Modified JPEG Plus-Minus 1 algorithm for high security steganography

To modify the security of Plus-Minus 1 algorithm used in JPEG steganography (J-PM1), a new method is proposed based on adaptive flipping probability estimation. First, the least square matching(LSM) method is introduced to calculate the flipping probability of each coefficient by minimizing the difference between the original distribution (i.e. the histogram) and that of the stego image. Second, a plus 1 or minus 1 (PM1) operation is performed on a host signal according to the flipping probabilities. Thus the embedded bits could be more imperceptible to a great extent. Experimental results show that less changes of the coefficient distributions occurred when compared to J-PM1, totally with around 58.8% decrease of histogram distortion; it also resists the chi-square analysis and cropping analysis more successfully than J-PM1 and F5 algorithms.