An adaptive gray-scale image watermarking scheme using smooth and edge areas of an image

In this paper, we propose an adaptive watermarking scheme for gray-scale images. The proposed scheme use the difference between the consecutive and non-overlapping pair of pixels to embed the watermark bits. The watermark is embedded into the pair of pixels using least-significant bit(LSB) substitution method. The difference between pair of pixels is used to determine the smooth and edge regions of the image. In smooth region less number of watermark bits are embedded and in edge region more number of watermark bits are embedded. The pixels of the cover image are categorized into different types using the embedding capacity which is determined by the difference between the pair of pixels. For any pair of consecutive pixels, both pixels are embedded with variable bits of watermark using LSB substitution method. Here, the number of bits to be embedded is decided based on the category to which the difference value belongs. After embedding, the difference value between embedded pair of pixels is retained by readjustment so that the quality of the image is maintained and embedding capacity is improved. The experimental results show that the proposed scheme has high embedding capacity and less distortion in embedded images.