1. Home
  2. IT
  3. Networks and Telecommunications
  4. Fax

  5. Coding

Article | REF: TE7650 V1

Fax

Authors: Bernard REVILLET, Gérard BOULAY, Jean-Paul DICK, Jérôme CUDELOU

Publication date: May 10, 2001

You do not have access to this resource.
Click here to request your free trial access!

Already subscribed? Log in!

7. Coding

7.1 The need for coding

Group 3 and Group 4 fax machines cut images into lines and pixels.

Analyzed at the typical resolution of 8 dots/mm x 7.7 lines/mm, and without halftones, an A4 page represents 500 kilobytes, or a transmission time of 7 minutes for a standard fax machine, at 9600 bit/s, which is prohibitive.

A classic image is highly redundant (uniform areas, lines, etc.).

The coder's role is to exploit this redundancy to significantly reduce the volume of information to be transmitted. The compression ratio achieved, i.e. the ratio between the size of the original document and that of the coded document, is one of the performance criteria for coding algorithms. A second factor to take into account is the...

You do not have access to this resource.

Exclusive to subscribers. 97% yet to be discovered!

You do not have access to this resource.
Click here to request your free trial access!

Already subscribed? Log in!

The Ultimate Scientific and Technical Reference

A Comprehensive Knowledge Base, with over 1,200 authors and 100 scientific advisors
+ More than 10,000 articles and 1,000 how-to sheets, over 800 new or updated articles every year
From design to prototyping, right through to industrialization, the reference for securing the development of your industrial projects

This article is included in

Networks and Telecommunications

This offer includes:

Knowledge Base

Updated and enriched with articles validated by our scientific committees

Services

A set of exclusive tools to complement the resources

Practical Path

Operational and didactic, to guarantee the acquisition of transversal skills

Doc & Quiz

Interactive articles with quizzes, for constructive reading

Subscribe now!

Ongoing reading
Coding
Outline