Blind image watermarking via exploitation of inter-block prediction and visibility threshold in DCT domain

In this paper, the backward-propagation neural network (BPNN) technique and just-noticeable difference OD) model are incorporated into a block-wise discrete cosine transform (DCT)-based scheme to achieve effective blind image watermarking. To form a block structure in the DCf domain, we partition a host image into non-overlapped blocks of size 8 x 8 and then apply DCT to each block separately. By referring to certain DCT coefficients over a 3 x 3 grid of blocks, the BPNN can offer adequate predictions of designated coefficients inside the central block. The watermarking turns out to be a process of adjusting the relationship between the intended coefficients and their BPNN predictions subject to the JND. Experimental results show that the proposed scheme is able to withstand a variety of image processing attacks. Compared with two other schemes that also utilize inter-block correlations, the proposed one apparently exhibits superior robustness and imperceptibility under the same payload capacity. (C) 2015 Elsevier Inc. All rights reserved.