JP2868643B2 - Method for extracting closed area of figure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for extracting a part of a closed area from a line figure.

[0002]

2. Description of the Related Art In a plate making process, image processing is performed in which a part of a closed area in a figure is painted with a specific color or a picture image is pasted in the closed area.
In order to perform this image processing, it is necessary to first extract a closed region in the figure.

FIG. 15A shows two closed loops F1,
It is a figure showing the figure which has F2. Each of the two rectangular closed loops F1 and F2 is composed of a plurality of vectors forming a closed loop. In FIG. 15A, for example, a closed region R formed by two closed loops F1 and F2
a is extracted, and image processing is performed on the closed region Ra.

As a method of extracting a closed region in a figure,
For example, there is one described in Japanese Patent Publication No. 61-25190. In this publication, a method of extracting a closed area in a figure is described as a method of obtaining an “AND figure”. According to this method, when tracking the vector,
When the intersection of the two closed loops F1 and F2 is reached, a minute vector (a vector having a minute unit length) is obtained for each of a plurality of vectors coming out of the intersection.
Then, a vector whose minute vector exists in the other party's closed loop is selected as a vector to be tracked. By sequentially tracing the vectors in this manner, the closed region R
The vectors forming the contour of a are obtained.

[0005]

In the conventional method described above, a plurality of vectors must be classified into two closed loops in advance. Therefore, when a plurality of vectors representing a figure are not classified into a plurality of closed loops, there is a problem that a closed region cannot be extracted by this method.

When a graphic has a large number of closed loops, the processing by the above method may be complicated. FIG. 15B shows three closed loops F1, F2, and F3.
It is a figure which shows the figure which has. For example, in order to extract the closed region Rb, the operator needs to perform three closed loops F1, F2, F
3 and the closed region Rb. When the number of closed loops is further increased, there is a problem that it takes considerable time to specify the relationship between each closed loop and a closed region to be extracted.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems in the prior art, and does not require the operator to make complicated designations, and allows a closed area to be easily extracted from a part of the closed area. It is intended to provide an extraction method.

[0008]

In order to solve the above-mentioned problems, a closed region extracting method according to the present invention comprises: (1) a step of preparing vector data representing a plurality of vectors constituting a line figure in an image; (2) a step of designating a point inside a part of the closed region in the line figure as a designated point; and (3) a step of designating, from the plurality of vectors, Selecting the vector closest to the specified point as the tracking start vector; and (4) when the specified point is viewed in the traveling direction of the tracking start vector, left
Is the starting point of the tracking start vector
And the vector having the specified point as both end points and the tracking start
Determined based on the outer product of a vector, said when the specified point is to the left of the track starting vector is determined that the first tracking condition, the designated point when the second on the right side of the tracing starting vector (5) In the case of the first tracking condition, a plurality of vectors connected in series from the tracking start vector are stored in each vector.
Selecting a plurality of vectors forming a closed loop while sequentially tracking in a counterclockwise direction irrespective of the traveling direction of the torque, thereby extracting a closed loop vector group surrounding a minimum closed area including the designated point; In the case of the tracking condition, a plurality of vectors connected in series from the tracking start vector are
By selecting multiple vectors that form a closed loop while sequentially tracking clockwise regardless of the direction of travel ,
Extracting a closed loop vector group surrounding the smallest closed region including the designated point.

[0009]

[Operation] A vector tracking condition is determined based on a relationship between a specified point specified in a part of a closed area and a vector closest to the specified point, and the vector is rotated clockwise or Since the tracking is performed in the counterclockwise direction, a closed loop vector group surrounding the closed region can be extracted only by specifying the specified point. In addition, the vector tracking condition
By default, the specified point is on the left side of the tracking start vector
Or on the right based on the cross product of the vectors
The tracking conditions are uniquely determined according to the vector's traveling direction.
Can be specified. After the start of tracking, the vector
Tracking regardless of the direction of travel
You can track in the opposite direction.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing the configuration of an image processing apparatus that performs a closed region extraction process by applying an embodiment of the present invention.

