JPH09204530A - Contour extraction method for mesh graphics - Google Patents

Abstract

PROBLEM TO BE SOLVED: To extract an accurate contour for a mesh graphics where the binarized image information are optionally arrayed in every unit grating and even for such a graphics that branched out in the single grating width from a contour extraction start grating. SOLUTION: At first, a unit grating is found out of a mesh graphics as a contour extraction start point and also the extracting direction is initialized (101). Then the contour of the graphics is tracked clockwise with the contour extraction start grating defined as a start point (102 to 113). When the extraction of the unit grating that is tracked right before the clockwise tracking returns to the contour extraction start grating is set in a direction other than the prescribed one (YES of 104, 107 and 110), the contour extraction processing ends. If the extraction of the unit grating is set in the prescribed direction (YES of 113), the graphics contour is tracked clockwise again based on the returned contour extraction start grating and its extracting direction (202 to 213).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contour extraction method used for binarized images or map information, and more particularly to a contour extraction method for figures arranged in a mesh.

[0002]

2. Description of the Related Art As one type of image processing for images arranged in a mesh or map information, there is contour extraction processing for extracting the contour of a graphic pattern having either one of the binarized information. is there. Hereinafter, an example of the contour extraction method and its problems will be described by describing the binary information of the figure from which the contour is to be extracted as the first information and making the first information correspond to the logic 1.

FIG. 5 is a flow chart showing an example of a method for extracting a contour from a mesh figure, showing a procedure for connecting adjacent grid points having the same binary information to extract a closed loop.
FIG. 6 is a detailed flowchart of step 103 in FIG. Further, FIG. 7 is a diagram showing an example of a mesh-shaped figure in which binarized information is given to each 5 × 5 unit cell. Here, the information of the unit cell in FIG. 7 is binarized into a blank and a diagonal line. Hereinafter, a blank unit cell is associated with a logic 0, and a hatched unit cell is associated with a logic 1. Therefore, in the following description, the figure constituted by the diagonal unit cell is the figure whose contour is to be extracted.

In the figure of FIG. 7, the initial condition for contour extraction is set as follows. First, the bottom of the mesh-like figure is scanned from left to right, and when the scanning of one step is completed, the unit lattice of the mesh-like figure is scanned by the scanning method of moving to the upper stage and repeating the scanning. The unit grid representing the detected logic 1 is set as the contour extraction start grid. The direction from left to right is the initial value of the extraction direction. When this procedure is applied to the mesh figure of FIG. 7, the unit cell 13 is first extracted by the search from the left to the right in the second row from the bottom (step 10).
1). Therefore, the initial condition of this contour extraction processing is “contour extraction start unit grid 13, extraction direction (left → right)”.
Thereafter, as will be described below, the unit lattice 13, the unit lattice 15, the unit lattice 1 are used as a starting point.
6, the unit lattice 15, the unit lattice 17, the unit lattice 18, the unit lattice 19, and the unit lattice 13 are extracted in this order,
The closed loop shown by the thick frame in FIG. 7 is extracted.

Since a simplified representation is used in the flow chart of FIG. 5, the judgment or processing executed at each step will be described before describing the contour extraction processing. As described above, in the following description, the extraction target is the unit cell of logic 1.

Steps 102, 105, 108 in FIG.
In 111, the determination condition is expressed in the format of “extraction direction a → b?”. The extraction direction is the direction of the current grid of interest (current grid of interest) viewed from the unit grid of interest immediately before.
In other words, the extraction direction is the contour tracking direction. This determination condition is that the extraction direction when the current grid of interest is extracted is a
This means that YES is determined when the direction is represented by → b, and NO is determined when the direction is another direction. For example, when 13 is extracted as the unit cell of logic 1 and then 14 is extracted as the unit cell of logic 1 in the mesh-shaped figure of FIG. 7, the extraction direction of the current grid 14 of interest is from bottom to top. For this extraction direction given to the current grid 14 of interest, steps 102, 108, and 111 determine NO, and step 105 determines YES.

Steps 103, 106 and 109 of FIG.
112 is expressed in a format of “extract in order of x, y, z, w”. This step consists of four judgments that are executed in sequence, namely the first, second, third and fourth judgments. The first determination is to search for a unit cell adjacent to the x side of the current grid of interest, determine YES if the information of the unit cell is logical 1, and determine NO if the information is logical 0. The judgment of 2 is activated. The second determination is to search for a unit cell adjacent to the y side of the current grid of interest, determine YES when the information of the unit cell is logical 1, and determine NO when it is logical 0. The judgment of 3 is activated. The third determination is to search for a unit lattice adjacent to the z-side of the current lattice of interest, determine YES if the information on the unit lattice is logical 1, and determine NO if the information is logical 0. Start the judgment of. In the fourth determination, a unit lattice adjacent to the w side of the current lattice of interest is searched, YES is determined if the information of the unit lattice is logical 1, and NO is determined if the information of the unit lattice is logical 0. To finish. The judgment of NO in the fourth judgment is made when the figure is composed of only one unit lattice. YES in the first to fourth judgments
The branch is input to the next steps 104, 107, 110, 113.

