Patent ID: 7394567

Claim:
A method for embedding data in a two-sided print medium, comprising the steps of: (a) obtaining first data in RGB domain representing matter to be printed on the print medium; (b) coding each digital element of second data to be embedded in the print medium with either a cyan or a magenta color patch that is surrounded by a data space to form a data cell; (c) grouping the data cells into one or more data blocks as needed, each data cell being included in one of the data blocks and each data block including a plurality of data cells; (d) grouping the data blocks into one or more layout areas as needed, each data block being included in one of the layout areas and each layout area containing a plurality of data blocks; and (e) embedding the first data onto a first side of the print medium and embedding the second data on a second side of the print medium, wherein the second data is preferentially embedded opposite light tone regions of the first data and is preferentially not embedded opposite dark tone regions of the first data.