Classifications

• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR COUNTING
  • G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
  • G06V10/00—Arrangements for image or video recognition or understanding
  • G06V10/10—Image acquisition
  • G06V10/17—Image acquisition using hand-held instruments
• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR COUNTING
  • G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
  • G06V30/00—Character recognition; Recognising digital ink; Document-oriented image-based pattern recognition
  • G06V30/10—Character recognition
  • G06V30/32—Digital ink
  • G06V30/36—Matching; Classification
  • G06V30/373—Matching; Classification using a special pattern or subpattern alphabet

Definitions

• the present invention relates to an apparatus and method for identifying characters.
• an ideographic character detection apparatus for receiving and identifying handwritten ideographic characters.
• the apparatus requires that the ideographic character be written on an input device and that the written characters be formed from predetermined fundamental strokes or primitives which are typical strokes used by everyone who writes in the ideographic language.
• the apparatus examines the primitives forming the entered ideographic character and compares the entered primitives with the contents of a look-up table.
• the look-up table stores a plurality of variations of each of the predetermined primitives to accommodate variations in user's handwriting. Due to the large number of variations of each primitive stored in the table, the primitives forming the character are usually determined by the device.
• the table also stores the sets of primitives used to form each of the characters in the ideographic language. If the set primitives forming the entered character corresponds with one of the sets of primitives in the look-up table, an output code associated with the set of primitives is generated and conveyed to an output device. This allows a hard copy image of the entered ideographic character to be formed.
• a problem exists in that due to the large number of variations of each primitive stored in the table, the processing speed of the apparatus is greatly reduced making it unsuitable for real-time applications.
• the number of predetermined fundamental strokes or primitives used in-this apparatus has typically been chosen to be five or less or twenty or more.
• the number of predetermined fundamental strokes or primitives used in-this apparatus has typically been chosen to be five or less or twenty or more.
• said apparatus comprising: input means for receiving successively each of the primitives forming said character and generating input signals for each of said received primitives; processing means receiving said input signals and identifying each of said primitives received by said input means, said processing means generating a character code representing said character upon identification of said primitives; storage means storing a character code and an associated output code for each of the characters in said set; comparing means comparing said character code generated for said entered character with each of said character codes in " said storage means to identify said entered character; and output means in communication with said comparison means and generating a reproduction of said entered character upon the identification thereof by said comparison means.
• the apparatus further includes differentiation means examining said input signals generated for each of said primitives and performing operations thereon, when said character code is equivalent to a character code associated with a plurality of output codes to identify the output code associated with said character.
• the apparatus is provided with substitution means for selecting the character code stored in the storage means having the highest probability of being equivalent to the character code generated for the entered character, when the input
• BST rruTHSHser character code is not equivalent to any of the character codes stored in the storage means. It is also preferred that the output means comprises at least one device chosen form the group comprising a printer, audio synthesizer or video display terminal to allow a reproduction of the received ideographic character to be formed or an audio reproduction of the ideographic character to be produced.
• the character recognition apparatus is capable of recognizing characters written in all ideographic languages, upper case English language characters, and Russian characters.
• the predetermined set of fundamental primitives is chosen to comprise 20 unique primitives, the various combinations of which Will form substantially all characters in a plurality of different languages, whilst decreasing the occurrence of different characters being formed from the same series of primitives.
• the use of twenty distinct primitives decreases the occurrence of entered characters being represented character codes which are equivalent to a character code associated with more than one international output code. This of course, increases the probability of detecting the correct ideographic character.
• Figure 1 is a functional block diagram of an apparatus for identifying characters
• Figure 2 is an illustration of an ideographic character
• SUBSTITUTE SHEET Figure 3 are illustrations of the fundamental primitives used in the device illustrated in Figure 1;
• Figures 4a to 4c is an illustration of the method of forming the character shown in Figure 2 from the primitives shown in Figure 3;
• FIG. 5 is a more detailed functional block diagram of the device illustrated in Figure 1;
• Figure 6 is a detailed functional block diagram of a portion of the device illustrated in Figure 1;
• Figure 7 is an illustration of a coding method used in the device illustrated in Figure 1;
• Figures 8a and 8b are illustrations of entered fundamental strokes; Figures 9a and 9b are illustrations of still more ideographic characters;
• Figure 10 is an illustration of a probability matrix used in the device illustrated in Figure 1;
• Figure 11 is an illustration of an English character
• Figure 12 is an illustration of more English characters.
