A novel pixel-wise authentication-based self-embedding fragile watermarking method

Self-embedding fragile watermarking algorithms can perform detection of the manipulated areas as well as recovery of these detected areas. Most of the self-embedding fragile watermarking algorithms are performed block-wise authentication approach. However, entire block is marked as tampered in case one of the pixels in the block is detected as manipulated. This situation decreases the accuracy rate of the authentication process especially against pixel-based attacks such as salt and paper noise adding. Therefore, we present a novel pixel-wise authentication-based self-embedding fragile watermarking method for manipulation detection and recovery. In this proposed method, reference image is divided into four main blocks. Then, each main block is subdivided into 2x4 or 4x2 sized blocks according to block type determined using recovery quality. Recovery bits of each main block generated from sub-blocks are spreaded into the two main blocks in the other half of the image. For each pixel, two authentication bits are generated using the six most significant bits of the pixel with two pixel position bits and then embedded into the first and second least significant bits of the pixel. In experimental results, pixel-based attacks are applied to the images to demonstrate the success of the presented method. Also, performance of the presented method has been evaluated by applying different size of cropping attacks to the watermarked images. Experimental results show that the proposed method satisfactory detect and recover the manipulated areas.