WATERMARK INFORMATION DETECTION METHOD

摘要

There is provided a watermark information detection method capable of accurately detecting secret information from a document having secret information. The entire surface of an input image is subjected to a filtering process (S310) and a signal position is obtained by using a signal position search template so that the sum of the filter output values is maximum (S320). After this, a signal boundary is decided (S340). Even when a paper sheet is warped and the image is expanded or contracted, it is possible to correctly detect the signal position and accurately detect secret information from a document having the secret information.