ch7004c Chrontel, ch7004c Datasheet - Page 38

• Manufacturer Part Number: ch7004c
• Description: Digital Pc To Tv Encoder With Macrovisiontm
• Manufacturer: Chrontel

CHRONTEL
Contrast Enhancement Register
This register provides control of the contrast enhancement feature of the CH7004, according to the table below. At a
setting of 000, the video signal will be pulled towards the maximum black level. As the value of CE[2:0] is
increased, the amount that the signal is pulled towards black is decreased until unity gain is reached at a setting of
011. From this point on, the video signal is pulled towards the white direction, with the effect increasing with
increasing settings of CE[2:0].
38
Table 24. Contrast Enhancement Function
Bit:
Symbol:
Type:
Default:
CE[2:0]
000
001
010
011
100
101
110
111
Figure 26: Luma Transfer Function at different contrast enhancement settings
7
Contrast enhancement gain 3 Y
Contrast enhancement gain 2 Y
Contrast enhancement gain 1 Y
Normal mode Y
Contrast enhancement gain 1 Y
Contrast enhancement gain 2 Y
Contrast enhancement gain 3 Y
Contrast enhancement gain 4 Y
Description (all gains limited to 0-255)
6
out
256
224
192
160
128
96
64
32
0
= (1/1)*(Yin-0) = Normal Contrast
0
5
32
out
out
out
out
out
out
out
64
= (5/4)*(Y
= (9/8)*(Y
= (17/16)*(Y
= (17/16)*(Y
= (9/8)*(Y
= (5/4)*(Y
= (3/2)*(Y
4
96
128
in
in
in
in
in
-102) = Enhances Black
-57)
-0)
-0)
-0) = Enhances White
in
in
-30)
-0)
160
3
192
224 256
201-0000-024 Rev. 2.4, 6/24/2004
2
CE2
0
R/W
Address: 11H
Bits: 3
Symbol: CE
1
CE1
R/W
1
CH7004C
0
CE0
R/W
1