2004 Mar 16
60
Philips Semiconductors
Product specification
PC-CODEC
SAA7108E; SAA7109E
9.1.3.3
Brightness Contrast Saturation (BCS) control and decoder output levels
The resulting Y (CVBS) and C
B
-C
R
signals are fed to the BCS block, which contains the following functions:
Chrominance saturation control by DSAT7 to DSAT0
Luminance contrast and brightness control by DCON7 to DCON0 and DBRI7 to DBRI0
Raw data (CVBS) gain and offset adjustment by RAWG7 to RAWG0 and RAWO7 to RAWO0
Limiting Y-C
B
-C
R
or CVBS to the values 1 (minimum) and 254 (maximum) to fulfil “ITU Recommendation 601/656”
handbook, full pagewidth
LUMINANCE 100%
255
+
235
+
128
+
16
0
white
black
CB-COMPONENT
+
255
+
240
+
212
+
212
+
128
+
16
+
44
0
blue 100%
blue 75%
yellow 75%
yellow 100%
colourless
CR-COMPONENT
+
255
+
240
+
128
+
16
+
44
0
red 100%
red 75%
cyan 75%
cyan 100%
colourless
MHB730
Fig.25 Y-C
B
-C
R
range for scaler input and X port output.
“ITU Recommendation 601/656” digital levels with default BCS (decoder) settings DCON[7:0] = 44H, DBRI[7:0] = 80H and DSAT[7:0] = 40H.
Equations for modification to the Y-C
B
-C
R
levels via BCS control I
2
C-bus bytes DBRI, DCON and DSAT.
Luminance:
Chrominance:
It should be noted that the resulting levels are limited to 1 to 254 in accordance with “ITU Recommendation 601/656”
Y
OUT
Int-----68
Y
128
–
(
)
×
DBRI
+
=
C
R
C
B
(
)
OUT
IntD64
---------------
C
R
C
B
,
128
–
(
)
×
128
+
=
a. Y output range.
b. C
B
output range.
c. C
R
output range.