Data Compression


Criteria

Survey Formats

Basics

Compression Methods

Data Formats


Arithmetic Coding (AC)

Principle of the AC

Dividing into Intervals

Assignment to Codes

Sub-Intervals

Codes for 2 Symbols

Scheme Intervals "aaaa"

Scheme Intervals "abcd"

General Algorithm

AC versus Huffman

Data with high Redundancy

Adaptive AC

Implementations


Glossary

Index


Download


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Codes for 2 Symbols


If it is known that the current code identifies two symbols, any arbitrary number between 0.00 and 0.16 represents the character string "aa". The same rules apply to following examples:


Codes representing two symbols:


 Symbol   Interval     String
  0      [0.00; 0.16)    aa
  0.1    [0.00; 0.16)    aa
  0.14   [0.00; 0.16)    aa

  0.16   [0.16; 0.24)    ab
  0.2    [0.16; 0.24)    ab

  0.32   [0.32; 0.36)    ad
  0.34   [0.32; 0.36)    ad

  0.36   [0.36; 0.40)    ae
  0.399  [0.36; 0.40)    ae

On the basis of the decimal number system the character strings "aa" and "ab" could be encoded with one decimal position, "ac" and "ad" with two positions.


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Principle of the Arithmetic Coding Sub-Intervals Scheme Intervals aaaa