Samsung S5PC110 Manual page 1489

S5PC110_UM
7.8 ILLEGAL COLOR COMPENSATION (CVBS MODULE)
The CVBS sub-module also supports color compensation for illegal RGB data. Video data are usually processed
in the YCbCr coordinates. At the result of filtering and scaling, the values of YCbCr can exceed their nominal
range and values become invalid when they are transformed into RGB coordinates. This causes unwanted
artifacts at display. The Figure illustrates the relation between YCbCr coordinates and RGB coordinates:
255
Y
0
If YCbCr data converted to RGB data outside the RGB cube, the CVBS sub-module compensates the value so
that the result falls within the RGB cube. A constant luma and constant hue approach is used for this
compensation. The luminance Y is not altered while the chrominance Cb and Cr are limited to the maximum valid
values having the same hue as the invalid color prior to limiting. The SDO_RGB_CC register controls the size of
RGB cube that determine color compensation range. Meanwhile, if illegal YCbCr data are transformed to CVBS or
S-Video, there might be an overflow which exceeds DAC conversion range. The CVBS sub-module also
compensates this error. The SDO_CVBS_CC_Y1, SDO_CVBS_CC_Y2, and SDO_CVBS_CC_C registers are
used for the color compensation for CVBS output and the SDO_YC_CC_Y1, SDO_YC_CC_Y2, and
SDO_YC_CC_C registers are used for the compensation for S-video output, respectively.
W
Y
C
G
BK
CB
R = Red
G = Green
B = Blue
Y = Yellow
C = Cyan
M = Magenta
W = White
BK = Black
Figure 7-15 Color Cube Comparison
Y = 255,
CB = CR = 128
M
R
B
YCBCR Valid
Color Block
255
7 6BTVOUT & VIDEO DAC
All Possible
YCBCR Value
7-17