Document image scanning device that provides image of proper appearance while preserving image density

• US 7,336,399 B2
• Filed: 09/25/2001
• Issued: 02/26/2008
• Est. Priority Date: 09/26/2000
• Status: Expired due to Fees

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Nara, Wataru
• Primary Examiner(s): Lee; Thomas D.
• Assistant Examiner(s): Thompson; James A.
• Application Number:
  US09/961,256
• Publication Number:
  US 20020060819A1
• Time in Patent Office: 2,345 Days
• Field of Search: 358/1.9, 358/530, 358/518, 358/2.1, 358/519, 358/448, 358/461, 358/463, 358/464, 358/465, 358/401, 358/500, 382167-169, 382/172, 382/275
• US Class Current: 358/3.26
• CPC Class Codes: H04N 1/4072 dependent on the contents of the original
• CPC Class Codes: H04N 1/409 Edge or detail enhancement; Noise or error suppression

Abstract

A device for scanning a document includes a photoelectric conversion unit which scans a document, and supplies image data of the scanned document, a background detecting unit which detects a background level of the image data, an image processing unit which applies one or more types of image processing to the image data, and applies image processing identical to the one or more types of image processing to the detected background level, and a background removal unit which removes background noise from the image data having undergone the image processing according to a threshold that is derived from the background level having undergone the image processing.

Claims

1. A device for scanning a document, comprising:

a photoelectric conversion unit which scans a document, and supplies image data of the scanned document;

a background detecting unit which detects a background level of the image data so as to produce original background level value data that is separate from and not part of the image data and indicative of the background level;

an image processing unit which applies one or more types of image processing to the image data, and applies image processing identical to said one or more types of image processing to the original background level value data to produce image processed modified background level value data; and

a background removal unit which generates a threshold derived from the image processed modified background level value data, and which utilizes said generated threshold to remove background noise from the image processed data.

2. The device as claimed in claim 1, wherein said one or more types of image processing includes γ

conversion.

3. The device as claimed in claim 2, wherein the γ

conversion is performed at an end of said one or more types of image processing.

4. The device as claimed in claim 1, wherein said one or more types of image processing includes MTF correction.

5. The device as claimed in claim 1, wherein said one or more types of image processing includes a filtering process.

6. The device as claimed in claim 1, wherein said image processing unit applies said one or more types of image processing to the image data and the original detected background level through one operation.

7. The device as claimed in claim 6, further comprising a combining unit which includes the detected original background level into the image data as part of the image data prior to the image processing by said image processing unit.

8. The device as claimed in claim 7, wherein said combining unit generates a gate signal indicative of a position of the detected background level included in the image data, said device further comprising a background data extracting unit which extracts the detected original background level from the image data in response to the gate signal.

9. The device as claimed in claim 7, wherein said one or more types of image processing includes a filtering process, and said combining unit includes the detected original background level into the image data at a position of a blank period of the image data.

10. The device as claimed in claim 7, wherein said one or more types of image processing includes a filtering process, and said combining unit includes the detected original background level into the image data at a position of a valid data period of the image data such that the included detected background level has a data size larger than a filter size of said filtering process.

11. The device as claimed in claim 1, further comprising a printer unit which prints an image on a paper sheet according to the image data from which the background noise is removed by said background removal unit.

12. The device as claimed in claim 1, wherein the background detecting unit is configured to append, in a same data file for subsequent processing with the image data, the original background level value data to the image data in a part of the data file concatenated from the image data.

13. An apparatus for scanning a document, comprising:

a memory unit which stores therein scanned image data and original background level value data that is separate from the scanned image data;

an input unit which receives a user instruction making a choice between performing of background noise removal on the scanned image data and non-performing of the background noise removal on the scanned images; and

a background removal unit which generates a threshold derived from image processed modified background level value data, and which utilizes said generated threshold to remove background noise from the scanned image data stored in said memory unit in response to the user instruction indicative of performing of the background noise removal, and refrains from removing background noise from the scanned image data stored in said memory unit in response to the user instruction indicative of non-performing of the background noise removal,

wherein in response to the user instruction indicative of performing of the background noise removal, said original background level value data is modified by image processing identical to that applied to the scanned image data to produce said image processed modified background level value data.

14. The apparatus as claimed in claim 13, further comprising a controller which connects said memory unit to an external network so as to allow access to be made from the external network to the scanned image data stored in said memory unit.

15. A method of processing image data, comprising:

detecting a background level of image data of a scanned document so as to produce original background level value data indicative of the background level;

applying one or more types of image processing to the image data so as to generate image processed data, and applying image processing identical to said one or more types of image processing to the original background level value data that is separate from and not part of the image data to produce modified background level value data;

generating a threshold derived from image processed modified background level value data and

removing background noise from the image processed data having according to the generated threshold that is derived from the image processed modified background level value data.

