JP6447890B2 - Line segment extractor, control method and program for line segment extractor - Google Patents

Description

  The present invention relates to a line segment extraction apparatus, a control method for the line segment extraction apparatus, and a program.

  In recent years, mobile terminals such as smartphones, mobile phones, and tablets equipped with a camera function have become widespread, and it has become possible to take pictures easily.

  Various application software that processes and uses photographs taken using such portable terminals have been developed. For example, a technique for digitizing a business card taken using a mobile terminal has been developed (see, for example, Patent Document 1).

  A technique for extracting a contour from a set of edge points in an image has also been developed (see, for example, Patent Document 2).

JP 2003-296353 A JP 2004-234278 A

  However, the application software executed on the portable terminal is required to operate at high speed so that the waiting time of the user does not become long, and the same applies to the case where the business card is digitized as in Patent Document 1.

  For this reason, there is a demand for a technique that can identify a line segment that forms the outline of a polygonal object to be photographed, such as a business card, from a still image photographed by a camera.

  The present invention has been made in view of the above problems, and provides a line segment extraction apparatus, a line segment extraction apparatus control method, and a program capable of specifying a line segment from an image at higher speed. Objective.

  A line segment extraction device according to one aspect is a line segment extraction device that extracts a line segment from an image, and an edge detection unit that detects an edge from the image and extends at a predetermined interval in the first direction in the image The intersections on the first parallel lines of each pair of the first intersection specifying part for obtaining the intersection of the plurality of first parallel lines and the edge and the two adjacent first parallel lines are straight lines. A first intersection connecting portion connected by the connecting line and a plurality of the connecting lines connected at the intersection, and a set of the connecting lines having an angle difference in the extending direction within a predetermined range is extracted as the line segment. A line segment specifying unit.

  In addition, the problems disclosed by the present application and the solutions thereof will be clarified by the description in the column of the embodiment for carrying out the invention and the description of the drawings.

  It becomes possible to identify a line segment from an image at higher speed.

It is a figure which shows the hardware constitutions of the line segment extraction apparatus which concerns on one Embodiment of this invention. It is a function structure of the line segment extraction apparatus which concerns on one Embodiment of this invention. It is a figure which shows a mode that the outline of the business card was specified from the still image which concerns on one Embodiment of this invention. It is a figure which shows the still image which concerns on one Embodiment of this invention. It is a figure which shows a mode that the edge was detected from the still image which concerns on one Embodiment of this invention. It is a figure which shows a mode that a line segment is extracted from the still image which concerns on one Embodiment of this invention. It is a figure which shows a mode that the intersection of an edge and a mesh line is specified in the still image which concerns on one Embodiment of this invention. It is a figure which shows a mode that the line segment was extracted from the still image which concerns on one Embodiment of this invention. It is a figure which shows the line segment extracted from the still image which concerns on one Embodiment of this invention. It is a figure which shows a mode that a polygon is formed combining the line segment which concerns on one Embodiment of this invention. It is a figure which shows a mode that a polygon is formed combining the line segment which concerns on one Embodiment of this invention. It is a flowchart which shows the flow of the process which concerns on one Embodiment of this invention. It is a flowchart which shows the flow of the process which concerns on one Embodiment of this invention. It is a flowchart which shows the flow of the process which concerns on one Embodiment of this invention.

  At least the following matters will become apparent from the description of this specification and the accompanying drawings. Hereinafter, the present invention will be described in accordance with an embodiment thereof with reference to the accompanying drawings.

== Line segment extraction device ==
1 and 2 show a configuration of a line segment extraction apparatus 100 according to an embodiment of the present invention. The line segment extraction apparatus 100 according to the present embodiment is a portable information processing terminal having a camera function such as a smartphone, a mobile phone, a notebook computer, or a tablet.

