The embedding distortion of visible watermarking is usually larger than that of invisible watermarking. In order to maintain the signal fidelity after the watermark extraction, “lossless” property is highlighted in the visible watermarking. In this paper, we propose two lossless visible watermarking algorithms, Pixel Value Matching Algorithm (PVMA) and Pixel Position Shift Algorithm (PPSA). PVMA uses the bijective intensity mapping function to watermark a visible logo whereas PPSA uses circular pixel shift to improve the visibility of the watermark in the high variance region. For the application of medical and military, as they are sensitive to distortion, PVMA and PPSA can be used to insert a visible logo to prevent unauthorized use.
Shu-Kei Yip, Oscar C. Au, Chi-Wang Ho, Hoi-Ming Wo