On-line handwritten character recognition apparatus with non-ambiguity algorithm

Claim 2

A character recognition apparatus for identifying a handwritten of a predetermined set of characters formed from at least one primitive selected from a predetermined set of primitives illustrated in FIG. 3 with said set of primitives forming said handwritten character being written in an order determined by pre-defined rules, said apparatus comprising: input means for receiving successively and in accordance with said pre-defined rules each of the primitives forming said handwritten character and generating input signals for each of said received primitives; processing means for receiving said input signals and identifying each of said primitives received by said input means, said processing means generating a character code representing said handwritten character upon identification of said primitives forming said handwritten character; storage means for storing a character code and an associated output code for each of the characters in said predetermined set; comparing means for comparing said character code generated for said handwritten character with said character codes in said storage means to identify said handwritten character; and output means in communication with said comparing means and generating a reproduction of said handwritten character upon the identification thereof by said comparing means.

Claim 3

The character recognition apparatus as defined in claim 1 further comprising: differentiation means for examining said input signals generated for each of said received primitives and performing operations thereon when said character code generated for said handwritten character is equivalent to a character code in said storage means associated with a plurality of output codes to identify the output code associated with said handwritten character.

Claim 4

The character recognition apparatus as defined in claim 2 wherein said primitives in FIG. 3 are capable of forming every character in a plurality of languages while reducing the number of characters in said languages formed from the same series of primitives, said storage means storing a character code and an output code for each of said characters in said plurality of languages.

Claim 5

The character recognition apparatus as defined in claim 3 wherein said storage means further stores character test information, said test information being provided for each character code in said storage means associated with more than one output code, said differentiation means receiving said character test information and said input signals and performing said operations thereon in accordance with said character test information to detect the output code corresponding to said handwritten character.

Claim 6

The apparatus as defined in claim 3 wherein said processing means generated an unidentified primitive code for each handwritten primitive not detected as being in said set, said apparatus further comprising substitution means having means for receiving said character code generated for said handwritten character when it is not equivalent to any of said character codes in said storage means, said substitution means including comparator means comparing each primitive code forming character code generated for said handwritten character with the corresponding primitive code of said character codes in said storage means formed from the same number of primitive codes as the character code generated for said handwritten character; and a memory for storing the output code associated with each of the character codes in said storage means having fewer than a predetermined number of differences when compared with character code generated for said handwritten character.

Claim 7

The apparatus as defined in claim 5 wherein said substitution means further comprises a probability matrix, said probability matrix generating a substitution primitive code most likely to be the unidentified primitive code when said substitution means receives a character code generated for a handwritten character having at least one unidentified primitive code therein and replacing said unidentified primitive code with said substitution primitive code to form a character code equivalent to a character code stored in said storage means, and most likely to represent said handwritten character.

Claim 8

The apparatus as defined in claim 1 wherein said input means is an on-line digitizer tablet providing cartesian co-ordinate data for each of said primitives forming said handwritten character, said processing means further comprising encoding means for examining said cartesian co-ordinate data for each of said primitives forming said handwritten character and forming therefrom a series of unit vectors.

Claim 9

The apparatus as defined in claim 7 wherein said encoding means is a modified Freeman encoder which includes a plurality of freeman unit vectors, said encoder detecting only substantially vertical, horizontal and diagonal strokes forming the primitives constituting said handwritten character.

Claim 10

The apparatus as defined in claim 8 wherein said processing means further comprises: feature extraction means for receiving said series of unit vectors for each of said primitives and eliminating redundant unit vectors to form a vector code and an associated series of scalars for each of said handwritten primitives; holding means for storing vector codes and an associated primitive code representing each of said primitives in said set along with an unidentified primitive code; and comparator means for comparing said vector codes generated for said handwritten character with said vector codes stored in said holding means, said comparator means generating said primitive code when said vector code is equivalent to a vector code stored in said holding means and generating said unidentified primitive code when said vector code is not equivalent to a vector code stored in said holding means.

