Digital image dual watermarking using self-fractional fourier functions, bivariate empirical mode decomposition and error correcting code

摘要

In some legal, medical and military applications, image authentication is a mandatory requirement for copyright protection and security. In this paper, a novel dual (robust and fragile) watermarking scheme based on self-fractional Fourier functions and bivariate empirical mode decomposition with cyclic error correcting code is proposed. In this technique image is decomposed into M self-fractional Fourier function (SFFF) images, The SFFF images are further decomposed into intrinsic mode functions (IMFs) using bivariate empirical mode decomposition (BiEMD). Watermarks are encoded using cyclic error correction coding and embedded in the residue signal obtained by BiEMD of SFFF images. A procedure to generate a new type of fragile watermark called barmark is developed. Proposed scheme has the capability of self-authentication of the watermarked images along with robustness and security. The proposed decomposition technique provides flexibility in the number of watermarking bits that can be added (payload capacity) in a given image. Use of some transform before SFFF decomposition will provide additional degree of freedom in security and robustness. Robustness of recovery is improved by error correction coding of the watermarks. The proposed scheme can be used for complex images due to the use of bivariate EMD. Simulation results under different test conditions are presented to validate the efficacy of the proposed scheme.