Canon fax basic 2000 서비스 매뉴얼

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G3 FACSIMILE COMMUNICATIONS

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 

 by NTT and KDD. After revision, it was

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)

Make-up Code

2240

000000010110

2304

000000010111

2368

000000011100

2432

000000011101

2496

000000011110

2560

000000011111