JPH0146912B2 - - Google Patents

Description

[Detailed Description of the Invention] (1) Technical Field of the Invention The present invention provides a method for processing a group of contour point data obtained in the order of screen scanning for a binary image constituting the contour of an object.
The present invention relates to a contour line extraction method and apparatus for extracting contour line data along the contour of an object.

(2) Background of the technology Generally, in order to extract the shape of an object from a binary image that forms the outline of the object, or to determine various parameters such as the position of the center of gravity of the object and the circumference of the outline of the object, calculations are required. From the viewpoint of ease of use, it is necessary to extract contour data arranged along the contour of the object.

(3) Prior art and its problems As a conventional contour extraction method of this type, for example, as shown in FIG. 1, an X- Y
By setting a coordinate system in advance and scanning 2 the screen 1, a group of contour point data (X1,
Y1) (X2, Y2)...(Xn, Yn) are obtained in the screen scanning order, and these are stored in the contour point data memory 3,
Thereafter, the contour point data group is subjected to contour line extraction processing, and the contour point data group is converted into contour line data (X _A1 , Y _A1 ) ( X _A2 , Y _A2 )…(X _Ao , Y _Ao )
There is a method in which the contour line data is extracted and stored in the contour line data memory 4. In this method, as shown in FIG. 2, for example, as shown in FIG. 2, in this method, a starting point P (Xi, Yi) is determined in the contour point data, and eight surrounding positions A to G that can be connected to this starting point are After searching the contour point data memory 3 and extracting the next contour point connected next to the starting point P, the next contour point connected next to the extracted contour point is determined in the same manner as described above. By extracting the contour points and repeating this procedure thereafter, the extracted contour points are sequentially stored in the contour data memory as contour data.

However, in such conventional contour line extraction methods, in order to extract the next contour point connected to a certain contour point, data values at all eight locations surrounding one contour point are extracted. Since the contour point data memory 3 must be searched,
There is a problem in that the number of times the contour point data memory 3 is searched is required to obtain the final contour data, and the processing time for contour extraction takes a considerable amount of time.

(4) Purpose of the Invention The present invention has been made based on the above-mentioned viewpoints, and its purpose is to provide a contour line extraction method and an apparatus thereof, which are intended to shorten the processing time associated with contour line extraction. Our goal is to provide the following.

(5) Structure of the Invention The basic structure of the contour line extraction method according to the present invention is to extract a group of contour point data obtained in the screen scanning order from a closed-loop binary image that constitutes the contour of an object into the contour of the object. When extracting contour point data along the contour, the contour point data group is stored in advance in a contour point data memory, and the contour point data read first from the contour point data memory is used as the starting point of one of a pair of data point sequences. Out of the two points that can be connected to the starting point data, the upper and right contour point data is set as the other starting point of the pair of data point sequences, and at the stage when the starting point of the pair of data point sequences is extracted, either of the above While the contour point data connected to the end points of the data point sequence is detected as an extension point of the corresponding data point sequence, any contour point data sequentially read from the contour point data memory is the contour point data read out first. When not connected to the end points of a data point sequence, the above contour point data is used as one starting point of a new pair of data point sequences, and the other starting point and its extension point in this new data point sequence are sequentially processed in the same manner as described above. By detecting the contour point data, the contour point data group sequentially read out from the contour point data memory is stored in a point sequence buffer as multiple data point sequences, and then the end point data of each data point sequence is compared to connect each end point with each other. A contour line extraction method is characterized in that a relationship is determined, data point sequences that can be connected are combined and stored in a contour data memory.

The basic configuration of the device for carrying out the above method is to convert a group of contour point data obtained in the screen scanning order to a closed-loop binary image forming the contour of an object into contour data along the contour of the object. A contour line extraction device for extracting a contour line, which includes a contour point data memory that stores the contour point data group, and a point sequence buffer that sequentially stores contour point data sequentially read out from the contour point data memory as a predetermined data point sequence. and a point string end point register that sequentially stores each point string end point data corresponding to the end point of each data point string in this point string buffer, and a point string end point register that sequentially stores contour point data sequentially read from the contour point data memory. a determination means for determining whether or not the contour point data is adjacent to the point sequence end point data in the point sequence buffer; and when the determination means determines that the contour point data is not connected to the point sequence end point data, A start point detection means that sets a space for storing a point sequence, detects the contour point data as one starting point in a pair of data point sequences, and sends it to a point sequence buffer and a point sequence end point buffer, and the determination means. When it is determined that the contour point data is connected to the predetermined point sequence end point data, the contour point data is used as the other starting point in the pair of data point sequences or an extension point of the corresponding data point sequence to be stored in the point sequence buffer. Extended point detection means detects and sends this to a point sequence buffer and a point sequence end point register, and when all contour point data is stored in the point sequence buffer, the end point of each data point sequence in the point sequence buffer is detected. Closed loop forming means for comparing and determining the connection relationship between end points and extracting closed loop contour data by combining each point sequence that can be connected, and storing the contour data from this closed loop forming means. It is equipped with a contour line data memory.

