Methods and apparatus for identifying marking process and modifying image data based on image spatial characteristics

• US 6,353,675 B1
• Filed: 01/19/1999
• Issued: 03/05/2002
• Est. Priority Date: 01/19/1999
• Status: Expired due to Term

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Sharma, Gaurav
• Primary Examiner(s): Johns, Andrew W.
• Assistant Examiner(s): AZARIAN, SEYED H
• Application Number:
  US09/233,108
• Time in Patent Office: 1,141 Days
• Field of Search: 382/140, 382/141, 382/142, 382/143, 382/239.2, 382/201, 358/502, 358/505, 358/512, 358/515, 358/516, 358/517, 358/518, 358/523, 358/527, 358/534, 358/459, 358/302
• US Class Current: 382/141
• CPC Class Codes: G06T 7/80 Analysis of captured images to determine intrinsic or extrinsic camera parameters, i.e. camera calibration
• CPC Class Codes: H04N 1/00002 Diagnosis, testing or measuring; Detecting, analysing or monitoring not otherwise provided for error detection, error correction or monitoring in digital computers or digital computer components G06F11/00
• CPC Class Codes: H04N 1/00005 relating to image data
• CPC Class Codes: H04N 1/00039 Analysis, i.e. separating and studying components of a greater whole

Abstract

A marking process used to mark an image on a substrate, such as a photographic marking process, a lithographic marking process, an ink-jet marking process, a line-on-line xerographic marking process or a rotated-screen xerographic marking process, is automatically detected using at least one image spatial characteristic obtained from image information picked up from the image. The at least one spatial characteristic, which is unique to the type of marking process, is obtained, for example, by generating an image power spectrum and analyzing the power spectrum according to the existence, position, and/or color of spectral peaks, and/or the existence or absence of abnormally high energy at the high frequencies in the power spectrum.

Claims

1. A method of identifying a marking process used to form an image on a substrate, comprising:

obtaining at least one spatial characteristic based on a power spectrum of image data obtained from the image; and

determining the marking process used to form the image based on the at least one spatial characteristic.

2. The method as set forth in claim 1, further comprising scanning the image to obtain the image data.

3. The method as set forth in claim 1, wherein obtaining the at least one spatial characteristic comprises obtaining at least one power spectrum of the image.

4. The method as set forth in claim 3, wherein determining the marking process comprises at least one of:

determining whether there is at least one spectral peak away from an origin in the at least one power spectrum;

determining whether there is a specified pattern of predominant spectral peaks in the at least one power spectrum;

determining whether there is higher than normal high frequency energy in the at least one power spectrum; and

determining whether there is at least one spectral peak that contains color in the at least one power spectrum.

5. The method as set forth in claim 4, wherein the marking process is determined to be a photographic marking process when there are no spectral peaks away from the origin and there is no abnormally high energy contained in the high frequencies in the at least one power spectrum.

6. The method as set forth in claim 4, wherein the marking process is determined to be an ink-jet marking process when there are no spectral peaks away from the origin and there is higher than normal energy contained in the high frequencies in the at least one power spectrum.

7. The method as set forth in claim 4, wherein the marking process is determined to be a lithographic marking process when there are a plurality of spectral peaks away from the origin, the specified pattern is a substantially circular pattern, and a plurality of predominant spectral peaks are in the specified pattern in the at least one power spectrum.

8. The method as set forth in claim 4, wherein the marking process is determined to be a line-on-line xerographic marking process when there are two predominant spectral peaks away from the origin, the specified pattern is a line through the origin, the two predominant peaks are in the specified pattern symmetrically about the origin, and none of spectral peaks contain color in the at least one power spectrum.

9. The method as set forth in claim 4, wherein the marking process is determined to be a rotated screen xerographic marking process when there is at least one spectral peak away from the origin, the specified pattern is a substantially circular pattern, the at least one predominant spectral peak does not form the specified pattern in the at least one power spectrum, and at least one of the at least one spectral peak contains color in at least one power spectrum.

10. A marking process determining system that automatically detects a marking process used to form an image, comprising:

an image spatial analyzer that analyzes image data corresponding to the image to determine at least one spatial characteristic based on a power spectrum of the image data; and

a marking process detection system that detects the marking process based on the at least one spatial characteristic.

11. The marking process determining system as set forth in claim 10, wherein the image spatial analyzer comprises a power spectrum generator that generates at least one power spectrum of the image.

12. The marking process determining system as set forth in claim 11, wherein the at least one spatial characteristic comprises at least one spectral peak away from an origin in the at least one power spectrum.

13. The marking process determining system as set forth in claim 11, wherein the at least one spatial characteristic comprises an absence of spectral peaks away from an origin, and an absence of high frequencies in the at least one power spectrum.

14. The marking process determining system as set forth in claim 11, wherein the at least one spatial characteristic comprises an absence of spectral peaks away from an origin, and at least one high frequency in the at least one power spectrum.

15. The marking process determining system as set forth in claim 11, wherein the at least one spatial characteristic comprises a plurality of spectral peaks in a specified pattern in the at least one power spectrum.

16. The marking process determining system as set forth in claim 15, wherein the specified pattern is a substantially circular pattern.

17. The marking process determining system as set forth in claim 15, wherein there are two predominant spectral peaks away from an origin in the at least one power spectrum, the specified pattern is a line through the origin, the two predominant peaks are in the specified pattern symmetrically about the origin, and none of the spectral peaks contain color.

18. The marking process determining system as set forth in claim 11, wherein the at least one spatial characteristic comprises at least one spectral peak away from the origin in the at least one power spectrum, and a presence of color in at least one of the at least one spectral peak.

19. The marking process determining system as set forth in claim 10, wherein the marking process detection system detects the marking process to be one of a photographic marking process, a lithographic marking process, an ink-jet marking process, a line-on-line xerographic marking process and a rotated-screen xerographic marking process.

20. A scanner incorporating the marking process determining system as set forth in claim 10.

21. A digital copier incorporating the marking process determining system as set forth in claim 10.