Font characteristic driven halftoning

• US 7,224,489 B2
• Filed: 09/25/2001
• Issued: 05/29/2007
• Est. Priority Date: 09/25/2001
• Status: Expired due to Fees

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Loce, Robert P., Zack, Gregory W., Cheng, Xiaoxue
• Primary Examiner(s): Moore; David
• Assistant Examiner(s): Thompson; James A.
• Application Number:
  US09/962,904
• Publication Number:
  US 20030058474A1
• Time in Patent Office: 2,072 Days
• Field of Search: 358/1.9, 358/3.06, 358/3.15, 358/3.17, 358/3.2, 358/1.11, 358/538, 358/462, 358/470, 358/3.12, 382/139, 382/185, 382176-179, 382/195, 382/197, 382/203, 382/187, 392/187, 392/203, 345/467, 345/471
• US Class Current: 358/3.2
• CPC Class Codes: G06K 15/02 using printers
• CPC Class Codes: G06K 15/1807 relating to the print image preparation

Abstract

Characteristics of text or text components or features are considered when selecting halftoning screens. For example, an italic slant angle of text is recognized and used to select or generate a compatible halftone screen oriented at the same angle. A screen frequency may be selected based on a thickness of a text component. Descriptive tags associated with text or text components facilitate screen selection. Tags are assigned based on font descriptions included in a document during authoring. Alternatively, tags are assigned based on the results of document segmentation and character recognition techniques. An image processing system operative to consider characteristics of text or text components when selecting halftone screens includes a text component characteristic recognizer, a halftone screen selector and a halftoner. Optionally a print engine is also included. In a xerographic environment the print engine includes a xerographic printer.

Claims

1. A method of halftoning a text component, the method comprising:

determining a rendering quality related characteristic of the text component including at least one of a text component;

orientation, slant angle, curvature, dimension and thickness;

selecting or generating a halftone screen having at least one of;

a screen angle that closely matches, or is orthogonal to or nearly orthogonal to, the orientation or slant angle of the text component, and a screen frequency such that halftone lines, dots or structures of the screen fall compatibly on edges of the text component based on the curvature, dimension and/or thickness of the text component, and

halftoning the text component with the selected or generated halftone screen.

2. The method of halftoning a text component of claim 1 wherein determining a rendering quality related characteristic of the text component comprises:

determining a font type of the text component.

3. The method of halftoning a text component of claim 1 wherein determining a rendering quality related characteristic of the text comprises:

determining a font modification associated with the text component.

4. The method of halftoning a text component of claim 1 wherein determining a rendering quality related characteristic of the text comprises:

determining a predominant angle of the text component.

5. The method of halftoning a text component of claim 1 wherein determining a rendering quality related characteristic of the text component comprises:

determining a predominant dimension of the text component.

6. The method of halftoning a text component of claim 1 wherein selecting a halftone screen comprises:

selecting a halftone screen that is compatible with a predominant angle of the text component.

7. The method of halftoning a text component of claim 1 wherein selecting a halftone screen comprises:

selecting a halftone screen having a screen frequency such that halftone lines, dots or structures of the screen fall compatibly on edges of the text component.

8. A method of improving a rendering quality of gray, colored, anti-aliased or scanned text, the method comprising:

tagging italic text in the document;

selecting a halftone screen that is compatibly aligned with the text based on whether or not the text is tagged as italic, and

halftoning the text with the selected halftone screen.

9. The method of improving a rendering quality of gray, colored, anti-aliased or scanned text of claim 8 wherein selecting a halftone screen comprises:

selecting a halftone screen with a screen angle that matches a slant angle of the text tagged as italic.

10. The method of improving a rendering quality of gray, colored, anti-aliased or scanned text of claim 8 wherein selecting a halftone screen comprises:

selecting a halftone screen with a screen angle that is perpendicular to a slant angle of the text tagged as italic.

11. An image processor operative to halftone text based on a text component characteristic, the image processor comprising:

a text component characteristic recognizer operative to recognize rendering quality affecting characteristics of text features including at least one of a text component;

orientation, slant angle, curvature, dimension and thickness;

a halftone screen selector operative to communicate with the text component characteristic recognizer and select a halftone screen having at least one of;

a screen angle that closely matches, or is orthogonal to or nearly orthogonal to, the orientation or slant angle of the text component, and a screen frequency such that halftone lines, dots or structures of the screen fall compatibly on edges of the text component based on the curvature, dimension and/or thickness of the text component;

a halftoner operative to use the selected halftone screen to create a halftone version of the text component.

12. The image processor of claim 11 wherein the text component characteristic recognizer comprises:

a text feature tag interpreter.

13. The image processor of claim 12 further comprising:

a text feature tagger operative to tag pixels that make up a text component based on characteristics of the text component.

14. The image processor of claim 13 wherein the text feature tagger comprises:

a text angle tagger operative to tag pixels that make up a text component based on a predominant angle of the text component.

15. The image processor of claim 13 wherein the text feature tagger comprises:

a text thickness tagger operative to tag pixels that make up a text component based on a predominant thickness of the text component.

16. The image processor of claim 11 wherein the text component characteristic recognizer comprises:

a text component slope evaluator operative to determine a predominant slope of a text feature.

17. The image processor of claim 11 wherein the text component characteristic recognizer comprises:

a text component thickness evaluator operative to determine a predominant thickness of a text feature.

18. The image processor of claim 11 wherein the halftone screen selector comprise:

a halftone screen angle selector operative to specify a screen angle based on a predominant angle of a text component.

19. The image processor of claim 11 wherein the halftone screen selector comprises:

a halftone screen frequency selector operative to specify a screen frequency based on a predominant thickness of a text component.

20. The image processor of claim 11 further comprising:

a rendering device operative to render the halftone version of the text component.

21. The image processor of claim 20 wherein the rendering device comprises a xerographic printer.