7.2. RGB to YCrCb Color Conversion (SDTV).
Color information recorded in the color palette provided by each PGC is encoded as luminance and color difference coded signals (YCrCb). This encoding is popular among many component video systems and is used by the DVD-Video standard.

The reason for using YCrCb signal is that the human eye is less sensitive to chrominance than luminance. Compression algorithms can take advantage of this phenomenon and subsample the values of Cb and Cr without significant visual degradation of the original color signal.

On computers, color information is recorded as red-green-blue signal (RGB). Use the following equation to approximate the converted values of RGB color information into the YCrCb (YUV) components. The coefficients in the equation are recommended by the ITU-R BT.601-5 standard for 4:3 and wide-screen 16:9 aspect ratios and the conversion is most compatible with the usage of subpicture color on DVD.

The equations to compute the Y, Cr, and Cb components from R, G, B are demonstrated below. The complete equations and coefficients and other DVD related information are available from the Unofficial DVD Specifications 2.2 PDF ebook.
Enter values for R, G, B in decimal (from 0 to 255) R or choose from the following colors: G B	Y = 0 Cr = 128 Cb = 128