  Then, when the line segment extraction apparatus 100 according to the present embodiment captures a business card, the line segment extraction apparatus 100 performs image analysis of the still image 400 (described later), identifies the outline of the business card from the still image 400, and displays an image of the business card portion (name of the business card). The image of the part surrounded by the outline) is extracted as a business card image 410. In this way, the business card can be digitized.

<Hardware configuration>
A hardware configuration diagram of the line segment extraction apparatus 100 is shown in FIG. The line segment extraction device 100 includes a CPU 110, a memory 120, a communication device 130, a storage device 140, an input device 150, an output device 160, and a recording medium reading device 170.

  The storage device 140 stores a program 700 executed by the line segment extraction device 100 and various data. Various functions of the line segment extraction device 100 are realized by the program 700 and data stored in the storage device 140 being read into the memory 120 and executed by the CPU 110. Here, the storage device 140 is a nonvolatile storage device such as a hard disk, an SSD (Solid State Drive), or a flash memory.

  The recording medium reading device 170 reads the program 700 and data recorded on the recording medium 800 such as an SD card and stores it in the storage device 140.

  The communication device 130 exchanges various data and programs 700 with other computers (not shown) via a communication network (not shown) such as a LAN (Local Area Network) or the Internet. For example, the above-described program 700 and data can be stored in another computer, and the line segment extraction apparatus 100 can download the data and program 700 from this computer.

  The input device 150 includes various buttons and switches that accept input of commands and data by a user, a keyboard, a touch sensor that detects a touch position on a touch panel display, an input interface such as a microphone, an acceleration sensor, a temperature sensor, a camera 151, and the like. is there.

  The output device 160 is an output user interface such as a display device such as a display 161, a speaker, a vibrator, or illumination.

<Functional configuration>
FIG. 2 shows a functional block diagram of the line segment extraction apparatus 100. The line segment extraction apparatus 100 includes an image acquisition unit 101, an image display unit 102, and an image extraction unit 104. The image extracting unit 104 includes a line segment extracting unit 900, a polygon forming unit 910, an adjustment degree calculating unit 920, a contour specifying unit 930, and a shape comparing unit 940.

  Furthermore, the line segment extracting unit 900 includes an edge detecting unit 901, a first intersection specifying unit 902, a first intersection connecting unit 903, a first line segment specifying unit 904, a second intersection specifying unit 905, and a second intersection connecting unit 906. , And a second line segment specifying unit 907.

  Each of these functions is realized by executing the program 700 according to the present embodiment by the hardware of the line segment extraction apparatus 100.

  The image acquisition unit 101 acquires a still image 400 by photographing a business card. The image acquisition unit 101 is realized using a camera 151, for example.

  The still image 400 may be an image of one photograph obtained at the moment when the shutter of the camera 151 is pressed, or may be an individual image composed of a plurality of frames taken as a moving image. Further, the still image 400 may be an image detected by a CCD (Charge Coupled Device) displayed on the display 161 before the start of moving image shooting or before pressing the shutter at the time of photographing.

  The still image 400 may include not only a business card but also a non-business card such as a business card background or a person. A plurality of business cards may be shown in one still image 400.

  The image display unit 102 displays the business card still image 400 acquired by the image acquisition unit 101. The image display unit 102 is realized using, for example, a touch panel type display 161.

  A state in which the still image 400 is displayed on the display 161 of the line segment extraction apparatus 100 is shown in FIG. The example shown in FIG. 3 shows a state where three business cards are photographed simultaneously. As shown in FIG. 3, in the present embodiment, when a plurality of business cards are photographed simultaneously, the directions of the business cards need not be aligned.

  As will be described in detail below, the line segment extraction device 100 according to the present embodiment specifies the outline of the business card from the still image 400 at high speed, and the image of the business card part (the image of the part surrounded by the outline of the business card) ) As a business card image 410.

  Then, the image display unit 102 displays the business card marker 500 over the business card image 410 in order to show the extracted business card image 410 to the user. The business card marker 500 is a circular image of a predetermined color in the present embodiment, but the display mode is not particularly limited. Thus, by displaying the business card marker 500 superimposed on the business card image 410, the user can confirm that the business card has been correctly extracted.

