System for aligning document images when scanned in duplex mode

• US 6,995,874 B1
• Filed: 04/14/2000
• Issued: 02/07/2006
• Est. Priority Date: 05/07/1997
• Status: Expired due to Fees

• Current Assignee: Ricoh Company Limited, Ricoh Corporation (Ricoh Company Limited)
• Original Assignee: Ricoh Company Limited, Ricoh Corporation (Ricoh Company Limited)
• Inventors: Hull, Jonathan J., Peairs, Mark, Cullen, John F.
• Primary Examiner(s): Rogers, Scott A.
• Application Number:
  US09/549,967
• Time in Patent Office: 2,125 Days
• Field of Search: 358/3.26, 358/1.12, 358/1.14, 358/401, 358/406, 358/474, 358/498, 358/471, 358/468, 358/1.9, 382/254, 382/209, 382/217, 382/218, 382/221, 382/275
• US Class Current: 358/3.26
• CPC Class Codes: H04N 1/00572 with refeeding for double-sided scanning, e.g. using one scanning head for both sides of a sheet
• CPC Class Codes: H04N 1/00575 Inverting the sheet prior to refeeding
• CPC Class Codes: H04N 1/047 Detection, control or error compensation of scanning velocity or position H04N1/0402 and H04N1/17 take precedence
• CPC Class Codes: H04N 1/12 using the sheet-feed movement or the medium-advance or the drum-rotation movement as the slow scanning component, e.g. arrangements for the main-scanningsheet-feed movement by translatory movement of a flat picture-bearing surface H04N1/1008; main-scanning using oscillating or rotating mirrors H04N1/113; using multi-element arrays H04N1/19
• CPC Class Codes: H04N 1/32609 Fault detection or counter-measures, e.g. original mis-positioned, shortage of paper
• CPC Class Codes: H04N 1/3263 of reading apparatus or transmitter, e.g. original jam
• CPC Class Codes: H04N 1/32657 locally
• CPC Class Codes: H04N 1/40 Picture signal circuits H04N1/387 takes precedence
• CPC Class Codes: H04N 1/4095 Correction of errors due to scanning a two-sided document, i.e. show-through correction
• CPC Class Codes: H04N 2201/04703 using the scanning elements as detectors, e.g. by performing a prescan
• CPC Class Codes: H04N 2201/04743 by detecting the image directly
• CPC Class Codes: H04N 2201/04787 by changing or controlling the addresses or values of pixels, e.g. in an array, in a memory, by interpolation

Abstract

A system and method for handling duplex documents by exploiting bleed-through of the image on the back side of a document. The images of the back sides and front sides of documents are associated with one another to assure correct output in copying, faxing, scanning, etc. This increases reliability, eases recovery from errors including paper jams. Improved document handling capabilities also include avoiding twice duplicated and skipped pages and correcting page orientation errors.

Claims

1. A method for copying a multi-page document comprising:

scanning in a plurality of document pages to capture image data for each of the plurality of pages;

storing the image data for each of the plurality of pages; and

comparing, using a distance metric, the image data for each of the plurality of pages to identify twice scanned pages, wherein the distance metric is at least one of a Hausdorff distance metric and an Euclidean distance metric.

2. The method of claim 1 further comprising:

displaying a warning message upon identifying a twice scanned page during the comparison.

3. The method of claim 1 further comprising:

printing copies of the plurality of pages based on the image data, wherein for each twice scanned page identified in the comparing step, a single copy is printed.

4. A copier comprising:

a scanner configured to scan a plurality of pages to capture image data for each page of the plurality of pages;

a feature extractor module configured to extract a feature set for each page of the plurality of pages from the image data for the page;

a comparator module configured to perform comparisons, using a distance metric, between the extracted feature sets for the plurality of pages to identify pages from the plurality of pages which have been scanned more than once, wherein the distance metric is at least one of a Hausdorff distance metric and an Euclidean distance metric; and

a printing module configured to print the plurality of pages based on the image data for the pages, wherein a single copy is printed for image data corresponding to the pages which have been scanned more than once.

5. The copier of claim 4 wherein the feature set for each page from the plurality of pages comprises CCITT Group IV pass codes.

6. An apparatus for performing a first function on a plurality of pages, the apparatus comprising:

a scanner configured to scan the plurality of pages to capture image data for each page of the plurality of pages;

a feature extractor module configured to extract a feature set for each page of the plurality of pages from the image data for the page;

a comparator module configured to perform comparisons, using a distance metric, between the extracted feature sets for the plurality of pages to identify pages from the plurality of pages which have been scanned more than once, wherein the distance metric is at least one of a Hausdorff distance metric and an Euclidean distance metric; and

a function module configured to perform the first function on the plurality of pages based on the image data for the pages, wherein the first function is performed once on image data corresponding to the pages which have been scanned more than once.