The image processing apparatus 100 includes a CPU 10
A ROM 20 for storing a processing program and a RAM 3
0, image data input port 40, graphic image input port 50, terminal control unit 60, external storage device control unit 70
And These components 10 to 70 are connected to each other by a bus line 80. The image data input port 40 is connected to an external image processing device via a communication line, and receives multi-valued image data representing a picture image such as a photograph from the external image processing device. The graphic image input port 50 is an image scanner 110
Is a port that receives graphic image data representing a monochrome line graphic image from the image scanner 110. Further, the terminal control unit 60 and the external storage device control unit 70
Are connected to the input / output terminal 120 and the external storage device 130, respectively. The input / output terminal 120 has an input device such as a keyboard and a mouse, and a display device such as a CRT. An operator performs various data inputs and designations with the input device while looking at the display device.

The CPU 10 includes a vector data conversion means 1
1, a closed region extracting unit 12, and an image pasting unit 13. The vector data conversion means 11 obtains a figure having a width of one pixel by thinning the figure based on the raster data of the figure image, and generates vector data representing the figure. The closed region extraction means 12 performs a closed region extraction process described later based on the vector data. The image pasting means 13 performs a process of pasting a picture image in the extracted closed area. The vector data converting means 11, the closed area extracting means 12, and the image pasting means 13 are realized by the CPU 10 performing data processing according to a processing program stored in the ROM 20.

B. FIG. 2 is a flowchart showing a schematic procedure of a process performed by using the image processing apparatus. First, in step S1, a figure drawn as an original image is
By performing photoelectric scanning with 0, raster data representing a graphic image is read. FIG. 3 is a diagram showing an original image of the graphic FF. This figure FF has a shape in which two black rectangles partially overlap. Also, each side (line segment) of the figure
Has a width of several pixels to several tens of pixels.

In step S2, based on the raster data representing the graphic FF, the vector data converter 11 thins the graphic FF to obtain a graphic having a width of one pixel, and generates vector data representing the graphic. The obtained vector data is stored in the RAM 30.
FIG. 4 is a diagram showing a figure FFt (hereinafter, referred to as a “thinned figure”) obtained by thinning. This thin line figure FFt is a closed loop figure composed of a plurality of vectors V1 to V20.

As shown in FIG. 4, a thin line figure FFt is a rectangle composed of vectors V1 to V10 and a vector V1.
11 to V20. FIG.
FIG. 4 is a conceptual diagram showing a structure of vector data representing a vector of a thinned figure FFt. Each vector V1 to Vn
The vector data for (n = 20 in this embodiment) has the following data. (1) Start point coordinates (Xsi, Ysi) (2) End point coordinates (Xei, Yei) (3) Start point connection data a. Start point connection vector number Csi: the number of other vectors connected to the start point of this vector. Other vectors may be connected at either the start point or the end point. For the vector Vi in FIG. 6, the starting point connection vector number Csi = 2. b. Address Ai of start point connection vector: Address in RAM 30 of vector data of start point connection vector. (4) Endpoint connection data a. End point connection vector number Cei: the number of other vectors connected to the end point of this vector. Other vectors may be connected at either the start point or the end point. For the vector Vi in FIG. 6, the number of end point connection vectors Cei = 3. b. Address Bi of end point connection vector: Address in RAM 30 of vector data of each end point connection vector. (5) Tracked flag TFi: a flag indicating whether or not this vector has already been tracked. Initially, the tracked flags of all vectors are initialized to 0 (representing untracked).

The vector data conversion means 11 obtains each vector V1 to V20 of the thinned figure FFt,
The vector data shown in FIG. 5 is generated by examining the connection relation of each vector. Returning to FIG. 2, step S2
After creating the vector data in step S3
At S6, a process of extracting a closed region is performed. Here, a case will be described in which a closed region CR surrounded by the four vectors V3, V4, V18, and V19 in FIG. 4 is extracted.

In step S3, the operator sets the closed area C
One point CP inside R (hereinafter, referred to as “designated point”)
Specify the position of. This designation is performed by moving the cursor of the display device using a pointing device such as a digitizer or a mouse while looking at the thinned figure FFt displayed on the display device of the input / output terminal 120, and performing an input operation at the position of the designated point CP ( This is executed by performing a mouse click or the like. The coordinate values (Xc, Yc) of the designated point CP are stored in the RAM 30.

