Striatal Imaging Diameter Measurement System

Abstract

To enable the diameter of a striated body to be accurately measured without much concerning the posture of a camera imaging the striated body.SOLUTION: A recording / analyzing device determines right and left edge positions of a striated body silhouette image for each line image constituting a frame image represented by image data provided from a camera (a step 31), and determines the midpoint position of the silhouette image (a step 32). The recording / analyzing device then determines the center line of the striated body silhouette image included in the frame image from a midpoint position determined for each line image (a step 40). The recording / analyzing device further calculates the right and left and radiuses of the silhouette image for each line image using both end edge positions, the midpoint position and the inclination of the center line (a step 50) and determines the total amount of the maximums of the calculated right and left radiuses as the diameter of the striated body (a step 60).SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a stoma image diameter measuring system that measures the diameter of a stoma using image data. [Background technology]

[0002] Patent Document 1 discloses a wire rope inspection device that uses a camera to capture an image of a wire rope and calculates the actual diameter of the wire rope using the image obtained by capturing the image. A conversion factor (actual dimension per pixel) between the number of pixels in the width of the image area of ​​the wire rope captured by the camera and the actual width of the wire rope is set, and the actual width of the wire rope is calculated from the image of the wire rope using this conversion factor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5769875

[0004] When calculating the actual width of the wire rope from the number of pixels in the width of the image area of ​​the wire rope, the relationship between the camera's posture at the time of imaging and the longitudinal direction (traveling direction) of the wire rope must be correct. In other words, if the horizontal (row) arrangement of the imaging elements of the camera used to image the wire rope is correctly perpendicular to the longitudinal direction (traveling direction) of the wire rope, the actual width of the wire rope can be correctly calculated from the number of pixels in the width of the image area of ​​the wire rope. However, if the horizontal arrangement of the camera's imaging elements is not perpendicular to the longitudinal direction of the wire rope, a value greater than the wire rope's width will be calculated. The wire rope inspection device described in Patent Document 1 requires high precision in the installation posture of the camera that images the wire rope. Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to enable the diameter of a filament to be measured with high accuracy without having to pay great attention to the orientation of the camera that images the filament.

[0006] Another object of the present invention is to improve the measurement accuracy of the diameter of the filament.

[0007] It is a further object of the present invention to provide a measuring system suitable for measuring the diameter of a filament having a stranded structure. [Means for solving the problem]

[0008] The image diameter measuring system for a filament according to the present invention comprises a camera including an image sensor which images the filament so that the entire width direction is captured and outputs image data including the filament in the subject image, a lighting device provided on the opposite side of the camera across the filament, and an image processing device which processes the image data provided from the camera, wherein the image processing device is equipped with an edge position determination means which determines both end edge positions of the silhouette image of the filament for each line image constituting a frame image represented by the image data provided from the camera, a center line determination means which determines a midpoint position equidistant from the both end edge positions determined for each line image by the edge determination position means and determines a center line of the silhouette image of the filament included in the frame image using the determined midpoint position, and a diameter determination means which determines the length between both end edges of the silhouette image of the filament along a line segment perpendicular to the center line for each line image, using the both end edge positions, the midpoint position and the inclination of the center line.

[0009] The camera and the lighting device are arranged to face each other with the wire to be measured in between. With this arrangement, a silhouette image of the wire is formed on the image sensor of the camera. The camera is arranged so that the entire width of the wire is captured.

[0010] The image sensor may be an area sensor in which a number of image sensors are arranged two-dimensionally in the row and column directions, or a line sensor in which a number of image sensors are arranged two-dimensionally in the row direction. In either case, a rectangular frame image is formed by the image data output from the image sensor provided in the camera. The frame image includes a silhouette image of the umbilical cord including the entire umbilical cord in the width direction.

[0011] For each line image (a horizontal image represented by image data output from a plurality of image pickup elements for one line) constituting the frame image, the positions of both edge edges of the silhouette image of the filament are determined, and a midpoint position equidistant from the positions of both edge edges is determined. The center line of the silhouette image of the filament included in the frame image is determined using the midpoint position determined for each of the plurality of line images.

