Electronic retrieval of information from form documents
First Claim
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.
0 Assignments
0 Petitions
Accused Products
Abstract
A method for retrieving user-supplied information from a scanned version of a completed document is described. The method includes the steps of obtaining a first image of the document having information printed thereon in its blank format before other information has been added to it by the user. A second image of the document is obtained after information has been added to it by the user. The two images are aligned, and for each pixel in the first image which corresponds to information on the document, those pixels are deleted from the second image to create an image which corresponds to subtraction of the first image from the second image. Finally, a step is performed to electronically restore the information added by the user which was deleted during the subtraction operation.
-
Citations
25 Claims
-
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 Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
-
-
12. A method for restoring pixels in an image represented by pixels having known pixel values and pixels to be restored having unknown pixel values, the method comprising the steps of:
-
(a) obtaining, external to the image, an indication of which pixels have unknown pixel values; (b) specifying a threshold value and a neighborhood configuration, the neighborhood configuration defining a windows; (c) restoring each pixel having an unknown pixel value, by the steps of; (1) positioning the window relative to the pixel to be restored; (2) counting a number of pixels having known values in the window to obtain a known pixel count; (3) calculating, when the known pixel count exceeds the threshold value, a restored pixel value, said restored pixel value being a function of the pixel values of the pixels in the window having known pixel values; (4) assigning, when the known pixel count exceeds the threshold value, the restored pixel value to the pixel to be restored; and (5) repeating steps (1)-(4) until there are no pixels having unknown values remaining whose known pixel count exceeds the threshold value; and (d) adjusting the threshold value, when desired, and repeating step (c) above until a number of pixels having unknown values is less than a desired quantity. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
-
-
23. A computing system for restoring pixels in an image represented by pixels having known pixel values and pixels to be restored having unknown pixel values, the system comprising:
-
(a) means for obtaining, external to the image, an indication of which pixels have unknown pixel values; (b) means for specifying a threshold value, a neighborhood configuration and a desired quantity of unrestored pixels, wherein the neighborhood configuration defines a window; (c) means, coupled to said means for obtaining and said means for specifying, for restoring each pixel having an unknown pixel value, including; (1) means for positioning the window relative to the pixel to be restored; (2) means for counting a number of pixels having known values in the window to obtain a known pixel count; (3) means for comparing the known pixel count to said threshold value; (4) means, coupled to the means for comparing the known pixel count, for calculating a restored pixel value when the known pixel value exceeds said threshold value, wherein the restored pixel value is calculated as a function of the pixel values of the pixels in the window having known pixel values; (4) means, coupled to the means for comparing, assigning the restored pixel value to the pixel to be restored when the known pixel count exceeds the threshold value; and (5) means for determining when no pixels having unknown values whose known pixel count exceeds the threshold value remain; (6) means, coupled to said means for determining, for repeating the operation of the means for positioning, the means for counting, the means for comparing, the means for calculating, the means for assigning, and the means for determining, until no pixels having unknown values whose known pixel count exceeds the threshold value remain; (d) means for comparing a number of unrestored pixels having an unknown value to the desired quantity of unrestored pixels; and (e) means, coupled to the means for comparing a number of unrestored pixels and the means for restoring, for selectively adjusting the threshold value, and for repeating the operation of the means for restoring until the number of pixels having unknown values is less than the desired quantity of unrestored pixels. - View Dependent Claims (24, 25)
-
Specification