In steps S4 and S5, based on the position of the designated point CP, the closed region extracting means 12 (see FIG. 1) tracks the vectors one after another, thereby forming a vector forming a closed loop (surrounding the closed region CR). Vector). The detailed procedure of these steps S4 and S5 will be further described later, but the outline thereof will be described here with reference to FIG.

In step S4, the distance d to the designated point CP is calculated for each vector of the thin line figure FFt, and the vector having the minimum distance d is selected as the tracking start vector Vf0 (see FIG. 7A).

The relationship between the tracking start vector Vf0 and the designated point CP is classified into the following two, as shown in FIG. 7A: (a) The designated point CP in the traveling direction of the tracking start vector Vf0
When the designated point CP is seen on the left side of the tracking start vector Vf0 (in the case of the vector Vf0a in the figure). (B) The designated point CP in the traveling direction of the tracking start vector Vf0
When the designated point CP is seen on the right side of the tracking start vector Vf0 when viewed (in the case of the vector Vf0b in the figure).

In step S5, for each of the above two cases (a) and (b), the vector is tracked as follows: In the case of the above (a), as shown in FIG. Then, the vector is tracked counterclockwise. That is, among a plurality of vectors connected to the end point EP of the tracking start vector Vf0a, each vector angle θ1, θ0 is clockwise from the tracking start vector Vf0a around the end point EP.
2 are measured, and the vector Vf1 having the minimum angle θ1 is set as the next tracking vector.

In the case of the above (b), the vector is tracked clockwise as shown in FIG. 7 (2b). That is,
Among a plurality of vectors connected to the end point EP of the tracking start vector Vf0b, the degrees θ1, θ2 of the respective vectors in a counterclockwise direction from the tracking start vector Vf0b around the end point EP.
, And the vector Vf1 having the minimum angle θ1 is set as the next tracking vector.

In the example of FIG. 4, vectors V3, V4, V18, and V19 surrounding the closed region CR are selected as tracking vectors. For example, in step S4, the vector V19 is selected as the tracking start vector, and the vector V19 is selected.
3, V4 and V18 are sequentially selected as tracking vectors. When these tracking vectors form a closed loop, the tracking process ends. If there is another closed area to be extracted, the operator returns from step S6 to step S3 by designating continuation of the extraction processing, and repeats the above processing.

When the process of extracting the closed region CR is completed as described above, a predetermined image is pasted inside the closed region CR in step S7. The image to be pasted is a picture image represented by multi-valued image data. The image pasting process is performed inside the closed region CR (that is, the vectors V3 and V3).
This is performed by replacing the original image data of the area surrounded by 4, V18, and V19) with the multivalued image data. This image pasting process is performed by the image pasting means 13.

C. Detailed Procedure of Vector Tracking The following describes the vector tracking procedure in steps S4 and S5 in detail. FIGS. 8 and 9 are flowcharts showing the procedure of step S4 in detail.

In steps S401 to S404, first,
Specified point C for all vectors of thinned figure FFt
The distance from P is calculated. FIG. 10 is a diagram for explaining the processing in these steps. Each vector and designated point C
In order to determine the distance to P, first, in step S401, a perpendicular is drawn from the designated point CP to each vector, and an intersection between the perpendicular and each vector is determined. FIG. 10 shows the designated point CP.
From the vertical line NL to the vector Vi.

The coordinates of the start point Ps and the end point Pe of the vector Vi are (Xsi, Ysi) and (Xei, Yei), respectively.
Then, the vector Vi is represented by the following linear expression.

(Equation 1) Assuming that the coordinates of the designated point CP are (Xc, Yc), the perpendicular NL is represented by the following linear expression.

(Equation 2) From Expressions 1 and 2, the coordinates (Xp, Yp) of the intersection IP between the perpendicular NL and the vector Vi are expressed by Expressions 3 and 4, respectively.

