JPH0816782A - Line segment extracting system for binary drawing image - Google Patents

Abstract

PURPOSE:To extract a line segment from a binary drawing image even when the line segment is inclined, bent a little in the middle or interrupted in the middle. CONSTITUTION:A run data extracting means 10 extracts a run data group by longitudinally and laterally scanning a binary drawing image, and an indicated point detecting means 20 detects the positions of a start indicated point and an end indicated point. Corresponding to the inclination between the start indicated point and the end indicated point, a run data selecting means 30 selects either of longitudinal and lateral run data groups, and a start run detecting means 40 detects the run data, of which the run length is shorter than a specified value and the distance from the start indicated point is minimum, from the selected run data group and defines them as a start run. Then, a run trace means 50 traces the run data linked from the start run to the end indicated point up to the position of the end indicated point and defines the linkage of provided run data as the line segment.

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 line segment of a binary drawing image, and more particularly, to a line segment extraction of a binary drawing image which extracts a line segment using run data obtained by scanning the binary drawing image. About the method.

[0002]

2. Description of the Related Art A typical method for extracting a line segment using run data is as follows: (1) A method in which run data having a long run length is set as a line segment candidate and a group of line segment candidates is set as a straight line
196657, “Document Structure Recognition Method”),
(2) A method of obtaining a coordinate value group consisting of median values of run data having a frequent run length and obtaining a straight line that best approximates the coordinate value group (Japanese Unexamined Patent Publication No. H4-76555, "Method of detecting register mark position") See).

[0003]

In the method of the prior art (1) described above, if the line segment to be extracted is inclined, the line segment candidate is not run data having a long run length. Since the line segment cannot be represented, there is a problem that the line segment that can be extracted is restricted.

On the other hand, the method of the prior art (2) is a kind of a straight line fitting method for detecting run data located on a line having an allowable width as a straight line. Since it cannot be applied to one straight line, there is a problem that a condition is attached to a line segment that can be extracted.

In view of the above, an object of the present invention is to extract a line segment by performing tracing based on the width and connection of a run, so that the line segment is inclined, slightly bent in the middle, or interrupted in the middle. An object of the present invention is to provide a line segment extraction method for a binary drawing image, in which a line segment can be extracted even when the image is drawn.

[0006]

According to the present invention, a line segment extraction method for a binary drawing image designates a start designated point and an end designated point on a binary drawing image and connects the start designated point and the end designated point. Run data extracting means for scanning a binary drawing image in a vertical direction and a horizontal direction to extract a run data group in a line drawing extraction method of a binary drawing image extracting a line segment located near Designated point detecting means for detecting the position of the designated designated point and the end designated point; and the vertical and horizontal directions extracted by the run data extracting means in accordance with the inclination between the designated designated point and the designated designated end point detected by the designated point detecting means. A run data selecting means for selecting one of the run data groups in the direction; and a run having a run length equal to or less than a specified value and a minimum distance from the start instruction point from the run data group selected by the run data selecting means. Data obtained by tracing the run data detected by the start run detecting means and leading to a direction from the start point to the end point to the end point. Run trace means for connecting the run data to line segments.

[0007]

The present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a line segment extraction method for a binary drawing image according to an embodiment of the present invention. The line drawing extraction method of the binary drawing image of the present embodiment is 2
Run data extracting means 10 for scanning a value drawing image in the vertical and horizontal directions to extract a run data group, and designated point detecting means 2 for detecting the positions of a designated start point and a designated end point.
0 and the run data extraction means 1 according to the slope between the start designated point and the end designated point detected by the designated point detection means 20.
From the run data selecting means 30 for selecting one of the run data groups in the vertical direction and the horizontal direction extracted by 0, and the run length from the run data group selected by the run data selecting means 30 is equal to or less than the specified value from the start instruction point. A start run detecting means 40 for detecting run data having the minimum distance of
From the run trace means 50 which traces the run data connected to the direction from the start run detected by the start run detection means 40 to the designated end point to the position of the designated end point, and defines the connection of the run data obtained as a line segment. It is configured.

Referring to FIG. 2, a line segment extraction method for a binary drawing image according to the present embodiment includes a vertical and horizontal direction run data group extraction step S101, a start designated point / end designated point detection step S102, a run data Group selection step S10
3, a start run detection step S104, a trace step S105, and an end coordinate determination step S106.

Referring to FIG. 3, run trace means 50
The restart run detection process is performed by the plural run data extraction step S201 and the trace direction detection step S202.
, A virtual run generation step S203, a candidate run detection step S204, a run number determination step S205, and a restart run selection step S206.

