Two-dimensional linear interpolation and registration control for a hyperacuity printer

• US 6,519,055 B1
• Filed: 03/30/2000
• Issued: 02/11/2003
• Est. Priority Date: 10/28/1993
• Status: Expired due to Fees

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Curry, Donald J., Curry, Douglas N.
• Primary Examiner(s): Wallerson, Mark
• Assistant Examiner(s): HASKINS, TWYLER LAMB
• Application Number:
  US09/539,493
• Time in Patent Office: 1,048 Days
• Field of Search: 358/2.1, 358/1.1, 358/3.02, 358/3.27, 358/462, 382/300
• US Class Current: 358/2.1
• CPC Class Codes: G06K 15/1223 Resolution control, enlarging or reducing, edge or detail enhancement

Abstract

A hyperacuity printing system for rendering bitmapped image data on a photosensitive recording medium, the bitmapped image data being rendered as an array of pixels across the photosensitive recording medium in a fastscan direction, and an orthogonal slowscan direction. This system includes a data source for supplying grayscale input image data and a scanning device for rendering grayscale output image data onto the recording medium. The scanning device has a device for writing scan spots on the recording medium. Further included in this system is transformation circuitry for transforming the grayscale input image data into grayscale output image data. The transformation circuitry includes a halftoner, a thresholder, and a selection device, where the selection device selects either the thresholder or the halftoner to provide the grayscale output image data. Finally, included is a modulating device coupled between the transformation circuitry and the scanning device for intensity modulating each of the scan spots in accordance with the grayscale output image data.

Claims

1. A hyperacuity printing system, comprising:

a memory for storing grayscale image data;

a recording medium for rendering the grayscale image data as an array of pixels across the recording medium in both a fastscan direction and an orthogonal slowscan direction;

an output scanning device having a writing device for writing output image data onto the recording medium;

transformation circuitry for transforming the grayscale input image data into the output image data, the transformation circuitry including a registration controller for determining error compensation values, a phase resolution controller for providing a number for registration control, with the phase resolution controller connected to the registration controller to receive error compensation values and bias the number based on the received error compensation values, and a resampling interpolator for determining an interpolated value of the grayscale input image data that compensates for registration errors, with the resampling interpolator connected to the phase resolution controller to receive the biased number and adjust the interpolated value for determining the output image data; and

a modulating device for receiving the output image data from the transformation circuitry to drive the output scanning device.

2. The hyperacuity printing system according to claim 1, wherein the transformation circuitry further comprises a halftoner for rendering tonerart.

3. The hyperacuity printing system according to claim 2, wherein the transformation circuitry further comprises:

a thresholder for rendering lineart and text;

the thresholder receiving from the resampling interpolator the interpolated value and local rate of change of the interpolated value; and

a segmenter for switching between the thresholder and the halftoner to provide the output image data.

4. The hyperacuity printing system according to claim 3, wherein the interpolated value and local rate of change of the interpolated value are determined in both the fastscan and slowscan directions.

5. The hyperacuity printing system according to claim 2, wherein the halftoner is configured to modify position of a halftone screen with the error compensation values received from the registration controller to compensate for registration errors.

6. The hyperacuity printing system according to claim 5, wherein the halftone screen is a look-up table for providing multi-bit value output data that defines halftone dots;

the halftone-dots being arranged in the look-up table as a continuum from a lowest density value to a highest density value corresponding the grayscale input image data.

7. The hyperacuity printing system according to claim 1, wherein the registration controller is configured to determine the error compensation values based on feedback information from one of a mechanical and an optical component.

8. The hyperacuity printing system according to claim 1, further comprising a data source coupled to the memory for supplying the grayscale image data.

9. The hyperacuity printing system according to claim 1, further comprising:

a data source coupled to the memory for supplying binary image data; and

a grayscale converter for converting the binary image data to grayscale image data.

10. The hyperacuity printing system according to claim 1, wherein the number provided by the phase resolution controller controls one of phase and resolution of spots written on the recording medium by the output scanning device.

11. The hyperacuity printing system according to claim 1, wherein the interpolated value determined by the resampling interpolator is two dimensional slope information.

12. The hyperacuity printing system according to claim 1, wherein the registration controller determines error compensation values to compensate for registration errors in the hyperacuity printer with subscan precision.

13. The hyperacuity printing system according to claim 1, wherein the error compensation values determined by the registration controller compensate for one of Type I, Type II, Type II, and Type IV registration errors.

14. The hyperacuity printing system according to claim 1, wherein the error compensation values determined by the registration controller compensate for one of changes in skew, fastscan non-linearity, and scanline bow in the output image that are caused by imperfections in the output scanning device.

15. The hyperacuity printing system according to claim 1, wherein the recording medium is photosensitive.

16. The hyperacuity printing system according to claim 1, wherein the modulating device is a digital to analog converter.

17. The hyperacuity printing system according to claim 1, wherein the output scanning device comprises a laser diode.

18. The hyperacuity printing system according to claim 1, wherein the output scanning device comprises a raster output scanner.

19. The hyperacuity printing system according to claim 1, wherein the output scanning device comprises an image bar.

20. The hyperacuity printing system according to claim 19, wherein the image bar is an LED image bar.

21. The hyperacuity printing system according to claim 1, wherein the number is a fractional accumulated number.

22. The hyperacuity printing system according to claim 1, wherein the output image data is grayscale image data.