(Equation 3)

(Equation 4)

Next, at step S402, the intersection IP
Is on the vector Vi. If the coordinates (Xp, Yp) of the intersection IP satisfy the following condition, the intersection IP
Exists on the vector Vi. Xsi ≦ Xp ≦ Xei and Ysi ≦ Yp ≦ Yei If the above conditions are not satisfied, the intersection point IP does not exist on the vector Vi.

If the intersection point IP exists on the vector Vi, in step S403, the distance between the designated point CP and the intersection point IP is defined as the distance d between the designated point CP and the vector Vi (FIG. 10). (A-1) and (b-1)). In this case, the state flag Fi of the vector Vi is set to 1.

On the other hand, if the intersection point IP does not exist on the vector Vi, in step S404, the distances between the start point Ps and end point Pe of the vector Vi and the designated point CP are compared, and the smaller one is compared with the designated point CP. The distance d from the vector Vi is assumed (cases (a-2) and (b-2) in FIG. 10). In this case, the state flag Fi of the vector Vi is set to 0.

As described above, the distance d and the state flag Fi are obtained for all the vectors of the thin line figure. Next, in step S405, it is checked whether or not there are a plurality of vectors having the minimum distance d. The vector having the minimum distance d is referred to herein as a “candidate vector”. If there is only one candidate vector, step S40
At 6, the vector is selected as the tracking start vector.

If there are a plurality of candidate vectors, it is checked in step S407 whether or not any of the plurality of candidate vectors has a value of the state flag Fi of 1. If there is a candidate vector with the status flag Fi = 1, in step S408, any one of them is selected as the tracking start vector. This corresponds to (a-1) or (b-1) in FIG.
Corresponds to the case of The tracked flag of the vector selected as the tracking start vector is set to 1 (indicating that tracking has been completed).

On the other hand, when there is no candidate vector with the status flag Fi = 1, in step S409, a set of two vectors Vi and Vk connected to each other among the candidate vectors with the status flag Fi = 0 As the tracking start vector set. This corresponds to the case of (a-2) or (b-2) in FIG. Selecting the tracking start vector sets Vi and Vk is the same as selecting the vector Vi as the tracking start vector and further selecting the vector Vk as the next tracking vector. Whether or not the two candidate vectors Vi and Vk are connected can be determined by referring to the vector data shown in FIG. The tracked flags of the two vectors Vi and Vk selected as the tracking start vector set are both set to 1 (indicating that tracking has been completed).

In steps S410 to S416 in FIG.
Based on the relationship between the designated point CP and the selected tracking start vector Vf0, a flag DF (hereinafter, referred to as a "tracking direction flag") indicating the tracking condition is set as follows.

In step S410, it is checked whether or not the state flag Fi of the tracking start vector Vf0 is 1. FIG.
In the case of (a-1) and (b-1) of 0, the status flag Fi
Is 1, and in the case of (a-2) and (b-2) in FIG. 10, the status flag Fi is 0.

First, the cases of (a-1) and (b-1) in FIG. 10 will be described. If Fi = 1, step S
At 411, the sign of the magnitude | Vf0 * Vc | of the vector cross product Vf0 * Vc is examined. Here, the vector Vc is a specified point CP from the start point of the tracking start vector Vf0.
(Hereinafter, referred to as “designated point vector”). (A-1), (b-1), (a) of FIG.
-2) and (b-2) are (a-1) and (b-1) in FIG.
It is a figure which shows the relationship between the tracking start vector Vf0 and the designated point vector Vc in the case of (b-1), (a-2), (b-2).

The magnitude of the outer product | Vf0 × Vc | is given by the following equation (5).

(Equation 5) Here, the angle θc between the vectors is the tracking start vector V
It is an angle measured from the tracking start vector Vf0 to the designated point vector Vc counterclockwise around the start point Ps of f0. FIG. 12A shows a sine wave curve for reference. If the angle θc is equal to or smaller than π as in the example of FIG. 11A-1, | Vf0 × Vc | ≧ 0, and the tracking direction flag DF is set to 1 (step S413). on the other hand,
If the angle θc is larger than π as in the example of FIG. 11B-1, | Vf0 × Vc | <0, and the tracking direction flag DF
Is set to 0 (step S414). In other words, the tracking direction flag DF is set to 1 when the designated point CP is seen on the left side when viewed in the traveling direction of the tracking start vector Vf0 (step S413), and when the designated point CP is seen on the right side, the tracking is performed. The direction flag DF is set to 0 (Step S414).

