System and method for boundary artifact elimination in parallel processing of large format images

• US 7,742,658 B2
• Filed: 01/26/2006
• Issued: 06/22/2010
• Est. Priority Date: 01/26/2006
• Status: Expired due to Fees

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Cuciurean-Zapan, Clara, Malik, Ammal, Li, Xing, Nagarajan, Ramesh
• Primary Examiner(s): CHANG, JON CARLTON
• Application Number:
  US11/340,391
• Publication Number:
  US 20070172149A1
• Time in Patent Office: 1,608 Days
• Field of Search: 382/284, 382/303, 382/304, 382/275, 358/3.03
• US Class Current: 382/284
• CPC Class Codes: H04N 1/3876 Recombination of partial images to recreate the original image

Abstract

The disclosed systems and methods pertain to the processing of large format images in a manner to avoid introducing imaging defects, and more particularly to dividing the large image into bands, processing these bands in parallel and then putting them back together in to create the final processed image. The methods include the use of overlapping the image bands, padding of the bands prior to processing and the redefinition of image values at common boundaries of the bands to minimize or eliminate visible defects.

Claims

1. A method for processing an image, comprising:

receiving the image to be processed and storing the image in memory;

dividing the image into bands, each band including a plurality of pixels from a plurality of scanlines;

padding each band along at least an edge with additional non-zero data not found in the band;

processing at least a portion of the bands in parallel, using multiple image processing channels, to produce processed bands; and

recombining the processed bands to produce a processed image.

2. The method of claim 1, wherein padding each band comprises selecting data from an adjacent image band to effectively overlap adjacent image bands.

3. The method of claim 1, wherein the padding is accomplished using a pre-defined data pattern.

4. The method of claim 3, wherein the pre-defined data pattern comprises a uniform gray image value.

5. The method of claim 3, wherein the pre-defined data pattern comprises a pattern of mid-gray image values.

6. The method of claim 1, wherein padding comprises redefining image values along a common boundary shared by adjacent bands.

7. The method of claim 6, wherein redefining image values comprises selecting from image values along the common boundary.

8. The method of claim 7, wherein the selection is randomly performed from the values on both sides of the common boundary.

9. The method of claim 1, wherein dividing the image into bands comprises producing a plurality of unequally overlapping bands from the image data.

10. The method of claim 1, wherein recombining the processed bands to produce a processed image comprises selecting processed image values along a common boundary shared by adjacent bands.

11. The method of claim 10, wherein selecting processed image values comprises randomly selecting the image values from areas adjacent the common boundary shared by adjacent bands.

12. The method of claim 10, wherein selecting processed image values comprises identifying matching image values in areas adjacent the common boundary shared by adjacent bands, and upon detection of each match altering the area in which the image values are selected for output.

13. The method of claim 1, wherein a plurality of scanlines of the first band are processed prior to processing of the second band, and where output generated by processing of the plurality of scanlines of the first band is used as an input to the processing of the second band.

14. A method, operating on an image processor, for processing a large-format image stored in memory, comprising:

dividing the large format image into N overlapping segments called bands using an image splitter, each band including a plurality of adjacent pixels from a plurality of adjacent scanlines;

padding each of said N bands, along at least an edge, with additional non-zero data not found in said band;

parallel processing each of said N bands using a plurality of channels in the image processor to produce N processed bands, wherein said N processed bands each include processed image values derived from the additional image data; and

recombining the processed bands from said plurality of channels while eliminating overlapping regions thereof to produce a processed image.

15. The method of claim 14, wherein padding each band comprises selecting data from an adjacent image band to effectively overlap adjacent image bands.

16. The method of claim 14, wherein a plurality of scanlines of a band are processed prior to processing of a subsequent band, and where output generated by processing of the plurality of scanlines of the band is used as an input to the processing of the subsequent band.

17. A system for processing an image, comprising:

an image splitter for dividing the image into overlapping bands, each of said bands including a plurality of pixels from a plurality of scanlines and being assigned to one of a plurality of processing channels;

a preprocessing module, within each channel, for padding each band along at least an edge with additional data not originally found in the band;

an image processor for processing at least a portion of the image data in each band in parallel to produce processed bands; and

an image stitcher for recombining the processed bands to produce a processed image.

18. The system of claim 17, wherein said image splitter is capable of duplicating at least a portion of the data for an image band, and thereby divide the image into a plurality of overlapping bands, wherein image data found in one band is at least partially duplicated in an adjacent band.

19. The system of claim 17, further including an image data generator, said generator producing image data in accordance with a predetermined characteristic for addition to each image band within a particular channel.