Method and system for recognizing a boundary between characters in handwritten text
First Claim
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1. A handwriting recognition system, comprising:
- a feature extractor for extracting a plurality of features from cursive handwriting, the cursive handwriting comprising a plurality of characters and a segment stroke between the plurality of characters; and
a boundary classifier for generating a boundary classifier output signal based on the plurality of features, a plurality of discriminant function coefficients, and a discriminant function, wherein the plurality of discriminant function coefficients are derived from a plurality of cursive segment stroke examples, each of the cursive segment stroke examples connecting the end point of a first cursive character to the start point of a second cursive characterwherein the discriminant function has a form ##EQU2## Wherein y represents the boundary classifier output signal;
wherein I, m, and n are integers;
wherein wi-1 represents the plurality of discriminant function coefficients;
wherein x1, x2, . . . , xn represents the plurality of features; and
wherein g1i, . . . , gni represent a plurality of exponents of the discriminant function.
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Abstract
A method and system for identifying boundaries of characters in handwritten text by classifying segment strokes provides improved performance in a handwriting recognition system. A segment stroke is a portion of handwritten text which includes a boundary between two characters. The segment stroke is recognized by the same method used to recognized characters. Recognition of a segment stroke is accomplished by training a learning machine to act as a classifier which implements a discriminant function based on a polynomial expansion.
58 Citations
22 Claims
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1. A handwriting recognition system, comprising:
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a feature extractor for extracting a plurality of features from cursive handwriting, the cursive handwriting comprising a plurality of characters and a segment stroke between the plurality of characters; and a boundary classifier for generating a boundary classifier output signal based on the plurality of features, a plurality of discriminant function coefficients, and a discriminant function, wherein the plurality of discriminant function coefficients are derived from a plurality of cursive segment stroke examples, each of the cursive segment stroke examples connecting the end point of a first cursive character to the start point of a second cursive character wherein the discriminant function has a form ##EQU2## Wherein y represents the boundary classifier output signal;
wherein I, m, and n are integers;wherein wi-1 represents the plurality of discriminant function coefficients; wherein x1, x2, . . . , xn represents the plurality of features; and wherein g1i, . . . , gni represent a plurality of exponents of the discriminant function. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10)
- 8. The handwriting recognition system of claim 1, wherein the feature extractor generates the plurality of features by fitting a first order polynomial to an angular velocity profile
- space="preserve" listing-type="equation">v.sub.(k) =b.sub.0 +b.sub.1 v.sub.(k-1) +b.sub.2 v.sub.(k-2) +b.sub.3 v.sub.(k-3) ;
wherein v.sub.(k) represents the angular velocity of a kth sample datum, v.sub.(k-1) represents the angular velocity of a (k-1)th sample datum, v.sub.(k-2) represents the angular velocity of a (k-2)th sample datum, v.sub.(k-3) represents the angular velocity of a (k-3)th sample datum, k is an integer index, and b0, b1, b2, and b3 represent the plurality of features, and wherein the kth, (k-1)th, (k-2)th, and (k-3)th sample datum are derived from the cursive handwriting. - space="preserve" listing-type="equation">v.sub.(k) =b.sub.0 +b.sub.1 v.sub.(k-1) +b.sub.2 v.sub.(k-2) +b.sub.3 v.sub.(k-3) ;
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9. The handwriting recognition system of claim 1, further comprising:
a trainer, operatively coupled to the boundary classifier, for generating the plurality of discriminant function coefficients.
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10. The handwriting recognition system of claim 1, wherein the plurality of discriminant function coefficients are derived using a technique selected from least-squares estimation and matrix inversion.
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2. The handwriting recognition system 1, wherein the boundary classifier includes a neural network.
