Evolving distortion function by exploiting the differences among comparable adaptive steganography

摘要

So far, the most effective model for adaptive steganography is to minimize a well-defined distortion function, in which the distortion function determines the modification probability (MP) of each pixel. We found that the MPs of some pixels calculated by a group of steganographic methods may be very different even though these methods have close performances in resisting the detection of steganalysis. We call such pixels as controversial pixels, and consider that steganalysis is not sensitive to such pixels. Therefore we can assign more payloads to the controversial pixels by increasing MPs on them to generate a new steganographic distortion function. We call this evolutionary strategy as the rule of Controversial Pixels Prior (CPP). Taking the state-of-art methods {WOW, UNIWARD} and {HILL, MVG} as two pairs of examples, we show that the principle of CPP can improve the security of state of the art steganographic algorithms for spatial images.