  Returning to FIG. 2, the image extraction unit 104 will be described.

  The image extraction unit 104 extracts a business card image 410 from the still image 400.

  Hereinafter, the function and processing procedure of the image extraction unit 104 will be described in detail with reference to FIGS.

  First, a still image 400 before the business card image 410 is extracted is shown in FIG. When the image acquisition unit 101 acquires such a still image 400, the edge detection unit 901 detects the edge 420 from the still image 400 after adjusting the size of the still image 400 to a predetermined size according to the number of pixels. . The edge detection unit 901 detects an edge using a known technique such as a technique using a Canny method or a Sobel Filter.

  FIG. 5 shows how the edge detection unit 901 detects the edge 420 from the still image 400.

  Then, the first intersection specifying unit 902 obtains intersections 422 of the plurality of first mesh lines (first parallel lines) 421 extending at predetermined intervals in the first direction in the still image 400 and the edges 420. . This is shown in FIGS. 6A, 6B, and 6C.

  FIG. 6A is a diagram illustrating an edge 420 detected from the still image 400 and a plurality of first mesh lines 421 extending in the first direction in the still image 400.

  In this state, the first intersection specifying unit 902 specifies the intersection 422 between the edge 420 and the first mesh line 421 as shown in FIG.

  Note that the edge 420 and the first mesh line 421 are a set of discontinuous points as shown in FIG. 7A when the still image 400 is viewed at a level where individual pixels can be identified. Therefore, when the intersection angle between the edge 420 and the first mesh line 421 is small, as shown in FIG. 7B, the points where the edge 420 and the first mesh line 421 intersect are dispersed in a plurality of pixels. There is.

  Therefore, in the present embodiment, when the points where the edge 420 and the first mesh line 421 intersect are dispersed in a plurality of pixels, as shown in FIG. A point (for example, a middle point) is selected and specified as the intersection point 422. By such an aspect, it is possible to specify the intersection 422 between the edge 420 and the first mesh line 421 with accuracy in units of pixels. FIG. 6C shows how the first intersection specifying unit 902 obtains the intersection 422 in this way.

  Then, as shown in FIGS. 6 (D) and 6 (E), the first intersection coupling unit 903 then performs mutual first mesh lines for each pair of two adjacent first mesh lines 421. Intersection points 422 on 421 are connected by a straight coupling line 423.

  As shown in FIG. 6 (F), the first line segment specifying unit 904 is composed of a plurality of connecting lines 423 connected at the intersection 422, and the angle difference in the extending direction is within a predetermined range (for example, within ± 5 °). A set of coupled lines 423 is extracted as a line segment 430. At this time, the first line segment identification unit 904 extracts a set of coupled lines 423 having an angle of intersection greater than or equal to a predetermined angle (for example, 45 degrees or greater) with respect to the first mesh line 421 as a line segment 430.

  After that, the second intersection specifying unit 905, the second intersection coupling unit 906, and the second line segment specifying unit 907 are each using a second mesh line 421 (not shown) orthogonal to the extending direction of the first mesh line 421. A line segment 430 is further extracted by performing the same processing as the first intersection specifying unit 902, the first intersection coupling unit 903, and the first line segment specifying unit 904.

  That is, the second intersection specifying unit 905 obtains the intersections 422 of the plurality of second mesh lines 421 extending at a predetermined interval in the second direction orthogonal to the first mesh lines 421 and the edges 420. The second intersection coupling unit 906 connects the intersections 422 on the second mesh lines 421 with a straight coupling line 423 for each pair of two adjacent second mesh lines 421. The second line segment identification unit 907 includes a plurality of coupled lines 423 connected at the intersection 422, and the second line segment specifying unit 907 is the second of the set of coupled lines 423 whose angle difference in the extending direction is within a predetermined range (for example, within ± 5 °). A set of coupled lines 423 having an intersection angle exceeding a predetermined angle (for example, exceeding 45 °) with the mesh line 421 is extracted as a line segment 430.

