Image Steganography Using Contrast Enhancement Technique

Traditional image steganography techniques leverage different kinds of data hiding schemes to hide secret data while preserving good image visual quality. The image quality is measured by its PSNR value, which is based on the mean square error between the stego image and the cover image. From the viewpoint of visual experience, the adjustments of gray level values on the high contrast portions and on the smooth portions make completely different effects. A slight change of gray level on the smooth region will be noticed and explained as a noise, while increasing the contrast of an image edge will lead to a more pleasant visual effect. In this paper, we propose a novel method of data hiding. The cover image is divided into small blocks and each block is analyzed to classify into smooth block or high contrast block. For each high contrast block, the secret data are appended in the way that the block contrast is further enhanced. On the other hand, only half amount of secret data are embedded into a smooth block. Experimental results show that our method provides satisfactory results.