DEVICE, METHOD AND PROGRAM FOR EMBEDDING/READING ELECTRONIC WATERMARK AND PROGRAM RECORDING MEDIUM THEREOF

摘要

PROBLEM TO BE SOLVED: To realize the miniaturization and low power consumption of a device by reducing the quantity of arithmetic operations of conversion from a spatial domain of an image into a frequency domain and their inverse conversion in electronic watermark embedding/reading processing. SOLUTION: In watermark information embedding, a DCT device 1 performs DCT operation of only a frequency component in which watermark information is embedded, and a component value changing/analyzing device 2 calculates the difference value between a frequency component value before watermark information embedding processing and a frequency component value after the embedding processing at its component position. An IDCT device 3 returns the difference value of the frequency component to the spatial domain, a difference adder 4 adds the difference value in the spatial domain to an original value in the spatial domain. In watermark information reading, the DCT device 1 performs DCT operation of only a frequency component with the watermark component embedded, and the component value changing/analyzing device 2 reads the watermark information from the results of the DCT operation.