  In this manner, when the line segment 430 is extracted, it is only necessary to perform processing for the intersection point 422, and processing for a large number of points on the edge 420 can be made unnecessary, so that the line segment 430 can be extracted at a higher speed. Is possible.

  Unlike the case of detecting a straight line using Hough transform or the like, the boundary of the subject in the still image 400 can be extracted as a finite-length line segment 430. Therefore, as described below, these line segments 430 are combined. When the polygon 432 is formed, the ratio of the length (adjustment amount) of the adjustment portion 431 of the line segment 430 to the circumference of the polygon 432 can be calculated.

  In addition, by obtaining the intersection 422 with the edge 420 using the first mesh line 421 and the second mesh line 421, the intersection angle with the mesh line 421 no matter which direction the edge 420 extends in the still image 400. Since it is possible to specify the intersection point 422 such that the angle is 45 ° or more, the position of the intersection point 422 on the edge 420 can be more accurately specified.

  Note that if the interval between the mesh lines 421 is narrowed, the number of intersections 422 can be increased, so that the line segment 430 can be extracted more accurately, but the processing time increases accordingly. For example, the mesh lines 421 may be drawn at intervals of about 50 to 100 in the still image 400, but various changes can be made.

  In this way, the line segment 430 is specified from the still image 400 by the first line segment specifying unit 904 and the second line segment specifying unit 907. A state in which the line segment 430 is specified from the still image 400 is shown in FIG.

  Thereafter, the polygon forming unit 910 selects a line segment corresponding to the number of sides of the business card from the line segments 430 extracted from the still image 400 (that is, four line segments) for each combination. The length of the minute 430 is adjusted to form a polygon (that is, a quadrangle) 432 having the same number of vertices as the business card.

For example, as shown in FIG. 9, if five line segments 430A to 430E are extracted from the still image 400, combinations of selecting four lines from these line segments 430A to E are the following (1) to (5). There are five ways ( ₅ C ₄ = 5).

(1) 430A, 430B, 430C, 430D
(2) 430A, 430B, 430C, 430E
(3) 430A, 430B, 430D, 430E
(4) 430A, 430C, 430D, 430E
(5) 430B, 430C, 430D, 430E
Polygon forming unit 910 attempts to form quadrilateral 432 using each line segment 430 for each of these combinations. However, since the polygon forming part 910 is a parallel line in which the line segment 430B, the line segment 430D, and the line segment 430E extend in the same direction, the combination (3) and (5) including these three line segments 430 simultaneously. Can also be removed from the combination. By such an aspect, it becomes possible to efficiently eliminate useless processing and extract business cards at a higher speed.

  In this way, the polygon forming portion 910 forms a quadrilateral 432 having three combinations as shown in FIGS. 10 (A) to 10 (C). 10A corresponds to the combination (1), FIG. 10B corresponds to the combination (2), and FIG. 10C corresponds to the combination (4).

  In this way, for each combination shown in FIGS. 10A to 10C, the polygon forming portion 910 forms the quadrangle 432 in FIGS. 11A to 11C, respectively. Show.

  In the case shown in FIG. 11A, the polygon forming portion 910 forms a quadrangle 432 by adjusting the lengths of the line segments 430A, 430B, 430C, and 430D. In FIG. 11A, the adjustment part of the length of each line segment 430 is indicated by a broken line as the adjustment part 431.

  Similarly, in the case shown in FIGS. 11B and 11C, the polygon forming portion 910 adjusts the length of the line segment 430 to form the quadrangle 432.

