Systems and methods for estimating an image marking process using event mapping of scanned image attributes

• US 7,336,401 B2
• Filed: 12/19/2003
• Issued: 02/26/2008
• Est. Priority Date: 12/19/2003
• Status: Expired due to Fees

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Unal, Gozde, Eschbach, Reiner, Sharma, Gaurav
• Primary Examiner(s): Hoskins; Twyler L.
• Assistant Examiner(s): Zheng; Jacky X.
• Application Number:
  US10/739,176
• Publication Number:
  US 20050134934A1
• Time in Patent Office: 1,530 Days
• Field of Search: 358/3.06, 358/448, 358/401, 358/504, 358/3.28, 382/165, 345/418, 345/581
• US Class Current: 358/448
• 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 1/00018 Scanning arrangements
• CPC Class Codes: H04N 1/00034 Measuring, i.e. determining a quantity by comparison with a standard H04N1/00031 takes precedence
• CPC Class Codes: H04N 1/00055 automatically on a periodic basis
• CPC Class Codes: H04N 1/00087 Setting or calibrating picture signal circuits H04N1/40

Abstract

Methods and systems used to automatically identify the marking process used for an image on a substrate based on spatial characteristics and/or color of the image. Image types which are classified and identified include continuous tone images and halftone images. Among halftone images separately identified are inkjet images, xerographic images and lithographic images. Locally adaptive image threshold techniques may be used to determine the spatial characteristics of the image.

Claims

1. A method of analyzing a printed image, comprising:

scanning the printed image;

generating an event map for one or more input data blocks in the scanned printed image;

determining data statistics of the printed image from at least the event map generated;

determining spatial variations in the printed image based on the data statistics;

determining a histogram and a frequency distribution based on the data statistics; and

determining an image marking process used to create the printed image based on the determined spatial variations, the histogram and the frequency distribution in the printed image,

wherein the event map is generated by determining frequency distribution of colors, generating a first color level set, and generating a first binary image by setting dots pixels having the first color level set to 1 otherwise to 0, or by

generating a gray value for an image channel, calculating a threshold value for the image channel, generating a second color level set, and generating a second binary image channel by setting point pixels having the second color level set to 1 otherwise 0.

2. The method of claim 1, wherein spatial variations include local spatial variations of the scanned image data.

3. The method of claim 2, wherein a low value of the local spatial variation of the scanned image data is indicative of a photographic image marking process or background noise.

4. The method of claim 2, wherein a high value of the local spatial variation of the scanned image data is indicative of a halftone image marking process.

5. The method of claim 1, wherein the histogram includes a periodicity/variance distribution.

6. The method of claim 5, wherein a dispered/aperiodic distribution of the scanned image data is indicative of an inkjet image marking process.

7. The method of claim 5, wherein a clustered/periodic distribution of the scanned image data is indicative of a xerographic image marking process or an offset image marking process or a lithographic image marking process.

8. The method of claim 1, wherein spatial variations include at least one of an area variance and an area variance to mean ratio.

9. The method of claim 8, wherein a xerographic image marking process has low screen frequency and high screen noise characteristics.

10. The method of claim 8, wherein an offset or a Iithographic image marking process has high screen frequency and low screen noise characteristics.

11. The method of claim 1, wherein scanning the printed image comprises dividing scanned printed image into image data blocks.

12. The method of claim 11, wherein scanning the printed image further comprises selecting one or more image data blocks.

13. The method of claim 1, wherein determining the image marking process based on the determined spatial variations comprises determining at least one set of data statistics for the scanned printed image.

14. The method of claim 13, wherein determining at least one set of data statistics comprises determining one or more of an area average or mean of pixels in an image data block of the scanned printed image, an area variance of the pixels for the image data block, extreme minima value, min_a, of the pixels for the image data block, extreme maxima value, max_a, of the pixels for the image data block.

15. The method of claim 14, further comprising performing data evaluations using the determined one or more data statistics.

16. The method of claim 15, wherein performing data evaluations comprises one or more of determining a ratio of the area variance to mean determined for a given block, calculating a distribution of the mean values for large pixel areas, comparing the calculated mean value to the determined min_a and/or max_a values, and determining a distance between maxima/minima.

17. The method of claim 16, wherein determining an image marking process comprises determining histogram based on inter maxima/minima distances.

18. A method of determining an image marking process used to create a printed image, comprising:

scanning the printed image;

generating an event map for one or more input data blocks in the scanned printed image;

determining data statistics of the printed image from at least the generated event map;

determining local spatial variations in the printed image based on the data statistics;

determining a histogram and a frequency distribution based on the data statistics; and

determining the image marking process used to create the printed image based on the determined local spatial variations, the histogram and the frequency distribution in the printed image,

wherein an event map is generated by

determining frequency distribution of colors, generating a first color level set, and generating a first binary image by setting dots pixels having the first color level set to 1 otherwise to 0, or by

generating a gray value for an image channel, calculating a threshold value for the image channel, generating a second color level set, and generating a second binary image channel by setting point pixels having the second color level set to 1 otherwise 0.

