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G3 FACSIMILE COMMUNICATIONS
very effective when encoding a periodic pixel, similar to a dither pattern
image.
The position of AT in the figure is the beginning position of the AT pixel.
(3) The study table, as shown below, is constructed by all of the 10-bit
5–34
pixel patterns output by the model template, and their corresponding
status numbers and predicted values of the pixel to be encoded.
The predicted value of the pixel to be encoded and the status number is
compared to the actual pixel in the arithmetic encoding section every
time the model template is moved to the adjoining pixel.
The result of this comparison (matches / does not match predicted
value) and the status number are then checked by comparison to the
probability estimation table, and the study table is corrected (learned)
to a new prediction value and status number which will be used when
the same pixel pattern is found again.
By learning in this way, the probability of the study table matching the
next time is increased, and the need for encoding decreased.
1
2
3
4
5
6
7
X
9
10
3-line model template
Fig. 5-28 Positions of Pixels in Model Template
Table 5-8 Study Table (Initial values)
Pixel pattern in the model template
Hex
Dec
1
2
3
000h
0
0
0
0
001h
1
0
0
0
002h
2
0
0
0
003h
3
0
0
0
004h
4
0
0
0
005h
5
0
0
0
3FBh
1019
1
1
1
3FCh
1020
1
1
1
3FDh
1021
1
1
1
3FEh
1022
1
1
1
3FFh
1023
1
1
1
8
1
2
7
8
2-line model template
4
5
6
7
8
9
10
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
1
0
0
0
0
0
0
1
1
0
0
0
0
1
0
0
0
0
0
0
1
0
1
1
1
1
1
0
1
1
1
1
1
1
1
0
0
1
1
1
1
1
0
1
1
1
1
1
1
1
0
1
1
1
1
1
1
1
3
4
5
6
X
9
10
Predicted
Status No. (ST)
value of pixel
0 (White)
0
0 (White)
0
0 (White)
0
0 (White)
0
0 (White)
0
0 (White)
0
0 (White)
0
0 (White)
0
0 (White)
0
0 (White)
0
0 (White)
0
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