• the apparatus 10 comprises an input device 12 connected to a data processor 14.
• the input device 12 receives the handwritten character and converts the character into a series of signals that are conveyed to the data processor 14.
• the data processor 14 processes the received signals in order to detect the character entered on the input device 12.
• An output device 16 is also connected to the data processor 14 and receives an international ASCII output code representing the handwritten character that was received by the input
• the apparatus 10 is operable in a number of 5 modes, each mode of which allows handwritten characters of a different language to be recognized and reproduced.
• Selection means 18 are provided to allow a user to select the language in which the apparatus 10 is to operate.
• the processing means 14 is responsive to
• the selection means 18 and is partitioned into sections 14a, 14b,..., 14n so that appropriate information for each language is separately stored and accessible depending on the mode selected by the selection means 18.
• an ideographic character IC is shown. As can be seen, the ideographic
• 2.5 character IC is formed from a number of fundamental strokes or primitives, the primitives being labelled as Pr- to Pr 3 respectively.
• the primitives Pr x to Pr 3 are fundamental strokes used when writing in the ideographic language.
• the writing order of the sequence of strokes for ideographic characters is mainly based on logic efficiency, experience and natural human habits. According to several research findings, there exist a
• Each Chinese character may employ one or more of the above rules in the formation of the character.
• Examples of basic stroke sequences of ideographic characters are illustrated in Table 1 hereinbelow:
• the fifteen primitives Pr a to Pr 0 are members of the set of fundamental strokes typically used in the formation of ideographic characters. This sub-set of primitives is chosen since all of the ideographic characters in the various languages can be formed from various combinations of the primitives Pr a to Pr 0 .
• the primitives Pr to Pr t are used with some of the primitives Pr a to Pr ⁇ when- the apparatus is operating to detect characters written in another language as will be described.
• the input device 12 comprises an on-line digitizer tablet 20 having a stylus 20a.
• the ideographic character to be recognized is written on the tablet 20 with the stylus 20a.
• This causes a series of cartesian co-ordinate data point signals PN 0 to PN N to be generated for each of the primitives Pr a to Pr 0 entered that form the ideographic character IC.
• the upper case "N" of the data point signal refers to the order in which the primitive was entered when forming the character IC while the subscript "N" refers to the number of the sampled point along the primitive.
• the data point signals are then conveyed to the data processor 14.
• a memory 22 is located in the data processor 14 and is connected to the digitizer tablet 20.
• the memory 22 receives the raw cartesian co-ordinate data point signals and stores them prior to processing.
• a pre-processor 24 receives a copy of the cartesian co ⁇ ordinate data point signals PN 0 to PN N for each entered primitive and processes the data to remove redundant and spurious data.
• the pre-processed cartesian co-ordinate data signals are conveyed from the pre-processor 24 to a feature extraction section 26 which converts the cartesian co-ordinate data point signals for each of the entered primitives Pr into a vector code and a series of scalars.
• the vector code and series of scalars generated by the feature extraction section 25 are
• SUBSTITUTESHEET applied to a primitive detection section 28 which compares the vector code generated for each entered primitive Pr a to Pr 0 forming the character IC with the contents of a look-up table or dictionary. This allows the processor 14 to detect whether the entered primitives are members of the fifteen primitives Pr. to Pr 0 .
• a primitive code a to o is generated and conveyed to a memory 30. This process is performed for each vector code representing each primitive Pr forming the entered ideographic character IC.
• a series of primitive codes or a character code is generated for the entered character which represents the ideographic character IC.
• the detection section 28 performs tests on the series of scalars associated with the generated vector code to detect the correct entered primitive.
• the generated character code is conveyed from the memory 30 to a character detection section 32 and compared with the contents of a second look-up table or dictionary.
• Section 32 stores the character code representing each of the ideographic characters in the language.
