In many watermarking methods, the tradeoff between robustness and image quality is controlled by watermarking strength. Thus the image quality was evaluated relatively under the condition of keeping the robustness against assumed attacks. Then another axis of keeping the image quality of watermarked images based on the absolute evaluation is useful for the improvement of watermarking methods. In this paper, we propose a new watermarking model based on the selection of the suitable pixel value from pixel value candidates near to an original pixel value. The proposed model can keep the absolute image quality of watermarked images by defining the set of pixel values for embedding. In the proposed model, embedding procedure is equal to the selection of the suitable pixel value from the set. We use a watermarking method in color space for the implementation of the conventional and the proposed watermarking model because the problem of watermarking methods with non-linear color transform can be solved by using the proposed model.
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