[0012] The center line of the striate silhouette image can be determined by connecting the midpoint positions determined for each of the multiple line images. In order to determine the center line more precisely, the center line may be a regression line obtained by the least squares method using the midpoint positions determined for each line image.

[0013] If the longitudinal direction of the filament is perpendicular to the horizontal direction of the image sensor of the camera (the direction in which multiple image sensors are arranged), the center line will match the vertical direction of the frame image. If the longitudinal direction of the filament is not perpendicular to the horizontal direction of the image sensor of the camera, the center line will not match the vertical direction of the frame image and will be tilted.

[0014] According to this invention, the length between both edge ends of the filament silhouette image is determined for each line image along a line segment perpendicular to the center line using the both edge positions, midpoint position, and the inclination of the center line. That is, by using the inclination of the center line of the filament silhouette image, the width (diameter) of the filament silhouette image is determined along the line segment perpendicular to the center line, i.e., along the width direction of the filament silhouette image (direction perpendicular to the longitudinal direction of the filament silhouette image), rather than the length simply connecting the both edge positions.

[0015] Specifically, the cosine or sine of the length connecting the positions of both edge ends can be found using the inclination of the center line (whether cosine or sine is used is determined by whether the reference for the inclination of the center line (zero inclination) is vertical or horizontal). Even if the striatal silhouette image is captured at an angle, the length between both edge ends can be determined correctly along the width direction of the striatal silhouette image.

[0016] The calculated length between both ends is based on the silhouette image of the streak body represented by the image data. The diameter (actual size) of the streak body corresponding to the length between both ends is calculated according to the pixel resolution (dimension per pixel). The pixel resolution can be uniquely determined from the field of view size and the number of pixels of the image sensor.

[0017] Thus, according to the present invention, even if the image of the umbilical cord is taken at an angle, the diameter of the umbilical cord can be measured correctly. There is no need to pay much attention to the position of the camera that takes the image of the umbilical cord, which is particularly advantageous when measuring the diameter of a umbilical cord that is in use.

[0018] Preferably, the diameter determination means includes a radius calculation means for calculating the left and right radii of the streak silhouette image using the both end edge positions and the midpoint position. The left and right radii can be calculated along a line perpendicular to the center line, i.e., correctly along the width direction of the streak silhouette image. By separately measuring the left and right radii, the diameter of the streak can be measured more accurately.

[0019] In one embodiment, the diameter determining means determines the length between the two end edges as the sum of the maximum values ​​of the left and right radii calculated for each line image by the radius calculating means. When the cross section of the filament is not a perfect circle, the diameter of the circumscribing circle can be obtained.

[0020] In one embodiment, the edge position determining means determines the positions of the centroids of peaks represented by the amount of change in luminance of horizontally adjacent pixels of the line image as the positions of both edge ends. The positions of both edge ends can be determined finer than a pixel unit, and the measurement accuracy of the diameter of the umbilical cord can be improved even if the number of pixels of the image sensor is small (pixel resolution is low).

[0021] In another embodiment, the edge position determining means determines the positions showing the maximum value of the luminance change amount of the horizontally adjacent pixels of the line image as the end edge positions. The end edge positions can be easily determined without obtaining the center of gravity position.

[0022] In the case where the filament is a wire rope formed by twisting together a plurality of strands, the diameter calculation means preferably uses an image portion including one peak of the silhouette image of the wire rope included in the frame image to determine the length between both edges of the silhouette image of the filament along a line segment perpendicular to the center line. When the silhouette image includes a plurality of peaks (when the frame image includes a wire rope with a length equivalent to a plurality of pitches), it is possible to avoid discrepancies between the calculated positions of the left radius and the right radius.

[0023] The present invention also provides a filament image diameter measuring device and program suitable for the above-mentioned filament image diameter measuring system. [Brief description of the drawings]

[0024] [Figure 1] FIG. 1 is a block diagram of a wire rope diameter measurement system. [Diagram 2] A frame image is shown. [Diagram 3] 1 is a flow chart showing an image processing algorithm for measuring diameter. [Figure 4] 11 is a graph showing the luminance and the amount of change in luminance of a line image. [Diagram 5] The principle of calculating the diameter of a wire rope is shown below. [Figure 6] 1 is a graph showing the results of measuring the diameter of a wye rope. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] FIG. 1 is a block diagram showing a schematic diagram of a wire rope diameter measurement system.