• the stored character codes are based on the requirement that the ideographic characters are formed from a combination of the fifteen primitives illustrated in Figure 3 and that the characters are entered on the tablet 20 in an order as determined by the previously mentioned rules. Since the previously mentioned rules are generally used when writing in an ideographic language, character codes which can represent
• the character detection section 32 When the character code generated for the entered ideographic character IC is equivalent to a character code found in the character detection section 32, an associated output code or international ASCII output code is outputted to a memory 34. However, if the character code is equivalent to a character code representing more than one ideographic character, the character detection section 32 performs operations on the raw cartesian co-ordinate data point signals stored in the memory 22 to determine the correct ideographic character IC to which the character code represents.
• a substitution and correction means 36 is also provided and examines the entered character code when it is not equivalent to a character code stored in the character detection section 28.
• the substitution means 36 substitutes for the entered character code, the most probable character code that the entered character code was supposed to represent and conveys it back to the character detection section 32 wherein the above- mentioned process is performed.
• the international ASCII code representing the ideographic character IC stored in the memory 34 is applied to the output device or devices 16 which typically include a video display terminal (VDT) 16a, printer 16b and/or a video synthesizer 16c wherein an audio and/or visual reproduction of the ideographic character IC can be formed.
• VDT video display terminal
• FIG. 6 the processing means 14 is better illustrated.
• the pre-processor 24 comprises a comparator 24a and a memory 24b which function in a manner to be described to eliminate redundant and 5 spurious cartesian co-ordinate data point signals.
• the feature extraction section 26 includes a second comparator 26a and a look-up table or dictionary 26b which, function to generate vectors for adjacent cartesian co-ordinate data point signals forming each 0 primitive Pr.
• a memory 26c receives the vectors and in turn conveys the vectors to a third comparator 26d.
• the comparator 26d examines the vectors and removes redundant information to form a series of unit vectors or a vector code for each primitive Pr and a series of 5 scalars.
• the scalars represent the length of each unit vector in the vector code generated for each primitive.
• the vector code and series of scalars generated for each primitive Pr are conveyed to a memory 26e and stored prior to being conveyed to the primitive detection 0 section 28.
• the primitive detection section 28 includes a fourth comparator 28a connected to a second look-up table or dictionary 28b.
• the table 28b stores a list of
• the primitive detection section 28 also comprises a memory 28c which holds the scalars generated for each vector
• test section 28d performs operations on the series of scalars if the vector code associated therewith is equivalent to a vector code which represents more than one of the fifteen primitives. This allows the correct primitive
• SUBSTITUTE SHEET the primitive code a to o associated therewith is applied to the memory 30.
• the series of primitive codes or character code generated for the entered ideographic character IC is conveyed to the character detection section 32 which comprises a fifth comparator 32a and a third look-up table or dictionary 32b.
• the dictionary 32b stores a list of the character codes forming each of the ideographic characters in the language and an associated international output code.
• the comparator 32a and the dictionary 32b function to detect whether the character code representing the entered ideographic character IC is equivalent to a character code representing one or more of the ideographic characters.
• the character detection section 32 also includes a differentiator 32c which performs tests on the raw cartesian co-ordinate data point signals if the character code is equivalent to a character code which represents more than one ideographic character. This allows the correct ideographic character to be detected.
• the international ASCII code associated therewith is conveyed to the memory 34 and in turn to the output device 16.
• the substitution section 36 includes a probability matrix 36a, a sixth comparator 36b and a memory 36c which collectively function to determine the most probable character code that the character code generated for the entered ideographic character IC was supposed to be. This increases the probability of
• the stylus 20a When an ideographic character IC is to be entered into the apparatus 10 via the digitizer tablet 20, the stylus 20a is placed on the tablet 20 and each of the primitives Pr forming the ideographic character IC is drawn separately.
• the primitives used to form the ideographic character IC must be substantially equivalent to one of the fifteen primitives Pr. to Pr 0 .
• this limitation does not pose many problems since each of the fifteen primitives are fundamental strokes used by substantially everyone who is capable of writing in an ideographic language.
• the primitives Pr a to Pr 0 are chosen to reduce the number of entered characters that generate the same character code when inputted into the apparatus 10 and to simplify processing in section 14.
