ABSTRACT:The technique of image compression means reduce the size of image data in a way that can be reconstructed to its necessary components. This technique convert image data to an effective code, then this code can be decoded to reconstruct the approximate image.
In this paper we implement image compression using wavelet transform. After loading image data, it will divide into three-color components (red, green and blue). Where each component processed independently. Each component transformed using wavelet transform to subbands (low subband and high subbands). Where the number of subbands depends on the number of transform passes. After completing the transformation process, the coding is divided into two necessary parts:
First: Process the coefficients of low subband using Differential Pulse Code Modulation (DPCM) to reduce the size of coefficients. Then these coefficients coded using S-Shift coder.
Second: Process the other subbands by dividing each subband in to eight bit slices. Then these bit sliced are coded by using chain encoder.
After completing the coding processes, the compressed data stored into file. Then these compressed data are decompressed using algorithms similar to that are used in compressed system but with inverse order.
The compression ratio in this work is up to 57 with accepted level or error and quality.