In the case of (a-2) and (b-2) of FIG. 10, since the vector set Vf01 and Vf02 composed of two vectors are selected as the tracking start vectors, the state flag Fi is set to 0. It is. At this time, the process moves from step S410 to step S412.

In step S412, the sign of the magnitude | Vf00 × Vc | of the cross product of the combined vector Vf00 of the tracking start vector set (hereinafter, referred to as “combined tracking start vector”) and the designated point vector Vc is as follows. It can be checked in the same way. As shown in (a-2) and (b-2) of FIG. 11, the designated point vector Vc is the tracking start composite vector Vf
A vector from the start point of 00 to the designated point CP.

In step S412, | Vf00 × V
If c | ≧ 0, the tracking direction flag DF is set to 1 in step S415, and if | Vf00 × Vc | <0, the tracking direction flag DF is set to 0 in step S416.
Is set to

Note that the setting of the tracking direction flag DF using the tracking start composite vector Vf00 when the state flag Fi is 0 and the tracking start vector set is selected is as shown in FIG. In cases like c),
This is to enable the tracking direction flag DF to be set correctly. In the case of FIG. 11C, the first vector Vf01 of the tracking start vector set is used, and the sign of the outer product | Vf01 × Vc1 | of the vector Vc1 and the vector Vf01 from the start point to the designated point CP is checked. The direction flag DF becomes 1. On the other hand, when the sign of the cross product | Vf02 × Vc2 | between the vector Vc2 and the vector Vf02 from the start point to the designated point CP is examined using the second vector Vf02, the tracking direction flag DF becomes 0. That is, the value of the tracking direction flag DF may differ depending on which of the two vectors of the tracking start vector set is used to set the tracking direction flag DF. Therefore, when the tracking start vector set is selected, by setting the tracking direction flag DF as described above using the combined tracking start vector Vf00, the designated point CP in the net direction of the tracking start vector set can be set. The position can be determined correctly.

Note that the tracking start composite vector Vf00 is set to 1
If the tracking start vector is regarded as one, the above-described processing means that it is determined which side the designated point CP is on when viewed in the traveling direction of the tracking start composite vector Vf00.

As described above, the tracking start vector Vf
When 0 (or Vf00) is selected and the designated point CP is seen to the left of the tracking start vector when the designated point CP is viewed in the traveling direction of the tracking start vector, the tracking direction flag DF is set to 1. If the designated point CP is visible to the right of the tracking start vector, the tracking direction flag DF is set to 0.
Is set to The tracking direction flag DF is a flag for representing a tracking condition in the present invention.

FIG. 13 is a flowchart showing a detailed procedure of the closed loop vector tracking process in step S5 of FIG. In step S501, it is checked whether a plurality of vectors are connected to the end point of the current tracking vector. This is checked by referring to the end point connection data shown in FIG. The “current tracking vector” at the beginning of the process is the tracking start vector Vf0.

If only one vector is connected to the end point of the current tracking vector, step S5
The process proceeds to 05, and the connected vector is selected as the next tracking vector.

On the other hand, if a plurality of vectors are connected to the end point of the current tracking vector, it is determined in step S502 whether the value of the tracking direction flag DF is 1 or 0. If DF = 1, in step S503,
Track the vector in a counterclockwise direction and select the next tracking vector candidate. That is, as shown in FIG. 14A, of the plurality of vectors Vm1 to Vm3 connected to the end point EPi of the current tracking vector Vi, each vector angle θm1 is clockwise from the tracking vector Vi around the end point EPi. , Θm2, and θm3, and the vector Vm1 having the minimum angle θm1 is determined as the next tracking vector candidate (hereinafter, referred to as
It is simply called a “tracking candidate vector”. ).

