View source for YPbPr

{{Short description|Color space used in analog video}}
[[File:Component-cables.jpg|thumb|right|200px|YPbPr is the [[analog video]] signal carried by component video cable in consumer electronics. The green cable carries ''Y'', the blue cable carries ''P<sub>B</sub>'' and the red cable carries ''P<sub>R</sub>''.]]

'''YPbPr''' or '''<math>Y'P'bP'r</math>''', also written as '''{{YPbPr|}}''', is a [[color space]] used in [[video]] [[electronics]], in particular in reference to [[component video]] cables. Like [[YCbCr|YC<sub>B</sub>C<sub>R</sub>]], it is based on [[gamma correction|gamma corrected]] [[RGB]] primaries; the two are numerically equivalent but YP<sub>B</sub>P<sub>R</sub> is designed for use in [[analogue electronics|analog systems]] while YC<sub>B</sub>C<sub>R</sub> is intended for [[digital video]].<ref>{{Cite web |date=2024 |title=YUV, YCbCr, YPbPr colour spaces |url=https://discoverybiz.net/enu0/faq/faq_YUV_YCbCr_YPbPr.html |access-date=2021-04-16 |website=DiscoveryBiz.Net}}</ref> The EOTF (gamma correction) may be different from common [[SRGB#Transformation|sRGB]] EOTF and [[High-dynamic-range video#SDR transfer function|BT.1886]] EOTF. Sync is carried on the Y channel and is a bi-level sync signal, but in HD formats a [[tri-level sync]] is used and is typically carried on all channels.<ref name=":0" /> 

YP<sub>B</sub>P<sub>R</sub> is commonly referred to as ''component video'' by manufacturers; however, there are many types of component video, most of which are some form of [[component video#RGB analog component video|RGB]]. Some [[video card]]s come with [[video-in video-out]] (VIVO) ports for connecting to component video devices.

==Technical details==
{{further|YCbCr#CbCr}}

'''<math>Y'P'bP'r</math>''' can be derived from a gamma corrected '''<math>R'G'B'</math>''' signal with a typical range of 0-700 [[Millivolt|mV]]. The first step is converting to '''<math>Y'</math>''', '''<math>R'-Y'</math>''' and '''<math>B'-Y'</math>'''.<ref name=":1">{{Cite book |url=https://download.tek.com/document/25W_16653_0.pdf |title=Applications - High Definition Analog Component Measurement |date=2003 |publisher=Tektronix |pages=2}}</ref>

'''<math>Y'</math>'''carries [[Luma (video)|luma]] (brightness or ''luminance'') and synchronization (sync) information. Luma is defined as:
* <math>Y' = 0.212 R + 0.701 G + 0.087 B</math> for [[Multiple sub-Nyquist sampling encoding|Hi-Vision]];
* <math>Y' = 0.2126 R + 0.7152 G + 0.0722 B</math> for [[High-definition television|HDTV]];
* <math>Y' = 0.299 R + 0.587 G + 0.114 B</math> for [[Standard-definition television|SDTV]];
'''<math>R'-Y'</math>'''carries the difference between red and luma, defined as:
* <math>R'-Y' = 0.7874 R' - 0.7152 G' - 0.0722 B'</math>for Hi-Vision and HDTV;
* <math>R'-Y' = 0.701 R' - 0.587 G' - 0.114 B'</math> for SDTV.
'''<math>B'-Y'</math>'''carries the difference between blue and luma, defined as:
* <math>B'-Y' = - 0.2126 R' - 0.7152 G' + 0.9278 B'</math> for [[Multiple sub-Nyquist sampling encoding|Hi-Vision]] and [[High-definition television|HDTV]];
* <math>B'-Y' = - 0.299 R' - 0.587 G' + 0.886 B'</math> for SDTV.
These '''<math>R'-Y'</math>''' and '''<math>B'-Y'</math>''' values are then scaled to obtain normalized '''<math>P'r</math>''' and '''<math>P'b</math>''' values in the range of +/- 350 mV:<ref name=":1" />

* '''<math>P'b = (B'-Y')/1.826</math>''' and '''<math>P'r = (R'-Y')/1.576</math>''' for Hi-Vision;
* '''<math>P'b = [0.5/(1-0.0722)](B'-Y')</math>''' and '''<math>P'r = [0.5/(1-0.2126)](R'-Y')</math>''' for HDTV;
* '''<math>P'b = 0.564(B'-Y')</math>''' and '''<math>P'r = 0.713(R'-Y')</math>'''  for SDTV.

