Ising-model image rendition, and consolidated masking and/or filtering, in incremental printing

• US 8,233,194 B2
• Filed: 01/26/2005
• Issued: 07/31/2012
• Est. Priority Date: 01/26/2005
• Status: Expired due to Fees

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: de Pena, Alejandro Manuel, Garcia Reyero, Santiago, Garcia, Joan Manuel
• Primary Examiner(s): Zimmerman, Mark K
• Assistant Examiner(s): THOMAS, ASHISH
• Application Number:
  US11/043,587
• Publication Number:
  US 20060164688A1
• Time in Patent Office: 2,743 Days
• Field of Search: 358/1.9, 358/1.8, 358/497, 358/484, 358/3.03, 358/445, 358/448, 358/3.04, 358/474, 358/304, 382/237, 382/276, 382/128, 382/152, 382/252, 382/275, 348/245, 348/445, 347/9, 347/7, 375/240.05, 345/426
• US Class Current: 358/3.04
• CPC Class Codes: G06K 15/107 Mask selection
• CPC Class Codes: H04N 1/405 Halftoning, i.e. converting the picture signal of a continuous-tone original into a corresponding signal showing only two levels

Abstract

One aspect of the method/apparatus finds, for each input-image pixel, an “offset weighted average” of neighboring-pixel interactions—and uses the averages to make a final image. Another aspect assumes a value for each pixel, to use in a final rendered image form—and, at each in a series of approximations, determines whether to change the value, and finds a probabilistic weight to help determine. Yet another finds, for each pixel, a numerical representation of neighboring-pixel interactions—and establishes a distance cutoff for use in defining “neighbor”, and uses the representation to decide whether to change color values. Still another finds a desired or ideal number of print passes, and adapts the number of passes actually used to the found number. Another combines halftoning and printmasking into one procedure and prints images prepared thereby. Another integrates halftoning and image filtering, to obtain esthetic visual effects, into one procedure—and prints images thus prepared.

Claims

1. A method for printing a digital-array representation of an input image having pixels of a given bit depth, said method comprising the steps of:

providing at a printing system the input image to be printed;

generating with an image pipeline module of the printing system a final processed form of the image having pixels of a reduced bit depth less than the given bit depth and compatible with tonal levels of the printing system by

calculating, for substantially each particular pixel in the digital array, an offset weighted average of neighboring-pixel interactions with the particular pixel, wherein different non-zero weights are assigned to at least some neighboring pixels; and

using the offset weighted averages to develop the final processed form of the image; and

printing the final processed form of the image with the printing system.

2. The method of claim 1, wherein:

the using step comprises determining changes in the offset weighted averages, at substantially each stage in a series of successive approximations of values for the pixels of the image that converges to the final processed form of the image, wherein each stage in the series of successive approximations comprises calculating the offset weighted average for a plurality of the particular pixels in the digital array.

3. The method of claim 2, wherein:

the using step further comprises applying the changes to decide whether a value for the particular pixel, at a particular stage, should be modified in said particular stage to a different value in the next stage.

4. The method of claim 3, wherein:

the using step comprises calculating a probabilistic weight for use in determining whether to perform a modification of the assumed value of the particular pixel.

5. The method of claim 4, wherein:

the using step further comprises applying a randomly selected discriminator to modulate the calculated probabilistic weight, in determining whether or not to actually modify the assumed value.

6. The method of claim 4, wherein:

the modification is a level flip.

7. The method of claim 2, further comprising the step of:

finding the final processed form of the image, through convergence of a multiplicity of said successive approximations.

8. The method of claim 1, wherein:

the calculating step comprises finding each offset weighted average as

9. The method of claim 8, wherein:

each weighted average is offset from a simple weighted average by the terms +i_j and +1, in numerator and denominator respectively.

10. The method of claim 8, wherein:

for a binary-value system, a particular binary value selected for the term +i_j depends upon algebraic sign of the value i_j; and

for a multiple-discrete-value system, a particular discrete value selected for the term +i_j depends upon a digital resolution, within the available multiple values, of the value i_j.

11. The method of claim 1, wherein:

each particular pixel in the digital array is selected in turn, for performance of the calculating and using steps, by random walk thru the array.

12. The method of claim 2, wherein the calculating, determining and using steps, considered in the aggregate, comprise:

defining discrete levels at the reduced bit depth and the error, if any, between each of them and the true contone level at each pixel at the given bit depth;

but

no explicit distribution of error from each pixel, after its calculation, to neighboring pixels.

13. The method of claim 12, wherein:

said discrete levels are two binary levels.

14. The method of claim 12, wherein:

said discrete levels are multiple levels.

15. The method of claim 1, wherein:

the image processing comprises image rendering in preparation for incremental printing.

16. The method of claim 1, wherein:

the image processing comprises printmasking in preparation for incremental printing.

17. The method of claim 1, wherein the reduced bit depth is at least three bits less than the given bit depth.

18. The method of claim 1, wherein the image pipeline module comprises parallel processors each configured to process at least some different ones of the pixels of the input image.

19. The method of claim 1, wherein the digital-array representation of the input image and a digital-array representation of the final processed form of the image have substantially the same number of pixels.

20. The method of claim 1, wherein the neighboring-pixel interactions comprise interactions with the particular pixel of at least some nearest neighboring pixels disposed in the digital-array representation within one row and one column of the particular pixel, and of at least some non-nearest neighboring pixels disposed a plurality of rows or columns in the digital-array representation away from the particular pixel.

21. The method of claim 20, wherein the neighboring-pixel interactions disregard interactions with the particular pixel of the non-nearest neighboring pixels further than a particular number of rows or columns in the digital-array representation away from the particular pixel.

22. The method of claim 1, wherein the particular pixel has a defined value that is used in the calculating of the offset weighted average.

23. The method of claim 1, wherein:

the image processing comprises both image rendering and printmasking in preparation for incremental printing.

24. The method of claim 23, wherein the image rendering comprises matrix-based halftoning performed in an integrated procedure with the printmasking.

25. The method of claim 1, wherein a first neighboring pixel nearest to the particular pixel is assigned a higher non-zero weight, and a second neighboring pixel more remote from the particular pixel than the first neighboring pixel is assigned a lower non-zero weight.

26. A system for printing a digital-array representation of an input image having pixels of a given bit depth, comprising:

printing hardware configured to print a final processed form of the image that has pixels of a reduced bit depth that are compatible with tonal levels of the printing hardware; and

an image pipeline module configured to generate the final processed form of the image from the input image by

calculating, for substantially each particular pixel in the digital-array representation, an offset weighted average of neighboring-pixel interactions with the particular pixel, wherein different non-zero weights are assigned to at least some neighboring pixels; and

using the offset weighted averages to develop the final processed form of the image.

27. The system of claim 26, wherein:

the image pipeline module is further configured to determine changes in the offset weighted averages, at substantially each stage in a series of successive approximations of values for the pixels of the image that converges to the final processed form of the image, wherein the offset weighted averages for a plurality of the particular pixels in the digital array is calculated at each stage in the series of successive approximations.

28. The system of claim 27, wherein:

the image pipeline module is further configured to apply the changes to decide whether a value for the particular pixel, at a particular stage, should be modified in said particular stage to a different value in the next stage.

29. The system of claim 28, wherein:

the image pipeline module is further configured to calculate a probabilistic weight for use in determining whether to perform a modification of the assumed value of the particular pixel.

30. The system of claim 29, wherein:

the image pipeline module is further configured to apply a randomly selected discriminator to modulate the calculated probabilistic weight, in determining whether or not to actually modify the assumed value.

31. The system of claim 29, wherein:

the modification is a level flip.