If the tracking direction flag DF = 0, in step S504, the vector is tracked clockwise to select a tracking candidate vector. That is, as shown in FIG. 14B, the end point E of the current tracking vector Vi
Among a plurality of vectors connected to Pi, respective vector angles θm1, θm2, θm3 are measured counterclockwise from the tracking vector Vi around the end point EPi, and the minimum angle θm1
Is the next tracking candidate vector.

Here, the calculation processing used in the above-described tracking candidate vector selection processing will be described using the case of FIG. 14B as an example. First, according to the inner product formula, the inverse vector (−Vi) of the current tracking vector Vi and the vectors Vm1 and Vm connected to the end point EPi of the tracking vector Vi.
cosine of the angle between m2 and Vm3 (= cos θm
k) is calculated by the following equation (6).

(Equation 6) Here, k = 1 to 3. The coordinates of the start point SPi of the current tracking vector Vi are (Xsi, Ysi), and the end point E
The coordinates of Pi are (Xei, Yei), and the coordinates of the end point EPm of the vector connected to the tracking vector Vi are (Xemk, Yei).
emk). The angle θmk is an angle measured counterclockwise from the inverse vector (−Vi) of the tracking vector to the vector Vmk of interest around the end point of the tracking vector Vi.

However, the end point is the end point EP of the current tracking vector Vi, as in the vector Vm3 in FIG.
For the vector i, the angle formed by the inverse vector (−Vm3) and the inverse vector (−Vi) of the tracking vector is calculated by the following equation (7).

(Equation 7)

When obtaining the value of the angle θmk from the value of cos θmk, it is necessary to determine which of the two values θa and θb is between 0 and 2π, as shown in FIG. There is. Therefore, the magnitude | (−Vi) × Vmk | of the cross product of the inverse vector (−Vi) of the tracking vector Vi and the vector Vmk of interest is calculated by Expression 8.

(Equation 8)

The magnitude of the outer product | (−Vi) × Vmk |
It is proportional to the sine (sin θmk) of the angle θmk they make. Therefore, as can be seen from the sine curve in FIG. 12A, if the magnitude of the cross product | (−Vi) × Vmk | is positive, the angle θa from 0 to π is selected as the value of the angle θm, and If the magnitude | (−Vi) × Vm | is negative,
If the angle θb from π to 2π is selected as the value of the angle θm, the correct angle θmk can be obtained.

When the value of the tracking direction flag DF is 1,
As shown in FIG. 14A, “clockwise” from the inverse vector (−Vi) of the tracking vector to the vector of interest
The vector with the smallest angle measured in the above is set as a tracking candidate vector. By the way, the angle θmk obtained by the above method is
The angle measured "counterclockwise" from the inverse vector (-Vi) of the tracking vector to the vector of interest Vmk around the end point EPi of the tracking vector Vi, so the angle measured clockwise is (2π-θmk). , And this is defined as the angle of each vector Vmk. Clockwise angle θm with respect to each vector Vm1 to Vm3 thus obtained
By comparing 1 to θm3, a vector Vm1 having the minimum angle θm1 is selected as a tracking candidate vector.

On the other hand, when the value of the tracking direction flag DF is 0, as shown in FIG. 14B, "counterclockwise" from the inverse vector (-Vi) of the tracking vector to the vector Vmk of interest. The vector with the smallest angle measured in the above is set as a tracking candidate vector. Therefore, the angle θmk obtained by the above method is used as it is for each vector. The angle θm1 of each vector Vm1 to Vm3 thus obtained is
By comparing θm3, a vector Vm1 having the minimum angle θm1 is selected as a tracking candidate vector.

As described above, step S503 or S
When the tracking candidate vector is selected in 504, the value of the tracked flag TF of the tracking candidate vector is checked in the next step S505. If the tracked flag TF of the tracking candidate vector is 1, since the vector group forming the closed loop has already been selected, the entire process of step S5 ends. On the other hand, if the tracked flag TF of the tracking candidate vector is 0, the process returns to step S501, and a vector group forming a closed loop is selected by repeating the above processing.

In step S503 or S504, if a vector whose end point is connected to the end point of the tracking vector Vi, such as the vector Vm3, is selected as a tracking candidate vector, the next step S501 is executed. In the processing of step S504, one of the vectors connected to the start point SPm3 of the vector Vm3
One is selected as the next tracking candidate vector.

