Robust contourlet-based blind watermarking for depth-image-based rendering 3D images

The copyright protection for 3D multimedia has attracted considerable attention and depth-image-based rendering (DIBR) has been playing a critical role in 3D content representation due to its numerous advantages. In this paper, we propose a new blind watermarking scheme for DIBR 3D images. Considering the directional multiresolution image representation and convenient tree structures of contourlet transform (CT), we perform the watermark embedding and extraction in contourlet domain. The center view and the depth map are available at the content provider side. After applying contourlet transform to the center view, we embed the watermark into the selected contourlet subbands of the center view by quantization on certain contourlet coefficients. The virtual left and right views are generated from the watermarked center view and the associated depth map using DIBR technique at the receiver side. The statistical differences between quantized and unquantized contourlet coefficients are used for watermark extraction. The watermark can be detected with a low bit error rate (BER) from the center view, the left and right views even when each view is distorted and distributed separately. The simulation results demonstrate that the proposed scheme is very robust to image compression, noise addition and geometric attacks such as rotation, scaling and cropping. Moreover, the proposed scheme has good performance in terms of depth image variation and baseline distance adjustment.