19. The method of claim 18, wherein the histogram includes at least a periodicity/variance distribution.

20. The method of claim 18, wherein spatial variations include at least one of an area variance and an area variance to mean ratio.

21. The method of claim 18, wherein determining the image marking process based on the determined local spatial variations comprises determining one or more data statistics for the scanned printed image.

22. The method of claim 21, wherein determining one or more data statistics comprises determining one or more of an area average or mean of pixels in an image data block of the scanned printed image, an area variance of the pixels for the image data block, extreme minima value, min_a, of the pixels for the image data block, extreme maxima value, max_a, of the pixels for the image data block.

23. The method of claim 22 further comprising performing data evaluations using the determined one or more data statistics.

24. The method of claim 23, wherein performing data evaluations comprises one or more of:

determining a ratio of the area variance to mean determined for a given block, calculating a distribution of the mean values for large pixel areas, comparing the calculated mean value to the determined min_a and/or max_a values, and determining a distance between maxima/minima, and determining the histogram based on inter maxima/minima distances.

25. A computer-readable medium that is encoded with computer-readable instructions and provides instructions for determining an image marking process used to create a printed image, instructions, which when executed by a processor, cause the processor to perform operations comprising:

scanning the printed image;

generating an event map for one or more input data blocks in the scanned printed image;

determining data statistics of the printed image from at least the event map generated;

determining local spatial variations in the printed image based on the data statistics;

determining a histogram and a frequency distribution based on the data statistics; and

determining the image marking process used to create the printed image based on the determined local spatial variations, the histogram and the frequency distribution in the printed image.

wherein an event map is generated by

determining frequency distribution of colors, generating a first color level set, and generating a first binary image by setting dots pixels having the first color level set to 1 otherwise to 0. or by

generating a gray value for an image channel, calculating a threshold value for the image channel, generating a second color level set, and generating a second binary image channel by setting point pixels having the second color level set to 1 otherwise 0.

26. The computer-readable medium according to claim 25, wherein the histogram includes at least a periodicity/variance distribution.

27. The computer-readable medium according to claim 25, wherein spatial variations include at least one of an area variance and an area variance to mean ratio.

28. The computer-readable medium according to claim 25, wherein determining the image marking process based on the determined local spatial variations comprises determining one or more data statistics for the scanned printed image.

29. The computer-readable medium according to claim 28, wherein determining one or more data statistics comprises determining one or more of an area average or mean of pixels in an image data block of the scanned printed image, an area variance of the pixels for the image data block, extreme minima value, min_a, of the pixels for the image data block, extreme maxima value, max_a, of the pixels for the image data block.

30. The computer-readable medium according to claim 29 further comprising performing data evaluations using the determined one or more data statistics.

31. The computer-readable medium according to claim 30, wherein performing data evaluations comprises one or more of:

determining a ratio of the area variance to mean determined for a given block, calculating a distribution of the mean values for large pixel areas, comparing the calculated mean value to the determined min_a and/or max_a values, and determining a distance between maxima/minima and determining the histogram based on inter maxima/minima distances.

32. A media/image marking process identification system for a printed page, comprising:

a memory; and

a media/image marking process identification determination circuit, routine or application that identifies at least one of a media type for the printed page or an image marking process used to process the printed page, by processing the printed page to generate an event map for one or more input data blocks in the printed image, determine data statistics of the printed image from at least the event map generated;

statistically analyzing the data statistics of the printed image;

determining local spatial variations in the printed image based on the data statistics;

determining a histogram and a frequency distribution based on the data statistics; and

determining the media/image marking process used to create the printed image based on the determined spatial variations, the histogram and the frequency distribution in the printed image,

wherein the event map is generated by

determining frequency distribution of colors, generating a first color level set, and generating a first binary image by setting dots pixels having the first color level set to 1 otherwise to 0, or by

generating a gray value for an image channel, calculating a threshold value for the image channel, generating a second color level set, and generating a second binary image channel by setting point pixels having the second color level set to 1 otherwise 0.

33. The media/image marking process identification system according to claim 32, wherein local spatial variations include at least one of a variance and a variance to a mean ratio.

34. The media/image marking process identification system according to claim 32, wherein the histogram includes a periodicity/variance distribution.

35. The media/image marking process identification system according to claim 32, wherein determining the media/image marking process based on the determined local spatial variations comprises determining one or more data statistics for the scanned printed image.

36. The media/image marking process identification system according to claim 35, wherein determining one or more data statistics comprises determining one or more of an area average or mean of pixels in an image data block of the scanned printed image, an area variance of the pixels for the image data block, extreme minima value, min_a, of the pixels for the image data block, extreme maxima value, max_a, of the pixels for the image data block.

37. The media/image marking process identification system according to claim 36 further comprising performing data evaluations using the determined one or more data statistics.

38. The media/image marking process identification system according to claim 37, wherein performing data evaluations comprises one or more of:

determining a ratio of the area variance to mean determined for a given block, calculating a distribution of the mean values for large pixel areas, comparing the calculated mean value to the determined min_a and/or max_a values, and determining a distance between maxima/minima, and determining the histogram based on inter maxima/minima distances.