JP6851296B2 - Image processing device, image processing control program - Google Patents

Description

The present invention relates to an image processing device and an image processing control program that develop a circular image captured by an imaging means to generate a rectangular image.

Patent Document 1 has been proposed as a technique of photographing the inner surface of a cylinder with a camera whose optical axis is positioned along the axis of the cylinder, developing the captured image in a Cartesian coordinate system, and observing the image.

In Patent Document 1, when the captured image is developed in the Cartesian coordinate system, the distortion of the developed image is corrected by using the edge of the cylinder as a correction information source. That is, when the axis of the inner peripheral surface of the cylinder to be observed and the optical axis of the camera (observation system) are deviated, the edge on the developed image becomes a curved line, so that this is developed so as to be a straight line. I am trying to correct the image.

Japanese Unexamined Patent Publication No. 2003-315024 (Patent No. 3915583)

However, Patent Document 1 basically presupposes that the deviation between the axis of the inner peripheral surface of the cylinder to be observed and the optical axis of the camera (observation system) is the deviation of translation. In other words, the image of the circular inner peripheral surface may become elliptical due to the misalignment at an angle.

Further, in the case of an angular axis deviation, the axis is gradually displaced toward the depth direction of the captured image, and when a developed image is generated, the depth (y-axis) direction is determined by the x-coordinate after the development. However, in the prior art including Patent Document 1, such a magnification fluctuation cannot be corrected.

Further, since the magnification in the depth (y-axis) direction is different due to the perspective method, for example, the loci of the observation target (point-shaped foreign matter) are expressed as different lengths even within the same time. May occur.

In consideration of the above facts, the present invention considers the above facts, and when a circular image obtained by imaging the inner peripheral surface of the tubular body is developed to generate a rectangular image, the strain caused by the misalignment between the axis of the tubular body and the imaged optical axis. The purpose is to obtain an image processing device and an image processing control program capable of accurately correcting the above.

In the present invention, an annular image representing the inner peripheral surface of a tubular body extending from a predetermined position along an axial direction is imaged by an imaging means installed at the predetermined position with the axis of the tubular body as an optical axis. An image processing device that develops a circular image captured by the imaging means to generate a rectangular image. A specific means for identifying a vanishing point in the perspective method from the circular image captured by the imaging means, and imaging by the imaging means. The distance from the center to the vanishing point and the vanishing point from the center of the outermost circumference are centered on each point along a straight line from the center of the outermost circumference of the circular image to the vanishing point. An extraction means for extracting a plurality of circumferential images consisting of pixels on the circumference formed with a radius corresponding to the ratio to the distance to a point, and the direction along the circumference as the x-axis, along the axis. It is an image processing apparatus having a generation means for generating the rectangular image by assigning each circumferential image extracted by the extraction means to a coordinate plane having the y-axis in the direction.

According to the present invention, the imaging means captures an annular image representing the inner peripheral surface of a tubular body extending from a predetermined position along the axial direction.

The specific means identifies the vanishing point in perspective from the annular image captured by the imaging means.

The extraction means is centered on each point along a straight line from the center of the outermost circumference of the circular image captured by the imaging means to the disappearance point, and the distance from the center to the disappearance point and the circumference of the outermost edge. A plurality of circumferential images consisting of each pixel on the circumference formed with a radius corresponding to the ratio to the distance from the center to the vanishing point are extracted.

The generation means generates a rectangular image by assigning each circumferential image extracted by the extraction means to a coordinate plane having a direction along the circumference as the x-axis and a direction along the axis as the y-axis.

By executing the image processing in the above steps, even if there is a deviation between the axis of the tubular body and the optical axis of the imaging means, a rectangular image obtained by developing an image of the inner peripheral surface of the regular tubular body. Can be generated.

The present invention is characterized in that the rectangular image is an image obtained by cutting out a part of the annular image captured by the imaging means in the direction along the axis.

In the present invention, the specific means sets a point of interest on the outermost circumference of the annular image, and obtains the center point of the outermost circumference and the center point of the inner circumference of the annular image. , The point on the inner circumference corresponding to the point of interest is obtained, and the extension line of the line connecting the center point of the outermost circumference and the center point of the inner circumference of the annular image, and the above It is characterized in that the point where the point of interest and the extension line of the line connecting the points on the inner circumference corresponding to the point of interest intersect is specified as the vanishing point.

By using the movement of the image (point of interest), the vanishing point can be reliably identified.

The present invention is further characterized by further comprising a conversion means for correcting distortion of the cyclic image captured by the imaging means and converting it into a regular circular image.

When an image is taken by the imaging means, if there is an angled axis deviation, for example, even if the inner peripheral surface is circular, it may be imaged as an ellipse. Therefore, the conversion means corrects the distortion of the circular image to obtain a regular circular image. As a result, distortion due to the misalignment between the axis of the tubular body and the optical axis of the imaging means can be corrected.

The present invention is further characterized in that it further includes a correction means for correcting a magnification in the axial direction of the rectangular image.

In perspective, the magnification differs in the depth direction (axis direction), so this magnification can be corrected.