(6) Embodiments of the Invention Hereinafter, a contour line extraction method and an apparatus thereof according to the present invention will be explained in detail based on embodiments shown in the accompanying drawings.

FIG. 3 is a block diagram showing an embodiment of the contour extraction device according to the present invention.

In the same figure, 3 stores a group of contour point data obtained in the screen scanning order for a closed-loop binary image that constitutes the outline of an object (see FIG. 5 b), as shown in FIG. 5 a, for example. contour point data memory,
Reference numeral 4 denotes a contour data memory for storing, for example, the contour point data group shown in FIG. 5b as contour line data along the outline of the object (see FIG. 5f), and 10 denotes a memory as shown in FIGS. 5b and 5d, for example. In addition, a point sequence buffer 11 stores the contour line data group sequentially read out from the contour point data memory 3 as two data point sequences T1 and T2, as shown in FIG. 5d and e, for example. Each data point sequence T1 in the column buffer 10,
This is a point sequence end point register that sequentially stores each point sequence end point data corresponding to the end point of T2, and this point sequence end point data consists of two X coordinates (X _T1 , X _T2 ) and one Y coordinate.
It consists of coordinate values.

In this embodiment, 12 also determines whether or not the Y coordinate value of the contour point data has changed compared to that of the previously read contour point data until the scanning of the contour point data memory 3 is completed. This is a process determination circuit that determines whether or not the scan goes down one step.This is a processing determination circuit that updates the Y coordinate value in the point sequence end point register 11 when the raster scan goes down one step. Upon completion, a raster scanning end signal S is output.

Further, 13 refers to the X coordinate value of the point sequence end point register 11 to determine which data point sequence in the point sequence buffer 10 the contour point data read from the contour point data memory 3 is connected to. This is a connection point determination circuit. FIG. 6 shows combinations of contour points located adjacent to the initial starting point. In the figure, the hatched part is the starting point of the other of the pair of point sequences. In addition, in cases 4, 5, and 6, the second contour point becomes the other starting point. Reference numeral 14 denotes a start point detection circuit that operates when the connection point determination circuit 13 determines that the contour point data is not connected to the data point sequence in the point sequence buffer 10; A space for storing a pair of data point sequences is set, the contour data is detected as the starting point of one of the pair of data point sequences, and this is sent to the point sequence buffer 10, and a point is set as new initial point sequence end point data. The data is sent to the column end point register 11. On the other hand, 15
is an extension point detection circuit that operates when the connection point determination circuit 13 determines that the contour point data is connected to the data point sequence in the point sequence buffer 10;
This means that if the other starting point of the pair of data point sequences in the point sequence buffer 10 is empty data, the contour point data is detected as the other starting point of the pair of data point sequences; If the starting point of the data point sequence is set, the above contour point data is detected as an extension point of the corresponding data point sequence,
This is sent to the point string buffer 10 and also to the point string end point register 11 as point string end point data to be updated.

Further, reference numeral 16 is a closed loop forming circuit that is activated by the raster scan end signal S from the processing determination circuit 12, and this circuit compares the end points of each data point sequence in the point sequence buffer 10 and determines the relationship between each end point. The connection relationship is determined, each point string that can be connected is connected, and each point string in the point string buffer 10 is read out in a closed loop.

Next, the operation of the contour point extracting device according to this embodiment will be explained using FIGS. 3 to 5.

