Method for adaptively masking off a video window in an overscanned image
First Claim
1. In a system for processing a scanned image stored within a frame buffer, wherein the scanned image contains pixels that collectively form an image of a document, a method for extracting pixel values from said frame buffer and associated with at least a portion of the image of the document, said method comprising the steps of:
- determining horizontal pixel locations for left and right edges of the image of the document for each of a plurality of scan lines located within said scanned image, wherein each of said scan lines contains at least one pixel that comprises the image of the document;
ascertaining, in response to the left and right edges in said plurality of scan lines, first and second vertical pixel locations of corresponding top and bottom edges of an escribing rectangle located within a frame buffer that stores said scanned image, wherein said escribing rectangle completely contains said image of the document;
determining, in response to said horizontal pixel locations for said left edge, a location where a first pre-determined percentage of said left edges has occurred in order to select a first horizontal pixel location in said scanned image at which a leading edge of the escribing rectangle occurs;
determining, in response to said horizontal pixel locations for said right edge, a location where a second pre-determined percentage of said right edges has occurred in order to select a second horizontal pixel location in said scanned image at which a trailing edge of said escribing rectangle occurs;
determining, in response to said first and second horizontal pixel locations and said first and second vertical pixel locations, memory addressing information relating to where pixel values, that are contained within said escribing rectangle, are located within said frame buffer;
accessing, in response to said information, contents of various memory locations, stored within said frame buffer, in order to obtain selected pixel values; and
providing said selected pixel values to an output connection as the pixel values that are associated with at least a portion of the image of the document.
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Abstract
A method for extracting (masking off) a desired video window, such as that which forms a scanned image of a document or a portion thereof, from a overscanned image stored in a frame buffer is disclosed herein. Specifically, this method involves first determining horizontal pixel locations for left and right edges of the document for each of a plurality of scan lines located within said scanned image. Then, histograms of the left and right edge locations are fabricated. Once this has occurred, the positions of top and bottom edges of an escribing rectangle is found. The escribing rectangle is a rectangular area, located within the frame buffer, which includes the entire document. Now, with the top and bottom edge locations known, the inventive method locates the right and left edge locations of the escribing rectangle by suitably analyzing the histogram results. Next, memory address corresponding to the first pixel location in the escribing rectangle and the vertical and horizontal size of the rectangle are determined, using all the edge locations of the escribing rectangle, and then applied as input to addressing circuitry located within the frame buffer. Once this occurs, then all (or a portion of) the pixel values stored within the frame buffer and located on and within the escribing rectangle are successively accessed and routed to an output connection as being those pixel values that form the image, or a selected portion thereof, of the document.
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Citations
17 Claims
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1. In a system for processing a scanned image stored within a frame buffer, wherein the scanned image contains pixels that collectively form an image of a document, a method for extracting pixel values from said frame buffer and associated with at least a portion of the image of the document, said method comprising the steps of:
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determining horizontal pixel locations for left and right edges of the image of the document for each of a plurality of scan lines located within said scanned image, wherein each of said scan lines contains at least one pixel that comprises the image of the document; ascertaining, in response to the left and right edges in said plurality of scan lines, first and second vertical pixel locations of corresponding top and bottom edges of an escribing rectangle located within a frame buffer that stores said scanned image, wherein said escribing rectangle completely contains said image of the document; determining, in response to said horizontal pixel locations for said left edge, a location where a first pre-determined percentage of said left edges has occurred in order to select a first horizontal pixel location in said scanned image at which a leading edge of the escribing rectangle occurs; determining, in response to said horizontal pixel locations for said right edge, a location where a second pre-determined percentage of said right edges has occurred in order to select a second horizontal pixel location in said scanned image at which a trailing edge of said escribing rectangle occurs; determining, in response to said first and second horizontal pixel locations and said first and second vertical pixel locations, memory addressing information relating to where pixel values, that are contained within said escribing rectangle, are located within said frame buffer; accessing, in response to said information, contents of various memory locations, stored within said frame buffer, in order to obtain selected pixel values; and providing said selected pixel values to an output connection as the pixel values that are associated with at least a portion of the image of the document. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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Specification