关于yuv与rgb的互转

来自以下网址：http://stackoverflow.com/questions/9465815/rgb-to-yuv420-algorithm-efficiency

 #define CLIP(X) ( (X) > 255 ? 255 : (X) < 0 ? 0 : X)

 // RGB -> YUV
 #define RGB2Y(R, G, B) CLIP(( (  66 * (R) + 129 * (G) +  25 * (B) + 128) >> 8) +  16)
 #define RGB2U(R, G, B) CLIP(( ( -38 * (R) -  74 * (G) + 112 * (B) + 128) >> 8) + 128)
 #define RGB2V(R, G, B) CLIP(( ( 112 * (R) -  94 * (G) -  18 * (B) + 128) >> 8) + 128)

 // YUV -> RGB
 #define C(Y) ( (Y) - 16  )
 #define D(U) ( (U) - 128 )
 #define E(V) ( (V) - 128 )

 #define YUV2R(Y, U, V) CLIP(( 298 * C(Y)              + 409 * E(V) + 128) >> 8)
 #define YUV2G(Y, U, V) CLIP(( 298 * C(Y) - 100 * D(U) - 208 * E(V) + 128) >> 8)
 #define YUV2B(Y, U, V) CLIP(( 298 * C(Y) + 516 * D(U)              + 128) >> 8)

 // RGB -> YCbCr
 #define CRGB2Y(R, G, B) CLIP((19595 * R + 38470 * G + 7471 * B ) >> 16)
 #define CRGB2Cb(R, G, B) CLIP((36962 * (B - CLIP((19595 * R + 38470 * G + 7471 * B ) >> 16) ) >> 16) + 128)
 #define CRGB2Cr(R, G, B) CLIP((46727 * (R - CLIP((19595 * R + 38470 * G + 7471 * B ) >> 16) ) >> 16) + 128)

 // YCbCr -> RGB
 #define CYCbCr2R(Y, Cb, Cr) CLIP( Y + ( 91881 * Cr >> 16 ) - 179 )
 #define CYCbCr2G(Y, Cb, Cr) CLIP( Y - (( 22544 * Cb + 46793 * Cr ) >> 16) + 135)
 #define CYCbCr2B(Y, Cb, Cr) CLIP( Y + (116129 * Cb >> 16 ) - 226 )

经验证，非常好用。mark