A blind color image watermarking algorithm combined spatial domain and SVD

It has great significance for protecting the image copyright with color image digital watermarking technique, which needs the watermarking algorithm has high robustness, good imperceptibility and short running-time. A blind colour image watermarking algorithm combined spatial domain and singular value decomposition (SVD) is designed to protect the rightful ownership of color image in this paper. The theoretical principle combined SVD and spatial domain is first discussed and proposed in this paper. Based on the derived principle, the watermark information can be directly embedded into the maximum singular value (MSV) of the host image in the spatial domain by the new quantization index modulation with variable quantization step, and the embedded watermark information can be directly extracted from the MSV of the watermarked image block in the spatial domain with geometrical correction. The contributions of this paper include the following four points: (1) the relationship between the changed MSV of SVD and the average changed value of image pixel in the spatial domain is the first derived in this paper; (2) the presented method has the merits of both spatial-domain technique and transform-domain technique; (3) the relationships of each component of the color image are used to improve the invisibility and the geometrical correction of watermarked image is also adapted to further improve the robustness; and (4) this presented method overcomes the false-positive problem that existed in many watermarking methods based on SVD. Simulation results demonstrate the new presented color image watermarking technique has better imperceptibility, higher robustness and shorter running-time compared with some state-of-the-art methods.