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11. In a handwriting recognition system, a method for recognizing a character, the method comprising the steps of:
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extracting a plurality of features from cursive handwriting, the cursive handwriting comprising a plurality of characters and a boundary between the plurality of characters; generating the plurality of features by fitting a first order polynomial to a curvilinear velocity profile
space="preserve" listing-type="equation">v.sub.(k) =a.sub.0 +a.sub.1 v.sub.(k-1) +a.sub.2 v.sub.(k-2) +a.sub.3 v.sub.(k-3) ;wherein v.sub.(k) represents the curvilinear velocity of a kth sample datum, v.sub.(-1) represents the curvilinear velocity of a (k-1)th sample datum, v.sub.(k-2) represents the curvilinear velocity of a (k-2)th sample datum, v.sub.(k-3) represents the curvilinear velocity of a (k-3)th sample datum, k is an integer index, and a0, a1, a2, and a3 represent the plurality of features, and wherein the kth, (k-1)th, (k-2)th, and (k-3)th sample datum are derived from the cursive handwriting, distributing the plurality of features to a plurality of character classifiers; generating a plurality of character classifier output signals; distributing the plurality of features to a boundary classifier;
,generating a boundary classifier output signal by applying the plurality of features to a boundary discriminant function; and identifying the character based on the plurality of character classifier output signals and the boundary classifier output signal. - View Dependent Claims (12, 13)
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14. In a handwriting recognition system, a method for recognizing a character, the method comprising the steps of:
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extracting a plurality of features from cursive handwriting, the cursive handwriting comprising a plurality of characters and a boundary between the plurality of characters; generating the plurality of features by fitting a first order polynomial to an angular velocity profile
space="preserve" listing-type="equation">v.sub.(k) =b.sub.0 +b.sub.1 v.sub.(k-1) +b.sub.2 v.sub.(k-2) +b.sub.3 v.sub.(k-3) ;wherein v.sub.(k) represents the angular velocity of a kth sample datum, v.sub.(k-1) represents the angular velocity of a (k-1)th sample datum, v.sub.(k-2) represents the angular velocity of a (k-2)th sample datum, v.sub.(k-3) represents the angular velocity of a (k-3)th sample datum, k is an integer index, and b0, b1, b2, and b3 represent the plurality of features, and wherein the kth, (k-1)th, (k-2)th, and (k-3)th sample datum are derived from the cursive handwriting, distributing the plurality of features to a plurality of character classifiers; generating a plurality of character classifier output signals; distributing the plurality of features to a boundary classifier; generating a boundary classifier output signal by applying the plurality of features to a boundary discriminant function; identifying the character based on the plurality of character classifier output signals and the boundary classifier output signal.
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15. A handwriting recognition system, comprising:
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a feature extractor for extracting a plurality of features from handwriting, the handwriting comprising a plurality of characters and a boundary between the plurality of characters; a plurality of character classifiers for generating a plurality of character classifier output signals in response to the plurality of features; a boundary classifier for generating a boundary classifier output signal by applying the plurality of features to a polynomial discriminant function;
wherein the polynomial discriminant function Y(X) has a form ##EQU3## wherein X={x0, x1, . . . , xn } represents the plurality of features, Y represents the boundary classifier output signal, wi represents a discriminant function coefficient, gji represents an exponent, and i, j, m and n are integers; anda selector for identifying the plurality of characters based on the plurality of character classifier output signals and the boundary classifier output signal. - View Dependent Claims (16, 18, 19, 20, 21, 22)
- 21. The handwriting recognition system of claim 15, wherein the feature extractor generates a plurality of polynomial coefficients by fitting a first order polynomial to an angular velocity profile
- space="preserve" listing-type="equation">v.sub.(k) =b.sub.0 +b.sub.1 v.sub.(k-1) +b.sub.2 v.sub.(k-2) +b.sub.3 v.sub.(k-3) ;
wherein v.sub.(k) represents the angular velocity of a kth sample datum, v.sub.(k-1) represents the angular velocity of a (k-1)th sample datum, v.sub.(k-2) represents the angular velocity of a (k-2)th sample datum, v.sub.(k-3) represents the angular velocity of a (k-3)th sample datum, k is an integer index, and b0, b1, b2, and b3 represent the polynomial coefficients, and wherein the kth, (k-1)th, (k-2)th, and (k-3)th sample datum are derived from the handwriting. - space="preserve" listing-type="equation">v.sub.(k) =b.sub.0 +b.sub.1 v.sub.(k-1) +b.sub.2 v.sub.(k-2) +b.sub.3 v.sub.(k-3) ;
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22. The handwriting recognition system of claim 15, wherein the boundary classifier comprises:
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a plurality of computing elements for generating a plurality of polynomial discriminant function terms; and a summing circuit for generating the boundary classifier output signal in response to the plurality of polynomial discriminant function terms.
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17. The handwriting recognition system 15, wherein the boundary classifier includes a neural network.
Specification