The present invention is characterized in that it further has a compositing means for synthesizing a plurality of rectangular images generated by the generating means.

By synthesizing the rectangular images of the region captured by the imaging means, for example, the movement locus of the point-shaped foreign matter existing on the inner peripheral surface is displayed as an image, and an image that is easy to observe can be obtained.

The present invention is an image processing control program that operates a computer as the image processing device.

As described above, in the present invention, when the annular image obtained by imaging the inner peripheral surface of the tubular body is developed to generate a rectangular image, the strain caused by the misalignment between the axis of the tubular body and the imaged optical axis is generated. It can be corrected with high accuracy.

It is a schematic diagram of the pipe material manufacturing apparatus and the functional block diagram of the image processing control apparatus which concerns on this embodiment. It is a figure which shows the transition state of the image by the normalization processing executed in the conversion part of the image processing control apparatus which concerns on this embodiment. It is a normalized image which shows the flow of the image processing executed in the vanishing point identification part and the center movement locus determination part of the image processing apparatus which concerns on this embodiment. (A) is a normalized image showing the flow of image processing executed by the circumferential image generation unit of the image processing apparatus according to the present embodiment, and (B) is the development unit of the image processing apparatus according to the present embodiment. It is a rectangular image showing the flow of image processing to be executed. It is a rectangular image which shows the flow of image processing executed by the magnification correction part of the image processing apparatus which concerns on this embodiment, (A) shows before correction, (B) shows after correction. FIG. 5 is a flowchart showing an image processing control routine for generating a developed image for observing a foreign object from an image of the inner peripheral surface of the cylindrical tube 12A captured by the camera 20 executed by the image processing control device 22 shown in FIG. ..

FIG. 1 shows an outline of the pipe material manufacturing apparatus 10 according to the present embodiment.

The pipe material manufacturing apparatus 10 includes, for example, a storage unit 14 for storing a raw material 12 made of synthetic resin.

The pipe material manufacturing apparatus 10 has a heating means (not shown), and the raw material 12 stored in the storage unit 14 is heated by the heating means and guided to the extrusion block 16 in a state of being softened with an appropriate viscosity. It has become.

The extrusion block 16 is provided with an annular guide path 16A through which the raw material 12 is guided. The guide path 16A has a so-called tapered shape in which the diameter dimension gradually decreases from the supply side end surface 16B of the extrusion block 16 to the discharge side end surface 16C.

As a result, the raw material 12 discharged from the discharge side end surface 16C of the extrusion block 16 is molded into a cylindrical tube 12A (cylindrical body), and the diameter dimension gradually decreases even after discharge. The post-processing unit 18 is reached while maintaining the axis of the guide path 16A. The post-treatment unit 18 has, for example, a cooling function, and solidifies by cooling a softened cylindrical tube 12A whose diameter dimension gradually decreases, and a cylindrical tube having a predetermined constant diameter dimension (for example, a resin). Pipe 12B) is completed.

Here, in the tube material manufacturing apparatus 10 of the present embodiment, the camera 20 that captures an image for observing whether or not foreign matter (projections, dents, scratches, etc.) is present on the inner peripheral surface of the cylindrical tube 12A is used. It is attached.

The camera 20 is attached to the central portion of the ejection side end surface 16C of the extrusion block 16. Here, the extrusion block 16 is provided with a through hole 16D at the center thereof, so that the wiring 20A of the camera 20 can be laid without hindering the extrusion work of the raw material 12.

The camera 20 is positioned so that its imaging optical axis L coincides with the axis of the guide path 16A, and as a result, the image captured by the camera 20 is a part of the image of the inner peripheral surface of the cylindrical tube 12A. (See FIG. 2 (A)).

For example, the image captured by the camera 20 is expanded to generate a rectangular image (see FIG. 4B).

At this time, since the captured image has a perspective relationship, a predetermined magnification correction is required when expanding the captured image into a rectangular image. In perspective, the back side looks smaller than the front side. Therefore, for example, the magnification correction is performed by increasing the magnification toward the back side with the image on the front side as a reference.

By continuously performing imaging by the camera 20 and synthesizing the generated rectangular image, the movement locus of the foreign matter can be observed in the presence of the foreign matter. For example, even if the foreign matter is point-shaped, it is expressed as a linear image by synthesizing the images over time, so that the foreign matter can be easily observed (discovered).

As the rectangular image, a region obtained by cutting out a part of the image in the axial direction of the cylindrical tube 12A captured by the camera 20 may be extracted.

By the way, as shown in FIG. 1, in the present embodiment, the optical axis L of the camera 20 is positioned so as to always coincide with the axis of the guide path 16A of the extrusion block 16.

This positioning is based on the premise that the axis of the cylindrical tube 12A extruded from the extrusion block 16 until it reaches the post-processing unit 18 coincides with the axis of the guide path 16A.

However, the cylindrical tube 12A does not always move on the axis of the guide path 16A to reach the post-processing unit 18, and even within the permissible range for maintaining the quality of the resin pipe 12B of the product, the camera 20 A misalignment between the optical axis L and the axis of the cylindrical tube 12A may occur.

