Canon fax basic 2000 서비스 매뉴얼

G3 FACSIMILE COMMUNICATIONS

5–10

The Modified READ coding scheme (MR coding scheme) and the Modi-

fied Modified READ scheme (MMR coding scheme) are widely used as

optional coding schemes for G3 facsimiles.

The JBIG (Joint Bi-level Image experts Group) coding scheme that started

to gain in popularity at the same time as V.34 MODEMs has also been rec-

ommended by

, and is expected to further gain in popularity.

The following describes the principles of operation of these coding

schemes in order.

4.2

MH Coding Scheme (One-dimensional Coding

Scheme)

The following describes an example using an A4 size document.

If a document is viewed in unit of single lines, text areas are black, and

areas without text are white. All of the scanlines are expressed as a group

of white runs and black runs.

The length of these runs is called the “run length”. The MH coding scheme

codes each line using two elements, the run length and the run color.

Fig. 5-8 Example of Scanline

Scanline

1728 bits

Run

length

white

Run

length

white

Run

length

lac

run

A4 size document (1728 bits)

Run

length

1708

white

Run

length

lac

run