- Rec. 709
ITU-RRecommendation BT.709, more commonly know by the abbreviations Rec. 709 or BT.709, standardizes the format of High-definition television, having 16:9 ( widescreen) aspect ratio.
Rec. 709 refers to HDTV systems having roughly two million luma samples per frame. Rec. 709 has two parts: Part 1 codifies what are now referred to as 1035i30 and 1152i25 HDTV systems. The 1035i30 system is now obsolete, having been superseded by 1080"i" and 1080"p" square-sampled (“square-pixel”) systems. The 1152"i"25 system was used for experimental equipment in Europe and was never commercially deployed.
Part 2 codifies current and prospective 1080"i" and 1080"p" systems with square sampling. In attempt to unify 1080-line HDTV standards, part 2 defines a "common image format" (CIF) with picture parameters independent of the picture rate.
Rec. 709 specifies the following picture rates: 60 Hz, 50 Hz, 30 Hz, 25 Hz and 24 Hz. "Fractional" rates having the above values divided by 1.001 are also permitted.
Initial acquisition is possible in either progressive or interlaced form. Video captured as progressive can be transported with either progressive transport or
progressive segmented frame(PsF)transport. Video captures as interlaced can be transported with interlace transport. In cases where a progressive captured image is transported as a segmented frame, segment/field frequency must be twice higher than frame rate.
In practice, the above results in following frame rates ("fractional" rates specified in commonly used "decimal" form): 25i, 25PsF, 25p, 50p for 50 Hz systems; 23.98p, 23.98PsF, 24p, 24PsF, 29.97i, 29.97PsF, 29.97p, 30p, 30PsF, 59.94p, 60p for 60 Hz systems.
Rec. 709 coding uses “studio-swing” levels where reference black is defined as 8-bit interface code 16 and reference white is defined as 8-bit interface code 235. Interface codes 0 and 255 are used for synchronization, and are prohibited from video data. Eight-bit codes between 1 and 15 provide footroom, and can be used to accommodate transient signal content such as filter undershoots. Eight-bit interface codes 236 through 254 provide headroom, and can be used to accommodate transient signal content such as filter overshoots and specular highlights. Bit-depths deeper than 8 bits are obtained by appending least-significant bits. Ten-bit systems are commonplace in studios. (Desktop computer graphic systems ordinarily use “full-swing” encoding that places reference black at code 0 and reference white at code 255, and provide no footroom or headroom.) The 16..235 limits (for luma; 16..240 for chroma) originated with ITU Rec. 601. [ITU-R Rec. BT.601-5, 1995. Section 3.5.3.]
Note that red and blue are the same as the EBU primaries while green is halfway between EBU and SMPTE C.
When converting between the various HD and SD formats, it would be correct to compensate for the differences in the primaries (e.g. between the Rec. 709, EBU, and SMPTE C primaries). In practice, this conversion is rarely performed and such a conversion would create a liability for post production facilities as they would need to ensure that the color bars on all the new masters are redone. Correcting for differences in the primaries would cause the resulting color bars on the converted tape to be inaccurate. Incorrect color bars will cause a (sub)master to be rejected by quality control checks. [ [http://www.glennchan.info/articles/technical/hd-versus-sd-color-space/hd-versus-sd-color-space.htm] : Chan, Glenn, "HD versus SD Color Space."]
HDTV according to Rec. 709 forms luma ("Y’") using "R’G’B’" coefficients 0.2126, 0.7152, and 0.0722. These coefficients are different from those of Rec.601 (for no good reason, according to some experts [ [http://www.poynton.com/papers/SMPTE_98_YYZ_Luma/index.html] : Poynton, Charles, “Luminance, luma, and the migration to DTV” (Feb. 6, 1998)] ). Although worldwide agreement on a single R’G’B’ system was achieved upon the adoption of Rec. 709, adoption of different luma coefficients created a second flavour of "Y’C"B"C"R. Whenever SDTV is upconverted to HDTV, or HDTV is downconverted to SDTV, at the studio or at the consumers’ premises, luma-chroma matrixing is required.
Rec. 709 is written as if it specifies the capture and transfer characteristics of HDTV encoding - that is, as if it were scene-referred. However, in practice it is output (display) referred with respect to a 2.4-power function display. (Rec. 709 and
sRGBshare the same primary chromaticities and white point chromaticity; however, sRGB is explicitly output (display) referred.) [cite book |title=Digital Video and HDTV Algorithms and Interfaces |last=Poynton |first=Charles |year=2003 |publisher=Morgan Kaufmann |location=San Francisco |isbn=1-55860-792-7|page=263 ]
Rec. 601, a comparable standard for standard definition television
* [http://www.itu.int/rec/R-REC-BT.709/en ITU-R BT.709-5] : "Parameter values for the HDTV standards for production and international programme exchange." April, 2002. Note that the -5 is the current version, in May 2008; previous versions were -1 through -4.
* [http://www.poynton.com/notes/PU-PR-IS/index.html] : Poynton, Charles, "Perceptual uniformity, picture rendering, image state, and Rec. 709." May, 2008.
Wikimedia Foundation. 2010.
Look at other dictionaries:
Rec. 709 — La recommandation ITU R BT 709 ou plus communément Rec. 709 est un standard de l industrie audiovisuelle pour la Haute définition. La première révision de la recommandation a été publiée par la SMPTE en 1990. Sommaire 1 Détails techniques 1.1… … Wikipédia en Français
Rec. 601 — ITU R Recommendation BT.601, more commonly know by the abbreviations Rec. 601 or BT.601 (or its former name, CCIR 601,) is a standard published by International Telecommunication Union Radiocommunications sector (formerly CCIR) for encoding… … Wikipedia
Rec.arts.sf.tv.babylon5.moderated — is a notable and influential moderated Usenet newsgroup that focuses on the science fiction television series Babylon 5 and the works of writer J. Michael Straczynski. It was spun off from its un moderated version, rec.arts.sf.tv.babylon5, in… … Wikipedia
Luma (video) — As applied to video signals, luma represents the brightness in an image (the black and white or achromatic portion of the image). Luma is typically paired with chroma. Luma represents the achromatic image without any color, while the chroma… … Wikipedia
Телевидение сверхвысокой чёткости — На схеме показаны разрешения форматов 8K UHDTV, 4K UHDTV, HDTV (1080p) и SDTV … Википедия
High-definition television — Logo High definition television (HDTV) is video that has resolution substantially higher than that of traditional television systems (standard definition television). HDTV has one or two million pixels per frame, roughly five times that of SD… … Wikipedia
HSL and HSV — Fig. 1. HSL (a–d) and HSV (e–h). Above (a, e): cut away 3D models of each. Below: two dimensional plots showing two of a model’s three parameters at once, holding the other constant: cylindrical shells (b, f) of constant saturation, in this case… … Wikipedia
YUV — Y UV is a color space typically used as part of a color image pipeline. It encodes a color image or video taking human perception into account, allowed reduced bandwidth for chrominance components, thereby typically enabling transmission errors… … Wikipedia
ITU-R — 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 communication. Its role is to manage the international radio frequency… … Wikipedia
SRGB — is a standard RGB (Red Green Blue) color space created cooperatively by HP and Microsoft for use on monitors, printers, and the Internet. sRGB uses the ITU R BT.709 5 primaries, the same as are used in studio monitors and HDTV, [cite book | title … Wikipedia