Patent ID: 6700993
Filing Date: 2004-03-02
Classification: G06T,H04N

Abstract:
An on-line digital watermark detection system which comprises:a user terminal for extracting a watermark embedded in images; and a detection center connected with said user terminal for generating an extraction key, encryption key and authentication key for said watermark, wherein: said user terminal outputs toward said detection center a first information which consists of the encrypted watermark and encrypted authentication information which is prescribed; said detection center decodes, and quantizes said first information, and outputs toward said user terminal a second information namely the quantized first information; and said user terminal authenticates said second information and extracts said watermark from said second information; and wherein said detection center comprises; demodulation matrix generation means for generating a demodulation matrix required to extract said watermark; extraction and encryption key generation means for transmitting an extraction key and encryption key required to extract and encrypt said watermark to said user terminal; second information generation means for decoding and quantizing a first information containing the encrypted watermark and the encrypted authentication information transmitted by said user terminal, and for transmitting the quantized first information to said user terminal as a second information.