METHOD FOR INSERTING ROBUST DIGITAL ELECTRONIC WATERMARKED SIGNAL AND METHOD FOR DETECTING ELECTRONIC WATERMARK

摘要

PROBLEM TO BE SOLVED: To obtain a digital electronic watermarking procedure for data that is applicable to image, audio, video and multimedia data.

SOLUTION: Data which are to be electronically watermarked are divided into a set of n×n blocks, such as, 8×8 pixel blocks of MPEG, and these blocks are summed to form one summed block to insert an electronic watermark. The same electronic watermark signal can be distributed throughout the set of blocks in a large variety of ways. This allows the insertion algorithm to be changed without affecting the decoders. The decoding procedure first sums together the DCT coefficients for each set of 8×8 blocks and then extracts the electronic watermark from the summed block. Since the sum of the DCT blocks is equal to the DCT of the sum of the pixel value blocks, efficient decoding can be carried out both the spatial and the frequency domains. The symmetric nature of the decoding process allows geometric distortions to be handled in the spatial domain and other signal distortions to be handled in the frequency domain.

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