FIG. 6 is a detailed flowchart of step 103 which is an example of the step of "extracting in the order of x, y, z and w". Judgment 103 ₁ , 103 constituting step 103
_2, 103 _3, 103 _4, respectively, on the current focused grid,
As a result of searching the adjacent grids on the right, bottom, and left, a YES determination is generated when a logical 1 is extracted, and a NO determination is generated when a logical 0 is extracted. For example, in FIG. 7, after the unit cell 14 is extracted as the unit cell having the logic 1,
When the unit grid 15 is extracted, the extraction direction of the unit grid 15 is from left to right. Therefore, when the next unit cell is extracted based on the current grid 15 of interest, step 102 returns YE.
Generate an S decision. The YES judgment in step 102 activates the first judgment step 103 _{1 of} step 103, and the upper unit cell 16 is searched first. Since the unit cell 16 has logic 1 information, decision step 103 ₁ produces a YES decision. After this time, the current grid of interest becomes the unit grid 16. Then, step 104
By this, it is determined whether or not the current grid 16 of interest matches the contour extraction start grid defined in the initial setting. If they do not match, the process returns to step 102 and the contour extraction processing further proceeds. The extraction direction of the current grid 16 of interest is from bottom to top. Therefore, step 102 outputs a NO determination, and the process proceeds to step 105.

Based on the fact that the "extraction a → b?" Type step and the "extraction in the order of x, y, z, w" type steps execute the above-described processing, the processing flow of FIG. The outline extraction processing of the figure in FIG. 7 will be described.

First, in step 101, the unit cell search is started from left to right at the bottom of the figure.
In the case of FIG. 7, since the unit cell of logic 1 cannot be extracted in the lowermost stage, move to the upper stage and perform similar search processing,
The unit grid 13 is extracted as a contour extraction start grid. At this time, the extraction method of the unit cell 13 is from left to right. Therefore,
A YES determination is output in step 102. Next, in step 103, the upper unit cell 14 is extracted. At this time, the extraction direction of the unit lattice 14 is from bottom to top. Next, focusing on the unit grid 14, it is determined in step 104 whether or not the unit grid 14 is the same as the contour extraction start grid 13, and when a NO determination is output, the determination of step 102 for the current grid 14 of interest. Is done. Since the extraction direction of the current grid 14 of interest is from bottom to top, step 1
NO determination is output by 02, and the process proceeds to step 10
It branches to 5, and a YES determination is output here. Next, in step 106, the unit cell on the left of the current grid 14 of interest,
The upper unit lattices are searched in order, but none of them is the unit lattice of logical 1, so the right unit lattice is searched next, and the logical unit of 1 is obtained.
A unit cell 15 of is obtained. The extraction direction of the unit grid 15 at this time is from left to right. Next, it is determined that the current grid 15 is not the contour extraction start grid 13 (step 107),
The determination in step 102 is YES, and the current grid of interest 1
The unit cell 16 of logic 1 above 5 is extracted. The extraction direction of this unit grid 16 is from bottom to top. Next, it is determined that the current grid 16 is not the contour extraction start grid (step 1
04), the YES judgment is generated in step 105 for the extraction direction of the current grid 16 of interest, that is, downward → upward. Hereinafter, similar processing is repeated as follows. Step 1
06 (unit grid 16 extraction) → step 107 → step 102 → step 105 → step 108 → step 1
11 → step 112 (extract unit grid 17) → step 113 → step 102 → step 103 (unit grid 1)
8 extraction) → step 104 → step 102 → step 105 → step 108 → step 111 → step 1
12 (unit grid 19 extraction) → step 113 → step 102 → step 105 → step 108 → step 1
09 (unit grid 13 extraction)-> step 110-> end. In this way, the unit lattice 13 → unit lattice 14 → unit lattice 15 → unit lattice 16 → unit lattice 15 → unit lattice 17 in FIG.
The contour of the graphic (slope) of logic 1 can be extracted in the order of the unit grid 18 and the unit grid 19.

[0011]

With the above-described contour extraction method, the contour of a figure can be extracted by a relatively simple process. In addition, by expanding the search range of the unit grid to be traced next to the current grid of interest not only to the left, front and right of the extraction direction of the current grid of interest, but also to the rear,
Even if a unit grid that is adjacent to three unit grids having logic 0 becomes the current grid of interest, such as the unit grid 16 of FIG. 7, the contour extraction can be continued without causing a processing stalemate. .

However, the above-mentioned contour extraction method still has a problem to be solved. This is correct in the case of a figure in which the figure is branched from the unit grid 0 or the unit grid 5 which is the contour extraction start grid by one unit grid width, like the figure shown in the shaded area in FIGS. 2 and 3. It is impossible to extract a proper contour. That is, when the processing of FIG. 5 is applied to the figure of FIG. 2, for example, unit lattice 0 → unit lattice 1 → unit lattice 2 → unit lattice 1 → unit lattice 0 → end, and unit lattices 3 and 4 are not extracted. is there.

An object of the present invention is to provide a contour extraction method for a mesh-shaped figure which can accurately extract the contour of a figure having a shape as shown in FIGS.

[0014]

According to the present invention, an image obtained by binarizing each of a plurality of unit lattices arranged in a two-dimensional lattice so as to correspond to first and second logical values. The contour of the figure pattern having the first information corresponding to the first logical value of the mesh figure in which the binary information of 1 is arranged is extracted by the following procedure.

