JPH03226877A - Hand-written character and graphic separating method - Google Patents

Abstract

PURPOSE:To obtain the separation result of high precision by discriminating the stroke discriminated as a character stroke once to discriminate the final character or graphic stroke. CONSTITUTION:A recognizing device consists of an input part 1, a first processing part 2, a coordinate memory 3, a stroke memory 4, and a second processing part 5. After graphic strokes other than character strokes are surely separated in the first processing, strokes changing from characters to graphic or changing from graphics to characters out of discrimination results obtained by the first processing are finally discriminated as character strokes or graphic strokes again by the second processing based on proximity relations to graphic strokes. Thus, strokes are correctly separated to improve the precision of character recognition and graphic recognition.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a handwritten character/figure separation method for separating and determining characters and figures handwritten using a tablet into characters and figures.

[Prior art] As this type of conventional technology, for example, Japanese Patent Application Laid-Open No. 60-233
A method disclosed in Japanese Patent No. 780 is known. In this method, a rectangular frame is set circumscribing each stroke constituting a character or figure, and the strokes are separated according to the length of the long side of the rectangular frame. In other words, a line figure handwritten on a tablet is input as time-series coordinate data, and one stroke is defined as from pen-down to pen-up, and the maximum and minimum values are calculated from the time-series coordinate data (xt, y+) of this one stroke. The stroke was determined by calculating the value, performing a desired calculation on it, and comparing the result of the calculation with a threshold value.

Here, time series coordinate data of one stroke (xt, y,)
, let the maximum value of X be X max and the minimum value X
The maximum value of m1n and y is Y max and the minimum value is Y
ΔX = X max −X min
, ΔY = Y max −Y +l1in. Here, if the larger value of ΔX and ΔY is larger than a predetermined threshold, the stroke within the rectangular frame is determined to be a stroke that constitutes a line figure other than a character; otherwise, It is determined that the strokes constitute a character.

[Problems to be Solved by the Invention] However, the conventional method described above has a problem in that short graphic strokes other than original character strokes are also classified as individual character strokes.

FIG. 2(a) is a diagram for explaining a conventional stroke recognition method, and 81 to 823 indicate strokes forming a character or a figure, respectively. Also the second
Figure (b) shows the circumscribed rectangular frame and its coordinates set for the stroke unit. In the conventional method, as shown in FIG. 2(a).

1-stroke S representing a short connecting line],
Strokes S1, S2, S that represent 4 or part of a symbol
15 is separated as a character. Therefore, there are problems in that errors in character recognition increase, and jets increase in figure recognition due to reasons such as partial omission of symbol strokes.

Therefore, in order to solve the above-mentioned problems, the present invention further performs a determination on strokes that have been determined to be character strokes, and determines the final character or figure stroke, thereby obtaining highly accurate separation results. The purpose is to provide a method for separating handwritten characters and figures.

[Means for Solving the Problems] The present invention provides a handwritten character/figure separation method for separating characters/figures handwritten on a tablet into characters and figures.
Set a rectangular frame that circumscribes each stroke, compare the length of the long side of this rectangular frame with a preset threshold, and if the length of the long side is greater than the threshold, the length of the rectangular frame is A first process in which a stroke is determined to be a figure stroke, and in other cases it is determined to be a character stroke, and in the first process, the determination result of the previous and subsequent strokes is from a character stroke to a figure stroke, or from a figure stroke to a character stroke. If the character stroke has changed, a second process is provided in which the character stroke is re-determined as a character stroke or a graphic stroke based on whether or not the end point of the character stroke is in a proximity relationship with the graphic stroke. It is something that

[Operation] In the first step of the present invention, graphic strokes other than characters are first reliably separated by setting a stroke frame with a separation determination size larger than a preset character frame size. Next, strokes that are smaller than the threshold and are determined to be characters may be part of a figure stroke, so in the second process, strokes that are smaller than the threshold and judged as characters are selected as character strokes among strokes that change from a character to a figure or from a figure to a character. The final character stroke or graphic stroke is obtained by focusing on the character stroke and performing a simple feature determination of the proximity relationship with the graphic stroke.

[Example 1] FIG. 1 is a block diagram of a recognition device used to implement the handwritten character/figure separation method of the present invention.

