JPS6053918B2 - Stroke pair crossover detection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for detecting the intersection of stroke pairs by examining the intersection relationship between segments belonging to one stroke and segments belonging to the other stroke. This relates to the detection method.

In an online recognition system for handwritten characters, the number of strokes that make up a character, the intersection of strokes, etc.
This is an important feature in identifying characters.

FIG. 1 shows a character consisting of three strokes.

As is clear from FIG. 1, in the character ``ni'', 1, 2, and 3 are all stably non-intersecting. Character '゛±'
In ', stroke 1 and stroke 2 always intersect stably, and stroke 1 and stroke 3 intersect unstablely. In the character ``above'', stroke 1 and stroke 2 intersect unstably, and stroke 1 and stroke 3 intersect unstably. In this way, in recognizing handwritten characters, the number of strokes, intersection relationships, and the like are important features in identifying characters. As a conventional stroke pair detection method, for example, the nearest distance method is known.

FIG. 2 shows an example in which a crossover is detected by the nearest distance method. When inputting characters from a handwritten character input device, character strokes are generally stored as a set of sampling points P1 to Pi. In the nearest distance method, when detecting the intersection of stroke A and stroke B, sampling points PAI to PA7 belonging to stroke A and sampling point PBI belonging to stroke B are used.
or PB6, calculate the nearest distance dmin, and calculate the nearest distance d
It is determined that there is a crossover when min is smaller than the set value do, and it is determined that there is no crossover when the nearest distance dmln is larger than the set value do. The nearest distance method has the advantage of a simple detection algorithm, but if the distance between sampling points is large, it may be determined that there is no crossover even though there is a crossover, as shown in Figure 3. There is.

The distance between sampling points becomes smaller when the writing speed of handwritten characters is slow, and increases when the writing speed is fast. Furthermore, if the stroke A and the stroke B have a relationship as shown in FIG. 4, it is determined that there is a crossover even though there is no crossover. The present invention is based on the above consideration, and an object of the present invention is to provide a stroke pair detection method that can always reliably detect an intersection between two strokes.

Therefore, in the stroke pair detection method of the present invention, in a stroke pair crossover detection method that detects the intersection of two types of strokes A and B, each of which is composed of a continuous segment series, the segment information of the stroke A is Cross-relationships are detected using the stored A stroke buffer, the B stroke buffer in which the segment information of the stroke B is stored, the segment information read from the A stroke buffer, and the segment information read from the B stroke buffer. a 2-segment series crossover relationship detection circuit; a crossover position and type output circuit that outputs a crossover position, crossover type, and number of crossovers based on the detection results of the 2-segment relationship detection circuit; address determining means for determining the addresses of the next two segments to be compared based on the address determination means, and the process of examining the cross-relationship between the segment of stroke A and the plurality of segments on stroke B is performed for each of the plurality of segments on stroke A. The present invention is characterized in that it is configured such that the number of intersections, the intersection position, and the intersection type of stroke A and stroke B can be detected. below,. The present invention will be explained with reference to the drawings. FIG. 5 shows a case where stroke A expressed by sampling points PAl to PA7 and stroke B expressed by sampling points PBl to PB8 have two intersections.

When the number of samplings of stroke A- and the number of samplings of stroke B are Na and rlb, respectively, stroke A is represented by a series of (Na-1) consecutive segments. A segment means a line segment between adjacent sampling points. In order to check whether there is an intersection between stroke A and stroke B, in principle, the process of checking the intersection relationship between one segment belonging to stroke A and multiple segments belonging to stroke B is It is sufficient to perform this for all segments belonging to A.

Figures 6 to 10 illustrate the types of crossovers.

FIG. 6 shows a case where segment Ai and segment Bj do not intersect.

