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YUV的
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Example of UV color plane, Y' value = 0.5, represented within RGB color gamut紫外颜色平面，Y的值= 0.5为例，在代表的RGB色域

An image along with its Y', U, and V components.随着形象的一个其Y'，U和V组件。
YUV is a color space typically used as part of a color image pipeline . YUV的是一个色彩空间通常是用来作为部分彩色图像管道 。 It encodes a color image or video taking human perception into account, allowing reduced bandwidth for chrominance components, thereby typically enabling transmission errors or compression artifacts to be more efficiently masked by the human perception than using a "direct" RGB-representation.它编码一个彩色图像或视频考虑到人类感知，让带宽降低色度成分，从而使传输错误通常或压缩文物，更有效地代表蒙面由RGB的人的看法比使用“直接”。 Other color spaces have similar properties, and the main reason to implement or investigate properties of Y'UV would be for interfacing with analog or digital television or photographic equipment that conforms to certain Y'UV standards.其他彩色空间具有相似的性质，原因和主要执行或调查的Y'UV将负责与模拟或数字电视或摄影器材，以符合某些Y'UV standards接口属性。
The scope of the terms Y'UV, YUV, YCbCr , YPbPr , etc., is sometimes ambiguous and overlapping.该条款的范围Y'UV和YUV， YCbCr ， 色差等，有时是含糊和重叠。 Historically, the terms YUV and Y'UV were used for a specific analog encoding of color information in television systems, while YCbCr was used for digital encoding of color information suited for video and still-image compression and transmission such as MPEG and JPEG .从历史上看，YUV和Y'UV的条款被用于特定的模拟电视系统的信息编码的颜色，而YCbCr是信息使用的彩色数字编码传输适合视频和静止图像压缩和诸如的MPEG和JPEG格式 。 Today, the term YUV is commonly used in the computer industry to describe file-formats that are encoded using YCbCr.今天，这个词是常用的YUV在计算机行业来描述文件，YCbCr格式进行编码使用。
The Y'UV model defines a color space in terms of one luma (Y') and two chrominance (UV) components.该Y'UV模型定义了一个色彩空间中的一个条款， 亮度 （Y的）和两个色度 （紫外线）组件。 The Y'UV color model is used in the NTSC , PAL , and SECAM composite color video standards.该Y'UV颜色模型是用于NTSC制式 ， PAL制式和SECAM制式 的复合彩色视频标准。 Previous black-and-white systems used only luma (Y') information.以前的黑与白的系统只用亮度（Y的）信息。 Color information (U and V) was added separately via a sub-carrier so that a black-and-white receiver would still be able to receive and display a color picture transmission in the receiver's native black-and-white format.颜色信息（U和V）分别增加了通过子载波 ，使一个非黑即白接收器将仍然能够接收并显示接收的彩色图像传送机在黑与白的格式。
Y' stands for the luma component (the brightness) and U and V are the chrominance (color) components; luminance is denoted by Y and luma by Y' – the prime symbols (') denote gamma compression , [ 1 ] with "luminance" meaning perceptual ( color science ) brightness, while "luma" is electronic (voltage of display) brightness.代表的Y' 亮度分量（亮度）和U和V是色度 （颜色）的组成部分;亮度亮度是表示为Y和由Y' -首要符号（'）表示伽玛压缩 ， [1]与“亮度“意思感性（ 彩色版 ）的亮度，而“亮度”是电子（显示电压）的亮度。 The YPbPr color model used in analog component video and its digital version YCbCr used in digital video are more or less derived from it, and are sometimes called Y'UV.该色差颜色模型用于模拟分量视频和数字版本YCbCr数字视频使用，或多或少都从它派生，而且有时也被称为Y'UV。 (C B /P B and C R /P R are deviations from grey on blue–yellow and red–cyan axes, whereas U and V are blue–luminance and red–luminance differences.) The Y'IQ color space used in the analog NTSC television broadcasting system is related to it, although in a more complex way. （丙乙 / P B和C /人R是不同亮度偏差从灰色蓝色黄色和红色，青色ü轴，而和V是蓝色的亮度和红色。）的Y'IQ色彩空间的使用模拟NTSC制式电视系统有关，但更复杂的方式。
