Abstract: A method for processing a digital image of a document to provide one or more bitonal digital copies of selected image quality that are optimized for specific purposes. The method is suited for use with such documents as bank checks and commercial forms that have printed or handwritten textual characters overlaid on potentially obscuring backgrounds. The method may provide a clean bitonal digital copy with reduced background optimized for use in optical character recognition or an archival copy with meaningful background retained that is optimized for archiving the original document. A set of bitonal copies of the digital image of a document is derived covering a range of contrast sensitivities. The copies are compared and a numerical measure is provided representing the amount of change in going from one copy to the next. The collection of such numerical measures defines a numerical sequence representing variations in the digital image as the contrast sensitivity is monotonically varied.

Abstract: A method for improved readability of digitally captured document images that include printed or handwritten textual material overlaid on background graphics. Text in the document is generally composed at least in part of strokes characterized by pairs of edges in close proximity to one another. The digital image comprises an array of pixels representing at least a portion of the document. The edges in the pixel array are first identified and then grown by an effective amount so as to cause pairs of edges characterizing each stroke substantially to merge. The grown edges are then shrunk by an effective amount so as to cause non-stroke edges to be substantially eliminated without eliminating the merged stroke edges.

Abstract: A method for processing a digital image of a document to provide one or more bitonal digital copies of selected image quality that are optimized for specific purposes. The method is suited for use with such documents as bank checks and commercial forms that have printed or handwritten textual characters overlaid on potentially obscuring backgrounds. The method may provide a clean bitonal digital copy with reduced background optimized for use in optical character recognition or an archival copy with meaningful background retained that is optimized for archiving the original document. A set of bitonal copies of the digital image of a document is derived covering a range of contrast sensitivities. The copies are compared and a numerical measure is provided representing the amount of change in going from one copy to the next. The collection of such numerical measures defines a numerical sequence representing variations in the digital image as the contrast sensitivity is monotonically varied.