  Then, the adjustment degree calculation unit 920 calculates a value representing the degree of adjustment amount of the length of the line segment 430 necessary for forming the quadrangle 432 for each of the above combinations. For example, the adjustment degree calculation unit 920 calculates the ratio of the length (adjustment amount) of the adjustment portion 431 to the circumferential length of the quadrangle 432 formed by adjusting the length of the line segment 430.

  The contour specifying unit 930 assigns each line segment 430 constituting the combination as the contour of the business card in order from the combination having the smallest adjustment amount.

  For example, when it is assumed that the value indicating the degree of adjustment amount is small in the order of FIGS. 11A, 11B, and 11C, the contour specifying unit 930 first sets the line segment 430 of the combination illustrated in FIG. (Line segments 430A, 430B, 430C, 430D) are specified as the outline of the business card.

  In this way, when the line segments 430A, 430B, 430C, and 430D are assigned as the outlines of business cards, the remaining line segment is only 430E1, and the quadrangle 432 can no longer be formed, so the processing of the image extraction unit 104 ends.

  In this way, the line segment extraction device 100 according to the present embodiment specifies the outline of a business card. As shown in FIG. 3, even when there are a plurality of business cards in the still image 400, it is possible to specify the outline of the business cards in ascending order of the adjustment amount for each combination of the line segments 430. It is.

  Note that the line segment extraction apparatus 100 according to the present embodiment further includes a shape comparison unit 940.

  The shape comparison unit 940 compares the index value representing the shape of the quadrangle 432 formed by adjusting the length of the line segment 430 with a reference value representing the shape of the business card.

The outline specifying unit 930, among the combinations of line segments 430 this index value is rectangle 432 such that within a predetermined range with respect to the reference value is formed, in order from the combination degree of the adjustment amount is small, the combination Is specified as the outline of the business card.

  For example, the shape comparison unit 940 compares the intersection angle of adjacent line segments 430 with a reference value in a quadrangle 432 configured by combining four line segments 430. For example, if the reference value is set to 90 ° ± 5 °, the contour specifying unit 930 has an inner angle of 90 ° ± 5 ° among various quadrilaterals 432 configured by combining four line segments 430. A rectangle or square that falls within the range is selected, and among these, the line segment 430 constituting the combination is specified as the outline of the business card in order from the combination having the smallest adjustment amount. By such an aspect, it becomes possible to specify a business card more accurately.

  Alternatively, the shape comparison unit 940 compares the length of each line segment 430 with a reference value in a quadrangle 432 configured by combining four line segments 430. As a reference value, for example, if the short side = 50 mm to 60 mm and the long side = 85 mm to 95 mm are defined, the contour specifying unit 930 is composed of various quadrilaterals 432 configured by combining four line segments 430. A rectangle having such a side length is selected, and among these, the line segment 430 constituting the combination is specified as the outline of the business card in order from the combination having the smallest adjustment amount. Also according to such an aspect, it becomes possible to specify a business card more accurately.

  Next, the process flow of the line segment extraction apparatus 100 according to the present embodiment will be described with reference to the flowcharts shown in FIGS.

  First, the line segment extraction apparatus 100 captures a business card and acquires a still image 400 (S1000). The image acquisition unit 101 is realized using a camera 151, for example.

  Next, the line segment extraction device 100 adjusts the size of the still image 400 to a predetermined size determined according to the number of pixels (S1010). For example, the line segment extraction apparatus 100 adjusts so that one side of the still image 400 is 1000 pixels or less. With such an aspect, it is possible to reduce the processing amount when the line segment extraction apparatus 100 performs image analysis, and to specify the outline of a business card from the still image 400 at high speed.

  Next, the line segment extraction apparatus 100 detects an edge 420 from the still image 400 (S1020), and then extracts a line segment 430 from the still image 400 from which the edge is detected (S1030).

  FIG. 13 shows a processing flow when the line segment extraction apparatus 100 extracts the line segment 430 from the still image 400.

  First, the line segment extraction apparatus 100 acquires the still image 400 in which the edge 420 is detected (S2000).