Next, the second embodiment of the present invention constructed as described above will be described.
The operation of the line segment extraction method of the value drawing image will be described.

The run data extracting means 10 extracts and stores a run data group in both the vertical and horizontal scanning directions of a binary drawing image represented by a binary having a background of "0" and a line element of "1". (Step S101). Here, what is stored as the run data is a continuous “1” in the scanning direction.
Is the start coordinate value and the run length.

When a point near the start and end positions of the line segment to be extracted is designated on the displayed binary drawing image, the designated point detecting means 20 converts the coordinate values of the designated position into a start designated point and an end designated. Detected and stored as a point (step S
102). In general, an operator looks at an image reduced and displayed on a display (not shown) and designates a position using a pointing device (not shown) such as a mouse or a tablet.

Next, the run data selection means 30 calculates the inclination between the start instruction point and the end instruction point based on the ratio of the difference between the coordinate values of the start instruction point and the end instruction point stored in the instruction point detection means 20. , One of the vertical and horizontal run data groups is selected (step S103). If the inclination of the horizontal direction (horizontal direction) is 0 degrees is less than 45 degrees, the run data group extracted by the vertical scan is selected. Otherwise, the run data group extracted by the horizontal scan is selected. .

Subsequently, the start run detecting means 40 is located at a position closest to the coordinate value of the start designated point stored in the designated point detecting means 20 from the run data group selected by the run data selecting means 30 and has a run length. Is obtained and stored as a start run (step S104). Here, the specified value, which is the run detection width, is a value determined by the line width and the inclination of the extraction target. For the run data group extracted by the vertical scanning, the start instruction point where the horizontal direction is 0 degree , Due to an increase in the slope between the end instruction points. For the run data group extracted by the horizontal scanning, the horizontal direction is set to 0.
The inclination between the start instruction point and the end instruction point in degrees increases by decreasing from 90 degrees. The position of the run data is set to an intermediate coordinate value between the start coordinate value and the end coordinate value (= start coordinate value + run length-1) of the run, thereby obtaining the distance value from the coordinate value of the start instruction point.

The run trace means 50 traces the run while checking the connection from the start run detected by the start run detection means 40 to the direction of the designated end point (step S).
105) is performed up to the coordinate position of the end instruction point (step S
106).

The connection of the runs is checked by comparing the run length and the coordinate values of the runs. For example, it is assumed that there are runs i and k obtained by scanning in the horizontal direction as shown in FIGS. The run i in the scan line j satisfies the following condition a and does not satisfy the condition b.
Trace the run as if it were connected to run k at +1).

[0018] conditions ^{_{a: X e j + 1,}} k -X s j + 1, k <T ( specified value) Condition ^{_{b: X s j + 1,}} k> X e j, i or X _e ^{j + 1, k}
<X _s ^{j, i} where X _s ^{j, i} is the start X coordinate of run i in scan row j, X _e ^{j, i} is the end X coordinate of run i in scan row j,
X _s ^{j + 1, k} represents the start X coordinate value of run k in scan row (j + 1), and X _e ^{j + 1, k} represents the end X coordinate value of run k in scan row (j + 1).

For example, run i and run k in FIG.
Is determined has led does not satisfy the condition b satisfies the condition a, but satisfy the run i and run k condition a of FIG. 4 (b), since also meet condition b (X _{e
^{j + 1, k <X s}} j, it), is determined not to be connected.

In the case of a trace for a run data group extracted by scanning in the horizontal direction (X direction), the end coordinate position of the trace is the Y coordinate value of the end instruction point. On the other hand, in the case of a trace for a run data group extracted by scanning in the vertical direction (Y direction), the end coordinate position of the trace is the X coordinate value of the end instruction point.

When the trace cannot be continued because there is no connected run, the run trace means 50 performs the following processing to continue the trace.

First, the run trace means 50 reads a plurality of run data immediately before the run data cannot be continued (step S201), obtains a center coordinate value from a start coordinate value and an end coordinate value of each run data, and obtains a plurality of center coordinates. The ratio of the difference between the values is obtained as a trace direction value (step S202).
This trace direction value corresponds to a variation value of the coordinates when the trace continues in the same direction.

Next, the run trace means 50 adds a trace direction value to the coordinate value of the interrupted run, and generates a virtual run as shown in FIG. 5 which takes the obtained start coordinate value and end coordinate value. (Step S203), tracing is continued with the run data connected to the generated virtual run as a restart run (Step S204). When a plurality of runs are connected to the virtual run (a plurality of runs in step S205), the run trace unit 50 continues tracing with each run as a candidate run, and the center coordinate value of the run extending from the candidate run is instructed to start. The run closest to the line segment connecting the point and the end instruction point is selected as the restart run (step S206), and tracing is continued.