Claim 11

The apparatus as defined in claim 9 wherein said holding means is further provided with primitive test information, said information being uniquely associated with vector codes which represent more than one primitive in said set, said processing means further comprising a test section receiving said primitive test information and said series of scalars associated with said vector code and performing operations thereon to detect the correct primitive code associated with said vector code generated for said handwritten the primitive when said vector code is equivalent to a vector code representing more than one primitive.

Claim 12

The apparatus as defined in claim 1 wherein said output means is selected form the group comprising: a printer, an audio-synthesizer and a video display terminal.

Claim 13

An apparatus as defined in claim 9 further comprising pre-processing means for receiving said cartesian co-ordinate data, said preprocessing means comparing the distance between first and adjacent second co-ordinates and removing said second co-ordinate if said distance is less than a predetermined threshold value thereby reducing the amount of redundant data.

Claim 16

A character recognition apparatus for identifying a handwritten character formed from at least one primitive, said character and said primitives being members of predetermined sets, said apparatus comprising: input means for receiving successively and in order determined by pre-defined rules, each of the handwritten primitives forming said handwritten character said input means generating input signals for each of said handwritten primitives; processing means receiving said input signals for each of said primitives, said processing means converting the input signals generated for each primitive into data representing a series of generally horizontal, vertical and diagonal vectors and comparing said data with stored information therein and generating a primitive code for each of the primitives when said data are detected as being equivalent to stored information associated with a single primitive; first differentiation means in communication with said processing means and performing discriminatory tests on said data when said data are detected as being equivalent to stored information associated with a plurality of primitives to determine the primitive associated with said data to permit said processing means to determine said primitive code, the series of primitive codes generated by said processing means forming a character code; storage means storing a character code and an associated output code for each of the characters in said predetermined set; comparing means comparing said character code generated for said handwritten character with said character codes in said storage means to identify said entered handwritten character; second differentiation means examining said input signals generated for each of said handwritten primitives and performing discriminatory tests thereon when said character code generated for said handwritten character is equivalent to a character code in said storage means associated with a plurality of output codes to identify the output code associated with said handwritten character; and output means in communication with said comparing means and said second differentiation means and generating a reproduction of said handwritten character upon identification of the output code associated with the handwritten character.

Claim 17

A character recognition apparatus for identifying a handwritten character formed from at least one primitive, said character and said primitives being members of predetermined sets, said apparatus comprising: input means for receiving successively and in order determined by pre-defined rules, each of the handwritten primitives forming said handwritten character said input means generating input signals for each of said handwritten primitives; processing means receiving said input signals for each of said primitives, said processing means converting the input signals generated for each primitive into data representing a series of generally horizontal, vertical and diagonal vectors and comparing said data with stored information therein and generating a primitive code for each of the primitives when said data are detected as being equivalent to stored information associated with a single primitive; first differentiation means in communication with said processing means and performing discriminatory tests on said data when said data are detected as being equivalent to stored information associated with a plurality of primitives to determine the primitive associated with said data to permit said processing means to determine said primitive code, the series of primitive codes generated by said processing means forming a character code; storage means storing a character code and an associated output code for each of the characters in said predetermined set; comparing means comparing said character code generated for said handwritten character with said character codes in said storage means to identify said entered handwritten character; second differentiation means examining said input signals generated for each of said handwritten primitives and performing discriminatory tests thereon when said character code generated for said handwritten character is equivalent to a character code in said storage means associated with a plurality of output codes to identify the output code associated with said handwritten character; and output means in communication with said comparing means and said second differentiation means and generating a reproduction of said handwritten character upon identification of the output code associated with the handwritten character.

Claim 18

The character recognition apparatus as defined in claim 14 wherein said primitives are capable of forming substantially every character in a plurality of languages, said storage means storing a character code and an output code for each of said characters in said plurality of languages.

Claim 19

The character recognition apparatus as defined in claim 15 wherein said storage means further stores character test information, said test information being provided for each character code associated with more than one output code, said second differentiation means receiving said character test information and said output signals and performing said discriminatory test on said input signals in accordance with said character test information to detect the output code corresponding to said handwritten character.

Claim 20

The character recognition apparatus a defined in claim 16 wherein said predetermined set of primitives includes twenty distinct primitives, the various combination of said twenty primitives being capable of forming substantially all characters in said plurality of languages, a substantial portion of said primitives being formed from only substantially horizontal, substantially vertical and substantially diagonal components.

