Digital blind watermarking based on depth variation prediction map and DWT for DIBR free-viewpoint image

The free-view image could suffer from a viewpoint change attack, although it may be not malicious. This paper focuses not only on this viewpoint change attack, but also on the other traditional and the geometric attacks. We propose a digital watermarking scheme to protect the ownership of a free-view 2D or 3D image, such that the viewer watches the image(s) by rendering an arbitrary viewpoint image (or multiple images) with the received texture image and its depth image. First, the proposed scheme generates a special map, termed the depth variation prediction map (DVPM), to find locations that are safe from viewpoint change. A 3-level Mallat-tree 2-dimensional discrete wavelet transform (2D DWT) is also used, from which the three horizontally low-pass filtered and vertically high-pass filtered subbands are used as the watermark embedding regions, in conjunction with the DVPM. Next, Multiples of the watermark data are embedded into the three subbands, and each watermark bit is embedded into a 2D DWT coefficient by a quantization index modulation (QIM) method, where the quantization step is decided by considering the energy of each subband. In extracting the watermark data, the multiple watermark data are extracted, and the most frequent value in each bit position is taken from the extracted data to form the final data. We experiment the proposed method with various test images for the various attacks, and compare our scheme with the previous methods, to show that the proposed method has excellent performance.