High capacity blind information hiding schemes using Tchebichef moments

In this paper, we present two high capacity information hiding schemes in which large amount of information can be hidden in gray level images with high transparency using Tchebichef moments. In particular, the hidden information is a gray level image of the same size as the original image. A watermark image is also hidden in the original image for hidden data authentication and tampering localization purposes. The novelty of our work comes from combining both steganography and digital watermarking in one scheme. The first scheme is a secure fragile information hiding scheme with tampering localization capability. By fragile we mean that the watermark will be distorted under any kind of attack applied on the watermarked images including geometric attacks. The second scheme is a semifragile scheme. It is based on the first scheme with some modifications to make it withstand geometric attacks, but with some compromise in security. Both proposed schemes are moment-based, in which the hidden information and the watermark are embedded in the Tchebichef moments of the original image. Transparent watermarked images with PSNR (Peak Signal to Noise Ratio) of 40 and above are obtained. Watermark and hidden images are extracted successfully at the receiver side with high accuracy.