ical transformation of RGB designed solely for storage and
 transmission.  YCbCr images must be converted to RGB before they can
 actually be displayed.  In the YCbCr colorspace, the Y (luminance)
 component represents the black & white portion of the original image, and
 the Cb and Cr (chrominance) components represent the color portion of the
 original image.  Originally, the analog equivalent of this transformation
 allowed the same signal to drive both black & white and color televisions,
 but JPEG imag