yuv和yCbCr的差异

Peter Lee 2006.02.28 videosky.9126.com

今天在看intel ipp tutorial的时候，看到了讲色彩模型的部分。以前，一直没明白yuv和YcbCr之间的差异，想必有些朋友也会有同样的疑惑。所以，我看完之后就记载下来了。

一、和rgb之间换算公式的差异

yuv<-->rgb

border-alt: solid windowtext .5pt; mso-padding-alt: 1.0pt 4.0pt 1.0pt 4.0pt" align="left">Y'= 0.299*R' + 0.587*G' + 0.114*B'

border-alt: solid windowtext .5pt; mso-padding-alt: 1.0pt 4.0pt 1.0pt 4.0pt" align="left">U'= -0.147*R' - 0.289*G' + 0.436*B' = 0.492*(B'- Y')

border-alt: solid windowtext .5pt; mso-padding-alt: 1.0pt 4.0pt 1.0pt 4.0pt" align="left">V'= 0.615*R' - 0.515*G' - 0.100*B' = 0.877*(R'- Y')

border-alt: solid windowtext .5pt; mso-padding-alt: 1.0pt 4.0pt 1.0pt 4.0pt" align="left">R' = Y' + 1.140*V'

border-alt: solid windowtext .5pt; mso-padding-alt: 1.0pt 4.0pt 1.0pt 4.0pt" align="left">G' = Y' - 0.394*U' - 0.581*V'

border-alt: solid windowtext .5pt; mso-padding-alt: 1.0pt 4.0pt 1.0pt 4.0pt" align="left">B' = Y' + 2.032*U'

yCbCr<-->rgb

border-alt: solid windowtext .5pt; mso-padding-alt: 1.0pt 4.0pt 1.0pt 4.0pt" align="left">Y’ = 0.257*R' + 0.504*G' + 0.098*B' + 16

border-alt: solid windowtext .5pt; mso-padding-alt: 1.0pt 4.0pt 1.0pt 4.0pt" align="left">Cb' = -0.148*R' - 0.291*G' + 0.439*B' + 128

border-alt: solid windowtext .5pt; mso-padding-alt: 1.0pt 4.0pt 1.0pt 4.0pt" align="left">Cr' = 0.439*R' - 0.368*G' - 0.071*B' + 128

border-alt: solid windowtext .5pt; mso-padding-alt: 1.0pt 4.0pt 1.0pt 4.0pt" align="left">R' = 1.164*(Y’-16) + 1.596*(Cr'-128)

border-alt: solid windowtext .5pt; mso-padding-alt: 1.0pt 4.0pt 1.0pt 4.0pt" align="left">G' = 1.164*(Y’-16) - 0.813*(Cr'-128) - 0.392*(Cb'-128)

border-alt: solid windowtext .5pt; mso-padding-alt: 1.0pt 4.0pt 1.0pt 4.0pt" align="left">B' = 1.164*(Y’-16) + 2.017*(Cb'-128)

Note: 上面各个符号都带了一撇，表示该符号在原值基础上进行了gamma correction

二、来源上的差异

yuv色彩模型来源于rgb模型，

该模型的特点是将亮度和色度分离开，从而适合于图像处理领域。

应用：basic color model used in analogue color TV broadcasting.

YCbCr模型来源于yuv模型。YCbCr is a scaled and offset version of the YUV color space.

应用：数字视频，ITU-R BT.601 recommendation

ps:

通过上面的比较可以确定，我们在h.264,mpeg等编码标准中用的yuv其实是YcbCr，大家不要被名称搞混淆了。