METHOD AND DEVICE FOR ADDITIONAL INFORMATION SUPERPOSITION PROCESSING, METHOD AND DEVICE FOR ADDITIONAL INFORMATION DETECTION PROCESSING, AND COMPUTER PROGRAM

摘要

PROBLEM TO BE SOLVED: To provide a method and a device for additional information superposition processing and a method and a device for additional information detection processing, which are capable of sure additional information detection tolerant to data conversion or the like. SOLUTION: Additional information superposed on original information is detected as follows; a second data value V2 of a specific information area is calculated by operation between a first data value V1 being a data value of the specific information area and a peripheral data value V1 around based on a data value of an area in the vicinity of the specific information area, and difference data V3 between the first and second values V1 and V2 is calculated by a difference information extracting means, and integral processing of the difference data V3 calculated by the difference information extracting means is executed to extract the additional information.