• the stylus 20a is removed from the tablet 20 for a predetermined length of time. This results in a time-out signal being generated which allows the data processor 14 to recognize that the primitive Pr has been completely entered. Thereafter, the next primitive forming the character is entered and a time-out signal is generated. This process continues until each primitive forming the character has been entered into the apparatus 10.
• a series of cartesian co ⁇ ordinate data point signals are generated.
• the data processor 14 samples the cartesian co-ordinate data point signals generated for each primitive at a sampling rate of approximately 100 samples per second and stores the sampled co-ordinate data signals in the memory 22.
• the sampled data for each primitive is continuously
• the second sampled data point signal is deleted and the distance between the first and the third sampled cartesian co-ordinate data point signals is examined. This process continues until the distance between two data point signals is greater than the threshold value.
• the first data point signal is conveyed to the memory 24b and the other data point signal is compared with the next preceding data point signal.
• the second cartesian co-ordinate data point signal is compared with the third data point signal. If the distance between the second and third data point signals is larger than the second threshold value, the second data point signal is assumed to have been generated due to an inadvertent miscoupling of the stylus 20a and the tablet 20 and is deleted. However, if the distance between the second data point signal and the third data point signal is less than the second threshold value, the first data point signal is assumed to have been generated inadvertently and is deleted. This process is performed on the sampled cartesian co-ordinate data point signals for each of the entered primitives forming the entered character and hence, reduces the amount of data that requires processing.
• the ideographic character IC illustrated in Figure 2 is entered into the apparatus 10, the primitives Pr x to Pr 3 forming the character IC are entered on the tablet 20 separately.
• the data processor 14 samples the cartesian co-ordinate data generated by the tablet 20 for the first primitive P ⁇ and stores the sampled cartesian co-ordinate data point signals Pl ⁇ to Pl 5 in the memory 22 as shown in Figures 4a to 4c.
• the processor 14 samples the cartesian co-ordinate data point signals P2 X to P2 8 and P3 X to P3 8 generated for the next two primitives Pr 2 and Pr 3 respectively and stores the sampled cartesian co ⁇ ordinate data point signals in the memory 22.
• the cartesian co-ordinate data point signals are conveyed separately to the pre ⁇ processor 24 wherein they are stored in the comparator 24a.
• the sampled cartesian co-ordinate data point signal Pl ⁇ for the first primitive Pr ⁇ is compared with the outer boundary cartesian.co-ordinates of the digitizer tablet 20. If the sampled data point signal is detected as being outside the boundary of the tablet 20, it is deleted.
• each of the remaining data point signals Pl 2 to Pl 5 are compared with the previous data point signal Pl ⁇ . For example, if the distance between the data points Pl 2 and Pl ⁇ is less than a predetermined value, the data point signal Pl 2 is deleted and the data point signals Pl 3 is compared with the data point signal Pl ⁇ .
• the data point signal Pl 1 is stored in 5 the memory 24b and the above-mentioned process is recommenced examining the data point signals Pl 3 and Pl 4 .
• This process is performed for each data point signal sampled for the first primitive P ⁇ 1 until the co ⁇ ordinate data representing the inputted primitive P ⁇ 0 has been reduced.
• This process is also performed on the sampled cartesian co-ordinate data point signals for each of the other entered primitives Pr 2 and Pr 3 and thus, the memory 24b stores the reduced cartesian co ⁇ ordinate data point signals for each of the entered
• entered primitive are converted into a vector code and series of scalars in order to simplify the process of detecting the primitives that were entered on the tablet 20.
• ordinate data is examined to detect whether it has been reduced to a single pair of co-ordinates by the pre ⁇ processor 24. This occurs if the. primitive Pr e is entered on the tablet 20. If this primitive is detected, the primitive code e is outputted to the
• the feature extraction section 26 implements the use of a
• SUBSTITUTE SHEET modified Freeman coding system FC which is illustrated in Figure 7 when forming the vector codes and scalars to determine the other primitives.
• the Freeman coding system allows a series of cartesian co-ordinate data point signals (P 0 , P x , ... P ⁇ , P i + 1 ) where P 0 is equal to (X 0 , Y 0 ) and P ⁇ is equal to ( ⁇ , Y ⁇ ), to be converted into a series of unit vectors, each vector of which has an associated length.
