我做了一些小測試, 8-bit Adobe RGB和sRGB的R和B, 足以應付8-bit YUV。G訊號則兩者同樣有精度不足的情況, 一般情況下Adobe RGB的精度只是比sRGB差約5%, 不是明顯的差別.....因此Adobe RGB令精度下降的理據不能成立
以下是測試結果:
YUV = 8-bit YUV in BT.709
RGB1 = sRGB
RGB2 = Adobe RGB
YUV: = 128, 240, 128
R1 = 142.05130392557763
G1 = 85.713995581226953
B1 = 353.25381529454563
R2 = 128.07472621786590
G2 = 86.351580436974132
B2 = 351.68658995822108
YUV = 128, 239, 128
R1 = 142.05130392557763
G1 = 86.226702757775797
B1 = 351.42201526505130
R2 = 128.16101768858272
G2 = 86.836108848278428
B2 = 349.78019699372294
U相差1, G1相差0.512707176548844, G2相差0.484528411304296, 大約差5.5%
YUV = 128, 16, 128
R1 = 142.05130392557763
G1 = 196.76882929013414
B1 = -119.41522045522095
R2 = 158.66490306161219
G2 = 195.40422459255262
B2 = -109.32952975868774
YUV = 128, 17, 128
R1 = 142.05130392557763
G1 = 196.28577165233239
B1 = -117.42808272254530
R2 = 158.48635720923551
G2 = 194.91560333597610
B2 = -107.33009689592011
U相差1, G1相差0.48305763780175, G2相差0.48862125657652, 這情況Adobe RGB比sRGB還要好
YUV = 128, 128, 240
R1 = 322.10525874657026
G1 = 119.74336490900019
B1 = 142.05130392557763
R2 = 284.64629325930088
G2 = 118.95918553167317
B2 = 139.94761440626800
YUV = 128, 128, 239
R1 = 320.53961689956520
G1 = 119.94379658171306
B1 = 142.05130392557763
R2 = 283.27998702629179
G2 = 119.15371411166562
B2 = 139.95421138497682
V相差1, G1相差0.20043167271287, G2相差0.19452857999245, 大約差3%
YUV = 128, 128, 16
R1 = -85.378041383100680
G1 = 164.10609797664833
B1 = 142.05130392557763
R2 = 59.239152670891684
G2 = 162.60742036627565
B2 = 141.74533659463614
YUV = 128, 128, 17
R1 = -83.651235486482619
G1 = 163.91018618617619
B1 = 142.05130392557763
R2 = 60.829561541756846
G2 = 162.41226423971023
B2 = 141.73587046533200
V相差1, G1相差0.19591179047214, G2相差0.19515612656542, 大約差0.4%
P.S. 計算上的誤差是因為D65的數值不準, 我現在我的數值是x = 0.31271; y = 0.32902, 而不是實際數字, 因此可能少許誤差, 但不太影響結果