16. The method as claimed in claim 15, wherein said one or more types of image processing includes γ

conversion.

17. The method as claimed in claim 15, wherein the γ

conversion is performed at an end of said one or more types of image processing.

18. The method as claimed in claim 15, wherein said one or more types of image processing includes MTF correction.

19. The method as claimed in claim 15, wherein said one or more types of image processing includes a filtering process.

20. The method as claimed in claim 15, wherein said image processing step applies said one or more types of image processing to the image data and the detected original background level value data through one operation.

21. The method as claimed in claim 20, further comprising combining the detected original background level value data into the image data as part of the image data prior to the image processing.

22. The method as claimed in claim 21, further comprising:

generating a gate signal indicative of a position of the detected original background level value data included in the image data; and

extracting the detected original background level value data from the image data in response to the gate signal.

23. The method as claimed in claim 21, wherein said one or more types of image processing includes a filtering process, and said combining combines the detected original background level value data into the image data at a position of a blank period of the image data.

24. The method as claimed in claim 21, wherein said one or more types of image processing includes a filtering process, and said combining combines the detected original background level value data into the image data at a position of a valid data period of the image data such that the included detected original background level value data has a data size larger than a filter size of said filtering process.

25. The method as claimed in claim 15, wherein detecting comprises:

appending, in a same data file for subsequent processing with the image data, the original background level value data to the image data in a part of the data file concatenated from the image data.

26. A method of scanning a document, comprising:

storing scanned image data and original background level value data that is separate from the scanned image data in memory;

accepting a user instruction making a choice between performing of background noise removal on the scanned image data and not-performing of the background noise removal on the scanned image data; and

removing background noise from the scanned image data stored in said memory in response to the user instruction indicative of performing of the background noise removal, and refraining from removing background noise from the scanned image data stored in said memory in response to the user instruction indicative of non-performing of the background noise removal,

wherein in response to the user instruction indicative of performing of the background noise removal, modifying said original background level value data by image processing identical to that applied to the scanned image data and generating a threshold derived from image processed modified background level value data by which to remove the background noise.

27. The method as in claim 26, further comprising allowing access to be made from an external network to the scanned image data stored in said memory.

28. A device for scanning a document, comprising:

scanning means for scanning a document, and for supplying image data of the scanned document;

background detecting means for detecting a background level of the image data so as to produce original background level value data that is separate from and not part of the image data and indicative of the background level;

image processing means for applying one or more types of image processing to the image data so as to generate image processed data, and for applying image processing identical to said one or more types of image processing to the original background level value data to produce image processed modified background level value data; and

background removal means for generating a threshold derived from the image processed modified background level value data, and for utilizing said generated threshold to remove background noise from the image processed data.

29. The device as claimed in claim 28, wherein the background detecting means are configured to append, in a same data file for subsequent processing with the image data, the original background level value data to the image data in a part of the data file concatenated from the image data.

30. A device for scanning a document, comprising:

a background detecting unit which detects background level data of image data of a scanned document;

a threshold generating unit which determines a threshold based on the detected background level data so as to produce an original threshold level value indicative of the threshold;

a clipping unit which clips to the threshold the image data above the original threshold level value;

an image processing unit which applies one or more types of image processing to the clipped image data so as to generate clipped image processed data and further to the original threshold level value to produce a modified threshold level value; and

a background removal unit which removes background noise from the clipped image data according to a generated threshold that is derived from the modified threshold level value.

31. The device as claimed in claim 30, further comprising a combining unit that includes the threshold into the clipped image data as part of the clipped image data prior to the image processing by said image processing unit.

32. The device as claimed in claim 31, wherein said one or more types of image processing includes a filtering process, and said combining unit includes the threshold into the clipped image data at a position of a valid data period of the clipped image data such that the included threshold has a data size larger than a filter size of said filtering process.

33. The device as claimed in claim 30, wherein the background detecting unit is configured to append, in a same data file for subsequent processing with the image data, the original background level value data to the image data in a part of the data file concatenated from the image data.

34. A device for scanning a document, comprising:

background detecting means for detecting a background level of image data of a scanned document;

threshold generating means for determining a threshold based on the detected background level so as to produce an original threshold level value that is separate from and not part of the clipped image data and indicative of the threshold;

clipping means for clipping to the original threshold the image data above the threshold;

image processing means for applying one or more types of image processing to the clipped image data so as to generate clipped processed data and further to the original threshold level value to produce a modified threshold level value; and

background removal means for removing background noise from the clipped image data according to a generated threshold that is derived from the modified threshold level value.

35. The device as claimed in claim 34, wherein the background detecting means are configured to append, in a same data file for subsequent processing with the image data, the original background level value data to the image data in a part of the data file concatenated from the image data.