JPH07117987B2 - Stroke identification method - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a stroke identification method, and particularly to a stroke capable of reliably determining whether or not characters written in an online handwritten character recognition device are input in a correct stroke order. Regarding identification method.

(B) Background of technology In addition to an optical character recognition device that recognizes the character to be recognized as a character that has been written prior to the recognition, an online handwritten character recognition that recognizes the character that is being written. There is a device. In such a character recognition device, it is necessary for character recognition to determine whether or not each stroke forming a character is drawn in the correct stroke order.

Although this kind of determination means is already known, technical improvement is required because of lack of certainty of the determination.

(C) Conventional Technology and Problems The first conventional stroke identification method is a vector matching method using simple absolute position coordinates.
That is, as shown in FIG. 1, the vector distance between the dictionary stroke L and the input stroke l Is a method for determining. According to this method, the second
As shown in the figure, when the glyph is different from that in the dictionary,
Even if the stroke order is correct, the distance becomes large, which hinders correct stroke order determination.

As a second stroke identification method, as shown in FIG. 3, the input stroke is moved in parallel (l 'is the input stroke after the parallel movement), for example, by adjusting the start points, and then the above-mentioned first stroke is detected. This is a method of performing vector matching similar to the stroke identification method of No. 1. The distance between vectors in this case is Becomes According to this method, as shown in FIG. 4, the distance becomes small even though the stroke order is different,
As a result, the correct judgment of the stroke order is impaired.

(D) Object of the invention The present invention has been made in view of the drawbacks of the above-described conventional methods, and its purpose is to determine whether or not the characters being written are written in the correct stroke order. It is to provide a stroke identification method capable of reliably performing the above.

(E) Configuration of the Invention In order to achieve this object, the first method of the present invention inputs a coordinate sequence of strokes for drawing a character and determines whether or not the stroke order of the strokes matches the stroke order of the dictionary. In the stroke identification method described above, the center of gravity movement vector is stored in the dictionary, and the center of gravity movement direction of two consecutive input strokes is determined in response to the feature point obtained from the coordinate series of the stroke and the center of gravity movement vector of the dictionary. The stroke center of gravity moving direction evaluating means for evaluation is provided to identify the input stroke in response to the output from the means. In the second method of the present invention, the coordinate series of strokes for drawing characters is input. Then, in the stroke identification method that determines whether the stroke order of the stroke matches the stroke order of the dictionary, the centroid movement vector is stored in the dictionary. The stroke center-of-gravity moving direction evaluating means for storing the center-of-gravity moving direction of two consecutive input strokes in response to the feature point obtained from the coordinate series of the stroke and the center-of-gravity moving vector of the dictionary. Stroke identification is performed in response to the evaluation value output from the center-of-gravity movement direction evaluation means and the evaluation value for the stroke shape obtained by the stroke shape evaluation means in response to the feature points and the dictionary feature points of the dictionary. It was done like this.

(F) Embodiments of the Invention Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 5 shows an embodiment including the first and second inventions of the present invention. In this figure, 1 is a tablet and 1A is a stylus pen used there. 2 is tablet 1
It is a representative point extraction circuit that converts a coordinate series of character strokes input from the above into characteristic points (for example, strokes sampled at equal intervals). 3 is a distance between strokes (evaluation value for stroke shape) d _s (for example, FIG. 3) in response to a feature point from the representative point extraction circuit 2 and a template (dictionary feature point) from the dictionary 4. It is a stroke shape evaluation circuit for obtaining the distance d ₂ ) described above. Reference numeral 5 calculates an input stroke center-of-gravity movement vector (described later) in response to the feature point from the representative point extraction circuit 3, and calculates the distance (evaluation value) between this vector and the template (dictionary stroke center-of-gravity movement vector) from the dictionary 4. ) D _g (for example,
It is a stroke center of gravity moving direction evaluation circuit for obtaining the distance d ₂ ) described with reference to FIG. Reference numeral 6 is a determination circuit that determines whether or not the correct stroke of the shape is input in the correct stroke order in response to the distance d _s from the stroke shape evaluation circuit 3 and the distance d _g from the stroke center of gravity moving direction evaluation circuit 5. .

FIG. 6 shows the stroke center of gravity moving direction evaluation circuit 5 in detail. This circuit 5 obtains the center of gravity ω _j of the stroke from the x component ω _xj and the y component ω _yj , and uses these components to calculate the center of gravity movement vector ▲ ▼ It is configured to obtain Δg _xj and Δg _yj for obtaining the distance d _g (see FIG. 7), and the circuit for obtaining the y component Δg _yj is the same as the circuit for obtaining the x component Δg _xj. Since it is configured, only the circuit for obtaining the x component will be described, and the description for the circuit for obtaining the y component will be omitted.

In FIG. 6, 10 is a centroid calculation circuit (details thereof are shown in FIG. 8), 11 is a delay flip-flop circuit, 12 is a subtraction circuit for _obtaining the x component g _xj of the input stroke centroid movement vector ▲ ▼, 13 Is an absolute value output subtraction circuit for obtaining a deviation Δg _xj between the x component of the input stroke centroid movement vector and the x component of the dictionary stroke centroid movement vector from the dictionary 14. The output value Δg _xj of the subtraction circuit 13 and the y component circuit 15
The output value Δg _{yj of the} subtractor that is also provided in
Supplied to and from it Is configured to be output.

In FIG. 8, reference numeral 20 denotes a control circuit, which is a multiplexer 21, an adder 22, a register 23 and a counter 24.
Is to control. Stroke feature point sequences X ₁ , X ₂ ... X _N are input to the input A of the multiplexer 21,
A two's complement N'of N is input to the input B. The output of the multiplexer 21 is the input B of the adder 22.
The output of the register 23 is connected to its input A. The output of the adder 22 is connected to the input of the register 23.

