Research And Implementation Of Personal Identity Picture's Compression Algorithm Based On EZW

Personal Identification picture is a kind of special picture, used to identify personal identity. It is comprehensively existed in all kinds of archives, certificates and so on. In the past, because of its small size, it was not compressed. In recent years, by the corresponding technologies' developing and the identity management system's updating, new generation of information-stored identity card came out, such as 2-dimension bar code card and IC card. For instance, China's second generation citizen ID card, which will be used in not far future, is a kind of IC card. The biggest difference between traditional card and information-stored card is that the latter not only has information printed on the card's surface, but also save more information in the bar code or IC of the card. Personal identification picture, the most important personal information, is one of storing contents of new generation card.However, either the 2-dimension bar code, or the IC card has limited capacity. The capacity of 2-D bar code commonly is 1024 bytes. IC card's memory capacity is larger than 2-D bar but cost increases with capacity's increasing. A piece of ordinary identity picture usually has at least 8 kilo-bytes . So, to store it in the bar code or IC card, it should be compressed. The compression of identity picture has been a key technology of new generation identity card.In this paper, 1 inch personal identification pictures, which are very common and used today, are taken as compressing object. Researching works include Embedded Zero Wavelet coding and coding based on Region of Interest. Compression quality and visual effect of personal identification picture of this paper's method are better than those of the basic EZW coding, which justify the effectiveness of ROI coding. In the first chapter, image compression's principal, significance and background of thesis' selection are introduced. Whereas personal identification picture's current compressing level in the world, the mainly used method also are expound. Based on these, this paper's research aimis brought forward. Research 's main content, method and technology are introduced subsequently. In the second chapter, wavelet theory, which is the theoretic basis of Embedded Zero Wavelet coding is introduced briefly, including wavelet transform 's local characteristics, multi-resolution analysis, discrete signal's fast decomposition and construction, wavelet and filter group. In the third chapter, EZW coding and ROI coding are introduced. How to implement ROI coding in the algorithm framework of Embedded Zero Wavelet coding is discussed in this part. In the fourth chapter, the procedure and method of compressing personal identity picture is explained in detail, and the experimental result is given. That part includes: the whole designation of compression algorithm, segment of ROI, implementation of wavelet's transformation, silhouette's coding and experimental result. In the final chapter, all the research work in this paper is summarized with a prospect about future's researching direction.