A New Lossless Visible Watermarking Method via the Use of the PNG Image

Che-Wei Lee and Wen-Hsiang Tsai


Lossless visible watermarking, PNG image, information hiding, signal and image processing, color image


A new lossless visible watermarking method via the use of the PNG image is proposed. The method transforms a color host image into the PNG format with an additional alpha channel plane and a visible watermark is then embedded into the color channel plane of the host image. During the embedding process, data of color pixels covered by the watermark are collected to form a data packet. The data packet is then embedded into the alpha channel plane in order to remove the visible watermark from the watermarked image later. Furthermore, pixel values in the alpha channel plane are mapped into a range near their maximum value of 255 to yield a nearly total transparent watermarked image. During the process of image recovery, the proposed method can remove the visible watermark from the watermarked image without the original watermark because all data that are needed to losslessly recover the watermarked image are embedded in the alpha channel plane. Experimental results demonstrating the effectiveness of the proposed method are also included.

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