• the unit vectors are formed by comparing a line drawn between adjacent cartesian co-ordinate data point signals P ⁇ ⁇ and P i + 1 with one of the eight Freeman unit vectors FV ⁇ to FV 8 in the Freeman code FC.
• the Freeman coding system FC uses a 20° tolerance for each of the Freeman unit vectors PV N and thus, allows any line formed between a pair of cartesian co-ordinate data point signals T? ⁇ and P i . x falling within one of the boundaries A ⁇ to A 8 to be assigned to the proper Freeman unit vector FV N associated with that boundary.
• the pre-processed cartesian co-ordinate data point signals are conveyed to the comparator 26a.
• the comparator 26a adjacent cartesian co-ordinate data point signals are examined and a line is formed therebetween.
• SUB S TITUTESHEET sampled cartesian co-ordinate data; due to inadvertent movement of the stylus 20a by the operator, the -length of the line formed between each adjacent data point signal is compared with a threshold value. If the length is less than that of the predetermined threshold length, the second data point signal is assumed to be the result of a spurious hand movement by the operator and is thus deleted. This process ensures that a horizontal line drawn by an operator with a slight undesired non-horizontal portion will be filtered to produce data representing the desired horizontal line.
• Freeman code FC If the line falls within one of the tolerance boundaries A t to A 8 , the Freeman unit vector FV ⁇ to FV 8 associated therewith is conveyed to the memory 26c. If the line formed between two cartesian co-ordinate data point signals falls within one of the invalid boundaries X- to X 8 in the Freeman code FC, the second cartesian co-ordinate data point signal is replaced by the next preceding cartesian co-ordinate data point signal and a new line is formed therebetween. Similarly, the new line is compared with the Freeman code FC once again to detect if the line lies within one of the valid boundaries A ⁇ to A 8 .
• the Freeman unit vector FV jj associated with the boundary A j is conveyed to the memory 26c. However, if a valid Freeman unit vector is not detected, the second data point signal of the pair is replaced by the next preceding data point and the same process is repeated. If a line falling in a valid boundary is still not detected after substituting each of the remaining cartesian co-ordinate data points generated for the entered primitive, the cartesian co-ordinates are represented by an invalid Freeman unit vector U' and the invalid Freeman vector is conveyed to the memory 26c.
• FV N or U' are formed for each of the entered primitives and are stored separately in the memory 26c.
• the series of unit vectors are then separately conveyed to the comparator 26d.
• the comparator 26d compares each unit vector FV i+1 with the previous unit vector FV ⁇ and if they are equivalent, a scalar count is incremented for that unit vector and the unit vector F ⁇ 7 ⁇ + 1 is deleted.
• This process is performed on the unit vectors generated for each of the entered primitives Pr. This operation results in the formation of a reduced series of unit vectors or a vector code for each entered primitive forming the character, each vector code of which has an associated series of scalars, which represent the length of each of the unit vectors in the vector code.
• the comparator 26a firstly examines the cartesian co ⁇ ordinate data points associated with the first primitive P ⁇ and forms the lines Ll x to Ll 4 between each adjacent data point Pl ⁇ to Pl 5 respectively.
• the lines Ll ⁇ to Ll 4 are then compared with the Freeman code FC and the associated Freeman vectors FV ⁇ to FV N are assigned to the lines.
• the primitive Pr ⁇ formed from cartesian co-ordinate data points Pl x to Pl 5 and generating lines Ll ⁇ to Ll 4 as illustrated in Figure 4 is assigned the Freeman vectors FV 3 , FV 3 , FV 3 , FV 3 since each of the lines Ll ⁇ to Ll 4 falls within the boundary A 3 (assuming that the length of each of the lines is above the threshold value).
• Figure 4a is processed to form the series of Freeman vectors FV 3 , FV 3 , FV 3 , FV 3 , FV 3 , the comparator 26d reduces the series of vectors to the vector code FV 3 having a scalar of 4. If, for example, a primitive was entered and a series of Freeman vectors equal to FV 3 , FV 3 , FV 3 , FV 4 , FV 4 , FV 4 , FV 4 , FV 5 , FV 5 , FV 3 was generated therefor, the series of unit vectors would be reduced to the vector code FV 3 , FV 4 , FV 5 , FV 3 , and a series of scalars equal to 3, 3, 2, 1 would be generated.
