Embedding a watermark in an image by changing selected DCT coefficients in the blocks and macro blocks of coefficients which represent the image. The changes in the blocks that comprise each macro block are done in a coordinated manner so that the phase of the watermark signal is preserved across the...http://www.google.fr/patents/US6229924?utm_source=gb-gplus-shareBrevet US6229924 - Method and apparatus for watermarking video images
Method and apparatus for watermarking video images
