Intraframe encoding - YCbCr colour space

• MPEG uses the 12-bit YCbCr (YUV) colour space rather than 8-bit RGB
  • Y - luminance (brightness)
  • Cb - blue colour difference
  • Cr - red colour difference
• Human Visual System more sensitive to changes in luminance (Y) than chrominance (CbCr)
• Most MPEG implementations use 4:2:0 specification, each pixel has it's own Y value but chrominance value is shared over a 2x2 block.
• The video must be filtered to produce reasonable chrominance values (ie. chrominance average over 2x2 block)

• Little visual degradation and halves uncompressed video size