YPbPr or Y'PbPr, also written as , is a
color space
A color space is a specific organization of colors. In combination with color profiling supported by various physical devices, it supports reproducible representations of colorwhether such representation entails an analog or a digital represen ...
used in
video
Video is an electronic medium for the recording, copying, playback, broadcasting, and display of moving visual media. Video was first developed for mechanical television systems, which were quickly replaced by cathode-ray tube (CRT) sy ...
electronics
The field of electronics is a branch of physics and electrical engineering that deals with the emission, behaviour and effects of electrons using electronic devices. Electronics uses active devices to control electron flow by amplification ...
, in particular in reference to
component video
Component video is an analog video signal that has been split into two or more component channels. In popular use, it refers to a type of component analog video (CAV) information that is transmitted or stored as three separate signals. Compo ...
cables. YP
BP
R is
gamma corrected YCBCR color space (it is not analog
YUV that was used for analog TV, though
component video
Component video is an analog video signal that has been split into two or more component channels. In popular use, it refers to a type of component analog video (CAV) information that is transmitted or stored as three separate signals. Compo ...
is an
analog interface); the two are numerically equivalent but YP
BP
R is designed for use in
analog systems while YC
BC
R is intended for
digital video
Digital video is an electronic representation of moving visual images (video) in the form of encoded digital data
Digital data, in information theory and information systems, is information represented as a string of discrete symbols eac ...
.
The EOTF (gamma correction) may be different from common
sRGB
sRGB is a standard RGB (red, green, blue) color space that HP and Microsoft created cooperatively in 1996 to use on monitors, printers, and the World Wide Web. It was subsequently standardized by the International Electrotechnical Commission ...
EOTF and
BT.1886
ITU-R BT.1886 is the reference EOTF of SDR-TV. It is a gamma 2.4 transfer function (a power law with a 2.4 exponent) considered as a satisfactory approximation of the response characteristic of CRT to electrical signal. It has been standardize ...
EOTF. Sync is carried on the Y channel and is a bi-level sync signal, however, in HD formats a
tri-level sync is used and is typically carried on all channels.
YP
BP
R is commonly referred to as ''component video'' by manufacturers; however, there are many types of component video, most of which are some form of
RGB. Some
video card
A graphics card (also called a video card, display card, graphics adapter, VGA card/VGA, video adapter, display adapter, or mistakenly GPU) is an expansion card which generates a feed of output images to a display device, such as a computer m ...
s come with
video-in video-out (VIVO) ports for connecting to component video devices.
Technical details
YP
BP
R is converted from the
RGB video signal, which is split into three components: Y, P
B, and P
R.
* Y carries
luma (brightness or ''luminance'') and synchronization (sync) information. Luma is defined as
in
SMPTE 274M
SMPTE 274M is a standard published by SMPTE
The Society of Motion Picture and Television Engineers (SMPTE) (, rarely ), founded in 1916 as the Society of Motion Picture Engineers or SMPE, is a global professional association of engineers, ...
(1920x1080 resolution) and
SMPTE ST 296 (1280x720). It uses
BT.709-2 matrix coefficients and digital
YCBCR. Before the advent of color television, the Y axis on an oscilloscope display of a video waveform represented the intensity of the scan line. With color, Y still represents intensity but it is a composite of the component colors.
* P
B carries the difference between blue and luma (
B − Y).
* P
R carries the difference between red and luma (
R − Y).
There are other standards of YP
BP
R components derivation available: 1920x1035 uses
SMPTE 240M (240M defined EOTF and uses SMPTE 170M primaries and white point) and
525 lines 60/1.001 Hz (SMPTE 273M) and
625 lines 50 Hz (
ITU-R BT.1358)
BT.601 matrix is used.
To send a
green
Green is the color between cyan and yellow on the visible spectrum. It is evoked by light which has a dominant wavelength of roughly 495570 nm. In subtractive color systems, used in painting and color printing, it is created by a combin ...
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 shift of a color reference
sub-carrier
A subcarrier is a sideband of a radio frequency carrier wave, which is modulated to send additional information. Examples include the provision of colour in a black and white television system or the provision of stereo in a monophonic radio broa ...
. 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
BP
R nomenclature derives from engineering metrics developed for the NTSC color standard.
The same cables can be used for YP
BP
R and
composite video
Composite video is an analog video signal format that carries standard-definition video (typically at 525 lines or 625 lines) as a single channel. Video information is encoded on one channel, unlike the higher-quality S-Video (two channe ...
. This means that the yellow, red, and white
RCA connector
The RCA connector is a type of electrical connector commonly used to carry audio and video signals. The name ''RCA'' derives from the company Radio Corporation of America, which introduced the design in the 1930s. The connectors male plug a ...
cables commonly packaged with most audio/visual equipment can be used in place of the YP
BP
R 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 YP
BP
R 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 Chroma dots are visual artifacts caused by displaying an unfiltered PAL analogue colour video signal on a black-and-white television or monitor. They are commonly found on black-and-white recordings of television programmes originally made in colour ...
. The same goes the other way around so long as 480i or 576i is used.
YPBPR advantages
Signals using YP
BP
R offer enough separation that no color
multiplexing
In telecommunications and computer networking, multiplexing (sometimes contracted to muxing) is a method by which multiple analog or digital signals are combined into one signal over a shared medium. The aim is to share a scarce resource - ...
is needed, so the quality of the extracted image is nearly identical to the pre-encoded signal.
S-Video
S-Video (also known as separate video, Y/C, and erroneously Super-Video ) is an analog video signal format that carries standard-definition video, typically at 525 lines or 625 lines. It encodes video luma and chrominance on two separate chann ...
and
composite video
Composite video is an analog video signal format that carries standard-definition video (typically at 525 lines or 625 lines) as a single channel. Video information is encoded on one channel, unlike the higher-quality S-Video (two channe ...
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
CRT units (see
dot crawl).
S-Video
S-Video (also known as separate video, Y/C, and erroneously Super-Video ) is an analog video signal format that carries standard-definition video, typically at 525 lines or 625 lines. It encodes video luma and chrominance on two separate chann ...
can mitigate some of these potential issues, as its luma is transmitted separately from chroma.
Among consumer analog interfaces, only YP
BP
R and
analog RGB component video are capable of carrying non-
interlaced
Interlaced video (also known as interlaced scan) is a technique for doubling the perceived frame rate of a video display without consuming extra bandwidth. The interlaced signal contains two fields of a video frame captured consecutively. This ...
video and resolutions higher than
480i
480i is the video mode used for standard-definition digital television in the Caribbean, Japan, South Korea, Taiwan, Philippines, Laos, Western Sahara, and most of the Americas (with the exception of Argentina, Paraguay, and Uruguay). T ...
or
576i
576i is a standard-definition digital video mode, originally used for digitizing analog television in most countries of the world where the utility frequency for electric power distribution is 50 Hz. Because of its close association wit ...
, up to
1080p
1080p (1920×1080 progressively displayed pixels; also known as Full HD or FHD, and BT.709) is a set of HDTV high-definition video modes characterized by 1,920 pixels displayed across the screen horizontally and 1,080 pixels down the screen ve ...
for YP
BP
R.
References
External links
Color FAQ Charles Poynton
{{Color space
Color space
Video signal
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