Note that segment Bj means a line segment between sampling point PAi and sampling point PAi+1, and segment Bj is a line segment between sampling point PBj and sampling point PB.
It means the line segment between j+1. Processing to determine whether or not there is an intersection between a segment and a segment Bj is performed as follows. The method of the straight line included in the segment and the equation of the straight line including the segment Bj are determined, and the coordinates of the intersection of the two are calculated. Then, it is determined whether the coordinate values of the intersection exist on segment A and segment B. If the coordinates of the intersection exist on segments A and B, then segment A and segment B intersect. Segment N
If there is no crossover between segment Ai and segment Bj, then the crossover relationship between segment Ai and segment Bj+1 is examined.

Perform the above steps sequentially to create segments and segment B.
After examining the crossover relationship between nb-1, next segment A
Examine the intersection relationship between i+1 and segments B1 to Bnb-1. When the cross-relationship check between segment Arla-1 and segments B1 to Bnb-1 is completed, all cross-relationship checks are completed. FIG. 7 shows a case where segment Ai and segment Bj are cross-connected.

The cruciform bond is called a cross type ``1'' bond.
After checking the cross-relationship between segment Ai and segment Bj, the cross-relationship between segment Ai and segment Bj+1 is checked. After checking the cross-relationships between segment Ai and segments B1 to Bnb-1 belonging to stroke B, the cross-relationships between segment Ai+1 and all segments belonging to stroke B are checked. FIG. 8 shows the case of a cross bond in which the end point of segment Bj contacts the midpoint of segment Ai. Such a crossover is called crossover type 662
It is called the crossover of ゛. If the segment Bj intersects with the intersection type ゜゜2゛, the cross relation between the segment Ai and the segment Bj is checked, and then the cross relation between the segment Ai and the segment Bj+2 is checked. The reason for omitting the check for the cross-relationship between segment Ai and segment Bj+1 is that there can be no other relationship between segment N and segment Bj+1 other than the starting point of segment Bj+1 touching the midpoint of segment Ai. After the cross-relationships between segment Ai and all segments belonging to stroke B are checked, the cross-relationships between segment Ai+1 and all segments belonging to stroke B are checked. FIG. 9 shows a case where the end point of segment Ai is cross-connected to the midpoint of segment Bj.

Such a crossover is called a crossover of crossover type ゜"3".After checking the crossover relationship between segment Ai and segment Bj, the crossover relationship between segment Ai and segment Bj+1 is checked.Segment A1 and stroke After checking the cross-relationships of all segments belonging to B, the cross-relationships between segment Ai+2 and the segments belonging to stroke B are checked.The cross-relationships between segment Ai+1 and the segments belonging to stroke B are checked. The reason why we omitted checking the cross-relationship between segment Ai+1 and the segment belonging to stroke B is that the length of the segment is sufficiently short, so if the starting point of segment Ai+1 is in contact with stroke B, stroke B is This is because it does not exist as a practical matter to intersect segment N+1 again. FIG. 10 shows a case where segment Ai and segment Bj are connected in an L-shape.

Such a crossover is called a crossover of crossover type "4". After checking the crossover relationship between segment Ai and segment Bj, the crossover relationship between segment Ai and segment Bj+2 is checked. After checking the cross-relationships of all the segments belonging to the stroke B, the cross-relationships of the segment Ai+2 and all the segments belonging to the stroke B are checked. FIG. 11 shows a stroke pair cross-over detection system. 1 is an address increment circuit, 2 is an address return/end circuit, 3 is an A stroke buffer, 4 is a B stroke buffer, 5 is a two-stroke crossover relationship detection circuit, and 6 is a crossover position/type output circuit. .

Also, RN is the crossover type display signal, i<5J is the current address information, Na is the sampling point number of stroke A, oil is the sampling point number of B stroke, i and j are the next address information, X8, and Yll are the segment Ai's sampling points. The starting point coordinate values, Xai+1 and Yai+1 are the ending point coordinate values of segment Ai, Xbj and Ybj are the starting point coordinate values of segment Bi,
XbJ+1 and Ybi+1 are the end point coordinate values of segment Bi, L<5L'' is the address adjustment signal, CNT is the number of crossovers, and A
C. ! 1. BC indicates a crossover position signal, respectively.
The address increment circuit 1 includes the immediately preceding comparison segment pair Ai,
．． The next address information 1'' is determined by the cross type signal of Bj.
+j''. This address increment circuit 1
are synchronized with the clock and address information 1, . Convert j as follows. Then, when L''=1, when L=0 and the start signal is RlJ, i''=1, j''=1, and L=0.

