Method For Scanning And Processing A Document With An Imaging Apparatus

• US 20080316549A1
• Filed: 06/19/2007
• Published: 12/25/2008
• Est. Priority Date: 06/19/2007
• Status: Abandoned Application

• Current Assignee: Lexmark International Incorporated (Ninestar Corporation)
• Original Assignee: Lexmark International Incorporated (Ninestar Corporation)
• Inventors: King, Anthony Michael, Rumford, Robert Warren, Bush, James Lesesne III, Cunnagin, Stephen Kelly
• Application Number:
  US11/764,822
• Publication Number:
  US 20080316549A1
• Time in Patent Office: Days
• US Class Current: 358/488
• CPC Class Codes: H04N 1/00681 Detecting the presence, position or size of a sheet or correcting its position before scanning H04N1/047 takes precedence; mode signalling H04N1/333; skew detection or correction in image signals H04N1/3878
• CPC Class Codes: H04N 1/00689 Presence
• CPC Class Codes: H04N 1/00737 using the scanning elements as detectors
• CPC Class Codes: H04N 1/00745 Detecting the leading or trailing ends of a moving sheet
• CPC Class Codes: H04N 1/00753 of a sheet relative to a particular backgroud
• CPC Class Codes: H04N 1/00758 using a prescan
• CPC Class Codes: H04N 1/00761 using reference marks, e.g. on sheet, sheet holder or guide
• CPC Class Codes: H04N 1/00782 Initiating operations
• CPC Class Codes: H04N 1/121 Feeding arrangements transporting sheets to or from the scanning position H04N1/0057; control or error compensation of sub-scanning velocity H04N1/0473
• CPC Class Codes: H04N 1/125 the sheet feeding apparatus serving an auxiliary function, e.g. as a white reference
• CPC Class Codes: H04N 2201/0094 Multifunctional device, i.e. a device capable of all of reading, reproducing, copying, facsimile transception, file transception

Abstract

A method for scanning and processing a document with an imaging apparatus, the imaging apparatus having a scanner with a scan bar, includes operating the scanner to obtain preliminary image data; performing at least one of translating the document across the scan bar and translating the scan bar across the document while operating the scanner; detecting an edge of the document based on a change in the preliminary image data; scanning the document to generate document image data based on the detecting the edge; and processing the document image data based on detecting the edge to generate a scanned image.

Claims

1. A method for scanning and processing a document with an imaging apparatus, said imaging apparatus having a scanner with a scan bar, said method comprising:

operating said scanner to obtain preliminary image data;

performing at least one of translating said document across said scan bar and translating said scan bar across said document while performing said operating said scanner;

detecting an edge of said document based on a change in said preliminary image data;

scanning said document to generate document image data based on said detecting said edge; and

processing said document image data based on said detecting said edge to generate a scanned image.

2. The method of claim 1, wherein said detecting said edge of said document based on said change in said preliminary image data includes detecting a change in contrast.

3. The method of claim 1, said edge being a leading edge, further comprising detecting a trailing edge of said document based on a reversal of said change in said preliminary data.

4. The method of claim 1, said preliminary image data including a plurality of scan lines, each scan line being represented by a plurality of pixel locations, wherein said detecting said edge of said document based on said change in said preliminary image data includes:

obtaining first pixel data from selected pixel locations of said plurality of pixel locations on a first scan line;

obtaining second pixel data from said selected pixel locations on a second scan line adjacent to said first scan line;

determining, for each pixel location of said selected pixel locations, a difference between said first pixel data and said second pixel data;

summing a magnitude of said difference at said each pixel location to yield a difference sum; and

comparing said difference sum to a threshold to thereby detect said edge.

5. The method of claim 4, wherein said threshold is determined based on image data obtained in the absence of said document.

6. The method of claim 4, said imaging apparatus including a press plate for directing said document against said scanner, wherein said threshold is determined based on press plate image data obtained by scanning said press plate.

7. The method of claim 4, said document having a leading edge and a trailing edge, wherein said leading edge is detected when said difference sum exceeds said threshold, and wherein after said leading edge is detected, said trailing edge is detected when said difference sum falls below said threshold.

8. The method of claim 1, said preliminary image data including a plurality of scan lines, each scan line being represented by a plurality of pixel locations, wherein said detecting said edge of said document based on said change in said preliminary image data includes:

obtaining test pixel data from selected pixel locations of said plurality of pixel locations on a scan line;

obtaining reference pixel data;

determining, for each pixel location of said selected pixel locations, a difference between said test pixel data and said reference pixel data;

summing a magnitude of said difference at said each pixel location to yield a difference sum; and

comparing said difference sum to a threshold to thereby detect said edge.

9. The method of claim 8, wherein said reference pixel data is stored in a memory of said imaging apparatus during a manufacturing of said imaging apparatus, and wherein said obtaining said reference pixel data is retrieving said reference pixel data from said memory.

