Image Authentication Technique Based On Digital Watermarking

After paying out a painful expense, people then realize that only one link delaying will result the whole industry standstill. How to protect the information being transferred through the network has become a stumbling block of the sustained development of network technique, especially the security of multimedia information. The watermark with a special function is embedded into the multimedia information to protect the copyright of the original author and authenticate the integrity and authenticity of the multimedia information. The watermark technique has become one focus of researcher.The attention of dissertation is focused on how to construct the IAS (image authentication system) based on the watermark and signature. In this dissertation, a systematical introduction of the origin, applications, classification and background of information hiding is given first, then the principles of IAS are described with their characteristics and designing requirements and limitations, before the ways of performance evaluation, attacks and countermeasures are introduced. The work is focused on the investigation of the IAS in different cases and requirement and can be summarized as follows:1. The IAS of binary image is studied and two IAS based on watermark are proposed. In the first algorithm, the watermark is embedded into the inside and outside edge of the binary text document image to avoid the visual distortion during embedding, and in the second technique, a weight matrix is constructed to evaluate the distortion of text image during watermark embedding, then the watermark is embedded into the document image with a least imperceptibility distortion.2. The IAS based on the fragile watermark scheme is studied particularly and two IAS based on the fragile watermark are proposed. In the first algorithm a composite key is constructed based on the one and only original key K and the different image feature F for different image to avoid the limitations of key resource of the block-wise independent invisible watermark schemes, and then three improved scheme, dynamic equivalent set, dynamic watermark and block-dependent scheme are proposed to prevent the counterfeiting attack. In the second scheme, the halftone image of original image is looked upon as watermark and embedded into theoriginal image with error diffusion scheme. The advantage of this kind scheme is that when the image encounters a local malicious modification, the change can be located and recovered based on the watermark hidden in the modified image.3. The IAS based on the semi-fragile watermarking is studied and three effective robust image authentication schemes are proposed. First based on the particular analysis of the relation between the probability of extraction error watermark and the embedding parameter, the Scalar Costa Scheme is used to authenticate the integrity and authenticity of the image. Because different observers and assailants have a different interest of a same image, so the same image in different application encounters different malicious manipulation and incidentally manipulation. Thus, in the second scheme, the signature information constructed from the image block including ROI (the region of interest) of user is composed of two parts, one part is authentication information to authenticate the integrity and authenticity of the image block and is self embedded into the image block, the second part is recovering information to rebuilt the region modified maliciously and is embedded into the image block without the ROI. Lastly, an improved Lin scheme is proposed. One of the parameters to construct signature come from the DCT coefficient matrix of image block, the second is generated based on the key and variance of DCT coefficients at the same location. When the image embedded signature is transferred, the receiver can first judge whether the received image is compressed by JPEG based on the consistency of boundary region and interior region of image block, then based on the DCT coefficients of received image block, the ste...