Research On Construction Of Designed Moire Pattern

The moire pattern is a new visible image when some basic layers are overplayed on each other. It can be achieved by layer overlaying without the aids of computers or special equipment and it is quite convenient. The algorithms can be applied in the information hiding, optical watermarking and image encryption. In the constructing algorithms of designed moire pattern, the target moire pattern is given at first and then the basic layers are generated. There’re some constructing algorithms of designed moire pattern. However, some algorithms leak the target moire pattern without overlaying and some output the moire pattern with random noise. Furthermore, some algorithms need computer or equipment to generate the moire pattern and it loses the convenience. Some algorithms lose the ability of moire pattern’s periodic construction. Thus, based on analyzing the existing algorithms, this paper proposes two constructing algorithms of designed moire pattern. The first one is the construction of designed moire pattern with random lines, and the second one is the construction of designed moire pattern with grid structure. In the two algorithms, the reference layer and deformed layer are generated according to the secret image and when they are overlapped, the secret image appears.In the first algorithm with random lines, the reference layer is periodic line grating. Meanwhile, the deformed layer is embedded with the secret image and it is scrambled with random lines. Furthermore, the probability of black pixels in local area is averaged in order to hide the secret image. Transformation mapping can be applied on these layers to enhance the security.In the second algorithm with gid structure, the reference layer is periodic grid. The deformed layer is embedded with the secret image and the count of black pixel in every grid is varied to hide the secret image and represent the meaningful cover image, which will reduce the risk being checked. Similarly, transformation mapping can be applied on these layers to enhance the security.The proposed two algorithms assure the feature of convinience that overlaying is decrypting, the periodic construction of moire pattern and no random noise in moire pattern, when achieving the hiding effect in the basic layer. Also, the proposed two algorithms can enhance the security feature by applying transformation mapping.