  Then, the line segment extraction apparatus 100 draws a plurality of first mesh lines 421 extending at a predetermined interval in the first direction in the still image 400 (S2010).

  Next, the line segment extraction device 100 obtains an intersection 422 between the first mesh line 421 and the edge 420 (S2020).

  Then, the line segment extraction apparatus 100 connects the intersections 422 on the first mesh lines 421 with each other with the straight connection line 423 for each pair of two adjacent first mesh lines 421 (S2030).

  The line segment extraction apparatus 100 includes a plurality of coupled lines 423 connected at the intersection point 422, and a set of coupled lines 423 whose angle difference in the extending direction is within a predetermined range is set as a candidate for the line segment 430 (S2040).

  At this time, the line segment extraction apparatus 100 extracts the line segment 430 after excluding the set of the combined lines 423 that are candidates for the line segment 430 and the edge 420 is not extracted at the position of the combined line 423. (S2050).

When the processing for the first mesh line 421 extending in the first direction is completed in this way, the line segment extraction device 100 rotates the still image 400 by 90 degrees (S2060, S2070), and performs the processing of S2010 to S2050. repeat. Performing the same processing by rotating the still image 400 by 90 ° means that the second intersection specifying unit 905, the second intersection connecting unit 906, and the second line segment specifying unit 907 are using the second mesh line 421 described above. This corresponds to performing a process of extracting the line segment 430.

Then, the line segment extraction apparatus 100 rotates the direction of the still image 400 by −90 ° to restore it (S2080), and outputs the detected line segment 430 (S2090).

  Returning to FIG. 12, the line segment extraction apparatus 100 searches for a quadrangle 432 that can be formed by combining the extracted line segments 430 (S1040).

  Specifically, as shown in FIG. 14, the line segment extracting apparatus 100 first has a number of line segments (that is, four line segments) corresponding to the number of sides of the business card among the line segments 430 extracted from the still image 400. For each combination of selecting (line segment), the length of the line segment 430 is adjusted to form a polygon 432 (that is, a quadrangle 432) having the same number of vertices as the business card (S3000).

  Then, the line segment extraction apparatus 100 removes those squares 432 whose angles (inner angles) formed by the squares 432 are not within a range of 90 ° ± 5 °, for example (S3010, S3020). By such an aspect, it becomes possible to efficiently eliminate useless processing and extract business cards at a higher speed.

  The line segment extraction apparatus 100 calculates a value (penalty) representing the degree of adjustment of the length of the line segment 430 necessary for forming the quadrilateral 432 for each combination of the line segments 430 constituting the quadrilateral 432. (S3030) and output (S3040). For example, the adjustment degree calculation unit 920 calculates, as a penalty, the ratio of the length (adjustment amount) of the adjustment portion 431 to the circumference of the quadrangle 432.

  Then, the line segment extraction apparatus 100 rearranges the combinations of the line segments 430 in ascending order of penalty (S3050).

  Then, the line segment extraction device 100 assigns each line segment 430 constituting the combination in order from the combination with the smaller penalty as the outline of the business card (S3060 to S3090). When there is no line segment 430 that can form the quadrangle 432 (S3100), the line segment 430 specified as the outline of the business card is displayed on the display 161 (S3110). At this time, the line segment extraction device 100 also displays the business card marker 500 so as to overlap the business card image 410 of the portion surrounded by the outline of the business card.

  Returning to FIG. 12, once the line segment extraction device 100 specifies the outline of the business card from the still image 400 in this way, the line segment extracting device 100 performs the same process on the still image 400 of the next frame. In this way, the line segment extraction apparatus 100 can specify the outline of a business card for a continuous still image 400 such as a moving image.