There are other standards of {{YPbPr|}} components derivation available: 

* [[YCbCr#SMPTE 240M conversion|SMPTE 240M]] (240M defined EOTF and uses SMPTE 170M primaries and white point) for 1920x1035;
* [[YCbCr#ITU-R BT.601 conversion|BT.601 matrix]] for [[525 lines|525 lines 60/1.001 Hz]] (SMPTE 273M) and [[625 lines|625 lines 50 Hz]] ([[PAL|ITU-R BT.1358]]).<ref name=":0">{{Cite book |url=https://download.tek.com/document/25W_16653_0.pdf |title=Applications - High Definition Analog Component Measurement |date=2003 |publisher=Tektronix}}</ref>

To send a [[green]] signal as a fourth component is redundant, as it can be derived using the blue, red and luma information.

When color signals were first added to the NTSC-encoded black and white video standard, the hue was represented by a [[Phase (waves)|phase shift]] of a color reference [[Subcarrier|sub-carrier]]. ''P'' for phase information or phase shift has carried through to represent color information even in the case where there is no longer a phase shift used to represent hue. Thus, the YP<sub>B</sub>P<sub>R</sub> nomenclature derives from engineering metrics developed for the NTSC color standard.{{Citation needed|date=March 2012}}

The same cables can be used for {{YPbPr|}} and [[composite video]]. This means that the yellow, red, and white [[RCA connector]] cables commonly packaged with most audio/visual equipment can be used in place of the YP<sub>B</sub>P<sub>R</sub> connectors, provided the end user is careful to connect each cable to corresponding components at both ends. Also, many TVs use the green connection either for luma only or for composite video input. Since {{YPbPr|}} is backwards compatible with the luminance portion of composite video even with just component video decoding one can still use composite video via this input, but only luma information will be displayed, along with the [[chroma dots]]. The same goes the other way around so long as 480i or 576i is used.

== YP<sub>B</sub>P<sub>R</sub> advantages ==

[[File:Component video jack.jpg|thumb|right|200px|Female [[RCA connector]]s used to output YPbPr component video from a set-top-box, DVD player or similar device. Female connections in this configuration are also used for YPbPr inputs on display devices such as TVs.]]

Signals using {{YPbPr|}} offer enough separation that no color [[multiplexing]] is needed, so the quality of the extracted image is nearly identical to the pre-encoded signal. [[S-Video]] and [[composite video]] mix the signals together by means of electronic multiplexing. Signal degradation is typical for composite video, as most display systems are unable to completely separate the signals, though HDTVs tend to perform such separation better than most [[Cathode-ray tube|CRT]] units (see [[dot crawl]]). [[S-Video]] can mitigate some of these potential issues, as its luma is transmitted separately from chroma.

Among consumer analog interfaces, only YP<sub>B</sub>P<sub>R</sub> and [[Analog RGB|analog RGB component video]] are capable of carrying non-[[Interlaced video|interlaced]] video and resolutions higher than [[480i]] or [[576i]], up to [[1080p]] for YP<sub>B</sub>P<sub>R</sub>.

== See also ==
Graphic chipsets that generate color internally based on {{YPbPr|}}:

* [[CTIA and GTIA]]
* [[MOS Technology VIC#Color palette|MOS Technology VIC]]
* [[MOS Technology VIC-II#Colors|MOS Technology VIC-II]]
* [[MOS Technology TED#Video capabilities|MOS Technology TED]]
* [[TMS9918#Colors|TMS9918]]
* [[Motorola 6847#Signal levels and color palette|Motorola 6847]]

==References==
{{reflist}}

==External links==
* [http://www.poynton.com/ColorFAQ.html Color FAQ], Charles Poynton

{{Analogvideo}}
{{AVconn}}
{{Color space}}

[[Category:Color space]]
[[Category:Video signal]]

[[zh:色差端子]]