[0026] The diameter measurement system for the wire rope 1 comprises a digital camera 11, a lens 12 provided in front of the digital camera 11, an illumination light source 13 and a recording / analysis device 14.

[0027] An illumination light source 13 is placed on one side of the wire rope 1, which is the object to be measured, and a digital camera 11 and a lens 12 are placed on the other side. Light emitted from the illumination light source 13 is partially blocked by the wire rope 1, and is received by an image sensor (not shown) of the digital camera 11 via the lens 12. The wire rope 1 may be in a state of running along its longitudinal direction or in a state of being stationary.

[0028] A telecentric lens is preferably used for the lens 12. By using a telecentric lens, only light incident parallel to the optical axis of the lens 12 is focused on the image sensor of the digital camera 11, making it possible to obtain an undistorted image of the subject.

[0029] The image sensor of the digital camera 11 may be an area sensor in which a plurality of imaging elements are arranged two-dimensionally in the vertical and horizontal directions, or may be a line sensor having a plurality of imaging elements arranged in the horizontal direction. The imaging elements may be C-MOS (Complementary Metal-Oxide Semiconductor) elements or CCD (Charge-Coupled Device) elements. The frame rate of the image sensor can be set arbitrarily depending on whether the traveling wire rope 1 or the stationary wire rope 1 is imaged, and further depending on the traveling speed of the traveling wire rope 1, and the wire rope 1 is imaged at a frame rate of, for example, about 10 to 500 fps. The number of pixels of the image sensor is arbitrary, but the more pixels there are, the more detailed (finer) the edge position described below can be determined.

[0030] The image data output from the digital camera 11 is transmitted to the recording / analysis device 14. The recording / analysis device 14 is a computer device equipped with a CPU (Central Processing Unit) that controls the overall operation of the recording / analysis device 14, a memory that temporarily stores various data, a storage medium that stores various data, a communication device for data communication with the digital camera 11, a display device for displaying the analysis results (graphs showing the measurement results of the diameter d of the wire rope 1) described later, etc., and the image data transmitted from the digital camera 11 is recorded in the storage medium provided in the recording / analysis device 14, and the diameter d of the wire rope 1 is measured using the image data recorded in the storage medium. The storage medium of the recording / analysis device 14 records the image data transmitted from the digital camera 11, as well as a program for causing the recording / analysis device 14 to execute the image processing described later, an operating system program, etc.

[0031] FIG. 2 shows an example of an image (hereinafter referred to as a frame image) 20 represented by one frame of image data captured by the digital camera 11 and recorded in a storage medium provided in the recording / analysis device 14.

[0032] As described above, the illumination light source 13 is installed on one side of the wire rope 1, and the digital camera 11 is installed on the other side, so that the frame image 20 captured by the digital camera 11 includes a dark image portion (hereinafter referred to as a wire silhouette image) 21 where the light emitted from the illumination light source 13 is blocked by the wire rope 1, and a bright image portion around it. As shown in Fig. 2, the digital camera 11 is installed so that the entire width of the wire rope 1 is captured.

[0033] If the longitudinal direction of wire rope 1 and the horizontally aligned imaging elements of digital camera 11 are correctly perpendicular to each other when capturing an image, wire silhouette image 21 will be aligned vertically in frame image 20. However, if there is a misalignment between the longitudinal direction of wire rope 1 and the horizontal alignment of imaging elements of digital camera 11, wire silhouette image 21 will be tilted in frame image 20, as shown in FIG.

[0034] The wire rope diameter measuring device of this embodiment has an algorithm that can correctly measure the diameter of the wire rope 1 even when using a frame image 20 in which the longitudinal direction of the wire rope 1 and the horizontal imaging elements of the digital camera 11 are not correctly aligned at right angles as shown in Fig. 2, and therefore the wire silhouette image 21 is tilted. The algorithm for measuring the diameter of the wire rope 1 will be described in detail below.

