4, 2016. Rec. 2100 uses a wide color gamut (WCG) which is the same as Rec. 2020 's. Rec. 2100 defines two sets of HDR transfer functions which are perceptual quantization (PQ) and hybrid log-gamma (HLG). HLG is supported in Rec. 2100 with a nominal peak luminance of 1,000 cd/m and a system gamma value that can be adjusted depending on background luminance. For

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