7. The apparatus of claim 6 wherein the first function comprises copying the plurality of pages.

8. The apparatus of claim 6 wherein the first function comprises faxing the plurality of pages.

9. The apparatus of claim 6 wherein the first function comprises communicating the plurality of pages via a communication link.

10. A method of performing a first function on a plurality of pages, the method comprising:

scanning the plurality of pages to capture image data for each page of the plurality of pages;

extracting a feature set for each page of the plurality of pages from the image data for the page;

performing comparisons, using a distance metric, between the extracted feature sets for the plurality of pages to identify pages from the plurality of pages which have been scanned more than once, wherein the distance metric is at least one of a Hausdorff distance metric and an Euclidean distance metric; and

performing the first function on the plurality of pages based on the image data for the pages, wherein the first function is performed once on image data corresponding to the pages which have been scanned more than once.

11. The method of claim 10 wherein performing the first function comprises printing a single copy of the image data corresponding to the pages which have been scanned more than once.

12. The method of claim 10 wherein performing the first function comprises faxing a single copy of the image data corresponding to the pages which have been scanned more than once.

13. The method of claim 10 wherein performing the first function comprises communicating a single copy of the image data corresponding to the pages which have been scanned more than once.

14. A computer program product stored on a computer-readable medium for performing a first function on a plurality of pages, the computer program product comprising:

code for scanning the plurality of pages to capture image data for each page of the plurality of pages;

code for extracting a feature set for each page of the plurality of pages from the image data for the page;

code for performing comparisons, using a distance metric, between the extracted feature sets for the plurality of pages to identify pages from the plurality of pages which have been scanned more than once, wherein the distance metric is at least one of a Hausdorff distance metric and an Euclidean distance metric; and

code for performing the first function on the plurality of pages based on the image data for the pages, wherein the first function is performed once on image data corresponding to the pages which have been scanned more than once.

15. The computer program product of claim 14 wherein the code for performing the first function prints a single copy of the image data corresponding to the pages which have been scanned more than once.

16. The computer program product of claim 14 wherein the code for performing the first function faxes a single copy of the image data corresponding to the pages which have been scanned more than once.

17. The computer program product of claim 14 wherein the code for performing the first function communicates a single copy of the image data corresponding to the pages which have been scanned more than once via a communication link.

18. A computer program product stored on a computer-readable medium for copying a multi-page document, the computer program product comprising:

code for scanning in a plurality of document pages to capture image data for each of the plurality of pages;

code for storing the image data for each of the plurality of pages; and

code for comparing, using a distance metric, the image data for each of the plurality of pages to identify twice scanned pages, wherein the distance metric is at least one of a Hausdorff distance metric and an Euclidean distance metric.

19. A copier comprising:

a scanner configured to scan a plurality of pages to capture image data for each page of the plurality of pages;

a feature extractor module configured to extract a feature set for each page of the plurality of pages from the image data for the page, the feature set comprising CCITT Group IV pass codes;

a comparator module configured to perform comparisons between the extracted feature sets for the plurality of pages to identify pages from the plurality of pages which have been scanned more than once; and

a printing module configured to print the plurality of pages based on the image data for the pages, wherein a single copy is printed for image data corresponding to the pages which have been scanned more than once.

20. An apparatus for performing a first function on a plurality of pages, the apparatus comprising:

a scanner configured to scan the plurality of pages to capture image data for each page of the plurality of pages;

a feature extractor module configured to extract a feature set for each page of the plurality of pages from the image data for the page, the feature set comprising CCITT Group IV pass codes;

a comparator module configured to perform comparisons between the extracted feature sets for the plurality of pages to identify pages from the plurality of pages which have been scanned more than once; and

a function module configured to perform the first function on the plurality of pages based on the image data for the pages, wherein the first function is performed once on image data corresponding to the pages which have been scanned more than once.

21. A method of performing a first function on a plurality of pages, the method comprising:

scanning the plurality of pages to capture image data for each page of the plurality of pages;

extracting a feature set for each page of the plurality of pages from the image data for the page, the feature set comprising CCITT Group IV pass codes;

performing comparisons between the extracted feature sets for the plurality of pages to identify pages from the plurality of pages which have been scanned more than once; and

performing the first function on the plurality of pages based on the image data for the pages, wherein the first function is performed once on image data corresponding to the pages which have been scanned more than once.