[0035] Fig. 3 is a flow chart showing an image processing algorithm for measuring the diameter d of the wire rope 1. The process shown in Fig. 3 is executed by the recording / analysis device 14. Fig. 5 shows the principle of calculating the diameter d of the wire rope 1, and will be referred to as appropriate in the following description.

[0036] As described above, image data output from the digital camera 11 is recorded in the storage medium of the recording / analysis device 14. The processing described below is executed on the image data recorded in the storage medium.

[0037] First, the basic concept of diameter measurement of the wire rope 1 will be briefly explained. Since the wire rope 1 is generally made by twisting together a number of strands, a spiral valley portion (groove portion, nip) is formed at the boundary between adjacent strands, and a peak portion (crown) is located between the valley portions. In measuring the diameter d of the wire rope 1, the diameter of the circumscribed circle of the cross section of the wire rope 1 along the peak portion of the wire rope 1 is used. As will be explained below, in the measurement process of the diameter d of the wire rope 1 using image data executed by the recording / analysis device 14, processing is also performed so that the image portion corresponding to the peak portion of the wire rope 1 is used to calculate the diameter d.

[0038] The frame image 20 includes a number of line images (hereinafter referred to as line images). First, each of the line images included in the frame image 20 is processed, and the left edge position (coordinate x L ) and the right edge position (coordinate x R ) is determined (step 31).

[0039] Figure 4 is a graph showing the brightness and brightness change of one line of a line image included in frame image 20, with the vertical axis of the upper graph representing brightness and the vertical axis of the lower graph representing the brightness change. The horizontal axis of each graph represents the horizontal position of the line image. The actual size of each pixel of the imaging element is known, and the horizontal axis (x coordinate) of the graph shown in Figure 4 is converted to the actual size.

[0040] As described above, the digital camera 11 is positioned so that the wire silhouette image 21 (both the left and right edges) is completely included in the frame image 20. The multiple line images that make up the frame image 20 include a low brightness portion that represents the wire silhouette image 21 and high brightness portions adjacent to the left and right of the low brightness portion.

[0041] When the difference in luminance between image data output from horizontally (left and right) adjacent imaging elements is calculated as the amount of luminance change, the graph shown in the lower part of FIG. 4 can be drawn from the graph shown in the upper part. More specifically, the amount of luminance change is calculated by subtracting the luminance value of the left imaging element from the luminance value of the right imaging element, using the luminance values ​​of the two image data output from each of the two horizontally adjacent imaging elements. If the luminance value of the right imaging element is smaller than the luminance value of the left imaging element, the calculated amount of luminance change will be a negative value. Conversely, if the luminance value of the right imaging element is larger than the luminance value of the left imaging element, the amount of luminance change will be a positive value. In the graph of the amount of luminance change, a peak P1 with a negative value corresponding to the left edge of the wire silhouette image 21 and a peak P2 with a positive value corresponding to the right edge appear.

[0042] Using the above-mentioned amount of brightness change, the left and right edge positions of the wire silhouette image 21 contained in the line image are respectively determined.

[0043] Left edge position x L is calculated using the following formula 1.

[0044]

number

[0045] Here, f(x) is a function that represents the curve of peak P1 when the horizontal position of the line image is x, and a and b are arbitrary horizontal positions that sandwich peak P1 on both sides. The x coordinate of the center of gravity of peak P1 is calculated by Equation 1, and this is the left edge position x of the line image. L is treated as such.

[0046] Right edge position of line image x R can also be calculated using the function representing the curve of peak P2 in the same manner as in Equation 1 above.

[0047] The left and right edge positions x calculated by Equation 1 L ,x Rcan be calculated in units smaller than one pixel, for example, 1 / 10 to 1 / 100 pixel units (subpixel units) (the exact pixel resolution is uniquely determined by the distance (field of view size) between the wire rope 1, which is the subject, and the digital camera 11 and the number of pixels of the image sensor), and the left and right edge positions (coordinates) x L ,x R can be determined with high accuracy.

[0048] The center of gravity of the peaks P1 and P2 of the brightness change is the left edge position x L ,x R Instead of this, the x-coordinates where the amount of brightness change is maximum are the left and right edge positions x L ,x R Since there is no need to calculate the center of gravity, the left and right edge positions x L ,x R can be conveniently determined.