Contents内容
[hide]
· 1 History 1 历史
· 2 Mathematical derivations and formulae 2 数学推导和公式
o 2.1 BT.709 and BT.601 2.1 BT.709规范和BT.601
· 3 Numerical approximations 3 数值逼近
· 4 Luminance/chrominance systems in general 4 亮度/色度系统一般
· 5 Confusion with Y'CbCr 五 困惑与Y'CbCr
· 6 Types of sampling 6 抽样类型
· 7 Converting between Y'UV and RGB 7 Y'UV和RGB之间转换
o 7.1 Y'UV444 7.1 Y'UV444
o 7.2 Y'UV422 7.2 Y'UV422
o 7.3 Y'UV411 7.3 Y'UV411
o 7.4 Y'UV420p (and Y'V12 or YV12) 7.4 Y'UV420p（和Y'V12或的YV12）
· 8 References 8 参考资料
· 9 External links 9 外部链接
[ edit ] History [ 编辑 ] 历史
Y'UV was invented when engineers wanted color television in a black-and-white infrastructure. [ 2 ] They needed a signal transmission method that was compatible with black-and-white (B&W) TV while being able to add color. Y'UV被发明时，工程师希望彩色电视在黑与白的基础设施。 [2]他们需要的信号传输方法为（兼容黑与白黑白）电视的同时，又可增添色彩。 The luma component already existed as the black and white signal; they added the UV signal to this as a solution.已经存在的亮度分量的黑色和白色的信号，他们将作为一个解决方案的紫外线信号这一点。
The UV representation of chrominance was chosen over straight R and B signals because U and V are color difference signals.紫外线的色度代表被选为了直线R和B信号，因为U和V是色差信号。 This meant that in a black and white scene the U and V signals would be zero and only the Y' signal would need to be transmitted.这意味着，在黑色和白色的场景U和V信号将是零，只有Y的信号将需要传输。 If R and B were to have been used, these would have non-zero values even in a B&W scene, requiring all three data-carrying signals.如果R和B组已被使用，这甚至会在B＆W的现场非零值，要求所有三种数据承载信号。 This was important in the early days of color television, because holding the U and V signals to zero while connecting the black and white signal to Y' allowed color TV sets to display B&W TV without the additional expense and complexity of special B&W circuitry.这是在彩色电视的早期重要的，因为持有的U和V信号为零，而连接的黑色和白色信号为Y'让彩电显示没有额外的费用和特殊B＆W的复杂电路的黑白电视机。 In addition, black and white receivers could take the Y' signal and ignore the color signals, making Y'UV backward-compatible with all existing black-and-white equipment, input and output.此外，黑人和白人接收机可以采取Y的信号，而忽略了彩色信号，使Y'UV向后兼容所有现有的黑与白设备，输入和输出。 It was necessary to assign a narrower bandwidth to the chrominance channel because there was no additional bandwidth available.有必要指定一个窄带宽的色度通道，因为没有额外的可用带宽。 If some of the luminance information arrived via the chrominance channel (as it would have if RB signals were used instead of differential UV signals), B&W resolution would have been compromised. [ 3 ]如果通过一些渠道来的色度亮度信息（如，因为它会经常被用来代替信号差紫外光信号），B＆W的决议将已被泄露。 [3]
[ edit ] Mathematical derivations and formulae [ 编辑 ] 数学推导和公式
Y'UV signals are typically created from an original RGB ( red , green and blue ) source. Y'UV信号通常创建从原始的RGB （ 红色 ， 绿色和蓝色 ）的来源。 The weighted values of R, G, and B are added together to produce a single Y' signal, representing the overall brightness, or luminance, of that spot.的R，G的加权值，B是相加产生一个Y的信号，代表整体亮度，亮度或该点。 The U signal is then created by subtracting the Y' from the blue signal of the original RGB, and then scaling; V is created by subtracting the Y' from the red, and then scaling by a different factor.美国的信号，然后创建减去从原始的RGB蓝色信号Y'，然后缩放; V是减去创造了从红Y的，然后由不同的因素缩放。 This can be accomplished easily with analog circuitry.这可以轻松地与模拟电路。
The relationship between Y'UV and RGB is dependent on the following defined constants: Y'UV和RGB之间的关系是基于以下定义的常量依赖：

