AK8851 Datasheet, PDF (29/80 Pages) Asahi Kasei Microsystems – NTSC/PAL/SECAM Digital Video Decoder

ASAHI KASEI
[AK8851]
(3) Sharpness Control
For sharpness control, the following signal processing is performed on the Luminance (Y) signal as shown in the block
diagram below. One of the 3 different type filter characteristics in the block is selected by [SHARP1: SHARP0]-bit of [Image
Control Register](R/W)[Sub Address 0x10]. The Coring level is adjustable within the range of 0 LSB ~ +/- 3 LSBs which is
set by [SHCORE1: SHCORE0]-bit.
Image Sharpness is controlled by properly selecting the filter characteristics.
[SHARP2:SHARP0]-bit [SHCORE1:SHCORE0]-bit
Luminance Data(Y)
Filter
Coring
Delay
Processed Luminance Data(Y)
4.5
4
3.5
3
2.5
2
1.5
1
0.5
0
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5
Frequency [MHz]
Bit Allocation of [Image Control Register] is shown.
Sub Address 0x10
bit 7
bit 6
bit 5
bit 4
bit 3
VBIIMGCTL
SEPIA
LUMFIL1
LUMFIL0 SHCORE1
Default Value
0
0
0
0
0
bit 2
SHCORE0
0
Default Value : 0x00
bit 1
bit 0
SHARP1
SHARP0
0
0
[ SHARP1:SHARP0]-bit:
* This selects sharpness filter types.
[ SHARP2:SHARP0]-bit
Selected filter
[00 ]
Through
[01 ]
Sharpness effect Min.
[10 ]
Sharpness effect Mid.
[11 ]
Sharpness effect Max.
Note
[SHCORE1:SHCORE0]-bit:
* This sets the Coring Level after sharpness filtering is done.
[ SHCORE1:SHCORE0]-bit
Coring Level
[ 00 ]
No Coring
[ 01 ]
+/- 1LSB
[ 10 ]
+/- 2LSB
[ 11 ]
+/- 3LSB
Note
MS0244-E-03
29
Confidential
2005 / 07