Research On The Image Compression Coding Of The Embedded Zerotree Wavelet Based On Wavelet Packet Transform

The wavelet transform have a better partial and space-frequency characteristics, an ability of describing the non-stationary image signal and a good function of adapting to the eye sense of visual characteristic. So it is extensively researched and applied in higher compression ratio of image coding field. The core of International Standard JPEG 2000 is based on the wavelet transform.EZW algorithm is the landmark in the research of wavelet image coding. It has been researched that EZW needs further improvement. The thesis is based on the research of EZW algorithm. The research expressed that the original EZW has some drawbacks. The old method uses the same way to decompose the high and low frequency bands. It doesn't use the detailed information of high frequency and uses the same way to scan the three directions. So it can not use the characteristics of coefficients after the wavelet transform. For these, a new algorithm about EZW is raised in this thesis. The image data was decomposed with fixed format .The decomposed coefficient was scanned by using the old EZW sequence in the whole construction with utilizing the characteristics of direction and coefficients in the high frequency information. The horizontal component was scanned horizontally. The vertical component was scanned vertically. The diagonal component was scanned by Z scanning. The original and improved EZW algorithms were simulated and their performances were compared. The improvement was proved to be efficient through the comparison between the data and the vision.