Y'CbCr in JPEG Standard

JPEG allows Y'CbCr where Y', Cb and Cr have the full 256 values:

　JPEG-Y'CbCr (601) from "digital 8-bit R'G'B' "
　===========================================
　Y' = + 0.299 * R'd + 0.587 * G'd + 0.114 * B'd
　Cb = 128 - 0.168736 * R'd - 0.331264 * G'd + 0.5 * B'd
　Cr = 128 + 0.5 * R'd - 0.418688 * G'd - 0.081312 * B'd
　===========================================
　R'd, G'd, B'd in {0, 1, 2, ..., 255}
　Y', Cb, Cr in {0, 1, 2, ..., 255}

from Wikipedia: YCbCr