[0049] Horizontal position x of the left edge L , the horizontal position of the right edge x R Once these two positions x are determined, L ,x R The coordinates of the midpoints equidistant from the midpoint position x M is determined (step 32).

[0050] The above-described processing is performed for each of the multiple line images included in the frame image.

[0051] For all line images included in the frame image 20, the left edge position x L , right edge position x R and midpoint position x M Once calculated, the midpoint position x M A regression line is calculated using the above formula, and this regression line is treated as the center line C of the wire silhouette image 21 included in the frame image 20. The least squares method is typically used to calculate the regression line (step 40).

[0052] By calculating the regression line (center line C), the inclination θ of the center line C of the wire silhouette image 21 with respect to the frame image 20 is grasped. With reference to Fig. 5, in this embodiment, the inclination θ of the center line C is defined as an angle from the vertical direction, with the vertical direction of the frame image 20 being used as the reference (inclination zero).

[0053] For all line images included in the frame image 20, the left edge position x L and the right edge position x R By calculating the above, edge curves similar to sine curves are drawn at the left edge position and the right edge position of the wire silhouette image 21. As described above, the wire rope 1 is constructed by twisting together a plurality of strands, and peaks and valleys appear repeatedly on the surface of the wire rope 1 along the longitudinal direction of the wire rope 1.

[0054] The left edge of the wire silhouette image 21 shown in Fig. 2 includes three peaks 21L1, 21L2, and 21L3, and the right edge also includes three peaks 21R1, 21R2, and 21R3. When the wire silhouette image 21 includes multiple peaks, one of them (a pair), for example, the image portion including the uppermost peaks 21L1 and 21R1 (for example, the image portion of about the upper 1 / 3 of the wire silhouette image 21 shown in Fig. 2) is set as the image portion to be processed for calculating the diameter d of the wire rope 1, which will be described below. This is to avoid the maximum values ​​of the left radius and right radius, which will be described below, being selected from different peaks when the wire silhouette image 21 includes multiple peaks (to avoid discrepancies between the calculation positions of the left radius and the right radius).

[0055] The image portion of the wire silhouette image 21 to be processed is used to determine the left edge position x for each of the line images. L , right edge position x R , midpoint position x M Using the inclination θ of the center line C, the left radius r of wire rope 1 L and the right radius r RThe left radius r L is (x M -x L )cosθ, right radius r R is (x R -x M ) cosθ (step 50). Even if the wire rope 1 is obliquely photographed by the digital camera 11 and the wire silhouette image 21 is tilted from the vertical direction of the frame image 20, the calculated left radius r L and the right radius r R It is not necessary to pay much attention to the posture of the digital camera 11 that captures the image of the wire rope 1, which is particularly convenient when measuring the diameter of the wire rope 1 in use at an installation site for an elevator or the like.

[0056] By carrying out the above-mentioned processing for each of the line images included in the processing target image portion of the wire silhouette image 21, a left radius r L and the right radius r R The calculated left radius r L and the right radius r R The sum of the maximum values ​​is determined as the diameter d of the wire rope 1 represented by the wire silhouette image 21 included in the frame image 20 to be processed (step 60).

[0057] In the case of a traveling wire rope 1, image data representing a plurality of frame images 20 captured at different locations is recorded in the storage device of the recording / analysis device 14. The above-mentioned processing is performed for each of the plurality of frame images 20, thereby calculating the diameters d of the wire rope 1 at multiple locations in the longitudinal direction.

[0058] FIG. 6 is a graph showing the measurement results of the diameter d of the wire rope 1 calculated using multiple frame images 20, with the vertical axis showing the diameter d of the wire rope 1 calculated using the above-mentioned algorithm and the horizontal axis showing the position of the wire rope 1 (here, as an example, the number of peaks appearing on the surface of the wire rope 1). Three very large peaks appear in the graph of FIG. 6, but these are diameters including the marking tape wound around the wire rope 1 in advance, and are not values ​​that represent the diameter of the wire rope 1. Since the diameter d is measured for each frame image 20, the diameter d of the wire rope 1 is measured at multiple points along the longitudinal direction.

