Research On Image Steganographic Algorithm Based On Pixel-Value Differencing

Steganography, severing as a means of secret communication, is to transmit the secret message without arousing the attention of the third part, and hence plays a very important role in military affairs, information and the security of a country. The basic requirements for steganography are security and embedding capacity. As the current steganalysis methods use the statistical analysis to detect the statistical abnormality of steganographic digital media, the statistical imperceptibility is the main factor that steganography method should take into consideration.The least significant bit (LSB)-based steganographic approach is easy to be implemented and has high embedding capacity, while the human visual system (HVS)-based steganographic method has better visual imperceptibility and provides high embedding capacity. The two types of steganographic schemes therefore have been widely used. However, many steganalysis methods have been proposed to be against them. This paper first discusses the basic purposes of steganography and steganalysis, and their principles and main techniques, followed by the review of the current research status of the area. This paper also analyzes the previous steganographic method, and then proposes steganographic algorithms that are able to effectively resist statistical analysis and are of high security based on the statistical abnormality of the existing method. The main contributions of this paper are as follows:(1) Based on drawbacks of the lossless pixel value differencing (PVD) method which cannot embed message when the threshold exceeds a specific value, we propose an improved algorithm, which achieves data embedding by taking advantage of the correlation of the horizontal pixels and vertical pixels. This method addresses the limitation of the original algorithm and thus improves the embedding capacity. The experimental results show the efficiency of the algorithm.(2) This paper presents a steganographic algorithm based on the characteristics of the pixels. The embedding capacity of each pixel varies with its features, that is to say, the capacity is dependent on whether the pixel is on an edge or a smooth area. The secret bits are then embedded into the pixel by employing the simple LSB substitution method. In order to improve the quality of the stego-image, we utilize the method of the optimal pixel adjustment process (OPAP).(3) Side matches(SM)-based steganography cannot extract the embedded information exactly and furthermore has the shortcoming of statistical abnormality of the pixel difference histogram. Based on this, we proposed an improved method. The capacity is determined by the difference between the maximum pixel value and the minimum pixel value, and the image quality of the stego-image is improved by using the method of OPAP. The experimental results show that the improved algorithm can not only recover the hidden information correctly from the stego-image, but also enhance the security of the steganographic algorithm.