First step: One of the unit lattices having the first information, which composes the contour, is defined as a contour extraction start lattice, and the contour extraction start lattice is set as the current grid of interest and the current grid of interest. Initialize the extraction direction of. For example, scan the bottom or top of the mesh figure from left to right, and when the scanning of one step is completed, move to the top or bottom and repeat the scanning to scan the unit grid of the mesh figure. In doing so, the unit grid of the first information detected first is set as the contour extraction start grid, and the contour extraction start grid is set as the current grid of interest, and the direction from left to right is extracted of the current grid of interest. Direction.

Second step: With reference to the extraction direction of the current grid of interest, the unit grid having the first information adjacent to the current grid of interest on the left side, front side, right side, and rear side of the current grid of interest is set to the left side. Search in front, right, and back.

Third step; the unit grid having the first information retrieved first in the second step is set as a new current grid of interest, and the direction of the current grid of interest with respect to the immediately preceding grid of interest. Is the extraction direction of the current grid of interest.

The above processing from the first to third steps is substantially the same as the processing in the method described in FIG. 5, and the following steps are different.

Fourth step: It is judged whether or not the unit grid newly set as the current grid of interest in the third step is the contour extraction start grid, and the unit grid is not the contour extraction start grid. Then return to the second step,
If the unit grid is the contour extraction start grid and the extraction direction of the unit grid is a predetermined direction, proceed to the fifth step below, otherwise, that is, the unit grid is A contour extraction start grid, and
When the extraction direction of the unit grid is a direction other than the predetermined direction, the contour extraction process ends.

Here, the "predetermined direction" is determined by the method of obtaining the contour extraction start grid. For example, when scanning the bottom of the mesh-shaped figure from left to right, and when the scanning of one step is completed, when scanning the unit lattice of the mesh-shaped figure by the scanning method of moving to the upper stage and repeating the scanning,
When the unit grid of the first information detected first is set as the contour extraction start grid, the contour extraction start grid is set as the current grid of interest, and the direction from left to right is set as the extraction direction of the current grid of interest. , "Predetermined direction" is from top to bottom. In addition, when the uppermost stage of the mesh-shaped figure is scanned from left to right, and when the scanning of one stage is completed, when the unit lattice of the mesh-shaped figure is scanned by the scanning method of moving to the lower stage and repeating the scanning, When the unit grid of the detected first information is set as the contour extraction start grid, the contour extraction start grid is set as the current grid of interest, and the direction from left to right is set as the extraction direction of the current grid of interest, The “predetermined direction” is right → left. Furthermore, when the bottom of the mesh figure is scanned from right to left, and when the scanning of one step is completed, when the unit grid of the mesh figure is scanned by the scanning method of moving to the upper stage and repeating the scanning, When the unit grid of the detected first information is set as the contour extraction start grid, the contour extraction start grid is set as the current grid of interest, and the direction from right to left is set as the extraction direction of the current grid of interest, The “predetermined direction” is from left to right. Furthermore, when the uppermost stage of the mesh-like figure is scanned from right to left, and when the scanning of one stage is completed, when the unit lattice of the mesh-like figure is scanned by the scanning method of moving to the lower stage and repeating the scanning, In the case where the unit grid of the first information detected in 1 is set as the contour extraction start grid and the contour extraction start grid is the current grid of interest, and the direction from right to left is the extraction direction of the current grid of interest, The “predetermined direction” is from bottom to top.

Fifth step; based on the extraction direction of the current grid of interest, the unit grid having the first information adjacent to the current grid of interest on the left side, front side, right side and rear side of the current grid of interest is left side, Search in front, right, and back.

Sixth step: the unit cell having the first information retrieved first in the fifth step is set as a new current grid of interest and the direction of the current grid of interest with respect to the previous grid of current interest. Is the extraction direction of the current grid of interest.

Seventh step: It is determined whether or not the unit cell newly defined as the current grid of interest in the sixth step is the contour extraction start grid, and if it is the contour extraction start grid, the contour extraction start grid is extracted. When the extraction processing is terminated and the contour extraction start grid is not reached, the process returns to the fifth step.

At the end of the contour extraction processing, the unit grid which is the current grid of interest in the above steps becomes the unit grid forming the contour of the figure pattern.

In the contour extraction method of the mesh figure having the above configuration, the contour of the figure having the first information is traced clockwise, but it may be traced counterclockwise. In this case, the procedure is as follows.

First Step One of the unit grids having the first information, which constitutes the contour, is defined as a contour extraction start grid, and the contour extraction start grid is set as the current grid of interest, and the current grid of interest is defined. Initialize the extraction direction. The method of obtaining the contour extraction start grid and the method of determining the initial extraction direction are the same as in the above configuration.

Second Step With reference to the extraction direction of the current grid of interest, the unit grid having the first information adjacent to the current grid of interest on the right, front, left, and rear sides of the current grid of interest is set to the right and front. , Search on the left side and then on the rear side.

Third Step A unit cell having the first information retrieved first in the second step is set as a new current lattice of interest, and
The direction of the current grid of interest with respect to the immediately preceding grid of interest is the extraction direction of the current grid of interest.