[0059] When the diameter d was measured at multiple points along the longitudinal direction of the wire rope 1 using the above-mentioned algorithm, the average value was 10.34 mm. When the diameter of the same wire rope 1 was measured at multiple points using a vernier caliper, the average value was 10.31 mm. It can be seen that by using the above-mentioned algorithm, the diameter of the wire rope 1 can be measured with almost the same accuracy as when using a vernier caliper. [Explanation of symbols]

[0060] 1 Wire rope 11 Camera 12 Lenses 13 Light source 14 Recording / analysis equipment 20 Frame Images 21 Wire Silhouette Images

Claims

1. a camera including an image sensor that captures an image of the filament so that the entire filament is captured in the width direction and outputs image data including the filament as a subject image; an illumination device provided on the opposite side of the camera across the filament; and an image processing device for processing image data provided by the camera, The image processing device, an edge position determining means for determining both end edge positions of a silhouette image of the filament for each line image constituting a frame image represented by image data provided by the camera; a center line determining means for determining a midpoint position equidistant from both end edge positions determined for each line image by the edge position determining means, and for determining a center line of a silhouette image of the filament included in the frame image using the determined midpoint position; and a diameter determining means for determining, for each line image, a length between both edges of the silhouette image of the filament along a line segment perpendicular to the center line, using the both edge positions, the midpoint position and the inclination of the center line; The diameter determination means is a radius calculation means for calculating a left radius and a right radius of a silhouette image of the filament using each of the end edge positions, the midpoint position, and the inclination of the center line; Image diameter measurement system for the striatum.

2. the diameter determination means determines the length between the two end edges as a sum of the maximum values ​​of the left radius and the right radius calculated for each line image by the radius calculation means; 2. The system for imaging diameter measurement of a filament according to claim 1.

3. The edge position determining means determining, as both end edge positions, the center positions of peaks represented by the amount of luminance change between horizontally adjacent pixels of the line image; 3. The image diameter measuring system for a striated body according to claim 1 or 2.

4. The edge position determining means The positions showing the maximum value of the luminance change amount of the horizontally adjacent pixels of the line image are determined as the end edge positions.

3. The image diameter measuring system for a striated body according to claim 1 or 2.

5. the center line determined by the center line determination means is a regression line calculated by a least squares method using a midpoint position determined for each line image; A system for measuring the diameter of a filament according to any one of claims 1 to 4.

6. The filament is a wire rope formed by twisting together a plurality of strands, The diameter determination means is Using an image portion including one peak of the silhouette image of the wire rope included in the frame image, a length between both end edges of the silhouette image of the filament is determined along a line segment perpendicular to the center line.

2. The system for imaging diameter measurement of a filament according to claim 1.

7. an image data input means for receiving an input of image data representing a frame image including an entire subject image of the filament in the width direction; edge position determining means for determining both end edge positions of the image of the filament for each line image constituting the frame image; a center line determining means for determining a midpoint position equidistant from both end edge positions determined for each line image by the edge position determining means, and for determining a center line of the image of the filament included in the frame image using the midpoint position determined for each line image; a diameter determining means for determining, for each line image, a length between both edge ends of the image of the filament along a line segment perpendicular to the center line, using the both edge positions, the midpoint position and the inclination of the center line; The diameter determination means is a radius calculation means for calculating a left radius and a right radius of the image of the filament by using each of the end edge positions, the midpoint position, and the inclination of the center line; Image diameter measurement device for the striatum.

8. A program for measuring the diameter of a filament using image data representing a frame image including the entire filament in the width direction in a subject image, determining edge positions at both ends of the image of the filament for each line image constituting the frame image; determining a midpoint position equidistant from both end edge positions determined for each line image, and determining a center line of the image of the filament included in the frame image using the midpoint position determined for each line image; Using the both end edge positions, the midpoint position, and the inclination of the center line, a length between both end edges of the image of the filament is determined along a line segment perpendicular to the center line for each line image; In determining the length between both end edges of the image of the filament, a left radius and a right radius of the image of the filament are calculated using each of the end edge positions, the midpoint position, and the inclination of the center line; Striatal image diameter measurement program.

Images