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G3 FACSIMILE COMMUNICATIONS
(2) MH coding
After being converted to run lengths, the scanlines are converted to MH
codes. These MH codes comprise terminating codes and make-up codes.
(See the table of page 5-14.) Different mechanisms are used for converting
to MH codes for when the run length is 0 to 63, and when the run length is
64 or more.
• Coding when the run length is 0 to 63
In this case, coding is performed with a suitable terminating code depend-
ing on the color and length of the run.
• Coding when the run length is 64 or more
In this case, coding is performed by a make-up code which shows the larg-
est run length without exceeding the run length of that run. Next, the dif-
ference between the actual run length and the length of the make-up code
is coded by a terminating code.
5–12
Scanline after
White run length
Black run length
conversion to
5
run length
MH codes
(terminating
1100
codes only)
Fig. 5-11 MH Coding When The Run Length is 0 to 63
Scanlines after
conversion to
run length
MH code (make-up code + terminating code)
Fig. 5-12 MH Coding When The Run Length is 64 or More
White run length
Black run length
3
9
10
10100
White run
length 1664
011000
Make-up code
White run length
3
1708
10
White run length
1708
White run
length 44
00101101
Terminating code
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