A fast and low complexity zero-watermarking based on average subimage in multiwavelet domain

In this paper, a simple and robust zero-watermarking algorithm using balanced multiwavelet transform is proposed. The latter transform we use achieves simultaneous orthogonality and symmetry without requiring any input prefiltering or border extending. This reduction in computational complexity makes the transform a good candidate for real-time watermarking implementations. Novelty of the system lies in 1) the use of a new multiwavelet suitable for watermarking, 2) the proposition of the average subimage of low frequency in multiwavelet domain, 3) zero watermarks generated from the average subimage in multiwavelet domain. The original image is transformed using the new multiwavelet and flags are created with the secret key. Then the extracted flags using the same key are compared with the original ones to confirm the copyright of digital products. Theoretical analysis and simulation results show that the proposed watermarking system has excellent robustness against various watermark attacks including slightly geometric modifications with the high quality of the watermarked image.