• the vector code and associated series of scalars for each primitive forming the entered character are conveyed to the primitive detection section 28.
• the vector codes are applied to the comparator 28a and the series of scalars are stored in the memory 28c.
• the vector codes received by the comparator 28a are compared with the vector codes stored in the primitive dictionary 28b.
• the dictionary 28b is partitioned into sixteen primitive code sections, the first fifteen sections of which are uniquely associated with one of the fifteen primitives Pr a to Pr 0 and store
• SUBSTITUTESHEET vector codes uniquely associated with that primitive.
• the sixteenth section holds ambiguous vector codes which can represent more than one of the primitives.
• the sixteenth section also holds unique test information for each ambiguous vector code to allow the correct entered primitives to be determined.
• the primitive code for an entered primitive is equivalent to a vector code found in one of the first fifteen sections of the dictionary 28b
• the primitive code a to o associated therewith is conveyed to the memory 30. This process is performed for each of the vector codes generated for each primitive forming the entered character. Thus, a series of primitive codes or a character code is generated, the character code of which represents the ideographic character entered on the digitizer tablet 20.
• the test information associated with the ambiguous vector code is applied to the test section 28d.
• the test section 28d receives the test information and examines it to determine which vector code is being examined. Thereafter, the test section 28d receives the series of scalars associated with the examined vector code and performs operations thereon, the operations of which are determined by the unique test information. The results of the tests are conveyed back to the dictionary 28b which in turn selects the correct primitive code that represents the entered primitive.
• the series of scalars provide suitable information to discriminate between each ambiguous vector code since although the vector codes are ambiguous, the value of each scalar in the series are typically very different.
• the vector code being compared with the contents of the dictionary 28b is not equivalent to a vector code located therein, the vector code is assigned an unidentified primitive code U which is similarly applied to the memory 30.
• the output of the primitive detection section 28 comprises a series of primitive codes or a character code, which represents the inputted ideographic character IC.
• the character code stored in the memory 30 is applied to the character code recognition section 32 and received by the comparator 32a.
• the comparator 32a compares the character code with the contents of the character dictionary 32b generated for the entered character.
• the dictionary 32b stores a character code for each of the possible ideographic characters in the language along with its
• SUBSTITUTE SHEET corresponding international ASCII output code The international ASCII output code is used internationally to represent the ideographic character. Since a number of ideographic characters are formed from the same primitives entered in the same order, some ideographic characters have identical character codes although the relative positions between the entered primitives are very different. To allow the apparatus 10 to detect the proper ideographic character when an ambiguous character code is received, the character dictionary 32b also contains test information uniquely associated with each ambiguous character code.
• a character code When a character code is received from the memory 30, it is compared with the contents of the dictionary 32b via comparator 32a. If received character code is equivalent to a character code found in the dictionary 32b that is uniquely associated with only one ideographic character, the international ASCII output code associated therewith is outputted from the dictionary 32b and stored in the memory 34. However, when the character code generated for the entered ideographic character is equivalent to an ambiguous character code that is associated with more than one ideographic character, the unique test information associated therewith is applied to the character differentiator 32c.
• the differentiator 32c Upon reception of the test information, the differentiator 32c retrieves the unprocessed cartesian co-ordinate data from the memory 22 and performs operations thereon as determined by the test information in order to determine the international ASCII output code that represents the inputted ideographic character. When performing the test operations, the unprocessed cartesian co-ordinate data points are used ' as opposed to
• a character code equal to "aba" would be generated and compared with the contents of the dictionary 32b.
• the character code would be detected as being ambiguous since the ideographic characters IC2 and IC3 shown in Figures 9a and 9b respectively are also represented by the same character code "aba".
• the unique test information associated with the character code "aba” would be applied to the differentiator 32c, along with the unprocessed cartesian co-ordinate data from the memory 22. For this example, the test information would cause the differentiator 32c to examine the position of the second primitive Pr 2 with respect to the first primitive Pr ⁇ to determine if the second primitive Pr 2 passes through the first primitive Pr x .