1 is an input section consisting of a styluse pen and a tablet; 2 is a screen 1 of handwritten characters and figures output from the input section 1;
- A first processing unit that performs separation processing between characters and figures by comparing the size of the stroke with a threshold value; 3 is a coordinate memory (MZ) that stores the coordinates of each point of a stroke; 4 is a character and a figure for each stroke; Stroke memory (MS) that stores figure judgment results, circumscribed rectangle information, link information with coordinate memory, etc.
, 5 is a second processing unit that refers to the coordinate memory 3 and the stroke memory 4 after inputting all strokes and makes a final character/figure separation determination.

An outline of the character/figure separation method according to the present invention using such a configuration device will be explained by taking as an example the case where a line drawing shown in FIG. 2(a) is input.

The input unit 1 recognizes the movement of the stylus pen on the tablet from pen down to pen up as one stroke, samples the movement of the stylus pen within this one stroke at a fixed time, and records the pen position in chronological order. Extract as coordinate data (xk, yk). Processing section 2
stores these coordinate data in the coordinate memory 3, and also stores the maximum value (Xmax) and minimum value (Xmi) of x as circumscribed rectangle information of the stroke as shown in FIG. 2(b).
n), and the maximum value (Ymax) and minimum value (Y
mjn), ΔX=Xmax −Xmin, and Δ
Calculate Y = Ymax - Ymin, and calculate the larger of them (], = max (ΔX, 8Y)) and the threshold (thi)
]≧thl, the stroke is determined to be a figure stroke (JFLG=1), and l<thl, the stroke is determined to be a character stroke (JFLG=1).
LG=O). These determination results, information on the circumscribed rectangle of the stroke, etc. are stored in the stroke memory 4. Note that the threshold value (thl) at this time is determined by using, for example, thl = 1. 5 Xmax (ΔX, Δy).

The above-mentioned character frame size is displayed in a predetermined area on the display screen using a tablet with integrated display and input (for example, a liquid crystal tablet), and is used as a guide for determining the character size and graphic size of the person filling out the form. I can do it.

The results of character/figure determination by the first processing section 2 as described above are shown in the first row of FIG. Here, 0.1 corresponds to the determination results for characters and figures, respectively.

At this stage, strokes S14 and 815 are erroneously determined to be character strokes.

Next, the second processing unit 5 refers to the determination results stored in the stroke memory 4, and focuses on strokes that are determined to be characters, with respect to strokes that change from characters to figures or from figures to characters, It is checked whether there is a stroke determined to be a figure near the start point or end point of the stroke. If there is a stroke determined to be a graphic at this time, the first stroke of interest is re-determined to be a graphic stroke. The above-described process is repeated until there is no new set of toslovs that change from a character to a figure or from a figure to a character.

The second line of FIG. 4 shows the processing results when focusing on the strokes S2, S5-815.818, and S22 with reference to the results of the processing section 1.

Since the starting points of stroke S2 and strokes S3 and S4 are located nearby, stroke S2 is determined to be a figure.
Also, the end points of stroke 1 to stroke 515 are stroke 816.8
Since it exists near the end point of No. 17, it is similarly determined to be a graphic stroke.

As a result of this re-determination process, strokes S1 to S1 and stroke S14 newly become the target strokes of interest. As for the stroke S1, since its end point exists near the end points of the strokes S3 and S4, similarly to the stroke S2, it is determined that the stroke S1 is a figure stroke. Also stroke S
14 is determined to be a graphic stroke because its end point and the midpoint of stroke S4.816 are close to each other. The result of this processing is shown in the third line of FIG. As a result, there is no new stroke that changes from a figure to a character or from a character to a figure, so the determination is final.

FIG. 5 is a flowchart showing the overall processing flow of the handwritten character/figure separation method of the present invention, and FIGS. 6 to 8 are flowcharts showing the detailed processing flow. The character/figure separation method of the present invention will be explained in more detail using these flowcharts.

When the process starts in FIG. 5 (step 5TO)
, a first process is performed using the time-series coordinates obtained from the input unit 1 (step 5TI), and the results are stored in the coordinate memory 3 and the stroke memory 4. After the first process is completed, set the variable i to the initial value 1 in step 5T2.
), and a variable CHGF indicating that there is a stroke whose determination has changed from character to graphic as a result of the second process is initialized (step 5T3). Next, flag information PFLGi is read from the stroke memory 4 at the address indicated by variable i.

