×

Electronic retrieval of information from form documents

  • US 5,694,494 A
  • Filed: 09/13/1996
  • Issued: 12/02/1997
  • Est. Priority Date: 04/12/1993
  • Status: Expired due to Term
First Claim
Patent Images

1. A method of electronically distinguishing information added to a form document from the form document itself, and of retrieving the information from said form document, the method comprising the steps of:

  • obtaining a first digital image of a form document to produce a first array of pixels representing printed areas of said form document, wherein each pixel of said first array of pixels has a pixel location and a pixel value;

    obtaining a second digital image of said form document having information added thereto to produce a second array of pixels representing printed areas of said form document and added information, wherein each pixel in said second array of pixels has a pixel location and a pixel value;

    identifying a subset of pixels in said second array which correspond to said first array of pixels by aligning the pixel locations of said first array of pixels with said second array of pixels;

    deleting the pixel value of each pixel in said subset of pixels, irrespective of whether any of said subset of pixels also correspond to said added information;

    designating as "unknown" the pixel value of those pixels whose pixel values were deleted in said deleting step, thereby producing a set of dropout pixels; and

    estimating a pixel value for one or more pixels in said set of dropout pixels to produce a third digital image representing said added information apart from said form document itself.

View all claims
  • 0 Assignments
Timeline View
Assignment View
    ×
    ×