ECE4253 Digital Communications
	Department of Electrical and Computer Engineering - University of New Brunswick, Fredericton, NB, Canada

Online Dictionary Compression Tool

In Dictionary Compression, codewords in multiples of 4 bits long are used to represent characters assumed to form an alphabetic list of English words. Codewords are assigned in a fixed table to use the shortest codewords for the most frequently occuring message characters. Further compression exploits the common letters shared by consecutive dictionary words. This specialized lossless compression scheme is quite effective for the one purpose of compressing an English language dictionary.

This online tool allows you to examine the workings of dictionary compression.

Compressed Text with Bits (hex)

C E9 H E1 R 8 O B M 5 A 3 T 1 E 0 F7 I 2 C E9 F8 N 4 F7 O B G C R 8 A 3 M 5 FB P E5 H E1 FD Y EC F5 E 0 F5 I 2 C E9 F6 U 7 M 5 F5 O B S 6 O B M 5 E 0

OUTPUT: 216 bits = 2.057 bits per character (average)

Compression Ratio = 216/840 = 0.257