Rotating non-rotationally symmetrical halftone dots for encoding embedded data in a hyperacuity printer

• US 5,537,223 A
• Filed: 06/02/1994
• Issued: 07/16/1996
• Est. Priority Date: 06/02/1994
• Status: Expired due to Term

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Curry, Douglas N.
• Primary Examiner(s): Boudreau, Leo
• Assistant Examiner(s): Tadayon, Bijan
• Application Number:
  US08/252,872
• Time in Patent Office: 775 Days
• Field of Search: 358/456, 358/429, 358/457, 358/458, 358/459, 358/460, 358/461, 358/454, 358/463, 382/295, 382/296, 382/237, 380/5, 380/54, 348/461-468
• US Class Current: 358/3.28
• CPC Class Codes: H04N 1/4055 producing a clustered dots or a size modulated halftone pattern

Abstract

A printing system for receiving grayscale input image data and rendering halftoned image data having embedded data on a recording medium includes an addressable three dimensional memory system. The memory system has a first set of address lines defining an x dimension, a second set of address lines defining a y dimension, and a third set of address lines providing an intensity dimension, and halftoning circuitry for receiving and transforming grayscale input image data into multi-bit value output data. A look-up table is used to match multi-bit value output data representing x dimension, y dimension, and intensity, to grayscale input image data. The system uses addressing circuitry for addressing the three dimensional memory system, with the first set of address lines and the second set of address lines defining a screen stored in the memory system, the first set of address lines and the second set of address lines providing x and y address values defined at a desired screen angle. Data is embedded in the halftone pattern by using rotation circuitry to modify the x and y address values as they are read from the look-up table. A modulating device receives this multi-bit value output data containing embedded data from the halftoning circuitry and converts it into modulated scan spots of defined intensity.

Claims

1. A hyperacuity printing system for receiving grayscale input image data and rendering halftoned image data having embedded data on a recording medium, the system comprising

an addressable three dimensional memory system, with a first set of address lines defining an x dimension, a second set of address lines defining a y dimension, and a third set of address lines providing an intensity dimension,

halftoning circuitry for receiving and transforming grayscale input image data into multi-bit value output data, using a look-up table to match multi-bit value output data representing x dimension, y dimension, and intensity, to grayscale input image data,

addressing circuitry for addressing the three dimensional memory system, with the first set of address lines and the second set of address lines defining a screen stored in the memory system, the first set of address lines and the second set of address lines providing x and y address values defined at a desired screen angle, wherein the addressing circuitry further comprises means for embedding data by application of rotation circuitry for modifying said x and y address values through rotating the halftone dots as halftone dots are read from the look-up table;

and

a modulating device for receiving multi-bit value output data from the halftoning circuitry and converting the multi-bit value output data into modulated scan spots of defined intensity encoding rotation embedded data.

2. The hyperacuity printing system of claim 1, wherein the halftone dots are rotated by the rotation circuitry about a center of the halftone dots.

3. The hyperacuity printing system of claim 1, wherein the halftone dots rotated by the rotation circuitry are elliptical.