We propose a novel approach for steganography using a reversible texture synthesis. A texture synthesis process re-samples a smaller texture image which synthesizes a new texture image with a similar local appearance and arbitrary size. We weave the texture synthesis process into steganography to conceal secret messages. In contrast to using an existing cover image to hide messages, our algorithm conceals the source texture image and embeds secret messages through the process of texture synthesis. This allows us to extract secret messages and the source texture from a stego synthetic texture. Our approach offers three distinct advantages. First, our scheme offers the embedding capacity that is proportional to the size of the stego texture image. Second, a steganalytic algorithm is not likely to defeat our steganographic approach. Third, the reversible capability inherited from our scheme provides functionality which allows recovery of the source texture. Experimental results have verified that our proposed algorithm can provide various numbers of embedding capacities, produce a visually plausible texture images, and recover the source texture. Texture Synthesis Steganography
The last decade many advances have been made in the area of digital media, and much concern has arisen regarding steganography for digital media. Steganography a singular method of information hiding techniques. It embeds messages into a host medium in order to conceal secret messages so as not to arouse suspicion by an eavesdropper . A typical steganographic application includes covert communications between two parties whose existence is unknown to a possible attacker and whose success depends on detecting the existence of this communication . In general, the host medium used in steganography includes meaningful digital media such as digital image, text, audio, video, 3D model , etc. A large number of image steganographic algorithms have been investigated with the increasing popularity and use of digital images
Most image steganographic algorithms adopt an existing image as a cover medium. The expense of embedding secret messages into this cover image is the image distortion encountered in the stego image. This leads to two drawbacks. First, since the size of the cover image is fixed, the more secret messages which are embedded allow for more image distortion. Consequently, a compromise must be reached between the embedding capacity and the image quality which results in the limited capacity provided in any specific cover image. Recall that image steganalysis is an approach used to detect secret messages hidden in the stego image. A stego image contains some distortion, and regardless of how minute it is, this will interfere with the natural features of the cover image. This leads to the second drawback because it is still possible that an image steganalytic algorithm can defeat the image steganography and thus reveal that a hidden message is being conveyed in a stego image.
We illustrate our proposed method in this section. First, we will define some basic terminology to be used in our algorithm. The basic unit used for our steganographic texture synthesis is referred to as a “patch.” A patch represents an image block of a source texture where its size is user-specified. Fig. 1(a) illustrates a diagram of a patch. We can denote the size of a patch by its width (Pw) and height (Ph). A patch contains the central part and an outer part where the central part is referred to as the kernel region with size of Kw×Kh, and the part surrounding the kernel region is referred to as the boundary region with the depth (Pd).
When generating a candidate patch, we need to ensure that each candidate patch is unique; otherwise, we may extract an incorrect secret message. In our implementation, we employ a flag mechanism. We first check whether the original source texture has any duplicate candidate patches. For a duplicate candidate patch, we set the flag on for the first one. For the rest of the duplicate candidate patches we set the flag off to ensure the uniqueness of the candidate patch in the candidate list.