The reliability and security of multimedia contents in transmission, communications, storage, and usage have attracted special attention. Robust image hashing, also referred to as perceptual image hashing, is widely applied in multimedia authentication and forensics, image retrieval, image indexing, and digital image watermarking. In this work, a novel robust image hashing method based on quaternion Zernike moments (QZMs) is proposed. QZMs offer a sound way to jointly deal with the three channels of color images without discarding chrominance information; the generated hash is thus shorter than the hash of three channels separately processing. The proposed approach's performance was evaluated on the color images database of UCID and compared with several recent and efficient methods. These experiments show that the proposed scheme provides a short hash in length that is robust to most common image content-preserving manipulations like JPEG compression, filtering, noise, scaling, and large angle rotation operations.

International audienceA blind color image watermarking scheme based on quaternion discrete Fourier transform (QDFT) and uniform log-polar mapping (ULPM) is proposed. In this scheme, a binary meaningful watermark is first embedded into the real part of QDFT coefficient of middle frequencies. In order to make it robust to geometric attacks, a bipolar binary watermark is inserted by the following ULPM method. This second watermark can resist geometric attacks and is used so as to invert such a transformation. Once the geometric transform is reversed, the meaningful watermark can be then extracted. Furthermore, several blocking watermarking embedding approaches in QDFT domain are compared to obtain better robustness against common signal operations. Compared to other existing methods, experimental results show that the proposed method achieves better performance against common signal operations and geometric attacks

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