10. The method of claim 8, wherein said reference pixel data is generated by said imaging apparatus based on said preliminary image data before said performing said at least one of said translating said document across said scan bar and said translating said scan bar across said document.

11. The method of claim 8, said document having a leading edge and a trailing edge, wherein said leading edge is detected when said difference sum exceeds said threshold, and wherein after said leading edge is detected, said trailing edge is detected when said difference sum falls below said threshold.

12. The method of claim 1, said preliminary image data including a plurality of scan lines, each scan line being represented by a plurality of pixel locations, wherein said detecting said edge of said document based on said change in said preliminary image data includes:

obtaining test pixel data from selected pixel locations of said plurality of pixel locations on a scan line;

obtaining reference pixel data;

determining, for each pixel location of said selected pixel locations, a difference between said test pixel data and said reference pixel data; and

detecting a side edge of said document based on a magnitude of said difference along said scan line.

13. The method of claim 12, further comprising:

subdividing said selected pixel locations into a plurality of pixel blocks;

determining for each pixel block a mean difference based on said difference for said each pixel location in said pixel block;

comparing said mean difference for said each pixel block to a threshold; and

determining said side edge based on a pair of adjacent pixel blocks, wherein one pixel block of said pair exceeds said threshold and the other pixel block of said pair does not exceed said threshold.

14. The method of claim 12, wherein said reference pixel data is said test pixel data for a previous said scan line.

15. The method of claim 12, wherein said reference pixel data is generated based on said preliminary image data before said performing said at least one of said translating said document across said scan bar and said translating said scan bar across said document.

16. The method of claim 1, said preliminary image data including a plurality of scan lines, each scan line being represented by a plurality of pixel locations, wherein said detecting said edge of said document based on said change in said preliminary image data includes:

obtaining test pixel data from selected pixel locations of said plurality of pixel locations on a scan line;

obtaining reference pixel data;

determining, for each pixel location of said selected pixel locations, a difference between said test pixel data and said reference pixel data; and

determining a skew angle of said document based on a magnitude of said difference.

17. The method of claim 16, further comprising:

subdividing said selected pixel locations into a plurality of pixel blocks;

determining for each pixel block a mean difference based on said difference for said each pixel location in said pixel block;

comparing said mean difference for said each pixel block to a threshold; and

determining said skew angle based on a number of scan lines between when said mean difference for a first pixel block exceeds said threshold and when said mean difference for a second pixel block exceeds said threshold.

18. The method of claim 16, wherein said processing said document image data to generate said scanned image includes compensating for said skew angle.

19. The method of claim 1, wherein said processing said document image data to generate said scanned image includes setting an automatic cropping boundary for said scanned image based on said edge.

20. The method of claim 1, wherein said processing said document image data based on said detecting said edge includes detecting a size of said document.

21. The method of claim 20, wherein said processing said document image data to generate said scanned image includes performing automatic scaling of said scanned image based on said size.

22. A method for scanning and processing a document with an imaging apparatus, said imaging apparatus having a scanner and a press plate for directing said document against said scanner, said method comprising:

obtaining reference image data for said imaging apparatus;

obtaining document image data by scanning said document with said scanner;

detecting an edge of said document based on a difference between said reference image data and said document image data; and

processing said document image data to generate a scanned image based on said detecting said edge.

23. The method of claim 22, further comprising comparing said difference to a threshold, where said edge is detected based on a result of said comparing.

24. The method of claim 23, further comprising detecting a skew angle of said document based on said result of said comparing.

25. An imaging apparatus configured for scanning and processing a document, said imaging apparatus comprising:

a scanner having a scan bar; and

a controller, said controller being configured to execute program instructions for;

operating said scanner to obtain preliminary image data;

performing at least one of translating said document across said scan bar and translating said scan bar across document while performing said operating said scanner;

detecting an edge of said document based on a change in said preliminary image data;

scanning said document to generate document image data based on said detecting said edge; and

processing said document image data to generate a scanned image.

26. The imaging apparatus of claim 25, said imaging apparatus further comprising a background component visible to said scan bar, wherein said change in said preliminary data is based on a contrast difference between said background component and said document.

27. The imaging apparatus of claim 26, said background component including a high contrast portion, wherein said change in said preliminary data is based on a contrast difference between said high contrast portion and said document.

28. The imaging apparatus of claim 27, said background component including a low contrast detect portion, wherein said scanning said document is performed with said scan bar positioned opposite said detect portion.

29. The imaging apparatus of claim 25, said edge being a leading edge, further comprising said controller being configured to execute program instructions for detecting a trailing edge of said document based on a reversal of said change in said preliminary data.

30. The imaging apparatus of claim 25, wherein said edge is a side edge of said document.