RGB<=>YCrCb Y=0.299*R + 0.587*G + 0.114*B Cr=(R-Y)*0.713 + 128 Cb=(B-Y)*0.564 + 128R=Y + 1.403*(Cr - 128) G=Y - 0.344*(Cr - 128) - 0.714*(Cb - 128) B=Y + 1.773*(Cb - 128)RGB=>HSV V=max(R,G,B) S=(V-min(R,G,B))*255/V if V!=0, 0 otherwise (G - B)*60/S, if V=R H= 180+(B - R)*60/S, if V=G 240+(R - G)*60/S, if V=Bif H<0 then H=H+360 The hue values calcualted using the above formulae vary from 0° to 360° so they are divided by 2 to fit into 8-bit destination format.
S=1-3*[min(R,G,B)]/(R+G+B)
H的式子比较复杂，这里打不出来
Y=0.299*R + 0.587*G + 0.114*B
Cr=(R-Y)*0.713 + 128
Cb=(B-Y)*0.564 + 128R=Y + 1.403*(Cr - 128)
G=Y - 0.344*(Cr - 128) - 0.714*(Cb - 128)
B=Y + 1.773*(Cb - 128)RGB=>HSV
V=max(R,G,B)
S=(V-min(R,G,B))*255/V if V!=0, 0 otherwise (G - B)*60/S, if V=R
H= 180+(B - R)*60/S, if V=G
240+(R - G)*60/S, if V=Bif H<0 then H=H+360
The hue values calcualted using the above formulae vary from 0° to 360° so they are divided by 2 to fit into 8-bit destination format.