System and apparatus for inserting electronic watermark data

摘要

The DCT converter (103) extracts block data(102)of a 8 x 8 pixel size from the original image (101) and then subjects it to DCT conversion. The quantizer (104) quantizes the DCT coefficient. The movement decision unit (106) obtains the difference between the number V(t) of DCT coefficients obtained by the DCT converter (103) and the number V(t-1) of DCT coefficients of the previous frame previously held. The movement decision unit (106) decides the movement as a large value if the difference exceeds a certain threshold value and decides the movement as a small value if the difference is less than the threshold value. The electronic watermark data inserter (105) extracts electronic watermark data W(j) which matches the location where 8 x 8 block data is extracted from the electronic watermark data table (109), the picture type and the movement and then inserts it into the data after quantization output from the quantizer (104).