12.1. About the Chroma Resampler IP
The human eye has higher visual acuity (resolution) for brightness than for tone (color). Color spaces that separate the luma (brightness) information from the chroma (color), such as YCbCr, can reduce the resolution at which the chroma data samples. These color spaces can reduce the bandwidth to transmit and store the data and the FPGA resources to process it.
4:4:4 sampling has the same number of samples on the luma (Y) and 2 chroma planes (Cb and Cr). For each Y sample there is one Cb sample and one Cr sample.
4:2:2 sampling reduces the Cb and Cr sampling by a factor of 2 in the horizontal direction. For each pair of Y samples there is now a single Cb sample and a single Cr sample.
4:2:0 sampling reduces the Cb and Cr sampling by a factor of 2 in both the horizontal and vertical directions. For each 2x2 group of 4 Y samples there is now a single Cb sample and a single Cr sample.