 U and V are bipolar signals which can be positive or negative, and are zero for greys, whereas YCbCr usually scales all channels to either the 16–235 range or the 0–255 range, which makes Cb and Cr unsigned quantities which are 128 for greys.Nevertheless, the relationship between them in the standard case is simple.In particular, the Y' channels of both are linearly related to each other, both Cb and U are related linearly to (B-Y), and both Cr and V are related linearly to (R-Y).