# US 5,710,636 A · Method and apparatus for generating halftone images having human readable patterns formed therein > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,710,636 A - Document ID: US5710636A - Status: Granted - Kind: A - Application number: 08/462,283 - Filed: 1995-06-05 - Granted: 1998-01-20 - Earliest claimed: 1995-06-05 - Assignees: Xerox Corporation - Inventors: Douglas N. Curry - Web page: https://patentgrep.com/patent/US5710636A ## CPC - H04N 1/405: Halftoning, i.e. converting the picture signal of a continuous-tone original into a corresponding signal showing only two levels - G06T 1/0028: {Adaptive watermarking, e.g. Human Visual System [HVS]-based watermarking} - H04N 1/32203: {Spatial or amplitude domain methods (H04N1/32309 takes precedence)} - H04N 1/32256: {in halftone data} - G06T 2201/0051: Embedding of the watermark in the spatial domain - H04N 2201/3261: of multimedia information, e.g. a sound signal - H04N 2201/3271: Printing or stamping - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION - G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL ## Abstract An apparatus and method for producing a halftone image generates halftone cells based on grayscale image data and bitmap code. A human readable pattern is embedded within the halftone image. Each of the halftone cells is formed from dot patterns having one of a plurality of predetermined shapes. The predetermined shapes of the halftone cells form the human readable pattern. The halftone cells are written onto a recording medium to produce the halftone image. Rotation of the halftone cells allows data to be encoded within each of the halftone cells without varying the tone of the image. The tone of the image may be controlled by selectively varying a thickness of the dot patterns within the halftone cells. ## Claims ### Claim 1 An apparatus for producing a halftone image, comprising: a bitmap generator that generates bitmap codes based upon at least one human readable pattern to be formed within the halftone image; a halftone generator for generating halftone cells from the bitmap codes and from grayscale image data, the halftone cells being formed from dot patterns, the halftone generator selecting one of a plurality of predetermined shapes for the dot patterns of each of the halftone cells; and an output device for writing the halftone cells on a recording medium to produce the halftone image, the halftone image having embedded therein at least one human readable pattern formed by the predetermined shapes of the halftone cells. ### Claim 2 (depends on 1) The apparatus of claim 1, wherein each of the halftone cells has four sides and the dot patterns of each of the halftone cells contact a center portion of each of the four sides. ### Claim 3 (depends on 1) The apparatus of claim 1, wherein the halftone cells each have a plurality of sides, end portions of the dot patterns contact a center portion of each of the sides of the halftone cells and each of the end portions contacts an end portion of the dot patterns of an adjacent one of the halftone cells. ### Claim 4 (depends on 1) The apparatus of claim 1, wherein the halftone generator varies a tone of the image by selectively varying a thickness of the dot patterns within individual ones of the halftone cells. ### Claim 5 (depends on 1) The apparatus of claim 1, further comprising an image generator connected to the halftone generator, wherein the image generator generates the grayscale image data. ### Claim 6 (depends on 1) The apparatus of claim 1, wherein a tone of the halftone image is independent of rotation of each of the halftone cells relative to adjacent halftone cells. ### Claim 7 (depends on 1) The apparatus of claim 1, wherein the human readable pattern is readable by a human only with the use of a magnifying device. ### Claim 8 (depends on 1) The apparatus of claim 1, further comprising encoding means for encoding data within each of the halftone cells. ### Claim 9 (depends on 8) The apparatus of claim 8, wherein the encoding means comprises a pattern rotating device for rotating the halftone cells based on encoding data. ### Claim 10 A method of generating a halftone image, comprising: generating bitmap codes based upon at least one human readable pattern to be formed within the halftone image; generating halftone cells from the bitmap codes and from grayscale image data, the halftone cells being formed from dot patterns, the bitmap codes selecting one of a plurality of predetermined shapes for the dot patterns of each of the halftone cells; and writing the halftone cells on a recording medium to produce the halftone image, the halftone image having embedded therein at least one human readable pattern formed by the predetermined shapes of the halftone cells. ### Claim 11 (depends on 10) The method of claim 10, wherein generating the halftone cells comprises generating halftone cells having four sides with the dot patterns of each of the halftone cells contacting a center portion of each of the four sides. ### Claim 12 (depends on 10) The method of claim 10, wherein generating the halftone cells comprises generating halftone cells having a plurality of sides with end portions of the dot patterns contacting a center portion of each of the sides and each of the end portions contacting an end portion of the dot patterns of an adjacent one of the halftone cells. ### Claim 13 (depends on 10) The method of claim 10, further comprising varying a tone of the image by selectively varying a thickness of the dot patterns within individual ones of the halftone cells. ### Claim 14 (depends on 10) The method of claim 10, further comprising generating the grayscale image data. ### Claim 15 (depends on 10) The method of claim 10, further comprising selectively rotating the halftone cells without affecting a tone of the image. ### Claim 16 (depends on 10) The method of claim 10, further comprising encoding data within each of the halftone cells. ### Claim 17 (depends on 16) The method of claim 16, wherein encoding data within each of the halftone cells comprises selectively rotating the halftone cells based on input encoding data. ### Claim 18 (depends on 16) The method of claim 16, wherein a rotational position of each of the halftone cells determines an encoded data value.