Digital watermarking technique for image authentication by neighbouring block similarity measure

The problem of image authentication by means of digital watermarking is considered. The inability of current solutions to deal with identification of the authentic and altered image parts, under certain types of tampering and attacks, is identified. A new image verification scheme based on the test of relative similarity between neighbouring image blocks is proposed. Some relative similarity patterns are described. The method constructs the image signature such that it is block-wise dependent, thus overcoming certain counterfeiting attacks suffered by previous methods. In addition, it can be used to identify cropping and block-shuffling types of attacks. Experimental results are included.