OCR classification based on transition ground data
First Claim
1. An OCR (optical character recognition) method of classifying an input image vector of an unclassified whole character with respect to a library of template image vectors of pre-classified characters, said method comprising the steps of:
- providing a library of template image vectors of pre-classified characters each in the form of a sequence of template elements, each template element having a numerical value representing the image intensity level of a corresponding element within the pre-classified character defined by the template vector, said template elements including image background elements, image foreground elements, and image transition ground elements that are situated between image background elements and image foreground elements and are caused by a progressive change from background intensity level to foreground intensity level;
providing an input image vector of an unclassified whole character in the form of a sequence of input elements, each input element having a numerical value representing an image intensity level signal component corresponding to an element within the unclassified character, said input elements being from the group of elements comprising image background elements, image foreground elements, and image ground elements that are situated between image background elements and image foreground elements and are caused by a progressive change from background intensity level to foreground intensity level;
entering the input vector and at least one of the template vectors into a classifier means; and
classifying the input vector with respect to the entered template vectors by comparing numerical values of elements of the input vector with numerical values of elements of entered template vectors.
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Abstract
An OCR system 10 classifies an input image vector of an unclassified symbol with respect to a library 14T of template image vectors of pre-classified characters. Each template vector is in the form of a sequence of elements representing the image intensity level of a pixel within the character defined by that template vector. Each template element is part of the image background, foreground, or transition ground between the background and foreground. Each input vector, like the template vectors, is also in the form of a sequence of elements. However, in the input vector, each element represents the sum or an image intensity level signal component defining the symbol within the image of the unclassified symbol plus a greyscale noise component. Each input element is also part of the background, foreground, or transition ground. The input vector and at least one of the template vectors are entered into a classifier device 18. The input vector is classified based on the backgrounds, foregrounds, and transition grounds. The presence of transition ground in the input vector and the template vector produces a robust classification response with a more uniform correlation coefficient between repeated classifications of the same input symbol. The classifier device may be a distance function classifier or a neural network classifier.
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Citations
36 Claims
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1. An OCR (optical character recognition) method of classifying an input image vector of an unclassified whole character with respect to a library of template image vectors of pre-classified characters, said method comprising the steps of:
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providing a library of template image vectors of pre-classified characters each in the form of a sequence of template elements, each template element having a numerical value representing the image intensity level of a corresponding element within the pre-classified character defined by the template vector, said template elements including image background elements, image foreground elements, and image transition ground elements that are situated between image background elements and image foreground elements and are caused by a progressive change from background intensity level to foreground intensity level; providing an input image vector of an unclassified whole character in the form of a sequence of input elements, each input element having a numerical value representing an image intensity level signal component corresponding to an element within the unclassified character, said input elements being from the group of elements comprising image background elements, image foreground elements, and image ground elements that are situated between image background elements and image foreground elements and are caused by a progressive change from background intensity level to foreground intensity level; entering the input vector and at least one of the template vectors into a classifier means; and classifying the input vector with respect to the entered template vectors by comparing numerical values of elements of the input vector with numerical values of elements of entered template vectors. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36)
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Specification