Fourth Step It is judged whether or not the unit cell newly defined as the current grid of interest in the third step is the contour extraction start grid,
When the unit grid is not the contour extraction start grid, the process returns to the second step, and when the unit grid is the contour extraction start grid and the extraction direction of the unit grid is a predetermined direction Proceed to the following fifth step, and in other cases, that is, when the unit grid is the contour extraction start grid and the extraction direction of the unit grid is a direction other than the predetermined direction, the contour The extraction process ends.

Here, the "predetermined direction" is determined by the method of obtaining the contour extraction start grid. For example, when scanning the bottom of the mesh-shaped figure from left to right, and when the scanning of one step is completed, when scanning the unit lattice of the mesh-shaped figure by the scanning method of moving to the upper stage and repeating the scanning,
When the unit grid of the first information detected first is set as the contour extraction start grid, the contour extraction start grid is set as the current grid of interest, and the direction from left to right is set as the extraction direction of the current grid of interest. , "Predetermined direction" is right → left. In addition, when the uppermost stage of the mesh-shaped figure is scanned from left to right, and when the scanning of one stage is completed, when the unit lattice of the mesh-shaped figure is scanned by the scanning method of moving to the lower stage and repeating the scanning, When the unit grid of the detected first information is set as the contour extraction start grid, the contour extraction start grid is set as the current grid of interest, and the direction from left to right is set as the extraction direction of the current grid of interest, The “predetermined direction” is from bottom to top. Furthermore, when the bottom of the mesh figure is scanned from right to left, and when the scanning of one step is completed, when the unit grid of the mesh figure is scanned by the scanning method of moving to the upper stage and repeating the scanning, When the unit grid of the detected first information is set as the contour extraction start grid, the contour extraction start grid is set as the current grid of interest, and the direction from right to left is set as the extraction direction of the current grid of interest, The “predetermined direction” is from top to bottom. Furthermore, when the uppermost stage of the mesh-like figure is scanned from right to left, and when the scanning of one stage is completed, when the unit lattice of the mesh-like figure is scanned by the scanning method of moving to the lower stage and repeating the scanning, In the case where the unit grid of the first information detected in 1 is set as the contour extraction start grid and the contour extraction start grid is the current grid of interest, and the direction from right to left is the extraction direction of the current grid of interest, The “predetermined direction” is from left to right.

Fifth step; based on the extraction direction of the current grid of interest, the unit grid having the first information adjacent to the current grid of interest on the right side, front side, left side, and rear side of the current grid of interest is set to the right side. Search in front, left, and rear.

Sixth step: The unit cell having the first information retrieved first in the fifth step is set as a new current grid of interest, and the direction of the current grid of interest with respect to the previous grid of current interest. Is the extraction direction of the current grid of interest.

Seventh step: It is determined whether or not the unit cell newly set as the current grid of interest in the sixth step is the contour extraction start grid, and if it is the contour extraction start grid, the contour extraction start grid is extracted. When the extraction processing is terminated and the contour extraction start grid is not reached, the process returns to the fifth step.

At the end of the contour extraction processing, the unit grid which is the current grid of interest in the above steps becomes the unit grid forming the contour of the figure pattern.

[0035]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an example of an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a flow chart showing a processing procedure of a contour extracting method according to an embodiment of the present invention. 2 and 3 are 5
An example of a mesh-like figure having x5 binarized information is shown. The mesh-like figure is a two-dimensional lattice figure arranged in a row direction and a column direction intersecting at right angles with the row direction, and is composed of a unit lattice. In FIGS. 2 and 3, the unit cell information is binarized into blanks and diagonal lines. Such a mesh figure is stored in, for example, the memory of the computer, and the outline of the figure is extracted by executing the program of the processing procedure shown in FIG. 1 on the computer.

Hereinafter, a blank unit cell is associated with a logic 0, and a hatched unit cell is associated with a logic 1. Therefore, in the following description, the figure constituted by the diagonal unit cell is the figure whose contour is to be extracted. The row direction is the left-right direction and the column direction is the up-down direction.

The contour extraction method of the embodiment of FIG. 1 includes three processing steps.

The first step is the processing step of detecting the contour extraction start grid and initializing the extraction direction. The second stage is a processing stage in which the contour extraction start lattice is used as a starting point and the unit lattices constituting the contour are sequentially traced until returning to the contour extraction start lattice again. Then, the third stage is a processing stage in which the unit lattices constituting the contour are traced again in order until the contour extraction start lattice is returned to again. The first and second stages are always carried out, whereas the third stage is carried out only in some cases.

In the first step of initializing the detection of the contour extraction start grid and the extraction direction, in the case of the present embodiment, the lowermost stage of the mesh-like figure is scanned from left to right, and when the scanning of one stage is completed. The unit cell of the mesh-like figure is scanned by a scanning method of moving to the upper stage and repeating scanning. Then, in the scan, the unit grid of the first information detected first is set as the contour extraction start grid, and this contour extraction start grid is set as the current grid of interest, and the direction from left to right is the current grid of interest. Is the extraction direction.

In the case of the present embodiment, the second step of tracing the unit grids that sequentially form the contours starting from the contour extraction start grid until returning to the contour extraction start grid is the clockwise (clockwise) direction of the contour. Around). This second step comprises decision steps 102, 105, 108, 111, processing steps 103, 106, 109, 112 and decision steps 104, 107, 110, 113.

