Watermarking Technique for Duple Copyright Protection of Digital Images

The small singular values are sensitive to the image content. The contrived tamper of the digital images can be detect by this feature. But it is not suitable for tamper positioning and copyright protection. The algorithm proposed in this paper firstly divided the original image data matrix into subblocks. Each fragile singular value of the corresponding subblock as well as the original watermark to be embedded formed a new watermark image. Then it was encrypted based on logistic chaotic sequences in two dimensions. The encrypted watermark was finally embedded into the least significant bit flat of the original digital image. The extraction of the watermark is the inverse process stated above which is the necessary step of the authentication. This algorithm can indentify and position tiny tampers effectively. Furthermore, it can indicate if one or both of the original image and the watermark are tampered. Both security and effeciency are guaranteed. It is competent for digital image authentication and integrity verification.