A Watermarking Algorithm of Gray Image Based on Histogram

Digital image histogram is an important global feature, in this paper, histogram will be used to embed binary watermark in the space domain. In the watermark embedding process, firstly, the corresponding histogram of image is generated according to the original images´ characteristics, which shows the probability of the corresponding pixel in gray scale; Secondly, the distances between adjacent elements of histogram are calculated, and found their maximum; Then, the histogram is adjusted according to the maximum and pretreated watermark; Finally, the watermark image is generated. In the watermark extracting process, in accordance with the histogram of watermark image and the original image, and the pixels embedded watermark are found, thereby extracting watermark. The experimental results show that the algorithm has good nature of against geometric attacks.