Judgment steps 102, 105, 108, 1
Reference numeral 11 is a step of determining the extraction direction of the current grid of interest. The extraction direction of the current grid of interest is the direction of the current grid of interest as seen from the grid of interest immediately before, as in the case described in the section of the related art. The terms top, bottom, left, and right described in FIG. 1 refer to the top and bottom of FIGS. 2 and 3, and the left and right toward the drawings, respectively.

Process steps 103, 106, 109, 1
12 is “extracted in the order of x, y, z, w” as described above.
It is a mold step. This processing step 103, 106,
In steps 109 and 112, the judgment steps 102, 105, 108, and 111 immediately before the self-step are performed, respectively.
Based on the extraction direction determined as ES, the unit grid adjacent to the left side of the current grid of interest, the unit grid adjacent to the front (extraction direction), the unit grid adjacent to the right side, and the backward (direction opposite to the extraction direction) The adjacent unit cells are searched in that order (clockwise from the left side to the right side) to extract the unit cells having the first information (logical 1), and the logical unit of the logical 1 first extracted by this search is extracted. The unit lattice is set to the next current lattice of interest. The processing steps 103, 106, 10 in FIG.
9, 112 uses the above-mentioned terms of upper, lower, left, and right. For example, step 103 is Y in step 102.
Extraction is performed in the order of left side, front side, right side, and rear side based on the ES-judged left-to-right direction, but in the notation in FIG.
It will be extracted in the order of right, bottom, left. Therefore, “up” in step 103 is “forward” when the left → right direction is the reference, and “down” in step 103 is “right” when the left → right direction is the reference, and step 103 "Left" means "rearward" based on the direction from left to right. In other words, in step 103, "up, right, down, left order"
Is based on the extraction direction, left → front → right → rear,
That is, the order is clockwise starting from the left. Similarly,
The search order in steps 106, 109, and 112 is also based on the extraction direction, left → front → right → rear,
That is, the order is clockwise starting from the left, that is, the order of priority to the left. Thus, processing steps 103, 10
The fact that the search order in 6, 109, and 112 is left priority is that when tracing the contour of a figure in the clockwise direction, it is necessary to extract the unit cell on the leftmost side of the figure as the contour in the tracking direction. Because there is. In the following description, the clockwise search described above is referred to as a clockwise search, and the process of extracting the unit cell having the first information searched first by the clockwise search as the current grid of interest is referred to as left priority extraction. In the embodiment shown in FIG. 4, which will be described later, the contour of the graphic is tracked in the counterclockwise direction, and thus the right priority extraction is performed by the counterclockwise search.

Decision step 104 included in the second stage,
107, 110 and 113 are the steps 103 and 1 immediately before.
This is a step of determining whether or not the unit grid extracted in 06, 109, and 112, that is, the unit grid to be the current grid of interest is the contour extraction start grid. When it is determined in these steps 104, 107, 110, 113 that the grid is not the contour extraction start grid, that is, when the determination is NO, the next grid of interest is set as the current grid of interest, and the process returns to step 102.
Continue the contour extraction processing. Also, steps 104 and 10
When it is determined in 7 and 110 that it is the contour extraction start grid, that is, when the determination is YES, the contour extraction processing is ended.
In this case, the contour extraction start grid, steps 103, 10
The unit grids extracted so far in 6, 109, and 112 become the unit grids that form the contour. On the other hand, when it is determined in step 113 that the grid is the contour extraction start grid, that is, YES
If yes, go to the third stage.

The third stage consists of steps 202-213. Steps 202, 205, 208, 211 are the same as steps 102, 105, 108, 111, respectively, and steps 203, 206, 209, 212 are the same as steps 103, 106, 109, 112, respectively, and step 204 , 207, 210, 213 are
These are the same as steps 104, 107, 110 and 113, respectively. However, steps 204, 207, 210, 2
In any of the steps of 13, when it is determined that the unit grid to be the current grid of interest is the contour extraction start grid, that is, when the determination is YES, the contour extraction processing is ended.
In this case, the contour extraction start grid, steps 103, 10
6,109,112,203,206,209,212
The unit grids extracted so far become the unit grids that form the contour.

Next, the operation of the present embodiment will be described by taking the mesh figure of FIG. 2 as an example.

First, in order to set the initial condition, the unit lattice having the first information is searched from the bottom of the mesh-shaped figure from left to right. In the case of FIG. 2, since the unit cell having the first information does not exist in the lowermost stage, the unit cell is moved to the upper stage and the same search process is performed to extract the unit lattice 0 first (step 101). Therefore, “contour extraction start unit grid 0, extraction direction (left → right)” is set as the initial condition of this contour extraction processing. Thereafter, as will be described below, with this unit grid 0 as a starting point, the unit grid 1, the unit grid 2, the unit grid 1, the unit grid 0, the unit grid 3, the unit grid 4, the unit grid 3, and the unit grid 0 The unit lattices are extracted in order, and the closed loop shown in the thick frame in FIG. 2 is extracted.

