Lossless Image Authentication Algorithm Based on Three-Compa Image Basic Blocks

As the existing block-wise loss less image authentication algorithms sacrifice the precision of locating distortions, a new loss less image authentication algorithm based on three-compa image basic blocks is proposed. The algorithm trisects the original image recursively in order to get basic blocks. When the watermark can´t be embedded into the authentication block, the algorithm tries to merge only one basic block into current authentication block. As a result, each authentication block´s size is expanded at a minimum level. Moreover, in order to prevent vector quantization attack, a digital signature algorithm is taken and signature is repeatedly embedded into the authentication block via a loss less watermarking algorithm. Theoretical analysis and experimental results demonstrate that the algorithm is more accurate than the algorithm based on adaptive combinations of image basic blocks.