YCoCg

Some modern video codecs (e.g. dirac) support the YCoCg colorspace. More correctly written this is YC_oC_g, with the 'o' and 'g' characters as subscripts. This is what the components represent:

   * Y = pseudo luminance, or intensity
   * Co = "orange chrominance"
   * Cg = "green chrominance"

This colorspace is invented to use similar encoding techniques as for YC_bC_r but with frames in RGB colorspace. It is possible to transform lossless from RGB to YCoCg when two more bits than used for RGB are available for the YCoCg represantation. This way it is possible to lesslessly transform a 30-bit RGB (10 bits for each color) frame into 32 bits in YCoCg and back.

Like with YCbCr it is also possible to use different sized planes for each component. Thus, every pixel in an image of a YCoCg encodec frame is associated with one Y sample, but possibly groups of pixels share C_o and C_g samples.

So this encodings are possible for instance

   * YCoCg 4:4:4
   * YCoCg 4:2:2
   * ...