A new spatial domain algorithm for gray scale images watermarking

This paper proposes a new algorithm of watermarking in spatial domain. We choose spatial domain to take advantage of its relatively low calculation complexity when compared to any technique requiring domain transforms. This algorithm is implemented via pixel by pixel comparison between host image and watermark. For the each pixel of host image, if its correspond value equal to compared pixel in watermark, we save its position as key. Therefore, we call this algorithm as ldquoSave Algorithmrdquo. Our accurate algorithm doesnpsilat make any change in host image, so, our new algorithm shows high invisibility. On the other hand, we have no problem for watermark extraction. In fact watermark extraction process is very simple. We also provided robustness evaluation of our proposed algorithm against several attacks by calculation of ldquopeak signal to noise ratiordquo (PSNR). In general, the higher PSNR values imply lowest change in image that is attacked by several methods.