Patent ID: 7065227

Claim:
A data processing apparatus for selecting one of a plurality of candidate data corresponding to watermark data embedded into object data to embed the selected one candidate data as said watermark data, comprising: object processing apparatus for dividing input data into a plurality of object blocks distributed in a spatial domain, each object block comprising an array of pixels, and using the object blocks as said object data for embedding; a variation indication data generation means for generating a plurality of variation indication data indicating variation between said object data and each of the object data obtained by embedding each of said plurality of candidate data, each of said plurality of candidate data comprised of a different block pattern having pixel element values adjusted from a selected basic pattern associated with an individual object block and having a same structure as said object block; a detectability indication data generation means for generating a plurality of detectability indication data, each indicating the detectability of each of said plurality of candidate data; a watermark data selection means for selecting one of said candidate data based on said plurality of variation indication data and said plurality of detectability indication data; and a data embedding means for embedding the selected candidate data into said object data as said watermark data, wherein said embedding is performed in said spatial domain.