Note that FIG. 9(a) shows the memory contents of the coordinate memory 3 and stroke memory 4 shown in FIG. PFLG is a flag that determines whether the subsequent steps ST5 and Sr1 are necessary; if PFLGi=1, step S
Proceed to step ST7 without performing the processing of T5 and Sr1,
If PFLGi=0, proceed to step ST5. Step S
At T4, from the stroke memory MS indicated by variables i, i-1, and i+1, J F LG+ , J F LG+
−+, JFL G s, r, and JFL
GI=O and JFLGl,,,=1 or JFLG
, =O and JFLGl, , =1, the second process is performed with stroke i as the stroke of interest (step 5T6).

If the above-mentioned conditions are not satisfied, the variable i is incremented in steps ST1-9, and the processes of steps ST4-ST6 are repeated for all input strokes (
In step 5T8), if CHGF=1 after the end (step 5T9), that is, if there is a stroke in which the determination result changes from a character to a figure, the process returns to step ST2 and the same process is performed. Further, if CHGF==0, the character/figure separation process is ended (step 5TIO).

Figure 6 shows a flowchart of the first process.
First, when the process starts (step 5TI00), a variable n for counting the number of strokes and a variable m for counting the cumulative number of coordinates are initialized (step 5TIOI), and a state variable 5TATUS is initialized (step 5T102).

Next, in step 5T103, input data is read. In addition to coordinate data, the input data also includes data indicating whether the pen is in contact with the tablet (pen up/down) or data indicating on/off of a switch for a specific application. In step 5T104, when the switch-on is detected, it is determined that all stroke inputs have been completed, and the process is ended (step 5T119). In step 5T105, the state of pen down or pen up is detected, and if the pen is up, the process proceeds to step STI12 and subsequent steps, and if the pen is down, the process proceeds to step ST'IO6 and subsequent steps. In step 5T106, check the 5TATUS variable and
If ATUS=0, it is determined that the state has changed from pen-on to pen-down, and the processes from step 5T107 to step 5T110 are performed. In step 5T107, in order to maintain the pen down state, 5TA
TUS=1 is set, and the start address of the coordinate memory where the coordinate information of the nth stroke is stored is held in TPAn (step 5TI08).

Furthermore, a variable Xm to obtain the circumscribed rectangle information of the stroke
Set the currently input coordinate values (x, y) as the initial values of 1n +'
'Y) is written to the coordinate memory 3. Step 5TI06
When 5TATUS=1, it means that the entry of 1st stage to 1st row is continuing, so step 5TILL
After updating the circumscribed rectangle information, the process proceeds to step 5T1108. When 5TATUS=O in step 5T112, the process returns to step 5T103, but when 5TATUS=1, it is determined that the pen-down state has changed to the pen-up state, that is, the input of one stroke has been completed, and the number of strokes is increased in step STI. 13), calculate the length (1) of the long side of the circumscribed rectangular frame (step 5T114.
). The character/figure of the m-th stroke is determined by comparing the value of ``length of this long side'' with the aforementioned threshold value thl (steps 5T116.5T117), and the determination result is used to determine the start address of the coordinate memory and the circumscribed The rectangle information is stored in the stroke memory MS(n) whose address is variable n (step 5T118). At this time, the term of the flag information PFLG mentioned above is stored as O.

FIG. 7 is a flowchart of the second process.

First, after starting the process (step 5T600), initialize the variable j (step 5T601), and write J F L G from the stroke memory MS (j) whose address is the variable J.
Read r (Step 5T602), and if the value is 1, that is, the figure stroke, Step 5T60
Perform step 3. Also, if JFLG=0, step 5 is used to repeat steps 5T602 and 5T603.
Proceed to T604.5T605. Here step 5T6
In Step 5T607, it is determined whether or not the noticed stroke i and the stroke j are close to each other by the method described later. ), the variable CH mentioned above
Set GF to 1. Furthermore, remember that there is a stroke where the judgment flag changes from text to figure.Step 5
T608), end the process (step 5T609)
,,Also, if it is determined through steps 5T603 to 5T605 that the first stroke j is not close to the graphics 1 to 5T605, remember that the stroke 1 of interest is finally determined to be a character (step 5T606), place
5 Finish the process.

