Application With Image Compression In 2-D Bar Code PDF417

Nowadays, image is one of the most important carriers for information communications, and it's also the media contains the largest amount of information. Human society is moving into the digital information age, but these digital signal have tremendous volume of data, despite massive storage technology, processor speed, and digital information system make rapid progress, the data storage capacity and data transmission bandwidth demand continues to exceed the capacity of existing technology. To make communication possible, and as far as possible to reduce communications costs, signal compression is necessary, so as image compression, as the key technology of multimedia communications, is of great realistic significance for the development of information technology.2-D bar code PDF417 has become internationally popular 2-D bar code. As a low-cost, high-speed portable data files, PDF417 are widely used in the field of certificate management, transportation, and other aspects. PDF417 can encode the feature of photograph, fingerprint, and other personal information into a bar code, which can solve the problem of forgery in certificate application.Before store information in PDF417, people must limit the capability of information in the range of PDF417's provisions. At present time, most products of bar code cannot store still image information. This mainly due to the small capability of bar code, and the enormous capability of still image information.My task is searching for and mending still image compression algorithm so that we can store still image information in PDF417. Since head-shoulder image can be distinguished by human vision easily, so we regard it as the character of people.JPEG compression standard is the most widely image compression standard. JPEG compression standard fully reflects the major research results of the first image coding phase. It adopts the lossless compression based on DPCM, and lossy compression algorithms of Huffman coding. Since in the low bit-rate environment, block DCT transform coding compress image with box-effects and mosquito noise. Different with JPEG, JPEG 2000 uses wavelet transform, and embedded coding technology, and accomplishes many new functions. JPEG2000 support different types of images, lossy or lossless compression. With a high quality, the compression ratio can be as high as 200:1, 10 times than JPEG. So JPEG2000 has broad application.JPEG2000 standard is the world's best still image compression standard. I use this standard as image compression tool, to perform image compression, and introduce the foundation of image compression, focusing on the implements of the core algorithm of JPEG2000, and how to get ROI with maxshift. We improved the algorithm of ROI coding, completed a series of experiments, got some results and finally put the pic ture into PDF417.