Then Y'UV is given in terms of RGB as (with R, G, B ranging from zero to one):然后Y'UV给出了RGB的角度来看，与R，G，B三个从0到1（）：

Note that the ranges of Y', U, and V respectively are [0, 1], [- U Max , U Max ], and [- V Max , V Max ].请注意，和V的范围的Y'，铀，分别是[0，1]，[ - ü 马克斯 ， 马克斯 ü]和[ - V 最大 ，V 最大 ]。 The above is a linear transform which can be easily inverted:以上是一个线性变换，可以很容易倒：

Equivalently, substituting numbers for symbols:等价地，为符号代数字：

There are some points regarding the RGB transformation matrix:有几点意见的RGB转换矩阵：
· The top row is identical to that of the Y'IQ color space第一行是相同的，说的Y'IQ色彩空间
·
· These formulas use the more traditional model of Y'UV, which is used for analog PAL equipment; digital PAL and digital NTSC HDTV do not use Y'UV but Y'CbCr.这些公式使用更传统的用于模拟模型Y'UV是，其中PAL制式设备，数码PAL制式和数码NTSC制式 的HDTV不使用Y'UV但Y'CbCr。
UV Planes in a range of [-1,1]飞机在紫外线的范围[-1,1]

Y' value of 0 Y的值为0

Y' value of 0.5 Y的价值0.5

Y' value of 1 Y的值1
[ edit ] BT.709 and BT.601 [ 编辑 ] BT.709规范和BT.601
When standardising high-definition video , the ATSC chose a different formula for the YCbCr than that used for standard-definition video.当标准化的高清晰度视频 ，在ATSC标准选择了不同配方的YCbCr比视频用于标准清晰度。 This means that when converting between SDTV and HDTV, the color information has to be altered, in addition to image scaling the video.这意味着，当信息SDTV和HDTV之间转换，颜色要改变，除了图像缩放视频。
The formulae above reference Rec.参考以上公式市盈率。 601 . 601 。 For HDTV, a slightly different matrix is used, where W R and W B in the above formula is replaced by Rec.高清晰度电视，稍有不同的矩阵使用，其中W R和W B在上述公式是取代市盈率。 709 : 709 ：

[ edit ] Numerical approximations [ 编辑 ] 数值逼近
Prior to the development of fast SIMD floating-point processors, most digital implementations of RGB->Y'UV used integer math, in particular fixed-point approximations.在此之前的快速发展的SIMD浮点处理器，-> Y'UV大多数数字实现对RGB的整数，特别是数学， 固定点逼近。 In the following examples, the operator " a >> b " denotes an integer division by a power of two, which is equivalent to a right-shift of a by b bits.在下面的例子中，经营者“1>> B”的指由B位整数分权的两个，这相当于一个右一个转变。
Traditional 8 bit representation of Y'UV with unsigned integers uses the following传统的8位无符号整数Y'UV代表与使用以下
Basic Transform基本变换

Scale down to 8 bits with rounding缩减至8位与四舍五入
Y ' = ( Y ' + 128) > > 8 Ÿ'=（是'+ 128）>> 8
U = ( U + 128) > > 8 ü =的（U + 128）>> 8
V = ( V + 128) > > 8 ν=（五+ 128）>> 8
Shift values移值
Y ' + = 16 Ÿ'+ = 16
U + = 128 ü + = 128
V + = 128 为V + = 128
Y' values are conventionally shifted and scaled to the range [16, 235] rather than using the full range of [0, 255]. Y的值是常规移动和缩放的范围[16，235]而不是使用了[0，255]齐全。 This confusing practice derives from the MPEG standards and explains why 16 is added to Y' and why the Y' coefficients in the basic transform sum to 220 instead of 255.这种混乱的做法源于MPEG标准，并解释为什么16添加到Y'，为什么在基本变换的总和为220而不是255的Y'系数。 U and V values, which may be positive or negative, are summed with 128 to make them always positive. [ 4 ] U和V值，这可能是正面还是负面，都概括为128，使他们总是积极的。 [4]

