Skip to Content
Wavelets and their Applications
book

Wavelets and their Applications

by Michel Misiti, Yves Misiti, Georges Oppenheim, Jean-Michel Poggi
May 2007
Intermediate to advanced
330 pages
7h 23m
English
Wiley
Content preview from Wavelets and their Applications

Appendix

The EZW Algorithm

This appendix supplements section 8.6.3.2 dedicated to the EZW algorithm used in wavelet image compression. It details the operation of the algorithm and presents an example of application. We successively tackle coding and decoding (we note by ⌊ x ⌋ the integer part of x).

For other insights on the EZW algorithm, see [CRE 97], [USE 01] and [VAL 99]. In the book by Strang and Nguyen (see [STR 96], p. 362-383), we will find a detailed presentation of the various operations related to compression: quantization, coding, etc.

A.1. Coding

A.1.1. Detailed description of the EZW algorithm (coding phase)

(1) Initialization. All the coefficients are placed on the principal list and the threshold is initialized by T0 = 2⌊log2(Cmax)⌋, where Cmax is the maximum of the absolute value of the coefficients.

(2) Principal stage. Go through the coefficients on the principal list in an appropriate order (see Figure 8.45) and compare each of them with the current threshold Tn. Attribute one of the four following symbols to each coefficient:

– P, if it is positive and has an absolute value higher than the threshold;

– N, if it is negative and has an absolute value higher than the threshold;

– Z, if its absolute value is lower than the threshold but if one of its children has an absolute value higher than the threshold;

– T if its absolute value is lower than the threshold and if all its children have absolute values lower than the threshold.

Thanks to the zerotree property ...

Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.

Read now

Unlock full access

More than 5,000 organizations count on O’Reilly

AirBnbBlueOriginElectronic ArtsHomeDepotNasdaqRakutenTata Consultancy Services

QuotationMarkO’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.
Julian F.
Head of Cybersecurity
QuotationMarkI wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.
Addison B.
Field Engineer
QuotationMarkI’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.
Amir M.
Data Platform Tech Lead
QuotationMarkI'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.
Mark W.
Embedded Software Engineer

You might also like

Wavelets: Theory and Applications

Wavelets: Theory and Applications

A. K. Louis, D. Maass, A. Rieder
What Successful Project Managers Do

What Successful Project Managers Do

W. Scott Cameron, Jeffrey S. Russell, Edward J. Hoffman, Alexander Laufer
Digital Image Interpolation in Matlab

Digital Image Interpolation in Matlab

Chi-Wah Kok, Wing-Shan Tam

Publisher Resources

ISBN: 9781905209316Purchase book