ELECTRONIC WATERMARK DATA INSERTING SYSTEM AND DEVICE

摘要

PROBLEM TO BE SOLVED: To realize an electronic watermark data insertion system that has a high detection efficiency without causing deterioration in image quality. SOLUTION: A DCT unit 103 extracts block data 102 of a size consisting of 8×8 pixels from an original image 101 and applies DCT to the data 102. A quantizer 104 quantizes DCT coefficients. A moving amount deciding unit 106 obtains the difference between the number V (t) of the DCT coefficients obtained from the DCT unit 103 and the number V (t-1) of DCT coefficients of a preceding frame having been stored in advance, and decides it to have a large moving amount when the difference is in excess of a threshold, and it to have a small moving amount when the difference is less that the threshold. An electronic watermark data insertion device 105 extracts electronic watermark data W (j) that coincide with an extracted position of the 8×8 block data, a picture type and the magnitude of the moving amount from the electronic watermark data table 109 and inserts the electronic watermark data to data after quantization outputted from the quantizer 104.