RGB to Y'UV conversion using 16 bit coefficients: RGB到Y'UV使用16位的转换系数：

Y'UV to RGB conversion using 16 bit coefficients: Y'UV到RGB的转换使用16位系数：

[ edit ] Luminance/chrominance systems in general [ 编辑 /色度系统一般 ] 亮度
The primary advantages of luma/chroma systems such as Y'UV, and its relatives Y'IQ and YDbDr , are that they remain compatible with black and white analog television (largely due to the work of Georges Valensi ).亮度的主要优势，如Y'UV /色度系统，其亲属Y'IQ和YDbDr ，他们仍然是黑色和白色兼容模拟电视 （主要是由于工作乔治Valensi ）。 The Y' channel saves nearly all the data recorded by black and white cameras, so it produces a signal suitable for reception on old monochrome displays.在Y'频道保存几乎所有的黑白摄像机记录数据，因此它产生的信号接收旧的单色显示器合适。 In this case, the U and V are simply discarded.在这种情况下，U和V是简单地丢弃。 If displaying color, all three channels are used, and the original RGB information can be decoded.如果显示颜色，所有三个通道的使用，原有的RGB和信息可以被解码。
Another advantage of Y'UV is that some of the information can be discarded in order to reduce bandwidth .另一个Y'UV优势是，信息一些可以被丢弃，以减少带宽 。 The human eye has fairly little color sensitivity: the accuracy of the brightness information of the luminance channel has far more impact on the image discerned than that of the other two.人类眼睛颜色的敏感度已经相当小：该通道的亮度亮度信息的准确性已远远比其他两个看出图像的影响。 Understanding this human shortcoming, standards such as NTSC reduce the bandwidth of the chrominance channels considerably, leaving the brain to extrapolate much of the color.要了解这个人的缺点，标准，如NTSC制式的渠道减少带宽的色度相当，离开大脑的颜色大部分的推断。
Therefore, the resulting U and V signals can be substantially "compressed".因此，由此产生的U和V信号，可大大“压缩”。 (In the NTSC (Y'IQ) and PAL systems, the chrominance signals had significantly narrower bandwidth (roughly 1 MHz) than that for the luminance.) Early versions of NTSC rapidly alternated between particular colors in identical image areas to make them appear adding up to each other to the human eye, while all modern analogue and even most digital video standards use chroma subsampling by recording a picture's color information at only half the resolution compared to the brightness information. （在NTSC制式（Y'IQ）和PAL系统，色度信号的带宽，显着缩小（约1兆赫兹）的亮度比。）早期迅速的NTSC色彩交替之间特别是在相同的图像区域版本，以使它们显得加入到对方的人的眼睛，而所有最现代化的模拟和数字视频标准，甚至使用色度抽样的记录只有一半的分辨率图片的颜色信息相比，亮度信息。 This ratio is the most common form, known as 4:2:2, which is the sample ratio of Y:U:V, or Y:I:Q.这个比率是最常见的形式，为4:2:2知道，这是Y的采样率：ü：五，或Y：我会问： The 4:x:x standard was adopted due to the very earliest color NTSC standard which used a chroma subsampling of 4:1:1 so that the picure carried only a quarter as much resolution in color than it did in brightness. 4所示：X：X标准由于采用了最早的色彩标准，它采用了NTSC制式的4:1:1色度抽样，使picure只进行了四分之一多的色彩分辨率比它的亮度一样。 Today, only high-end equipment processing uncompressed signals uses a chroma subsampling of 4:4:4 with identical resolution for both brightness and color information.今天，只有高端设备处理未压缩的色度信号采用4:4:4抽样与亮度和颜色信息都相同的决议。
The I and Q axes were chosen according to bandwidth needed by human vision, one axis being that requiring the most bandwidth, and the other (fortuitously at 90 degrees) the minimum.我和Q轴被选为根据人类视觉带宽，一轴被需要，要求最带宽，而有幸在90度，其它（）最低。 However, true I and Q demodulation was relatively more complex, requiring two analog delay lines, and NTSC receivers rarely used it.但是，真正的I和Q解调是比较复杂，需要两个模拟延迟线和NTSC接收器很少使用它。
However, this color space conversion is lossy , particularly obvious in crosstalk from the luma to the chroma-carrying wire, and vice versa, in analogue equipment (including RCA connectors to transfer a digital signal, as all they carry is analogue composite video , which is either YUV, YIQ, or even CVBS ), resulting in dot crawl and cross color artifacts respectively.然而，这种色彩空间转换损耗 ，特别是在明显的串扰从色度亮度的承载线，反之亦然，在模拟设备（包括RCA接口来传输数字信号，因为它们携带的所有模拟复合视频 ，其中要么是YUV的，采用YIQ，甚至CVBS等 ），导致点抓取和串色分别文物。 When the NTSC standard was created in the 1950s this was not a real concern since the quality of the image was limited by the monitor equipment, not the limited-bandwidth signal being received.在NTSC制式标准是创建于20世纪50年代以来，这是不是对图像质量真正关心的是有限的监控设备，而不是有限带宽信号被接收。 However today's modern television is capable of displaying more information than is contained in these lossy signals.然而今天的现代电视可以显示更多的信息比耗在这些信号所载的能力。 To keep pace with the abilities of new display technologies, attempts were made since the late 1970s to preserve more of the Y'UV signal while transferring images, such as SCART (1977) and S-Video (1987) connectors.为了保持技术的步伐，新的显示，让有能力的，试图使20世纪70年代末以来，以保持信号的多个Y'UV同时传输图像，如SCART的 （1977年）和S -视频 （1987）连接器。
Instead of Y'UV, Y'CbCr was used as the standard format for (digital) common video compression algorithms such as MPEG-2 .而不是Y'UV，Y'CbCr是为作为标准格式（数字）共同视频压缩的算法，如MPEG - 2的 。 Digital television and DVDs preserve their compressed video streams in the MPEG-2 format, which uses a full Y'CbCr color space, although retaining the established process of chroma subsampling.数字电视和DVD保存其压缩视频流中的MPEG - 2格式，它使用一个完整Y'CbCr色彩空间，但保留色度抽样建立过程。 The professional CCIR 601 digital video format also uses Y'CbCr at the common chroma subsampling rate of 4:2:2, primarily for compatibility with previous analog video standar