The address return/termination circuit 2 performs the following operations. When j = oil, and other times, when address information 1 is input to the A stroke buffer, coordinate values X8, Ya, and coordinate values X8j+1, Y are input.
Output ll+1.

When address information j is input, the B stroke buffer stores coordinate values Xb,, Yb, and coordinate values XbJ+1, Y
Output bj+1.

The two-segment crossover relationship detection circuit investigates the crossover relationship between segment Ai and segment Bj, and outputs the following crossover type signal RN depending on the crossover type.

When non-crossover RN=0 crossover type゜゜゛crossover RN=1 crossover type'621
When there is a crossover of RN=2 crossover type "゜3゛" When there is a RN=3 crossover type "゜゜4" crossover
The RN=4 crossover position/type output circuit 6 performs the following processing.

When the crossover type signal RN is not “0”, the crossover number signal C
Add 1 to NT.

Further, the following crossover position signals AC, . Output BC. Next, the operation of the stroke pair crossover detection system shown in FIG. 11 will be explained.

When the 4-star lower signal becomes logic RlJ, i″=1, j″
=^, L=0.

@ Address I. ．． The coordinate values of segment Ai and segment Bj corresponding to j are read from the A stroke buffer 3 and the B stroke buffer 4.

(c) Cross-relationship RN between segment Ai and segment Bj
seek.

When detecting 4 crossovers, the crossover number signal C is synchronized with the clock.
It outputs the NTl crossover position signal AC<5BC and the crossover type signal RN.

8 The next address 1゛,j'' by the address increment circuit 1
is determined according to the crossover type signal RN.

(F) When the crossover type signal RN is ゜゜3゛ or ゛4゛, L=1 is set in order to skip the reference segment on the next stroke A to segment Ai+2. Return to 4.

When 5j″=Nb, j returns to 1 and i=i″+1+L
Then, L″=1 and returns to L=0.

When the process reaches 7i''=Na, the END signal becomes 0N and the process ends.

As is clear from the above description, according to the present invention, intersections of stroke pairs can always be detected reliably, and the number of intersections and the location of the intersections can also be known.

[Brief explanation of the drawing]

Figure 1 is a diagram explaining character strokes and their intersection positions.
Figures 2 to 4 are diagrams explaining a conventional stroke pair crossover detection method, Figure 5 is a diagram showing an example of stroke pair crossover, and Figures 6 to 10 are diagrams explaining a crossover type. , FIG. 11 is a block diagram of one embodiment of the present invention.

Claims (1)

[Claims] 1. In a stroke pair crossover detection method that detects the intersection of two types of strokes A and B, each of which is composed of a continuous segment series, an A stroke buffer in which segment information of the stroke A is stored;
a B stroke buffer in which segment information of the stroke B is stored; a two-segment cross relationship detection circuit that detects a cross relationship using the segment information read from the A stroke buffer and the segment information read from the B stroke buffer; A crossover position/type output circuit that outputs the crossover position, crossover type, and number of crossovers based on the detection results of the 2-segment crossover relationship detection circuit, and a crossover position/type output circuit that outputs the crossover position, crossover type, and number of crossovers based on the detection results of the 2-segment crossover relationship detection circuit, and the next 2 segments to be compared based on the detection results of the 2-segment crossover relationship detection circuit. address determining means for determining the address of the stroke A, and performs a process of examining the intersection relationship between the segment of the stroke A and the plurality of segments on the stroke B for each of the plurality of segments on the stroke A, thereby determining the address of the stroke A. 1. A stroke pair crossover detection method, characterized in that the number of crossovers, the crossover position, and the crossover type of stroke B and stroke B can be detected.