• the differentiator 32c would acknowledge that the entered ideographic character IC is not equivalent to ideographic character IC2 since this feature is not present in the character IC2.
• the third primitive Pr 3 is compared with the first primitive Pr ⁇ forming the entered ideographic character IC and the relative sizes therebetween are examined. The result of this test enables the differentiator 32c to select the correct international ASCII output code since the primitive P ⁇ is smaller than the primitive Pr 3 .
• the dictionary 32b receives the results generated by the differentiator 32c and the correct international ASCII output code is conveyed to the memory 34.
• the international ASCII output code After the international ASCII output code has been determined and stored in the memory 34, it can be applied to output devices such as a printer 16a, a VDT terminal 16b or an audio synthesizer 16c in order to produce an image of the inputted ideographic character.
• output devices such as a printer 16a, a VDT terminal 16b or an audio synthesizer 16c in order to produce an image of the inputted ideographic character.
• the substitution and correction section 36 includes the probability matrix 36a, which is in the form of a sixteen row by fifteen column array of registers 36 a ' . As shown in Figure 10, each row of the matrix is associated with one of the possible sixteen primitive codes a to o including the unidentified primitive code U and each of the columns of the matrix is associated with one of the fifteen possible primitive codes a to o.
• Each of the registers 36 a ' holds a number representing the probability that the primitive code of the row could be mistaken for the primitive code of the column.
• the probability values stored in the registers along the left to right diagonal of the matrix 36a all have values of 1 since the probability that a primitive code will be detected as itself is high.
• the probability of two very dissimilar primitives being mistaken for one another is highly improbable and thus, the probability values stored in a register associated with two dissimilar primitives is typically zero.
• the probabilities in the row associated with the primitive code U are examined.
• the primitive code of the column is used to replace the unidentified primitive code U.
• the resultant character code is conveyed back to the comparator 32a and is compared with the contents of the character dictionary 32b to detect if the resultant character code is equivalent to a character code found therein. If the resultant character code is equivalent to a character code in the dictionary, the international ASCII output code is retrieved from the dictionary 32b and conveyed to the memory 34 wherein it is stored. If the resultant input character code is equivalent to an ambiguous character code, tests are performed on the cartesian co ⁇ ordinate data stored in the memory 22 in the same manner as previously described to determine the correct international ASCII output code.
• the character code is conveyed to the comparator 36b and examined to identify the number of primitive codes forming the character code.
• each character code in the character dictionary 32b formed from the same number of primitive codes is conveyed to the comparator 36b and compared with the unidentified character code. During this comparison, the number of differences between the primitive codes forming each of the character codes and the primitive codes forming the unidentified character code are examined. If the number of differences detected between the character code and the unidentified character code is greater than a threshold value, the character. code is discarded.
• the international ASCII output code associated therewith is stored in the memory 36c.
• the order of the international output codes stored in the memory 36c is chosen so that the first international ASCII output code in the memory is associated with the character code most similar to the unidentified character code.
• the international output codes stored in the memory 36c are then retrieved from the memory 36c and conveyed to the
• the VDT terminal thereby displaying to the user each of the ideographic characters that are most likely to be equivalent to the entered ideographic character.
• the user may then choose the ideographic character corresponding to the ideographic character that was entered into the apparatus 10 via suitable editing software. If the substitution section 36 does not produce the desired ideographic character, editing programs can be used to retrieve the correct international ASCII output code from the dictionary 32b.
• the ideographic character signals stored in the memory 34 can be coupled to the printer 16a to allow a reproduction of the inputted ideographic character to be generated. Furthermore, the character signals can be conveyed to the VDT screen 16b to allow the user to view the characters that has been entered into the apparatus 10.
• the apparatus 10 is also capable of functioning with known editing programs to allow the user to change the ideographic character signals stored in the memory 34.
• the same set of primitives shown in Figure 3 are used to form the characters. It should be apparent that the primitives shown in Figure 3 are particularly useful in forming ideographic and upper case English language characters since all of the characters in these languages can be formed from these primitives. However, it should be appreciated that other primitives may have to be added so that all of the characters in all languages can be formed, however, this will be rare since the twenty primitives should be capable of forming substantially all of the characters in every language.
