An steganographic scheme based on edges gradient and exploiting modification direction

In order to improve the embedding information capacity of picture, a steganographic method which based on edge detection and exploiting modification direction is proposed. According to the human visual system (HVS), our method embeds secret data into an edge region, no change is happening in smooth areas. In the process of this method, firstly, a cover image is divided into 3*3 blocks, and then compute the gradient in four directions(0, 45, 90 or 135 degree). For each block, secret data are embedded into six pixels, the other three pixels are used as adjuvant. The embedded secret data can be extracted from stego image without referencing the cover image. The number of embedded bits is dependent on the relation of those six pixels and the other three pixels according to the magic matrix. This method can use sharper edge region of each block for data hiding, while preserving other smoother blocks unchanged. The improved performance of the proposed method is proved by experimental results. Therefore, the idea is presented with more embedding capacity and got a better picture quality.