Watermarking using modulo algorithms for gray images

In this paper we propose a watermarking technique in the spatial domain using gray images. Algorithms based on modulo operations are developed to embed the watermark into the host image. Number of bits embedded in a pixel is determined by the degree of modulo algorithm being used. The size of the watermark is stored in the last few pixels as overhead bits. Extraction of data is done using the same degree of modulo algorithm that is used for embedding. In addition, the proposed method is quite simple because it primarily uses modulus operation. Capacity of 3.00 bits per pixel (bpp) and PSNR of 43.74 dB is achieved using this technique. These results indicate that the proposed scheme is superior to many existing reversible data hiding schemes introduced in the literature.