Novel Proposal and Evaluation of Information Extraction Method from Artificial Fiber Pattern Using a Camera

We previously proposed the artificial fiber (AF) patterns in order to be able to hide information in printed documents. AF pattern uses the features of the medium (e.g., paper). It has features of rotational invariance, low visibility of the hidden information. But it still suffered extraction threshold instability when using a camera to extract the information. This problem has now been overcome by using the calculated intensity ratio for adjacent AF patterns. Experimental results demonstrated that the intensity ratio can be calculated stably, which means that a common threshold can be used in any situation. Moreover, since a standard pattern is not used, the AF pattern has low visibility. Application of this method should reduce the leakage of information from printed material.