A Novel Image Compression Based on Lifting Wavelet Transform and Modified SPIHT

In this paper, a new approach of images coding by Shapiro algorithm (Embedded Zerotree Wavelet algorithm or EZW) is proposed. In this approach, the old Shapiro algorithm for image coding is modified. The new modified EZW (MEZW), distributes entropy differently and also optimizes the coding. This new version can produce good results that are a significantly improve the PSNR and compression ratio, without affecting the computing time. These results are also comparable with those obtained using the SPIHT and SPECK algorithms. The EZW, Spiht or Speck algorithms are based on the Wavelet transform. The principle of wavelet transform is to decompose hierarchically the input image into a series of successively lower resolution reference images and detail images which contain the information needed to be reconstructed back to the next higher resolution level. The sub-band images resulting from wavelet transform are not of equal significance. Some sub-bands contain more information than others (example the baseband sub band).