When the unit grid 0 is the current grid of interest and the extraction direction is left-to-right, a YES determination is generated in step 102, and the process proceeds to step 103. Next, in step 103, the upper adjacent grid 1 is extracted left preferentially, and the unit grid 1 becomes the current grid of interest. At this time, the extraction direction of the current grid 1 of interest is from bottom to top. Next, it is determined that the current grid 1 is not the contour extraction start grid (step 10
4), the YES determination is generated in step 105, and the process proceeds to step 106. Then by step 106,
The unit grid 2 is extracted by the left priority extraction, and this unit grid 2 is set as the current grid of interest. At this time, the extraction direction of the current grid of interest 2 is from bottom to top.

Next, it is determined that the current grid 2 of interest is not a contour extraction start grid (step 107), and Y is determined in step 105.
The ES determination is generated, and in step 106, the unit grid 1 is extracted by the left priority extraction, and this unit grid 1 is set as the current grid of interest. At this time, the extraction direction of the current grid 1 of interest is from top to bottom.

Next, it is determined that the current grid 1 of interest is not the contour extraction start grid (step 107), and since the extraction direction is from top to bottom, a YES judgment is generated in step 111, and the process proceeds to step 112, and the unit is selected by left priority extraction. The grid 0 is extracted and this unit grid 0 is set as the current grid of interest. The extraction direction of the current grid 0 of interest at this time is from top to bottom.

Next, at step 113, it is determined that the current grid 0 of interest is the contour extraction start grid. As a result,
A third stage process including steps 202 to 213 is executed.

First, since the extraction direction of the current grid of interest 0 is from top to bottom, a YES determination is generated in step 211, the unit grid 3 is extracted by left priority extraction in step 212, and this unit grid 3 is designated as the current grid of interest. To do. The extraction direction of the current grid 3 of interest at this time is from left to right.

Next, it is determined that the current grid 3 of interest is not a contour extraction start grid (step 213), and since the extraction direction is from left to right, a YES judgment is generated in step 202, and in step 203 the unit grid 4 is selected by left priority extraction. The unit grid 4 is extracted and used as the current grid of interest. At this time, the extraction direction of the current grid of interest 4 is from left to right.

Next, it is judged that the current grid of interest 4 is not the contour extraction start grid (step 204), the unit grid 3 is extracted by left priority extraction in step 203, and this unit grid 3 is made into the current grid of interest. At this time, the extraction direction of the current grid 3 of interest is from right to left.

Next, it is determined that the current grid of interest 3 is not a contour extraction start grid (step 204), and the extraction direction of the current grid of interest 3 is from right to left, so a YES determination is generated in step 208, and left priority extraction is performed in step 209. The unit lattice 0 is extracted by and the unit lattice 0 is set as the current grid of interest. And
In step 210, it is determined that the current grid of interest 0 is the contour extraction start grid, and the contour extraction processing ends.

When there are a plurality of contour-extracted figures, the unit grid extracted as described above and the unit grids inside thereof are already extracted so as not to be extracted again, and the second and subsequent contours are extracted. Extraction is performed in the same procedure. Further, for example, in FIG. 2, in the case where the unit lattices 3 and 4 are figures having a logic 0, that is, in the case where the figure is composed of the unit lattices 0, 1 and 2, the same contour as in the second stage is extracted again in the third stage. However, this does not cause a problem by removing overlapping contours in post-processing after extraction. Of course, another method such as a method in which the unit lattice extracted in the second stage (excluding the contour extraction start lattice) is not extracted again at the time of shifting to the third stage can be adopted.

By the contour extraction method described above, FIG.
It is possible to accurately extract the contour of the mesh-shaped figure as shown in FIG. That is, first, the unit grid 5 is initially set as the contour extraction start grid, and the left → right is set as the extraction direction.
Top → Bottom → Bottom → Right → Right → Right → Top → Top → Bottom → Bottom → Left → Left → Left in order of unit lattice 6 → Unit lattice 7 → Unit lattice 6 → Unit lattice 5 → Unit lattice 8 → Unit Lattice 9 → Unit Lattice 10 → Unit Lattice 11 → Unit Lattice 12 → Unit Lattice 11 → Unit Lattice 10 →
The unit lattice 9 → unit lattice 8 → unit lattice 5 is extracted, and the outline indicated by the thick line in the figure can be extracted.

In the embodiment of FIG. 1, step 101
In the first step of initial setting of, the bottom of the mesh figure is scanned from left to right, and when the scanning of one step is completed, the unit grid of the mesh figure is moved by moving to the upper step and repeating the scanning. When the scan is performed, the unit grid of the first information detected first is set as the contour extraction start grid, this contour extraction start grid is set as the current grid of interest, and the left → right direction is the extraction direction of the current grid of interest. And However, the initial setting does not necessarily need to be done by this method.The contour extraction start grid is set on the contour, and the extraction direction of the contour extraction start grid is set from the outside of the figure to the inside along the row direction or the column direction. If it is possible, any method can be adopted.

For example, when the uppermost stage of a mesh-like figure is scanned from left to right, and when one stage of scanning is completed, the unit lattice of the mesh-like figure is scanned by moving to the lower stage and repeating the scanning. , The first detected unit grid of the first information is set as the contour extraction start grid, the contour extraction start grid is set as the current grid of interest, and the direction from left to right is also set as the extraction direction of the current grid of interest. good. However, in this case, when YES is determined in step 110 of FIG. 1, the process is changed to proceed to the third stage.

