A Reversible Watermarking Based on Histogram Shifting

In this paper, we propose a reversible watermarking algorithm where an original image can be recovered from watermarked image data. Most watermarking algorithms cause degradation of image quality in original digital content in the process of embedding watermark. In the proposed algorithm, the original image can be obtained when the degradation is removed from the watermarked image after extracting watermark information. In the proposed algorithm, we utilize a peak point of image histogram and the location map and modify pixel values slightly to embed data. Because the peak point of image histogram and location map are employed in this algorithm, there is no need of extra information transmitted to receiving side. Also, because a slight modification on pixel values is conducted, highly imperceptibly images can be achieved. As locations of watermark embedding are identified using location map, amount of watermark data can dramatically increases through recursive embedding. Experimental results show that it can embed 5K to 130K bits of additional data.