For example, as shown in FIG. 6, the center coordinate values of runs extending from candidate runs a and b are represented by (Xra, Yr
a) and (Xrb, Yrb), assuming that the coordinate values of the start designated point and the end designated point stored in the designated point detecting means 20 are (Xs, Ys) and (Xe, Ye), a start instruction is made from the center coordinate value. The distance values La and Lb to the line connecting the point and the end instruction point are obtained by the following equations.

La = | (Ye-Ys) .Xra- (Xe
−Xs) · Yra + (Xe · Ys−Xs · Ye) | / L

Lb = | (Ye-Ys) .Xrb- (Xe
−Xs) · Yrb + (Xe · Ys−Xs · Ye) | / L

Here, L = ((Xe-Xs) ² + (Ye
−Ys) ² ) ^1/2

When La <Lb, candidate run a is replaced by La>
In the case of Lb, the candidate run b is selected as the restart run. In the example of FIG. 6, the candidate run a is selected as the restart run.

The run trace means 50 outputs the runs obtained by tracing to the position of the designated end point as line segment elements, and outputs the connection of these runs as line segments.

When the start coordinate value and the end coordinate value of the run constituting the extracted line segment are drawn with the background value “0”,
Line segments can also be deleted from the binary drawing image.

[0031]

As described above, the present invention is provided with the run data extracting means, the pointing point detecting means, the run data selecting means, the starting run detecting means and the run tracing means, and determines the run length (width) and connection of the runs. By tracing the original and extracting the line segment between the start point and the end point, the line segment is inclined, the line segment is slightly bent, or the line segment is interrupted. Even if there is, there is an effect that the line segment can be reliably extracted. Therefore, it is particularly effective for extracting a line segment from a handwritten binary drawing image in which inclination, bending, interruption, and the like of the line segment are likely to occur.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating a configuration of a line segment extraction method for a binary drawing image according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a process of a line segment extraction method for a binary drawing image according to the embodiment;

FIG. 3 is a flowchart showing a restart run detection process of the run trace unit in FIG. 1;

4A and 4B are diagrams for explaining the connection of runs detected by the run tracing unit in FIG. 1, wherein FIG. 4A shows a case where runs are connected, and FIG. 4B shows a case where runs are not connected; For example.

FIG. 5 is a diagram for explaining a virtual run generated by a run trace unit in FIG. 1;

FIG. 6 is a diagram for explaining a case in which a rerunning run is selected based on a relationship between a line segment connecting a designated start point and a designated end point and a candidate run in the run trace means in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Run data extraction means 20 Designated point detection means 30 Run data selection means 40 Start run detection means 50 Run trace means

Claims (4)

[Claims] 1. A line segment extraction of a binary drawing image for instructing a start designating point and an end designating point on a binary drawing image and extracting a line segment located near a line segment connecting the start designating point and the end designating point. In the method, a run data extracting means for scanning a binary drawing image in a vertical direction and a horizontal direction to extract a run data group, a pointing point detecting means for detecting the positions of a start designated point and an end designated point, and this designated inspection Run data selecting means for selecting one of the run data groups in the vertical direction and the horizontal direction extracted by the run data extracting means according to the inclination between the start designated point and the end designated point detected by the output means, and the run data selecting means. Start run detection means for detecting run data having a run length of a specified value or less and a minimum distance from the start instruction point from the run data group selected by the data selection means; And a run trace means for making a line segment the connection of the run data obtained by tracing the run data connected from the start run detected in the direction from the run detection means to the end designated point to the position of the end designated point. Characteristic binary line drawing image line segment extraction method. 2. The method according to claim 1, wherein the run data selection unit sets the horizontal direction to 0.
A run data group extracted by vertical scanning is selected if the inclination is less than 45 degrees, and a run data group extracted by horizontal scanning is selected if the inclination is 45 degrees or more.
The line segment extraction method of the described binary drawing image. 3. The run trace means obtains a trace direction from a plurality of run data immediately before when there is no run data connected by the run trace and the trace is interrupted, and the coordinates of the interrupted run data and the trace direction are obtained. The line segment extraction method for a binary drawing image according to claim 1, wherein a virtual run is further generated, and the trace is continued using the run data connected to the generated virtual run as restart run data. 4. The run trace means sets the run data closest to the line segment connecting the start designating point and the end designating point as the restart run data when a plurality of run data are connected to the virtual run. A method for extracting line segments from a binary drawing image.