When the lowermost stage of the mesh-shaped figure is scanned from right to left, and when the scanning of one stage is completed, the unit lattice of the mesh-shaped figure is scanned by moving to the upper stage and repeating the scanning. , The first detected unit grid of the first information is set as the contour extraction start grid, this contour extraction start grid is set as the current grid of interest, and the direction from right to left is also set as the extraction direction of the current grid of interest. good. However, in this case, when YES is determined in step 104 of FIG. 1, the process is changed to proceed to the third stage.

Further, when the uppermost stage of the mesh-like figure is scanned from right to left, and when the scanning of one stage is completed, the unit lattice of the mesh-like figure is scanned by moving to the lower stage and repeating the scanning. , The first detected unit grid of the first information is set as the contour extraction start grid, this contour extraction start grid is set as the current grid of interest, and the direction from right to left is set as the extraction direction of the current grid of interest. Is also good. However, in this case, when YES is determined in step 107 of FIG. 1, the process is changed to proceed to the third stage.

FIG. 4 is a flow chart showing a processing procedure of a contour extracting method according to another embodiment of the present invention. In the contour extraction method of the mesh figure of the embodiment of FIG. 1, the contour of the figure having the first information is traced clockwise, but in the present embodiment, it is traced counterclockwise. That is, steps 303, 306, 309, 31
2, 403, 406, 409, and 412 perform counterclockwise search and perform right priority extraction, which is a difference from the embodiment of FIG. The other steps are the same as those in the flowchart of FIG. In the initial setting of step 101 in the embodiment of FIG. 4, the bottom of the mesh-like figure is scanned from right to left, and when the scanning of one stage is completed, the mesh is moved to the upper stage and the scanning is repeated. When the unit grid of the circular figure is scanned, the unit grid of the first information detected first is set as the contour extraction start grid, and this contour extraction start grid is set as the current grid of interest, and right → left is the current grid. The extraction direction of the grid of interest. For this reason, when YES is determined in step 113, the process proceeds to the third stage.

Of course, step 10 in the embodiment of FIG.
The initial setting of 1 does not necessarily require this method,
Any method can be adopted as in the embodiment of FIG. For example, as in step 101 of FIG. 1, the bottom of the mesh-shaped figure is scanned from left to right, and when the scanning of one step is completed, the unit of the mesh-shaped figure is moved by moving to the upper step and repeating the scanning. When the grid is scanned, the first detected unit grid of the first information is set as the contour extraction start grid, and this contour extraction start grid is set as the current grid of interest, and the direction from left to right is the current grid of interest. The extraction direction of the grid may be used. However, in this case, in step 110, Y
It is changed so as to proceed to the third stage when the ES determination is made. In addition, when the uppermost stage of the mesh-shaped figure is scanned from left to right, and when the scanning of one stage is completed, when the unit lattice of the mesh-shaped figure is scanned by the scanning method of moving to the lower stage and repeating the scanning, The unit grid of the detected first information may be set as the contour extraction start grid, and this contour extraction start grid may be the current grid of interest, and the direction from left to right may be the extraction direction of the current grid of interest. However, in this case,
When YES is determined in step 107, the process is changed to the third stage. Furthermore, when the uppermost stage of the mesh-shaped figure is scanned from right to left, and when the scanning of one stage is completed, when scanning the unit lattice of the mesh-shaped figure by the scanning method of moving to the lower stage and repeating the scanning, The unit grid of the detected first information may be set as the contour extraction start grid, and this contour extraction start grid may be the current grid of interest, and the direction from right to left may be the extraction direction of the current grid of interest. However, in this case, when YES is determined in step 104, the process proceeds to the third stage.

[0064]

As described above, according to the present invention, when the contour of the figure having the first information is traced clockwise or counterclockwise, and when the contour extraction start grid is returned, the contour extraction start grid is returned. If the extraction direction of the unit grid tracked immediately before returning to is a predetermined direction, trace the contour of the figure again clockwise or counterclockwise according to the returned contour extraction start grid and its extraction direction. So, Figure 2
3 and the shaded portion of FIG. 3, it is possible to accurately extract the contour of a figure that is branched from the unit grid that is the contour extraction start grid by one unit grid width. it can.

[Brief description of drawings]

FIG. 1 is a flowchart showing a processing procedure of a contour extracting method according to an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a mesh-shaped figure having binarized information.

FIG. 3 is a diagram showing another example of a mesh-shaped figure having binarized information.

FIG. 4 is a flowchart showing a processing procedure of a contour extracting method according to another embodiment of the present invention.

FIG. 5 is a flow chart showing an example of a conventional method for extracting a contour from a mesh figure.

FIG. 6 is a detailed flow chart of step 103 of FIG.

FIG. 7 is a diagram showing an example of a mesh-shaped figure having binarized information.