As described above, in the above embodiment, the designated point C
The vector closest to P is the tracking start vector Vf
After selecting the vector as 0, by tracing the vector clockwise or counterclockwise, the vector group forming the smallest closed loop surrounding the specified point is selected, and the closed area surrounded by this closed loop is extracted. Therefore, the closed area can be easily extracted only by the operator designating the designated point CP.

The present invention is not limited to the above-described embodiment, but can be implemented in various modes without departing from the gist of the invention.

[0058]

As described above, according to the closed area extraction method of the present invention, the specified point specified in a part of the closed area is
The vector tracking condition is determined based on the relationship with the vector closest to the specified point, and the vector is tracked clockwise or counterclockwise according to the tracking condition. Can be extracted. Therefore, there is an effect that the operator does not need to perform complicated designation, and can easily extract a part of the closed region only by designating the designated point.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an image processing apparatus to which an embodiment of the present invention is applied.

FIG. 2 is a flowchart illustrating a schematic processing procedure according to the embodiment;

FIG. 3 is a diagram illustrating an example of a graphic to be processed;

FIG. 4 is an explanatory diagram showing a graphic represented by a vector.

FIG. 5 is a conceptual diagram showing the structure of vector data.

FIG. 6 is an explanatory diagram showing a connection relationship between vectors.

FIG. 7 is an explanatory diagram showing an outline of processing in the embodiment.

FIG. 8 is a flowchart showing a procedure for selecting a tracking start vector.

FIG. 9 is a flowchart showing a procedure for selecting a tracking start vector.

FIG. 10 is an explanatory diagram showing a procedure for selecting a tracking start vector.

FIG. 11 is an explanatory diagram showing a procedure for selecting a tracking start vector.

FIG. 12 is a graph showing a sine curve and a cosine curve.

FIG. 13 is a flowchart showing a vector tracking procedure.

FIG. 14 is an explanatory diagram showing a vector tracking procedure.

FIG. 15 is an explanatory diagram showing the contents of a closed region extraction process.

[Explanation of symbols]

 Reference Signs List 10 CPU 11 Vector data conversion means 12 Closed area extraction means 13 Image pasting means 20 ROM 30 RAM 40 Image data input port 50 Graphic image input port 60 Terminal control unit 70 External storage device control unit 80 Bus line 100 Image processing device 110 Image Scanner 120 I / O terminal 130 External storage device CP Designated point CR Closed area Cei End point connection vector number Csi Start point connection vector number DF Tracking direction flag FFt Thinned figure Fi State flag IP Intersection NL Vertical line Pe End point Ps Start point TFi Tracked flag V1 V20 Vector Vc Specified point vector Vf0 Tracking start vector Vf00 Tracking start composite vector

Claims (1)

(57) [Claims] 1. A method for extracting a part of a closed area from a line figure having a plurality of closed areas, comprising: (1) preparing vector data representing a plurality of vectors constituting a line figure in an image; (2) a step of designating a point inside a part of the closed area in the line figure as a designated point; and (3) the plurality of vectors based on the position of the designated point and the vector data. Selecting the vector closest to the specified point as the tracking start vector from among the following: (4) When the specified point is viewed in the traveling direction of the tracking start vector, the specified point Left side of start vector
Is the starting point of the tracking start vector
And the vector having the specified point as both end points and the tracking start
Determined based on the outer product of a vector, said when the specified point is to the left of the track starting vector is determined that the first tracking condition, the designated point when the second on the right side of the tracing starting vector (5) In the case of the first tracking condition, a plurality of vectors connected in series from the tracking start vector are stored in each vector.
Selecting a plurality of vectors forming a closed loop while sequentially tracking in a counterclockwise direction irrespective of the traveling direction of the torque, thereby extracting a closed loop vector group surrounding a minimum closed area including the designated point; In the case of the tracking condition, a plurality of vectors connected in series from the tracking start vector are
By selecting multiple vectors that form a closed loop while sequentially tracking clockwise regardless of the direction of travel ,
Extracting a closed loop vector group surrounding a minimum closed area including the designated point.