Canon FAX-L350, Руководство по обслуживанию

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FAX-L350 Chapter 2: Technical Reference
Example:
A brief explanation of how the study table works is given below.
It is assumed that each of the model template pixels 1~10 in the image below are white.
1. In this case, the model template pixel pattern is 000h.
2. The predicted value of pixel pattern 000h for pixel “X” is “white” , but it is actually black. Thus the
prediction is “inaccurate” .
3. The status ST is “0” , so the probability estimation table is consulted, and the next status is moved to “1” .
At the same time, by the reversal of the predicted value, the next prediction is for
“black”
.
Figure 2-20 Study Table Study Example 1
4. Next, the model template is moved to the adjoining pixel in order to perform the next prediction. At this
time, pixels 1~9 of the model template are white, and pixel 10 is black.
5. In this case, the model template pixel pattern is 001h.
6. The predicted value of pixel pattern 001h for pixel
“X”
is
“white”
, and it is actually white. Thus the
prediction is
“accurate”
.
7. The status ST is
“0”
, so the probability estimation table is consulted, and the next status is moved to
“1”
.
The prediction for the next pixel remains
“white”
.
Figure 2-21 Study Table Study Example 2
The study table is constantly updated in this way, increasing the probability of accurate predictions.
d) The probability estimation table, published in the ITU-T T.82. Its contents are fixed, differing from those
of the study table.
Study table for current pixel
Probability estimation table
Pixel
pattern
0 0 0 h
0 0 1 h
0 0 2 h
Predicted
value
0 (white)
Actual
value
1 (black)
Accurate/
Inaccurate
Inaccurate
Study table for next pixel
0 0 0 h
0 0 1 h
0 0 2 h
1
0
0
ST
X is actualy black
Original image
0
1
1 2 3
5
4 6
1 9 X
7 8
2
3
LSZ
5A1Dh
2586h
1114h
080Bh
NLPS
1
1
1
1
NMPS
1
2
3
4
SWITCH
1
0
0
0
Status
ST
Pixel
pattern
Actual
value
Accurate/
Inaccurate
Status
ST
0 (white)
0 (white)
0 (white)
0 (white)
Predicted
value
1 (black)
0 0 0 h
0 0 1 h
0 0 2 h 1
0
0 0 0 0 h
0 0 1 h
0 0 2 h 1
1
0
S
Move to next pixel
0
1
1 2 3
5
4 6
10 9 X
7 8
2
3
LSZ
5A1D
2586h
1114h
080B
NLPS
1
14
16
18
NMPS
1
2
3
4
SWITCH
1
0
0
0
X is actualy white
Study table for current pixel
Pixel
pattern
Predicted
value
Actual
value
Accurate/
Inaccurate
Study table for next pixel
Status
ST
Pixel
pattern
Actual
value
Accurate/
Inaccurate
Status
ST
Predicted
value
1 (black)
0 (white)
0 (white)
0 (white) Accurate
1 (black)
0 (white)
0 (white)
Probability estimation table