background image
ISO/IEC 10918-1 : 1993(E)
Table K.8 Decoder test sequence (sheet 7 of 7)
EC
D
MPS
CX
Qe
A
C
CT
B
(hexadecimal)
(hexadecimal)
(hexadecimal)
241
1
1
3C3D
CAD0
33E60000
0
242
1
1
3C3D
8E93
33E60000
0
Marker detected: zero byte fed to decoder
243
1
1
375E
A4AC
67CC0000
7
244
0
1
32B4
DA9C
CF980000
6
245
0
1
3C3D
CAD0
9EC00000
4
246
1
1
415E
F0F4
40B40000
2
247
1
1
415E
AF96
40B40000
2
248
1
1
3C3D
DC70
81680000
1
249
0
1
3C3D
A033
81680000
1
Marker detected: zero byte fed to decoder
250
1
1
415E
F0F4
75C80000
7
251
0
1
415E
AF96
75C80000
7
252
0
1
CE
4639
82BC
0F200000
6
253
1
1
4B85
F20C
3C800000
4
254
1
1
4B85
A687
3C800000
4
255
0
1
4639
B604
79000000
3
256
0
1
CE
4B85
8C72
126A0000
2
K.5
Low-pass downsampling filters for hierarchical coding
In this section simple examples are given of downsampling filters which are compatible with the upsampling filter defined
in J.1.1.2.
Figure K.5 shows the weighting of neighbouring samples for simple one-dimensional horizontal and vertical low-pass
filters. The output of the filter must be normalized by the sum of the neighbourhood weights.
1
2
1
1
2
1
TISO1770-93/d115
Figure K.5 Low-pass filter example
Figure K.5 [D115] = 4 cm = 156 %
The centre sample in Figure K.5 should be aligned with the left column or top line of the high resolution image when
calculating the left column or top line of the low resolution image. Sample values which are situated outside of the image
boundary are replicated from the sample values at the boundary to provide missing edge values.
If the image being downsampled has an odd width or length, the odd dimension is increased by 1 by sample replication on
the right edge or bottom line before downsampling.
CCITT Rec. T.81 (1992 E)
173
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