Now, assuming that the closed-loop binary image that constitutes the outline of the object is as shown in FIG. 5a, the contour point data memory 3 stores the following information as shown in FIG.
Contour point data (X2,
Y3)...(X2, Y1) is stored. The first contour point data (X2,
Y3) is read out, first, the processing determination circuit 12
In , the Y coordinate value, which is empty data, of the point sequence end point register 11 is set to Y3, and then, when the contour point data (X2, Y2) is sent to the connected point determination circuit 13, the point sequence end point register 13 is set. Since the X coordinate value is empty data, it is determined that there is no data point sequence to which the contour point data (X2, Y3) are connected, and the contour point data (X2, Y3) is sent to the starting point detection circuit 14. Then, this starting point detection circuit 14 detects the point sequence buffer 1 as shown in FIG.
0, set a space to store a pair of data point sequences T1 and T2, detect the above contour point data (X2, Y3) as the starting point of one data point sequence T1, and send it to the point sequence buffer 10. , the Y coordinate values of the contour point data (X2, Y3) are sent to a pair of storage units (X _T1 , X _T2 ) of the point sequence end point register 11 as initial point sequence end point data. At this stage, the data point sequence T1 of the point sequence buffer 10 is stored with the above contour data (X2, Y3) as the starting point, the starting point of the data point sequence T2 is empty data, and the contents of the point sequence end point register 11 are as follows. It is arranged as shown in Fig. 5e, 1.

Next, as shown in FIG. 5b, when the next contour point data (X3, Y3) is read out from the contour point data memory 3, the processing determination circuit 12 The coordinate value is compared with the Y coordinate value of the point sequence end point register 11, but since both are equal, the point sequence end point register 11 is not updated. Then, when the contour point data (X3, Y3) is sent to the connected point determination circuit 13, the X coordinate value of this contour point data (X3, Y3) is stored in the point sequence end point register 13.
The connection point determination circuit 13
determines that this contour point data (X3, Y3) is connected to any of the point sequence end points (X _T1 , X _T2 ) = (X2, Y2), and connects the above contour point data (X3, Y3)
is sent to the extension point detection circuit 15. Then, this extension point detection circuit 15 receives the contour point data (X3,
Y3) is detected as the starting point of the other data point sequence T2,
This is sent to the point sequence buffer 10, and the Y coordinate value of the contour point data (X3, Y3) is stored in one storage section of the point sequence end point register 11 as point sequence end point data.
Store in X _T2 . At this stage, each data point sequence T1, T2 of the point sequence buffer 10 is stored with each contour point data as a starting point, and the contents of the point sequence end point register 11 are as shown in FIG. 5.

Furthermore, when the next contour point data (X1, Y2) is read out from the contour point data memory 3, the processing determination circuit 12 determines that the Y coordinate value of the contour point data (X1, Y2) is stored in the point sequence end point register 11. Since it is different from the Y coordinate value, set the Y coordinate value of the point sequence end point register 11 to Y2.
Update to. Then, the above contour data (X1,
Y2) is sent to the connection point determination circuit 13, the connection point determination circuit 13 receives the contour point data (X1,
It is determined that the contour point data (X1, Y2) is connected to the point sequence end point data X _T1 =X2, and the contour point data (X1, Y2) is sent to the extension detection circuit 15. Then, this extension detection circuit 15 detects the contour point data (X3, Y3) as an extension point of one data point sequence T1, sends it to the point sequence buffer 10, and also detects the contour point data (X1, Y2) as an extension point of one data point sequence T1. ) is stored in one storage section X _T1 of the point sequence end point register 11 as point sequence end point data. Thereafter, processing is performed in the same manner as described above, and the contour point data (X3, Y2) is connected to the data point sequence T2, and at this stage the contents of the point sequence end point register 11 are as shown in Figure 5 e, 3. It's getting old. Then, when the contour point data (X1, Y1) is read from the contour data memory 3, the Y coordinate value of the point sequence end point register 11 is updated again, and the contour point data (X1, Y1) is read out from the data point sequence. Contour point data (X2, Y1) connected to T1 and finally read out
is also connected to the data point sequence T1. At this stage, scanning of the contour point data memory 3 is completed,
Each contour point data is stored in the point sequence buffer 10 in an arrangement as shown in FIGS. 5c and 5d. The contents of the point sequence end point register 11 are as shown in FIG. 5, e and 4.

In this case, the raster scanning end signal S is given from the processing determination circuit 12 to the closed loop forming circuit 16, and the closed loop forming circuit 16
It is determined that the end points (X2, Y1) (X3, Y2) of T1 and T2 are connected, and the data point sequence T1 is scanned in the forward direction and the data point sequence T2 is scanned in the reverse direction to obtain the data of each data point sequence. Read out. This read data is extracted as contour point data along the contour of the object shown in FIG. 5a in a counterclockwise direction.

