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4.3
MR Coding Scheme (Two-dimensional Coding
Scheme)
4.3.1 Outline of MR coding scheme
With G3 facsimiles, the MR coding scheme can be used as an option in
addition to the MH coding scheme. "MR" stands for Modified READ, and
"READ" stands for Relative Element Address Designative. This READ
scheme was proposed for
recognized as the Modified READ scheme. From here on, let's describe
simply how compression is performed.
Two consecutive scanlines are expanded as shown in Fig. 5-15. When the
black and white changing pixels (shown by black dots) of each scanline are
compared, it can be seen that they have shifted to the laterally. Data is
compressed by comparing the black and white changing pixels with the
previous scanline and by coding this shift.
Due to the fact that changes in the two-dimensional pixels are coded in an
interlocked manner with the previous scanline, this is also called the "two-
dimensional coding scheme."
Table 5-3 Make-up Code Table
Run Length (white and black)
2240
2304
2368
2432
2496
2560
G3 FACSIMILE COMMUNICATIONS
Make-up Code
000000010110
000000010111
000000011100
000000011101
000000011110
000000011111
ITU-T
by NTT and KDD. After revision, it was
1
2
3
4
5
6
ït
çi
5–17
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