Adaptive watermarking scheme using a gray-level computer generated hologram

We present a new adaptive blind watermarking scheme using a gray-level computer generated hologram in the discrete wavelet transform domain. By utilizing an improved fuzzy clustering technique and human visual system, the watermark can be adaptively embedded according to block classification. To keep imperceptibility and robustness, a novel iterative embedding algorithm is adopted to change the to-be-embedded coefficients. Compared with the standard Fuzzy c-means (FCM) clustering, the suggested improved FCM (IFCM) converges more quickly and can avoid local optimum effectively. The experimental results demonstrate that the proposed scheme provides good robustness to withstand different kinds of common attack. Compared with other methods, the proposed method has the distinct advantage of better robustness to a JPEG compression attack. (C) 2009 Optical Society of America