Research On Data Hiding Of Halftone Image And Video

With the rapid development of computer and network, when people enjoy a lot of resources on the Internet, how to ensure the security of information has become an urgent problem to be solved. Data hiding is one of the main technologies in the field of information security. Data hiding of image and video has become commonly used techniques,generally modifying the image and video to hide information, and after data hiding, the usage of image and video is not affected.Halftone image is a special kind of image that only uses black and white to represent an image. There are two kinds of halftone data hiding technologies: (1) halftone watermark: hiding a secret bit stream into a halftone image by using dot character; (2) halftone visual cryptography(HVC): hiding a secret pattern into several halftone images. In HVC, (2,2)HVC is a important direction, a secret image can be hided into two halftone images such that after two halftone images are processed, the secret image will be revealed. In previous (2,2) HVC, both the CDR of revealed pattern and the visual effect of halftone images still can be improved. (k,n) HVC methods have two disadvantages which are pixel expansion and code book needed, and with the increase of the number of users, the size of the shares will be expanded many times.Stereo video is an special video which a stereo frame consists of two images showing the same scene from two slightly different viewpoints corresponding to the distance of human eyes. Watermark of stereo video become more and more important. Because of the actual need, we need to realize a image watermak which can resist several kinds of attacks which includes encoding attack, cropping attack, line attack and zoom attack,and can guarantee the capacity of watermark.Research of this paper is focus on halftone data hiding, stereo video watermark and image watermark, and main contributions are as follows:(1) A (2,2) HVC in color halftone images based on new conjugate property. Proposing new conjugate property and applying this property to hide a secret pattern in color halftone images, and two novel methods which called data hiding by new color conjugate error diffusion (NCCED)and data hiding by new color conjugate dot diffusion (NCCDD) can be proposed. Through these methods a secret pattern can hide in two color halftone images. Using new conjugate property fewer components need to be toggled, as a result the correct decoding rate (CDR) of the revealed pattern will be increased, and the visual effect of halftone images can be improved. This paper proposes average distortion per pixel (ADPP) to measure toggling distortion in different methods accurately.(2) A high quality (2,2) HVC based on block conjugate. Constructing Least mean square filters (LMSF), and using LMSFs to evaluate the quality of halftone images. This paper proposes block conjugate property,and this property can be applied to hide a secret pattern. Therefore a high quality data hiding in halftone images based on block conjugate(HQDHBC) can be proposed. Through this method a secret pattern can hide in two error diffused halftone images. Two images should be divided into multiple blocks of M×N pixels, and in the corresponding block if the first M×N-1 pixels are conjugate or identical, the last pixel can implement normal halftone method instead of date hiding methods. By using block property the number of pixels to implement data hiding methods can be reduced, and therefore the quality of halftone images can be improved.(3) A (k,n) halftone visual cryptography based on Shamir's secret sharing (HVCSSS), and through this method a binary secret image can be hided into n halftone images, and the secret image can revealed by using any k halftone images. Firstly, using k-1 degree polynomials, a binary secret image can be shared into n meaningless shares; secondly, hiding n shares into n halftone images through halftone self-hiding methods; and then n extracted shares can be obtained through halftone self-decrypt methods from n halftone images; finally, picking any k shares from n extracted shares, the secret image can be revealed from k shares by using Lagrange interpolation.(4) A blind stereo video watermark algorithm in transform domain.According the features of DCT-based and DFT-based video watermark algorithms against attacks, a new robust blind video watermark algorithm in transform domain was proposed. DCT-based watermark and DFT-based watermark are embedded in left and right channels of a video frame by using opposite embedding rules, and the watermark can be extracted by integrating stereo video correlation, and more robust watermark is extracted from the DCT-based watermark and the DFT-based watermark by comparing their performance.(5) An efficient image watermark algorithm based on DFT transform.Based on realizing and analyzing the DFT-based algorithm, this paper proposes an efficient image watermark algorithm based on DFT transform. Firstly, the watermark information is encoded by using hybrid error correcting code, and the watermark is embedded into an image, and the code ensures that the correct rate of watermark extraction is 100% in the condition of the watermarked image under attacks. Secondly, through changing the way of embedding watermark in data block of transform domain, watermark capacity can be increased to 2 times of the original algorithm. Thirdly, through extending the frequency domain region of embedding watermark, watermark capacity can be increased.