FIG. 8 is a flowchart showing the proximity determination processing flow of step 5T603 described above. First step 5T
At 6031, the start address and end address for reading the coordinate information of stroke i and stroke j are read from the stroke memory 4. Then, the start and end addresses of the coordinate data of stroke i are is and 1e, respectively.
In addition, the start and end addresses of the coordinate data of stroke j are stored in js and je, respectively. Next, in step ST603, it is checked whether the strokes 1 and j are close to each other in terms of the positional relationship of the circumscribed rectangles. That is, strokes i, j
The position of the circumscribed rectangle is (Ximin, Y 1m1n),
(X jmax, Y imax) and (Xjmin,
Y jmin), (X jmax, Y jmax), Xjmjn-D≦X 1m1n, X jma
x≦X jmax+D (1) Yjmin−D≦Y
1m1n, Y imax≦Y Jmax+D
When (2) holds true, stroke i and stroke j
It is determined that the strokes are close to each other, and the following conditions are checked in step 5T6033. If this condition is not satisfied, step 5T60 described above
Return to 4. Here, the parameter D in the above-mentioned equations (1) and (2) is determined experimentally. Step 5T6033
Then, it is checked whether the distance between the end points of the stroke is less than or equal to the parameter D. That is, dis(i, j) = max(ΔXIj, ΔY
Ij)+(Δ8..

,Δu+a)/2'
(3) ΔXI J =]X1−Xj1. A Y
I J''(Yl-'/J) (4), d
is (i, j) < D (is, Js), (is, je
), (je, js), (ie, je), and if any of the pairs is satisfied, the stroke i determined to be a character is connected to the stroke j determined to be a figure at the end point. are close to each other, the process advances to step 5T607 described above. If the condition of step 5T6033 is not satisfied, the process proceeds to step 5T6034 and subsequent steps in order to further investigate the proximity relationship between the end point of stroke i and the midpoint of stroke j. Step 5603
Step 5T6035), step 5T6, set the variable j" in step 4, and apply it to the intermediate point excluding both end points of the stroke J.
Check the conditions of 036. That is, dis (i
s, je) < D or d i s (i e, je)
<Check whether one of the conditions D holds true. If established, the end point of stroke i and stroke j
It is determined that the intermediate point is close to each other, and the process proceeds to step 5T607, and if not satisfied, the process proceeds to step 5T604.

[Effects of the Invention] As described above in detail based on the embodiments, according to the present invention, graphic strokes other than characters are first reliably separated in the first process, and then the first process is separated in the second process. Among the judgment results obtained in , for strokes that change from characters to figures or from figures to characters, the final judgment is made between character strokes and figure strokes based on the proximity relationship with figure strokes. Because there are
Strokes that are incorrectly separated using conventional methods can be correctly separated. Therefore, it is expected that the precision of character recognition and figure recognition will be improved, and furthermore, the present invention can be applied to high-precision handwritten character and figure recognition devices.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a recognition device used to implement the handwritten character/figure separation method of the present invention, FIG. 2 is a diagram illustrating a conventional stroke extraction method, and FIG.
The figure is a diagram for explaining the setting of the character frame size and separation judgment size according to the present invention, Figure 4 is a diagram showing the separation result of characters and figures according to the present invention, and Figure 5 is the overall processing flow of the present invention. 6 is a flowchart showing the flow of the first process of the present invention, FIG. 7 is a flowchart showing the flow of the second process of the present invention, and FIG. 8 is a flowchart showing the flow of the proximity determination process according to the present invention. The flowchart shown in FIG. 9 is a diagram showing the contents of the coordinate memory and stroke memory used in the present invention. processing section.

Claims (1)

[Claims] In a handwritten character/figure separation method for separating characters/figures handwritten on a tablet into characters and figures, one stroke is defined as from pen down to pen up, and a rectangular frame circumscribing each stroke is set. Then, the length of the long side of this rectangular frame is compared with a preset threshold value, and if the length of the long side is larger than the threshold value, the stroke within the rectangular frame is determined to be a figure stroke, and otherwise, it is determined that the stroke is a character stroke. The first process of determining a stroke; and If the determination results of the previous and subsequent strokes in the first process change from a character stroke to a figure stroke, or from a figure stroke to a character stroke, this character stroke A handwritten character/figure separation method comprising: a second step of re-determining the character stroke as a character stroke or a figure stroke based on whether the end point is in a proximity relationship with the figure stroke.