4 preview path – Rainbow Electronics AT91CAP9S250A User Manual
Page 916
916
6264A–CAP–21-May-07
AT91CAP9S500A/AT91CAP9S250A
45.3.4
Preview Path
45.3.4.1
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.
Example:
Input 1280*1024 Output=640*480
Hratio = 1280/640 =2
Vratio = 1024/480 =2.1333
The decimation factor is 2 so 32/16.
Table 45-6.
Decimation Factor
Dec value
0->15
16
17
18
19
...
124
125
126
127
Dec Factor
X
1
1.063
1.125
1.188
...
7.750
7.813
7.875
7.938
Table 45-7.
Decimation and Scaler Offset Values
INPUT
OUTPUT
352*288
640*480
800*600
1280*1024
1600*1200
2048*1536
VGA
640*480
F
NA
16
20
32
40
51
QVGA
320*240
F
16
32
40
64
80
102
CIF
352*288
F
16
26
33
56
66
85
QCIF
176*144
F
16
53
66
113
133
170