Robust and imperceptible watermarking scheme based on Canny edge detection and SVD in the contourlet domain

To enhance the invisibility and the robustness of the watermarking algorithm, a robust and imperceptible watermarking scheme is presented by combining Canny edge detection, contourlet transform with singular value decomposition. The host image is firstly decomposed by the contourlet transform. Then the low frequency sub-band obtained by contourlet transform is partitioned into 4×4 non-overlapping blocks and the singular value decomposition is carried out for the specific blocks selected by the Canny edge detection. Finally, the watermark is embedded into the coefficient of matrix U. The embedded watermark could be recovered blindly in the watermark extraction stage. And the robustness and the imperceptibility are efficiently guaranteed with an optimal threshold k selected by the least-square curve fitting. Experimental results demonstrate that the proposed watermarking scheme is superior in terms of imperceptibility and robustness against common attacks.