Patent ID: 6947562

Claim:
An electronic watermark detecting/inserting device for producing, in response to an input digital image which comprises a first electronic watermark inserted therein and which has a first DCT (Discrete Cosine Transform) coefficient, an output digital image which comprises said first electronic watermark inserted therein and a second electronic watermark inserted subsequently to said first electronic watermark in said output digital image and which has a second DCT coefficient, said device comprising: a first DCT coefficient producing section ( 10 ) for producing said first DCT coefficient from said input digital image; an electronic watermark detecting section ( 30 ) for detecting said first electronic watermark from said first DCT coefficient and for producing a request for insertion of said second electronic watermark; an electronic watermark inserting section ( 20 ) for inserting, in response to said request for insertion of the second electronic watermark, said second electronic watermark into said input digital image subsequently to said first electronic watermark and for producing said output digital image which comprises said second electronic watermark inserted subsequently to said first electronic watermark in said output digital image and which has said second DCT coefficient; a second DCT coefficient producing section ( 40 ) for producing said second DCT coefficient from said output digital image; and a DCT coefficient supplying section ( 50 ) for supplying said second DCT coefficient from said second DCT coefficient producing section to said electronic watermark detecting section; said electronic watermark detecting section detecting, when supplied with said second DCT coefficient from said DCT coefficient supplying section, said second electronic watermark from said second DCT coefficient and producing a detection result representative of a detection intensity of said second electronic watermark to deliver said detection result to said electronic watermark inserting section; said electronic watermark inserting section adjusting, in response to said detection intensity represented by said detection result, an insertion intensity of said second electronic watermark to be inserted into said input digital image.