Image information has developed to such a degree that it is now widely used. With the rapid development of network technology,image information can be distributed and transformed on the Internet rapidly and conveniently. Because of the unsafe network,the image information may be lost or corrupted during the transmission; the plotter also may steal unauthorized image information by means of network. To solve these security problems,image encryption technologies are proposed.Digital Image information security includes Image Hiding, Digital Watermarking and Digital Image Sharing. Image sharing is an important subject of digital image information security. It is based on Secret Sharing Schemes.Secret sharing is an important part of the cryptography protocols. Since 1979, Shamir and Blakley first developed the concept of the (t,n) threshold secret sharing scheme . With the maturity of secret sharing schemes, scholars do many works in this field and apply these schemes to image encryption gradually.In this paper, we choose image secret sharing as our priority research areas. This dissertation focuses on the analysis of image sharing schemes, and designed of images sharing schemes. The main achievements and originality contained in this dissertation are as follows:(1) The research status and advances of images sharing schemes has been summarized, analyzed and reviewed. The analyzing method of images sharing in brief, and several existent key problems to be solved urgently have been pointed out.(2) We carried out experiments to attack the algorithm based on the Shamir (t, n) threshold image sharing schemes, pointed out the issues of the algorithm, and then we design a new algorithm to improve the security of image sharing.(3) The analysis of Image Sharing Based on Chinese Remainder Theorem by Yan etc is carried out. We pointed out that the method exist the issues of image loss, we propose an advanced image sharing scheme, and realize the scheme by experiments.The algorithm is a lossless image sharing schemes method. The size of each shadow image is smaller than the secret image in out method, only half parts of the secret image. This property gives the benefit in further process of the shadow images, such as storage, transmission, or image hiding.(4) Based on pre-existing image sharing Schemes, and the knowledge of number theory, we propose a method of image sharing based on quadratic residue theorem. Our work reveals a new research area of applying quadratic residue theorem in image sharing. We lay the theorem foundation for Image Sharing Schemes.(5) Finally, the research work of this paper is summarized, and the future research direction is indicated. |