AK8855 Datasheet, PDF (23/81 Pages) Asahi Kasei Microsystems – NTSC/PAL Digital Video Decoder

[ASAHI KASEI]
[ CNTSEL ]-bit
[ CNTSEL ]-bit sets the change-over point of Contrast adjustment.
[CNTSEL]-bit
Function
0
To be adjusted at Luminance 125 as a center point
1
To be adjusted at Luminance 16 as a center point.
Condition
AK8855
(2) Brightness Adjust Function
Brightness Adjust function is processed by adding to the Luminance signal ( Y ), a value which is set by
Brightness Control Register ( R/W ) [ Sub Address 0x07 ].
YOUT = YIN + BR
YOUT
YIN
BR
: Brightness arithmetic operation result
: before Brightness arithmetic operation
: Brightness coefficient ( register set value )
Variable range of Brightness adding coefficient is from – 127 to +127 and the value setting is made in 2’s
complement number.
When the arithmetic operation result exceeds the above range, it is clipped to the upper-limit of [ 254 ], or the
lower-limit of [ 1 ] ( output result ranges from 16 to 235 when 601 Limit-bit is at [ 1 ] ).
Bit allocation of Brightness Control Register is as follows.
Sub Address 0x07
Default Value: 0x00
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
BR7
BR6
BR5
BR4
BR3
BR2
BR1
BR0
Default Value
0
0
0
0
0
0
0
0
(3) Color Saturation Adjust Function
Color Saturation adjustment is processed by multiplying the Color Signal ( C ), by a value which is set by
Saturation Control Register ( R/W ) [ Sub Address 0x08 ].
Saturation coefficient is processed over C signal.
A multiplied result by Saturation coefficient is U / V de-modulated.
Variable range of Saturation multiplying coefficient is from 0 to 255 / 128 in 1 / 128 programmable step.
The default value of the register is un-adjusted value ( 0x80 ).
Bit allocation of Saturation Control Register is as follows.
Sub Address 0x08
bit 7
bit 6
bit 5
bit 4
bit 3
SAT7
SAT6
SAT5
SAT4
SAT3
Default Value
1
0
0
0
0
bit 2
SAT2
0
Default Value: 0x80
bit 1
bit 0
SAT1
SAT0
0
0
(4) Color Hue Adjust Function
The Color Hue can be rotated in the AK8855.
Rotation amount of Color Hue depends on a value which is set by HUE Control Register ( R/W ) [ Sub
Address 0x09 ].
Variable Rotation range of the phase is +/- 45 degrees ( in approximately 0.35 degree / step ).
Default value of the register is un-adjusted value ( 0x00 ). Set value is made in 2’s complement number.
Bit allocation of Hue Control Register is as follows.
Sub Address 0x09
bit 7
bit 6
bit 5
bit 4
bit 3
HUE7
HUE6
HUE5
HUE4
HUE3
Default Value
0
0
0
0
0
bit 2
HUE2
0
Default Value: 0x00
bit 1
bit 0
HUE1
HUE0
0
0
MS0319-E-03
23
2004 / 11