This contour data is then stored in the contour data memory 4 as shown in FIG. 5f.

In the above embodiment, the case where there are two data point sequences is explained, but if the present invention is applied to objects with complex outlines,
Since the start point detection circuit 14 operates on the contour point data that is being processed, the number of data point sequences increases accordingly, and contour line data can be extracted by appropriately combining each data point sequence. . Further, the specific configuration of the device according to the above embodiment may be modified as appropriate.

(7) Effects of the Invention As explained above, according to the contour line extraction method and device according to the present invention, the memory storing the contour point data group is scanned once to generate an intermediate data point sequence. Contour line data can be extracted by storing the data in a point sequence buffer and operating the point sequence buffer only once so as to combine each data point sequence. Therefore, it is possible to speed up the processing time associated with contour data extraction.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an example of a conventional contour extraction method, FIG. 2 is an explanatory diagram of the principle used in the contour extraction process, and FIG. 3 is an embodiment of the contour extraction device according to the present invention. Block diagram showing 4th
The figure is a flowchart showing the basic operation of the contour line extracting device shown in FIG. 3, FIG. 5 shows the specific operating state of the contour point extracting device shown in FIG. 3, and FIG. An example of a binary image is shown in Figure 5b.
shows the contents of the contour point data memory, FIG. 5c shows the order of storing data in the point sequence buffer, FIG. 5d shows the contents of the point sequence buffer, and FIG. FIG. 5f is an explanatory diagram showing the contents of the contour data memory, respectively, and FIG. 6 is a diagram showing combinations of ways in which contour points are present at locations adjacent to the initial starting point. 3... Contour point data memory, 4... Outline data memory, 10... Point sequence buffer, 11... Point sequence end point register, 12... Processing determination circuit, 13...
connection point determination circuit (determination means), 14...start point detection circuit (means), 15...extension point detection circuit, 16...
...Closed loop forming circuit.

Claims (1)

[Claims] 1. When extracting a group of contour point data obtained in the screen scanning order for a closed-loop binary image forming the contour of an object as contour point data along the contour of the object, the group of contour point data is extracted as contour point data along the contour of the object. The contour point data stored in advance in the contour point data memory and read out first from the contour point data memory is set as one starting point in a pair of data points, and the upper and rightmost point of the two points that can be connected to this starting point data is Set the contour point data as the other starting point of the pair of data points, and
At the stage when the starting point of a pair of data point sequences is extracted, the contour point data connected to the end point of one of the data point sequences is detected as an extension point of the corresponding data point sequence, and the contour point data are sequentially extracted from the contour point data memory. If any contour point data to be read is not connected to the end point of a data point sequence based on previously read contour point data, the contour point data is used as one starting point of a new pair of data point sequences, and this new data point is By sequentially detecting the other starting point in the row and its extension point in the same manner as described above, the contour point data group sequentially read out from the contour point data memory is temporarily stored in the point sequence buffer as a plurality of data point sequences. A contour extraction method characterized in that the end point data of each data point sequence is compared to determine the connection relationship between each end point, and data point sequences that can be connected are combined and stored in a contour data memory. Method. 2. A contour extraction device that extracts a group of contour point data obtained in screen scanning order from a closed-loop binary image constituting the contour of an object as contour data along the contour of the object, A contour point data memory for storing, a point sequence buffer for sequentially storing contour point data sequentially read from this contour point data memory as a predetermined data point sequence, and corresponding to the end points of each data point sequence in this point sequence buffer. A point string end point register that sequentially stores each point string end point data, and a determination that determines whether the contour point data sequentially read from the contour point data memory is adjacent to the point string end point data in the point string register. a means for setting a space for storing a pair of data point sequences in the point sequence buffer when it is determined by the determination means that the contour point data is not connected to the point sequence end point data; starting point detection means for detecting the contour point data as one of the starting points and sending it to a point sequence buffer and a point sequence end point buffer; Detect the contour point data as the other starting point of the pair of data point sequences to be stored in the point sequence buffer or an extension point of the corresponding data point sequence, and send this to the point sequence buffer and point sequence end point register. When all the contour point data are stored in the point sequence buffer, the extension point detection means compares the end points of each data point sequence in the point sequence buffer to determine the connection relationship between each end point, and can be connected. A contour extraction device comprising a closed loop forming means for extracting closed loop contour data by combining point sequences, and a contour data memory for storing the contour data from the closed loop forming means.