• the dictionaries in the processor 14 are partitioned with each partition holding the various primitive codes, character codes and ASCII output codes for each upper case character in the other languages.
• the upper case characters are stored in the apparatus since these characters are typically written in the same manner and order by everyone versed in the language.
• the various sections in the processor also include test information to allow different characters which generate the same character code to be recognized.
• the primitive detection and primitive code determination is performed in the same manner previously described using the Freeman coding except when one of the primitives Pr p to Pr t are entered on the tablet 20. Accordingly, When a primitive is entered on the tablet 20, the feature extraction section 26 examines the tangents of the lines formed between the sampled points along the primitive to determine the degree of curvature of the primitive (ie. 180°, 270°, 360°) prior to using the Freeman Coding.
• the primitive code s or t associated with the entered primitive Pr s or Pr t is immediately determined without further processing. If the curvature of the primitive is detected as being approximately 180° , the starting and ending co-ordinate data signals of the primitive are examined along with the direction of the tangents (ie. clockwise or counter-clockwise) This allows the primitives Pr to Pr r to be differentiated without requiring further processing. Other wise if the entered primitive is not detected as having a substantially constant gradient when examining the tangents, the pre- processed co-ordinate data signals are processed using the Freeman coding to determine the correct primitive code.
• the method of detecting the handwritten characters is the same although the apparatus must be conditioned to the appropriate mode via means 18. This is even necessary for languages like German ,French and English wherein the characters forming the language are the same .since the ASCII output codes therefor are different.
• the substitution matrix can also be used for each of the other languages although it is not necessary due to the small number of characters used in non-ideographic languages.
• the device when the apparatus 10 is conditioned to detect upper characters of a language, the device is also included with software for outputting the ASCII code for the lower case equivalent of the detected upper case character if desired.
• the lower case letters can be detected in a similar manner to the upper case letters, lower case letters are typically written differently by individuals thereby making the detection process more difficult and requiring more memory space to permit detection of the character in the many possible ways that it can be written.
• the present apparatus has been employed in an IBM PC XT personal computer manufactured by International Business Machines provided with a 20 Mb hard disk which functions to store the information for the dictionaries.
• the computer is supplied with the appropriate software which allows the input cartesian co-ordinate data point signals to be processed in the above-mentioned manner.
• a B-tree algorithm which is well known in the art is used to increase the speed of the detection between the character code generated for the inputted ideographic and the character codes stored therein.
• the B-tree algorithm increases processing speed, it also increases memory requirements, since indexing files are required.
• the present apparatus 10 can also be manufactured on a small integrated circuit board capable of being coupled to a conventional personal computer, the board of which is provided ROM components to store
• the present apparatus provides the advantages of being able to distinguish between characters which are formed from the same primitives entered in the same order. This decreases the occurrences of an operator having to halt data entry operations in order to choose the correct ideographic character. Moreover, the substitution means further decreases the above-mentioned occurrence since allowing the present apparatus to choose a different character code that is most similar to the entered character code, if the input character is not found in the apparatus 10. Furthermore, since the apparatus can be generated using software or manufactured using hardware components, the apparatus is versatile and can be used in various environments.
• the present device also provides further advantages in that the manner in which the entered strokes are processed in the apparatus, allows the strokes to be written substantially anywhere on the tablet surface except for the small number of characters which generate an ambiguous character code. Also, the processing used prior to the determination the primitives forming the character allows the entered characters to be determined irrelevant of the length of the entered primitives except for a few exceptions.

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• 1988
  • 1988-12-12 CA CA000585619A patent/CA1309774C/en not_active Expired - Lifetime
  • 1988-12-12 EP EP89900859A patent/EP0396593A1/en not_active Withdrawn
  • 1988-12-12 CN CN88109283A patent/CN1019612B/zh not_active Expired
  • 1988-12-12 JP JP1500666A patent/JPH03502841A/ja not_active Expired - Lifetime
  • 1988-12-12 KR KR1019890701515A patent/KR900700973A/ko not_active Application Discontinuation
  • 1988-12-12 WO PCT/GB1988/001100 patent/WO1989005494A1/en not_active Application Discontinuation

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