Next, a processing mode of the present invention under the above configuration will be described.

A coordinate series of character strokes written on the tablet 1 of FIG. 5 is given to the representative point extraction circuit 2. From that point
X ₁ , X ₂ ... X _N and Y ₁ , Y ₂ ... Y _N are output.

The stroke shape evaluation circuit 3 that responds to these characteristic points outputs the above distance d _S after performing known processing.

On the other hand, the stroke center-of-gravity movement evaluation circuit 5 which is a feature of the present invention performs the following processing.

First, the center of gravity calculation circuit 10 calculates the center of gravity ω _j = (ω _xj , ω _yj ).
Is required. X component for convenience of explanation The y component Is also the same.

Therefore, the control circuit 20 shown in FIG.
Feature points X ₁ to but supplied are outputted to the input A to the multiplexer 21, X ₂ ··· X _N while a letter to the adder 22, the characteristic point X ₁ on the control line 26, X ₂ · ·・_N pulses corresponding to X _N are sent to register 23, and register 23 Is retained.

After that, "1" is sent out on the control line 25, the multiplexer 21 sends the input B to the adder 22, and the clearing of the counter 24 is released to enable counting. At this time, pulses are sequentially output on the control line 26, and the number is counted by the counter 24. This operation is continued until the carry signal C is output from the adder 22. During this operation, the input B of the adder 22 is supplied with the 2's complement of N, so that the adder 22 functions as a subtractor.

The value held in the counter 24 when the carry signal C is generated from the adder is the x component of the center of gravity ω _j . Is.

The y component ω _yj of the center of gravity ω _j can be obtained in the same manner.

The center of gravity ω _xj thus obtained is set to ω _xj-1 through the delay flip-flop circuit (see FIG. 6), and the center of gravity ω _xj of the next stroke, which is a continuous stroke, is similarly obtained and the subtraction circuit 12 outputs g _xj = ω _xj −ω _xj-1 (the x component of the center _-of- gravity movement vector) (see FIG. 7), and the absolute value output subtraction circuit that responds to this g _xj and G _xj from the dictionary 14 13 outputs Δg _xj = | g _xj −G _xj |.

In parallel with the output of Δg _xj , y component circuit 15 outputs Δg _yj .

These Δg _xj and Δg _yj are supplied to the ROM 16 and from there Is output.

This d _g and the above-mentioned d _s are supplied to the decision circuit 6 and d _s + d _g
Is within a predetermined range, it is determined that the stroke having the correct shape is input in the correct stroke order. Explaining this with reference to FIGS. 9 and 10, even if the input characters have different glyphs (balance) from the dictionary as shown in FIG. 9,
When the stroke order is correct, the stroke center-of-gravity movement vector (arrow -----> in FIG. 9) is similar, so that accurate stroke order determination can be performed, and as shown in FIG. In this case, the stroke center of gravity movement vector is completely different even if the characters have the same balance (arrows for the third and fourth strokes in FIG. 10).
--->), it is possible to accurately determine the stroke order.

(G) Effect of the Invention As described above, according to the present invention, the stroke coordinate vector matching as the conventional stroke identification means, that is, the stroke shape evaluation technique, is added to the stroke center of gravity as the stroke moving direction evaluation means. Since the movement vector is taken into consideration, the effect that the stroke order can be surely determined is obtained.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a conventionally known first stroke fixing system, and FIG. 2 is a diagram illustrating a drawback of the FIG. 1 system.
FIG. 3 is a diagram for explaining a conventionally known second stroke identification method, and FIG. 4 is a diagram illustrating a drawback of the FIG. 3 method.
FIG. 5 is a diagram showing an embodiment of the present invention, FIG. 6 is a detailed diagram of a stroke center of gravity moving circuit of the embodiment of FIG. 5, FIG. 7 is a diagram for explaining a center of gravity moving vector, and FIG. 8 is FIG. 9 and FIG. 10 are detailed views of the center-of-gravity calculation circuit for explaining the effects of the present invention. In the figure, 1 is a tablet, 2 is a representative point extraction circuit, 3 is a stroke shape evaluation circuit, 4 is a dictionary, 5 is a stroke center of gravity moving direction evaluation circuit, and 6 is a determination circuit.

Claims (2)

[Claims] 1. A stroke identification method for inputting a coordinate sequence of strokes for drawing a character and determining whether or not the stroke order of the strokes matches the stroke order of a dictionary, and stores a center-of-gravity movement vector in the dictionary, and A feature point obtained from the coordinate series of the stroke, a feature point obtained from the coordinate series, and a stroke center-of-gravity moving direction evaluation for evaluating the center-of-gravity moving direction of two consecutive input strokes in response to the center-of-gravity moving vector of the dictionary. A stroke identification method comprising means for identifying an input stroke in response to an output from the means. 2. A stroke identification method for inputting a coordinate series of strokes for drawing a character and determining whether or not the stroke order of the strokes matches the stroke order of a dictionary, the feature points obtained from the coordinate series of the strokes. And a stroke center of gravity moving direction evaluating means for evaluating the center of gravity moving direction of two consecutive input strokes in response to the center of gravity moving vector of the dictionary, the evaluation value output from the stroke center of gravity moving direction evaluating means, and the characteristic A stroke identification method characterized in that the stroke is identified in response to the point and the evaluation value for the stroke shape obtained by the stroke shape evaluation means in response to the dictionary feature point of the dictionary.