Study Of The Digital Image Compression And Encryption Technology

The digital media has become a main way for information communication along with the wide use of network. At the same time, multimedia information transmission problems and security problems including copyrights piracy emerged as side effects of the popularity of digital representation and distribution over network. So the digital image compression technology and the digital image encryption technology have been born and applied in many field, such as multimedia, communication, medicine and so on. In the intending science and technology field, it continuously shows it's powerful life-force and developing potential. In this paper, we study the technologies of digital image compression and encryption.On the one hand, we discuss the digital image compression technology. At first, we introduce the general technology of digital image. Then we find that people attach more importance to choice the right compressing algorithms of inhomogeneous image in recent years. And the line of figure in the image is the most important to distinguish the major part from the whole in the image. So we present a technology of digital image binary-conversion and study a bi-level image compression standard, JBIG2. As a result, we present a line-based algorithm for compressing binary images, which aim at the research of the loss and lossless compression. The result of the lab shows that is superiority in line, especial the bias. Considering the lossless compression, the compression of the line is better than JBIG2. And the algorithm could be used to compress characteristic line in veins images.On the other hand, we are focus on researching the technology of digital image encryption. The digital image encryption originated from the early classical theory of encryption. In order to hiding the original information of the digital image, it must be transformed to another one which is based on the rule of transformation in spatial and frequency domain. So we implement the image encryption algorithm fully based on the logical operation. We define the coding transformation matrix for two digital images which is performed at the same time and the general structural model. We demonstrate the correctness and uniqueness of returning to the original image by means of the coding. And the minimum upper boundary for performing image coding is obtained. Because the logical XOR operation are fully applied to the scheme, the speed of coding and decoding is quickly. The coding scheme has the advantages of randomicity and multiformity in variation. It has been of a great value in military, bank, etc.