Canon FACSIMILE BASIC 2000 Service Manual page 178

G3 FACSIMILE COMMUNICATIONS
Example:
A brief explanation of how the study table works is given below.
It is assumed that each of the model template pixels 1 to 10 in the image
below are white.
5–36
• In this case, the model template pixel pattern is 000h.
• The predicted value of pixel pattern 000h for pixel "X" is "white," but
it is actually black. Thus the prediction is "inaccurate."
• 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."
Study table for current pixel
Original image
Pixel Predicted
pattern
value
000h 0 (white)
001h
0 (white)
002h 0 (white)
Probability estimation table
ST LSZ
0 5A1Dh
1 2 3 1 2586h
4 5 6 7 8 2 1114h
9 10 X
3 080Bh
X is actualy black
Fig. 5-29 Study Table Study Example 1
• Next, the model template is moved to the adjoining pixel in order to
perform the next prediction. At this time, pixels 1 to 9 of the model
template are white, and pixel 10 is black.
• In this case, the model template pixel pattern is 001h.
• The predicted value of pixel pattern 001h for pixel "X" is "white," and
it is actually white. Thus the prediction is "accurate."
• 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".
Move to next pixel Study table for current pixel
Pixel
Predicted
pattern
1 2 3
value
4 5 6 7 8
000h 1 (black)
9 10 X 0 (white)
001h
002h 0 (white)
Probability estimation table
X is actualy white
ST LSZ
0 5A1Dh
1 2586h
2 1114h
3 080Bh
Fig. 5-30 Study Table Study Example 2
Actual Status Pixel
Accurate/
value ST
Inaccurate pattern
1 (black) 0 000h
Inaccurate
0 001h
0
002h
NLPS NMPS SWITCH
1 1 1
14 2 0
16 3 0
18 4 0
Actual Status
Accurate/ Pixel
value
ST pattern
Inaccurate
1 0 00h
0 (white) Accurate 0
0 01h
0 0 02h
NLPS NMPS SWITCH
1 1 1
14 2 0
16 3 0
18 4 0
Study table for next pixel
Actual Status
Predicted Accurate/
value ST
value Inaccurate
1 (black) 1
0 (white) 0
0
0 (white)
Study table for next pixel
Actual Status
Predicted Accurate/
value ST
Inaccurate
value
1 (black) 1
0 (white) 1
0 (white) 0