Digital image halftone conversion with selective enhancement

Patent metadata

Field	Value
Publication number	US-9332155-B2
Application number	US-201414172827-A
Country	US
Kind code	B2
Filing date	Feb 4, 2014
Priority date	Feb 4, 2014
Publication date	May 3, 2016
Grant date	May 3, 2016

Abstract

A method is disclosed. The method includes receiving a first image as a continuous tone image, screening the image to render a second image as a (Halftone Image) HTI, selecting an area of the first image for enhancement, and iteratively processing the selected area of the first image to render a third image as a multibit HTI.

First claim

What is claimed is:

1. An article of manufacture comprising a machine-readable medium including data that, when accessed by a machine, causes the machine to perform operations comprising:
receiving a first image as a continuous tone image;
screening the image to render a second image as a (Halftone Image) HTI;
selecting an area of the first image for enhancement, including:
analyzing the first image to determine object types; and
comparing the object types to a predetermined ranked list of object types and selecting areas corresponding to the object types that rank highest on the list; and

iteratively processing the selected areas of the first image to render a third image as a multibit HTI.

2. The medium of claim 1 , wherein selecting an area comprises selecting an area containing natural scene image data.

3. The medium of claim 1 , wherein selecting an area comprises selecting an area corresponding to an image, provided that the image has a size that is less than a threshold image size.

4. The medium of claim 1 , wherein iteratively processing comprises applying a Direct Multibit Search (DMS) algorithm to render the third image as a multibit aperiodic HTI.

5. The medium of claim 4 , wherein applying a DMS algorithm comprises:
computing a change in pixel error for a first pixel by toggling a first pixel of the scaled image with possible output states; and
swapping the first pixel with all neighbor pixels.

6. The medium of claim 5 , wherein computing a change in pixel error comprises finding an operation with a maximum decrease in pixel error for the first pixel after computing the change in pixel error.

7. A method comprising:
receiving a first image as a continuous tone image;
screening the image to render a second image as a (Halftone Image) HTI;
selecting an area of the first image for enhancement, including:
analyzing the first image to determine object types; and
comparing the object types to a predetermined ranked list of object types and selecting areas corresponding to the object types that rank highest on the list; and

iteratively processing the selected areas of the first image to render a third image as a multibit HTI.

8. The method of claim 7 , wherein selecting an area comprises selecting a plurality of areas, the number of areas being limited by a buffer size of a processor for iterative processing.

9. The method of claim 8 , wherein selecting an area comprises selecting an area corresponding to an image, provided that the image has a size that is less than a threshold image size.

10. The method of claim 7 , wherein iteratively processing comprises applying a Direct Multibit Search (DMS) algorithm to render a third image as a multibit aperiodic HTI.

11. The method of claim 10 , wherein applying a DMS algorithm comprises:
computing a change in pixel error for a first pixel by toggling a first pixel of the scaled image with possible output states; and
swapping the first pixel with all neighbor pixels.

12. The method of claim 11 , wherein computing a change in pixel error comprises finding an operation with a maximum decrease in pixel error for the first pixel after computing the change in pixel error.

13. A printing system comprising:
a print engine; and
a print controller operable for:
receiving a first image as a continuous tone image;
screening the image to render a second image as a (Halftone Image) HTI;
selecting an area of the first image for enhancement, including:
analyzing the first image to determine object types; and
comparing the object types to a predetermined ranked list of object types and selecting areas corresponding to the object types that rank highest on the list; and

iteratively processing the selected areas of the first image to render a third image as a multibit HTI.

14. The system of claim 13 wherein selecting an area comprises:
analyzing the first image to determine object types; and
selecting an area having a particular object type.

15. The system of claim 14 , wherein selecting an area comprises selecting an area containing natural scene image data.

16. The system of claim 14 , wherein selecting an area comprises selecting an area corresponding to an image, provided that the image has a size that is less than a threshold image size.

Assignees

• Chandu Kartheek
• Stanich Mikel J
• Ricoh Co Ltd

Inventors

• Chandu Kartheek
• Stanich Mikel J

Classifications

• H04N1/40087

  Multi-toning, i.e. converting a continuous-tone signal for reproduction with more than two discrete brightnesses or optical densities, e.g. dots of grey and black inks on white paper · CPC title

• G06K15/1881

  Halftoning (halftoning of still images in general H04N1/405, H04N1/52) · CPC title

• H04N1/409

  Edge or detail enhancement; Noise or error suppression · CPC title

• H04N1/52

  Circuits or arrangements for halftone screening · CPC title

• H04N1/405 Primary

  Halftoning, i.e. converting the picture signal of a continuous-tone original into a corresponding signal showing only two levels · CPC title