초록 ▼

A data embedding technique that adds a watermark in the form of embedded data in the RGB domain in a duplex color laser printer. The data embedding algorithm employs a two-color (cyan and magenta) patch based coding scheme. Each bit of raw data is coded by a rectangular patch ("data area") of either

A data embedding technique that adds a watermark in the form of embedded data in the RGB domain in a duplex color laser printer. The data embedding algorithm employs a two-color (cyan and magenta) patch based coding scheme. Each bit of raw data is coded by a rectangular patch ("data area") of either cyan or magenta color surrounded by white space ("space area"). The combination of a single data area and corresponding space area is a "data cell".

대표청구항 ▼

What is claimed is: 1. 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

What is claimed is: 1. 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. 2. The method of claim 1, wherein the patch size of each data cell is based on a tone level of the to-be-printed matter. 3. The method of claim 1, wherein each digital element is a single bit. 4. A method for retrieving data embedded in a print medium, comprising the steps of: (a) converting a printed medium to digital data to recover a plurality of data blocks, each of which includes a plurality of data cells, each of which contains either a cyan or a magenta color patch and a space area surrounding the data area; (b) performing a block matching routine to find the best match location for each data block; and (c) performing a code retrieval routine that extracts a digital element from each data cell, the code retrieval routine comprising calculating a cyan signal estimator and a magenta signal estimator for each data cell and comparing the cyan signal and magenta signal estimators for a particular cell to determine the particular digital element extracted from that cell. 5. A printer having the capability to embed data into a two-sided print medium, the printer comprising: a processor; memory in communication with the processor; and a watermark module configured to operate in cooperation with the processor and the memory to: receive first data in RGB domain representing matter to be printed on the print medium, code 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, group 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, and group 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 embed the first data onto a first side of the print medium and embed 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. 6. The printer of claim 5, wherein the printer is a color laser printer. 7. A device-readable medium encoded with a program of instructions for causing a device to perform a method of retrieving data embedded in a print medium, the program of instructions comprising for: (a) instructions for converting a printed medium to digital data to recover a plurality of data blocks, each of which includes a plurality of data cells, each of which contains either a cyan or a magenta color patch and a space area surrounding the data area; (b) instructions for performing a block matching routine to find the best match location for each data block; and (c) instructions for performing a code retrieval routine that extracts a digital element from each data cell, the code retrieval routine comprising calculating a cyan signal estimator and a magenta signal estimator for each data cell and comparing the cyan signal and magenta signal estimators for a particular cell to determine the particular digital element extracted from that cell. 8. A device-readable medium encoded with a program of instructions for causing a device to perform a method of embedding data in a two-sided print medium, the program of instructions comprising: (a) instructions for receiving first data in RGB domain representing matter to be printed on the print medium; (b) instructions for 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) instructions for 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) instructions for 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) instructions for printing the to-be-printed matter on one side of the print medium and, embedding the second data on the other side of the print medium wherein the second data is preferentially embedded opposite light tone regions of the printed matter and is preferentially not embedded opposite dark tone regions of the printed matter. 9. The device-readable medium of claim 8, wherein the patch size of each data cell is based on a tone level of the to-be-printed matter. 10. The device-readable medium of claim 8, wherein each digital element is a single bit.