Methods and apparatus for modifying image data based on identification of marking process

• US 6,525,845 B1
• Filed: 01/19/1999
• Issued: 02/25/2003
• Est. Priority Date: 01/19/1999
• Status: Expired due to Fees

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Sharma, Gaurav, Shiau, Jeng-Nan, Schweid, Stuart A.
• Primary Examiner(s): Coles, Edward
• Assistant Examiner(s): Ghee, Ashanti
• Application Number:
  US09/234,107
• Time in Patent Office: 1,498 Days
• Field of Search: 358/401, 358/406, 358/505, 358/526, 358/504, 358/474, 358/1.4, 382/173, 382/267
• US Class Current: 358/504
• 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 1/00015 Reproducing apparatus
• CPC Class Codes: H04N 1/00037 Detecting, i.e. determining the occurrence of a predetermined state H04N1/00031 takes precedence
• CPC Class Codes: H04N 1/00087 Setting or calibrating picture signal circuits H04N1/40
• CPC Class Codes: H04N 1/2315 according to characteristics of the reproducing apparatus, e.g. capability
• CPC Class Codes: H04N 1/40062 Discrimination between different image types, e.g. two-tone, continuous tone

Abstract

Image information is re-calibrated based on the type of marking process and materials by which the image corresponding to the image information was marked on a substrate. The marking process is automatically detected by using, for example, at least one spatial characteristic obtained from the image information.

Claims

1. A method of re-calibrating image data obtained from an image formed on a substrate by an unknown marking process, comprising:

setting an initial calibration value;

inputting the image data;

determining the marking process used to form the image; and

re-calibrating the image data based on the determined marking process.

2. The method as set forth in claim 1, wherein the initial calibration value is a compromise calibration value between individual optimal calibration values for respective ones of a plurality of marking process.

3. The method as set forth in claim 1, wherein determining the marking process comprises:

obtaining at least one spatial characteristic of the image data; and

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

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

5. The method as set forth in claim 4, 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 the 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.

6. The method as set forth in claim 5, 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.

7. The method as set forth in claim 5, wherein the marking process is determined to be an inkjet 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.

8. The method as set forth in claim 5, wherein the marking process is determined to be a lithographic marking process when there are a plurality of the spectral peaks away from the origin, the specified pattern is a substantially circular pattern, and the plurality of the predominant spectral peaks are in the specified pattern in the at least one power spectrum.

9. The method as set forth in claim 5, 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 the spectral peaks contain color in the at least one power spectrum.

10. The method as set forth in claim 5, 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 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.

11. A data modifying system that automatically determines a marking process used to form an image on a substrate and re-calibrates image data corresponding to the image based on the determined marking process, comprising:

a marking process detection system that detects the marking process;

a re-calibration value determination system that determines a re-calibration value based on the detected marking process; and

a data modification system that modifies the image data using the re-calibration value.

12. The data modifying system as set forth in claim 11, further comprising an image spatial analyzer that analyzes at least one spatial characteristic of the image data, wherein the marking process system detects the marking process based on the at least one spatial characteristic.

13. The data modifying system as set forth in claim 12, wherein the image spatial analyzer comprises a power spectrum generator that generates at least one power spectrum of the image.

14. The data modifying system as set forth in claim 13, wherein the at least one spatial characteristic comprises at least one spectral peak away from an origin in the at least one power spectrum.

15. The data modifying system as set forth in claim 13, wherein the at least one spatial characteristic comprises an absence of spectral peaks away from an origin, and an absence of abnormally high energy in high frequencies in the at least one power spectrum.

16. The data modifying system as set forth in claim 13, wherein the at least one spatial characteristic comprises an absence of spectral peaks away from an origin, and higher than normal energy in the high frequencies in the at least one power spectrum.

17. The data modifying system as set forth in claim 13, wherein the at least one spatial characteristic comprises a plurality of spectral peaks in a specified pattern in the at least one power spectrum.

18. The data modifying system as set forth in claim 17, wherein the specified pattern is a substantially circular pattern.

19. The data modifying system as set forth in claim 17, 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.

20. The data modifying system as set forth in claim 13, 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.

21. The data modifying system as set forth in claim 11, 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.

22. A scanner incorporating the data modifying system as set forth in claim 11.

23. A digital copier incorporating the data modifying system as set forth in claim 11.