High reliability forensic color marking system
AssigneeHewlett-Packard Development Company, L.P.
InventorsEdward J Van Liew, Nobuko M Nathan, Birsen Ulupinar
Life of this patent
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Abstract
A forensic marking system and method for identifying the printing device on which a medium was printed. Encoded forensic markings which identify the device but are of low perceptibility to the human eye are superimposed on the printed image. The markings have a color, size, density, and repetition pattern that only minimally affect print quality while providing highly accurate identification of the printing device, even if the printed medium contains high-density image content.
Claims37
A system for printing a forensically marked image, comprising:
- a processor for superimposing onto source data at least one forensic marking so as to create output data corresponding to the forensically marked image, the at least one forensic marking having
- an information marker indicative of the system, and
- a checksum marker proximate the information marker and indicative of the information marker;
- and
- a printer coupled to the processor for printing the output data so as to produce the forensically marked image, the at least one forensic marking printed in a predetermined color having a low visual response to the human eye, but readily detectable by electronic scanning so as to identify the system.
A system for determining a device on which a printed medium was printed, comprising:
- a media receptor adapted to receive the printed medium;
- an image scanner in optical communication with the media handler for acquiring multicolor image data for the printed medium;
- a color separation unit coupled to the image scanner for segregating predetermined color image data from the multicolor image data;
- and
- a forensic identification unit coupled to the color separation unit for identifying in the predetermined color image data at least one forensic marking placed on the printed medium by the device, the forensic identification unit having
- a locator subsystem for locating an individual one of the at least one forensic marking within the predetermined color image data,
- a validation subsystem for analyzing the individual forensic marking so as to verify its integrity, and
- an identification subsystem for analyzing the individual forensic marking so as to identify the device on which the printed medium was printed.
A method for printing a forensically marked image with a printer, comprising:
- encoding system information identifying the printer into an information marker;
- calculating a checksum for the information marker;
- encoding the checksum into a checksum marker;
- superimposing onto source data at least one encoded forensic marking containing the information marker and the checksum marker so as to create output data corresponding to the forensically marked image;
- and
- printing the output data on a print medium so as to produce the forensically marked image, the at least one forensic marking printed using a predetermined color difficult to detect by the human eye, but readily detectable by electronic scanning so as to identify the system.
A method for printing a forensically marked image on a print medium with a swath printer, comprising:
- obtaining a swath of image data corresponding to a source image;
- if more than a threshold amount of color data exists in the swath of image data, superimposing onto the image data a swath of at least one forensic marking having an encoded pattern of image pixels in graphical form, the forensic marking including a checksum marker indicative of forensic marking validity;
- printing the image data on the print medium so as to generate a swath of the forensically marked image;
- and
- repeating the obtaining, superimposing, and printing until all the swaths of image data are printed.
A method of determining the printing device on which a forensically marked image was printed, the forensically marked image having at least one forensic marking including an information marker indicative of the printing device and a checksum marker indicative of the information marker, comprising:
- scanning the forensically marked image to locate an individual one of the at least one forensic marking;
- calculating a calculated checksum for the information marker of the individual forensic marking;
- decoding the checksum marker of the individual forensic marking to determine a printed checksum;
- and
- if the calculated checksum matches the printed checksum, decoding the information marker to determine the printing device.
A printer, comprising:
- an interface adapted for receiving printable image data;
- a processor for
- encoding system information identifying the printer into an information marker,
- calculating a checksum for the information marker,
- encoding the checksum into a checksum marker,
- combining the information marker and the checksum marker into a forensic marking, and
- superimposing onto the printable image data at least one copy of the forensic marking;
- and
- a print mechanism coupled to the processor for printing the printable image data in a graphic form detectable by electronic scanning but undetectable to the human eye.
Dependencies are inferred from the claim text.