25-08-2017, 09:32 PM
Image Coding using EZW and QM coder
Abstract
This project involves Matlab implementation of the Embedded Zerotree Wavelet (EZW)
coding algorithm followed by a QM coder. The Embedded Zerotree Wavelet (EZW)
algorithm is a wavelet-based image compression algorithm that yields a fully embedded code
as well as remarkable compression efficiency.
Statement of Work
This project is somewhere between an implementation and study project. The project was
started with an aim to understand and implement the EZW coding algorithm proposed by J.
M. Shapiro (1). We tried to understand the scope of improvement in the EZW algorithm (2)
and better ways to implement it eg. using SPIHT (3).
EZW based Image Coding
The Embedded Zerotree Wavelet (EZW) algorithm is based on four key concepts –
(1) A discrete wavelet transform or hierarchical subband decomposition.
(2) Prediction of absence of significant information in finer level wavelet coefficients
based on coarser level coefficients.
(3) Entropy-coded successive-approximation quantization.
(4) Lossless data compression based on an adaptive arithmetic coder. (In this project, the
coder used is the QM coder and we devote a separate section to it.)