AT91SAM9G45PRE Datasheet, PDF (900/1218 Pages) ATMEL Corporation – DDR2 Controller 4-bank DDR2/LPDDR, SDRAM/LPSDR

AT91SAM9G45
39.4.4 Preview Path
39.4.4.1
Scaling, Decimation (Subsampling)
This module resizes captured 8-bit color sensor images to fit the LCD display format. The resize
module performs only downscaling. The same ratio is applied for both horizontal and vertical
resize, then a fractional decimation algorithm is applied.
The decimation factor is a multiple of 1/16 and values 0 to 15 are forbidden.
Table 39-6. Decimation Factor
Dec value
0->15
16
17
18
19
...
Dec Factor
X
1
1.063
1.125
1.188
...
124
7.750
125
7.813
126
7.875
127
7.938
Table 39-7.
OUTPUT
VGA
640*480
QVGA
320*240
CIF
352*288
QCIF
176*144
Decimation and Scaler Offset Values
INPUT
352*288
640*480
F
NA
16
F
16
32
F
16
26
F
32
53
800*600
20
40
33
66
Example:
Input 1280*1024 Output = 640*480
Hratio = 1280/640 = 2
Vratio = 1024/480 = 2.1333
The decimation factor is 2 so 32/16.
1280*1024
32
64
56
113
1600*1200
40
80
66
133
2048*1536
51
102
85
170
6438F–ATARM–21-Jun-10
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