Using YCrCb to detect color

YUV and YCrCb mostly the same, YUV is more used in analog tv signals
while TCbCr refers to digital form.

Using Cr[0,255] and Cb[0,255] to detect road color, there are at least 2
Pos vs. RGB:
1. calculation is simpler, r*b*g->cb*cr
2. YCrCb is more often used in video singnal which we will use as
input one day.