The color difference channels are so named because they are derived from RGB by subtracting signals from the luma channel for each of the color channels (for example, R-Y or B-Y). S-Video (Y/C): An S-Video signal is also considered a component video signal because the luma and chroma signals are separate. However, the C signal is derived by combining the CB and CR component signals, which reduces the quality of the color channel compared to Yâ²CBCR.