Claim 21

The character recognition apparatus as defined in claim 17 further comprising: substitution means receiving the character code generated for said handwritten character when said character code is not equivalent to any of said character codes stored in said storage means, said substitution means including comparator means for comparing each primitive code forming said character code generated for the handwritten character with the corresponding primitive codes forming said character codes in said storage means having the same number of primitive codes as the character code generated for the handwritten character to detect differences between the character code and said character codes in said storage means; and a memory for storing the output code associated with each of the character codes in said storage means having fewer than a predetermined number of differences when compared with the character code generated for the handwritten character.

Claim 22

The character recognition apparatus as defined in claim 18 wherein said processing means generates an unidentified primitive code when said processing means and said first differentiation means do not detect said data as being equivalent to any information stored therein, said unidentified primitive code when generated forming part of said character code, said substitution means further comprising a probability matrix, said probability matrix generating a substitution primitive code most likely to be the unidentified primitive code when said substitution means receives a character code having at least one identified primitive code therein and replacing said unidentified primitive code with said substitution primitive code in an attempt to form a character code equivalent to a character code stored in said storage means and most likely to represent said handwritten character.

Claim 23

The character recognition apparatus as defined in claim 14 wherein said input means is an on-line digitizer tablet generating cartesian co-ordinate data for each of said primitives forming said handwritten character, said processing means further comprising encoding means for examining said cartesian co-ordinate data for each of said primitives and forming therefrom a series of vectors and associated series of scalars.

Claim 24

The character recognition apparatus as defined in claim 20 wherein said encoding means is a modified Freeman encoder, said encoder examining said series of vectors to detect substantially horizontal, substantially vertical and substantially diagonal unit vectors and converting said series of vectors into said data, said first differentiation means performing discriminatory tests on said associated scalars when said data generated for a primitive forming part of said handwritten character is detected as being equivalent to stored information associated with a plurality of primitives to determine the primitive associated with the data.

Claim 25

The character recognition apparatus as defined in claim 21 wherein said processing means further comprises feature extraction means receiving said series of vectors for each of said primitives and eliminating redundant vectors to form said data, said data being in the form of a vector code and said associated series of scalars for each of said handwritten primitives; holding means for storing vector codes and an associated primitive code representing each of said primitives in said set along with an unidentified primitive code; and comparator means for comparing said vector codes generated for said handwritten primitive with said vector codes stored in said holding means, said comparator means output said primitive code when said vector code is equivalent to a vector code stored in said holding means and output said unidentified primitive code when said vector code is not equivalent to a vector code stored in said holding means.

Claim 26

The apparatus as defined in claim 22 wherein said holding means is further provided with primitive test information, said information being uniquely associated with vector codes which represent more than one primitive, said first differentiation means receiving said primitive test information and said series of scalars associated with said vector code from said processing means and performing operation thereon to detect the correct primitive code associated with said vector code when said vector code is equivalent to a vector code representing more than one primitive code.

Claim 27

An apparatus as defined in claim 23 further comprising a pre-processing means for receiving and conditioning said cartesian co-ordinate data to eliminate spurious data and to reduce redundant data.

Claim 28

The apparatus defined in claim 14 wherein all primitives are generally horizontal vectors, generally vertical vectors, generally diagonal vectors, or a combination of generally horizontal, vertical and diagonal vectors.

Claim 31

The character recognition apparatus as defined in claim 14 wherein the discriminatory tests determine the relative length between two primitives forming said handwritten character or whether one primitive forming the handwritten character crosses another.

Claim 32

The character recognition apparatus as defined in claim 21 wherein the discriminatory tests determine the relative length of the vertical, diagonal and horizontal vectors generated for the primitive.

Claim 33

The character recognition apparatus as defined in claim 4 wherein said test information causes said differentiation means to determine the relative length between two primitives forming said handwritten character or whether one primitive forming the handwritten character crosses another.

Claim 34

The character recognition apparatus as defined in claim 10 wherein said test section examines said vector codes to determine the relative length of the vector codes generated for the handwritten character.