Diffusion-Based Image Compression in Steganography

We demonstrate that one can adapt recent diffusion-based image compression techniques such that they become ideally suited for steganographic applications. Thus, the goal is to embed secret images within arbitrary cover images. We hide only a small number of characteristic points of the secret in the cover image, while the remainder is reconstructed with edge-enhancing anisotropic diffusion inpainting. Even when using significantly less than 1% of all pixels as characteristic points, sophisticated shapes of the secret can be clearly identified. Selecting more characteristic points results in improved image quality. In contrast to most existing approaches, this even allows to embed large colour images into small grayscale images. Moreover, our approach is well-suited for uncensoring applications. Our evaluation and a web demonstrator confirm these claims and show advantages over JPEG and JPEG 2000.