MCD212 Motorola, MCD212 Datasheet - Page 84

• Manufacturer Part Number: MCD212
• Description: Video Decoder and System Controller(with JTAG)
• Manufacturer: Motorola

A.1
The MCD212 does not do the encoding of any image but this section is included as an informational
reference to the process of image coding using the delta YUV (DYUV) process. Natural images are
particularly well suited to DYUV encoding since there is usually little difference in the color or intensity
of adjacent pixels. This makes for a very efficient coding of an image.
The process to produce a normal resolution DYUV image (384 x 240) begins with a high resolution
RGB image (768 x 480). The process to change from RGB to YUV uses the equations below:
The normalized, eight–bit values of the components are obtained from the following equations:
In order to solve aliasing problems, the image is filtered, typically with a FIR filter to maintain the cor-
rect phase and then is subsampled by a factor of two in both the horizontal and vertical directions for
the Y component. For the U and V components, the subsampling is by a factor of two in the vertical
direction, but by a factor of four in the horizontal direction since the human eye is less sensitive to
changes in color as opposed to changes in luminance.
A.2
The YUV components are now delta coded in the horizontal direction only. An initial 24–bit absolute
value of the first pixel is used as the starting value (8 bits for each component). The YUV component
of each sample for the rest of the line is coded using a 16–level quantizer (shown in Table A–1).
MOTOROLA
DELTA YUV ENCODING
DELTA CODING
Y = 0.299 * R + 0.587 * G + 0.114 * B
U = 0.564 * (B – Y)
V = 0.713 * (R – Y)
|Y| = 219 * Y + 16
|U| = 224 * U + 128
|V| = 224 * V + 128
MCD212
APPENDIX
A
A–1