[Explanation of symbols]

101 ... Steps for performing initial settings 102, 105, 108, 111, 202, 205, 2
08, 211 ... Steps 103, 106, 109, 112, 203, 206, 2 for determining the extraction direction of the current grid of interest
09,212 ... Step 104, 107, 110, 113, 204, 207, 2 for extracting the next unit cell forming the contour by left-first extraction
10, 213 ... Steps for determining whether or not the grid has returned to the contour extraction start grid 303, 306, 309, 312, 403, 406, 4
09, 412 ... Step of extracting the next unit cell forming the contour by right-first extraction

Claims (4)

[Claims] 1. Binary information of an image binarized corresponding to the first and second logical values is arranged in each of a plurality of unit lattices arranged to form a two-dimensional lattice. In the contour extraction method of a mesh-shaped figure for extracting the contour of the figure pattern having the first information corresponding to the first logical value of the mesh-shaped figure, the unit lattice having the first information, which constitutes the contour. 1 is defined as the contour extraction start grid, the contour extraction start grid is set as the current grid of interest, and the extraction direction of the current grid of interest is initially set; A second step of searching for unit grids having first information adjacent to the current grid of interest on the left side, front side, right side, and rear side of the current grid of interest in the order of left side, front side, right side, and rear side, First searched in the second step The unit cell having the first information is set as a new current grid of interest, and
A third step in which the direction of the current grid of interest with respect to the immediately preceding grid of interest is the extraction direction of the current grid of interest, and the unit grid newly defined as the current grid of interest in the third step is the contour. Determine whether it is the extraction start grid,
When the unit grid is not the contour extraction start grid, the process returns to the second step, and when the unit grid is the contour extraction start grid and the extraction direction of the unit grid is a predetermined direction Go to the 5th step below, otherwise 4th step to end the contour extraction process, and the current focus on the left side, front side, right side, and rear side of the current grid of interest, based on the extraction direction of the current grid of interest. The fifth step of searching the unit cell having the first information adjacent to the grid in the order of left side, front side, right side, and rear side; and the first information searched first in the fifth step, In addition to defining the existing unit grid as the new current grid of interest,
The sixth step of setting the direction of the current grid of interest to the extraction grid of the current grid of interest to the previous grid of current grid, and the unit grid newly defined as the grid of current grid in the sixth step is the contour. Determine whether it is the extraction start grid,
When it is the contour extraction start grid, the contour extraction processing is ended, and when it is not the contour extraction start grid, a seventh step of returning to the fifth step is included. A contour extraction method for a mesh-shaped figure, wherein the unit lattice is a unit lattice forming the contour of the figure pattern. 2. Binary information of an image binarized corresponding to the first and second logical values is arranged in each of a plurality of unit lattices arranged to form a two-dimensional lattice. In the contour extraction method of a mesh-shaped figure for extracting the contour of the figure pattern having the first information corresponding to the first logical value of the mesh-shaped figure, the unit lattice having the first information, which constitutes the contour. 1 is defined as the contour extraction start grid, the contour extraction start grid is set as the current grid of interest, and the extraction direction of the current grid of interest is initially set; A second step of searching for unit grids having first information adjacent to the current grid of interest on the right side, front side, left side, and rear side of the current grid of interest in the order of right side, front side, left side, and rear side, First searched in the second step The unit cell having the first information is set as a new current grid of interest, and
A third step in which the direction of the current grid of interest with respect to the immediately preceding grid of interest is the extraction direction of the current grid of interest, and the unit grid newly defined as the current grid of interest in the third step is the contour. Determine whether it is the extraction start grid,
When the unit grid is not the contour extraction start grid, the process returns to the second step, and when the unit grid is the contour extraction start grid and the extraction direction of the unit grid is a predetermined direction Go to the 5th step below, otherwise 4th step to end the contour extraction process, and the current focus on the right side, front side, left side, and rear side of the current grid of interest, based on the extraction direction of the grid of current grid of interest. The fifth step of searching the unit cell having the first information adjacent to the grid in the order of right side, front side, left side, and rear side, and the first information searched first in the fifth step. In addition to defining the existing unit grid as the new current grid of interest,
The sixth step of setting the direction of the current grid of interest to the extraction grid of the current grid of interest to the previous grid of current grid, and the unit grid newly defined as the grid of current grid in the sixth step is the contour. Determine whether it is the extraction start grid,
When it is the contour extraction start grid, the contour extraction processing is ended, and when it is not the contour extraction start grid, a seventh step of returning to the fifth step is included. A contour extraction method for a mesh-shaped figure, wherein the unit lattice is a unit lattice forming the contour of the figure pattern. 3. In the first step, the lowermost or uppermost stage of the mesh-shaped figure is scanned from left to right, and when one scanning is completed, the scanning is repeated by moving to the upper or lower stage. When the unit grid of the mesh-shaped figure is scanned by the method, the unit grid of the first information detected first is set as the contour extraction start grid, and the contour extraction start grid is set as the current grid of interest. 3. The method for extracting contours of a mesh-like figure according to claim 1, wherein a direction toward the grid is set as an extraction direction of the current grid of interest. 4. In the first step, the bottom or top of the mesh-like figure is scanned from right to left, and when one scan is completed, the scan is repeated by moving to the top or bottom. When the unit grid of the mesh figure is scanned by the method, the unit grid of the first information detected first is set as the contour extraction start grid, and the contour extraction start grid is set as the current grid of interest, and from right to left. 3. The method for extracting contours of a mesh-like figure according to claim 1, wherein a direction toward the grid is set as an extraction direction of the current grid of interest.