== Other Embodiments ==
In the above embodiment, the polygon forming unit 910 selects, for each combination, the number of line segments (that is, four line segments) corresponding to the number of sides of the business card from the line segments 430 extracted from the still image 400. In addition, the length of the line segment 430 is adjusted to form a polygon (that is, a quadrangle) 432 having the same number of vertices as the business card. In this case, from the extracted n line segments 430, four vertices are formed. When the quadrangle 432 is formed, there are simply _n C _four combinations, and the amount of calculation is on the order of the fourth power of n.

  Therefore, in order to reduce the amount of calculation, the polygon forming unit 910 has a common end point among the line segments 430 extracted from the still image 400 and forms an angle with each other (for example, a range of 90 ° ± 5 °). The length of the four line segments 430 is extracted for each combination in which two line segments 430 are extracted as line segment pairs and two line segment pairs are selected from these line segment pairs. The square 432 may be formed by adjusting the height.

  That is, instead of directly selecting four lines from the extracted n line segments 430, a line segment pair composed of two line segments 430 that intersect each other at an angle substantially perpendicular to each other (within 90 ° ± 5 °) ( The shape of the line segment pair is extracted as ““ ”or“ ”” in the form of a square bracket, and the quadrangle 432 is formed by combining these line segment pairs.

According to such an aspect, since the number of combinations is _n C ₂ + _{(n / 2)} C ₂ , the calculation amount can be on the order of the square of n. As a result, the outline of the business card can be specified at a higher speed.

  Note that the end points of the two line segments 430 forming the line segment pair are common only when the end points of the first line segment 430 and the end points of the second line segment 430 are located on the same pixel. Not including the case of being located within a predetermined range (for example, within 10 pixels).

  As described above, the line segment extraction apparatus 100, the control method of the line segment extraction apparatus 100, and the program 700 according to the present embodiment have been described in detail. However, according to the present embodiment, the line segment 430 can be generated from the still image 400 at higher speed. It becomes possible to specify.

  The embodiments described above are for facilitating the understanding of the present invention, and are not intended to limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and equivalents thereof are also included in the present invention.

  For example, in the above embodiment, the case where the outline of a business card is specified from the still image 400 has been described as an example. However, not only the outline of a quadrangular plane such as a business card is specified, but also generally a triangle, pentagon, hexagon The present invention can be similarly applied to the case where the outline of a polygonal plane such as the above is specified.

DESCRIPTION OF SYMBOLS 100 Line segment extraction apparatus 101 Image acquisition part 102 Image display part 104 Image extraction part 110 CPU
120 Memory 130 Communication Device 140 Storage Device 150 Input Device 151 Camera 160 Output Device 161 Display 170 Recording Medium Reading Device 400 Still Image 410 Business Card Image 420 Edge 421 Mesh Line 422 Intersection 423 Join Line 430 Line Segment 431 Line Segment Adjustment Portion 432 Many Square (square)
500 Business card marker 700 Program 800 Recording medium 900 Line segment extraction unit 901 Edge detection unit 902 First intersection specifying unit 903 First intersection coupling unit 904 First line segment identifying unit 905 Second intersection identifying unit 906 Second intersection coupling unit 907 2-line segment specifying unit 910 polygon forming unit 920 adjustment degree calculating unit 930 contour specifying unit 940 shape comparing unit

Claims (11)

