RGB转YUV

float R = (float)r; float G = (float)g; float B = (float)b; float Y = 0.299*R + 0.587*G + 0.114*B; float U = -0.169*R - 0.331*G + 0.5 *B + 128.0; float V = 0.5 *R - 0.419*G - 0.081*B + 128.0;