Research On Constructing Assigned Moiré Patterns

A new pattern, called moiré pattern, appears when two related layers aresuperimposed. This kind of phenomenon is called moiré phenomenon, which hascharacteristics of periodicity and amplification. These characteristics have been widelyused in image encryption, information hiding and security domain. In practical use, it isnecessary to construct a meaningful pattern (assigned moiré pattern), but natural moirépatterns cannot be assigned. Existed algorithms can generate a pattern layer and anencrypted layer with traces of secret image. However, secret image cannot bereconstructed by just superimposing two layers, additional devices and computations areneeded. To solve the above problems, following studies are proposed in this paper.1. Reconstruction quality depends on selection of different parameters. However,the relationship may be ignored. In this paper, we first compare reconstructedimages with different parameters, and then give relationship amongreconstruction quality and parameters. Experimental results by analyzing twotraditional algorithms show validness of the obtained relationship.2. An algorithm based on visual cryptography and moiré pattern is proposed.Experimental results show that it can reconstruct the secret image periodicallyby superimposition.3. We use cover layers and adopt random disturbance to promote hiding effect.Also, we decrease the reconstruction period so that the secret image can bereconstructed in all relative superimposed locations. Moreover, relationshipbetween reconstruction quality and superimposed location is obtained.4. Based on above studies, an image encryption system based on moiré pattern isproposed, including image importing module, image encryption module,simulation module and quality envaluation module. This system has been usedin a security project.