A line segment extraction device for extracting a line segment from an image,
An edge detection unit for detecting an edge from the image;
A first intersection specifying unit for obtaining an intersection of a plurality of first parallel lines extending at a predetermined interval in the first direction in the image and the edge;
For each pair of two adjacent first parallel lines, a first intersection coupling portion that connects the intersections on the first parallel lines with a straight coupling line;
A first line segment specifying unit configured to extract a set of the coupled lines, which is composed of a plurality of the coupled lines connected at the intersection, and whose angle difference in the extending direction is within a predetermined range, as the line segment;
A line segment extraction apparatus comprising: The line segment extraction device according to claim 1,
A second intersection specifying unit for obtaining an intersection of a plurality of second parallel lines extending at a predetermined interval in a second direction orthogonal to the first direction in the image; and
For each pair of two adjacent second parallel lines, a second intersection coupling portion that connects the intersections on the second parallel lines with a straight coupling line;
A second line segment specifying unit that extracts a set of the coupled lines that are composed of a plurality of the coupled lines connected at the intersections and whose angle difference in the extending direction is within a predetermined range;
Further comprising
The first line segment specifying unit extracts the set of coupled lines having an angle of intersection greater than or equal to a predetermined angle with respect to the first parallel line as the line segment,
The second line segment specifying unit extracts, as the line segment, a set of coupled lines having an intersection angle exceeding a predetermined angle of the second parallel line. . The line segment extraction device according to claim 1 or 2,
For each combination of selecting the number of line segments corresponding to the number of polygon sides to be identified from the image from the line segments extracted from the image, the length of the line segment is adjusted to adjust the length of the line segment. A polygon forming part that forms a polygon having the same number of vertices as a square;
Out of the polygons formed for each combination, an outline specifying unit that specifies the outline of the polygon to be specified from the image;
A line segment extraction apparatus comprising: The line segment extraction device according to claim 3,
An adjustment degree calculation unit that calculates a value representing a degree of adjustment amount of the length of the line segment necessary for forming the polygon for each combination;
Further comprising
The outline specifying unit assigns each line segment constituting the combination as a polygon outline to be specified from the image in order from a combination with a small degree of adjustment. The line segment extraction device according to claim 4,
A shape comparison unit that compares a predetermined index value representing the shape of a polygon formed by adjusting the length of the line segment with a reference value representing the shape of the polygon to be identified from the image;
Further comprising
In the combination of the line segments in which the polygon is formed such that the index value is within a predetermined range with respect to the reference value, the contour specifying unit sequentially starts with the combination having the smallest adjustment amount. A line segment extracting apparatus, wherein each line segment constituting a combination is assigned as a polygonal outline to be specified from the image. The line segment extraction device according to claim 5,
The line value extracting apparatus, wherein the index value and the reference value include an intersection angle between two adjacent sides forming the polygon. The line segment extraction device according to claim 5 or 6,
The line segment extraction apparatus, wherein the index value and the reference value include the length of each side forming the polygon.   It is a line segment extraction device in any one of Claims 4-7,
  The value indicating the degree of the adjustment amount is a ratio of the adjustment amount to the circumference of a polygon formed by adjusting the length of the line segment.
A line segment extraction apparatus characterized by that.   A line segment extraction device according to any one of claims 3 to 8,
  The polygon to be identified from the image is a rectangle,
  The polygon forming unit extracts two line segments that have a common end point and form an angle with each other among the line segments extracted from the image, and then extracts the line segment pairs. For each combination of selecting two line segment pairs, adjust the length of the four line segments to form a polygon having the same number of vertices as the polygon to be identified from the image.
A line segment extraction apparatus characterized by that. A control method of a line segment extraction device that extracts a line segment from an image,
The line segment extraction device detects edges from the image;
The line segment extraction device obtains intersections between a plurality of first parallel lines extending at a predetermined interval in the first direction in the image and the edges,
The line segment extraction device connects the intersections on the first parallel lines of each pair of adjacent two first parallel lines with a straight connecting line,
The line segment extraction device includes a plurality of the connection lines connected at the intersection point, and extracts a set of the connection lines whose angle difference in the extending direction is within a predetermined range as the line segment. Control method of extraction device. A program that extracts line segments from an image.
Detecting an edge from the image;
A procedure for obtaining an intersection of a plurality of first parallel lines extending in the first direction at a predetermined interval in the image and the edge;
For each pair of two adjacent first parallel lines, a procedure for connecting the intersections on the first parallel lines with each other by a straight connecting line;
A procedure of extracting the set of coupled lines, which is composed of a plurality of the coupled lines connected at the intersection, and whose angle difference in the extending direction is within a predetermined range, as the line segment;
A program for running