Further, depending on the positioning accuracy of the optical axis L of the camera 20, an axial deviation between the optical axis L of the camera 20 and the axis of the cylindrical tube 12A may occur.

Axial deviation causes an error in magnification correction due to perspective. In addition, the magnification in the depth direction (y remaining amount after expanding into a rectangular image) differs depending on the direction (x coordinate after expanding into a rectangular image). In other words, the center position of each x-coordinate extracted at each coordinate in the y-axis direction is unknown.

Therefore, in the present embodiment, the image data captured by the camera 20 is subjected to image processing to specify the center position of each x-coordinate extracted at each coordinate in the y-axis direction.

As shown in FIG. 1, the camera 20 is connected to the image capture unit 24 of the image processing control device 22.

The image capture unit 24 is connected to the conversion unit 26, and sends the captured image captured from the camera 20 to the conversion unit 26.

The conversion unit 26 adjusts and normalizes the distortion of the captured image. In the present embodiment, the inner peripheral surface (cross section perpendicular to the axis) of the cylindrical tube 12A is circular, but if the optical axis L of the camera 20 and the axis of the cylindrical tube 12A are deviated from each other, the inner peripheral surface (axis) of the captured image is The right-angled cross section) has an elliptical shape (see FIG. 2A). Therefore, the conversion unit 26 converts the image of the inner peripheral surface of the ellipse from the ellipse to the circle. Hereinafter, the captured image after conversion is referred to as a normalized image.

(Normalization process)

FIG. 2 is a transition diagram showing details of the normalization process executed by the conversion unit 26.

As shown in FIG. 2A, the captured image is oval. In normalization, an approximate ellipse 28 at the outer peripheral edge is applied as a reference ellipse.

The center of the approximate ellipse 28 is the point O, the angle formed by the major axis with the x-axis of the captured image is + θ, the radius of the major axis of the approximate ellipse 28 is Ra, the radius of the minor axis is Rb, and the captured image is the point O. (See FIG. 2 (B)).

Next, the ellipse is transformed into a circle by doubling (Ra / Rb) in the y-axis direction (see the dotted line in FIG. 2B) and rotating the captured image by −θ around the point O. The image 30 can be obtained (see FIG. 2C).

The conversion unit 26 is connected to the vanishing point identification unit 32 and the circumferential image generation unit 34.

The vanishing point specifying unit 32 identifies the vanishing point V (see FIG. 3) of the normalized image 30 received from the conversion unit 26. The vanishing point V is a point where two or more straight lines intersect by perspective.

As shown in FIG. 1, when the optical axis L of the camera 20 and the axis of the cylindrical tube 12A are deviated from each other, the normalized image 30 (see FIG. 2C) is far from the near side (peripheral side) to the far side (center side). ), The axis of the inner peripheral surface (cross section perpendicular to the axis) of the imaged cylindrical tube 12A will be displaced. The vanishing point specifying unit 32 identifies the vanishing point V by utilizing the fact that the final end of the deviation of the axis is the vanishing point V, and sends the specified vanishing point V to the center movement locus determination unit 36.

In the center movement locus determination unit 36, a line connecting the center of the circumference of the initial image, for example, the side closest to the camera 20 (peripheral side of the normal image) and the vanishing point V is used as the movement locus of the center of the circumference. It is determined and sent to the circumferential image generation unit 34. This movement locus corresponds to the y-axis.

(Processing from vanishing point identification to center movement locus determination)

When, for example, a dot-shaped foreign matter is present on the inner peripheral surface of the cylindrical tube 12A, all the loci of the foreign matter appear to go toward one point in the normalized image.

This point is referred to as a vanishing point V. In the normalized image 30, the outer and inner circumference circles of the annular region representing the inner circumference surface of the cylindrical tube 12A are circular, and as shown in FIG. 3, the outer circumference circle 38 is a relatively outer circle. (Initial position, t0 seconds) and the inner circumference circle 40 (t1 seconds), which is a circle on the inner circumference side relatively, are set.

When all the points on the outer circle 38 are plotted at the positions reached after t seconds (t1 second, t2 second, and tI second in FIG. 3), they become circular (see the chain line in FIG. 3). In other words, the inner circumference circle 40 corresponds to the shape of the outer circumference circle 38 after tI seconds.

For each circle obtained by plotting the points reached based on time, including the outer circle 38 and the inner circle 40, the coordinates of each pixel on the circle so as to be parallel lines along the x-axis direction. By executing the conversion, it is possible to generate a rectangular image in consideration of the center shift.

Therefore, the center of the outer circle 38 is set as the point O and the predetermined position on the outer circle 38 is set as the point P0, the center of the inner circle 40 is set as the point I, and the inner circle corresponding to the point P0 on the outer circle 38 is set. Assuming that the position on 40 is the point PI, it can be seen that the triangle VOP0 (ΔVOP0) and the triangle VIPI (ΔVIPI) have a similar relationship as shown in FIG.

Therefore, an extension of the line connecting the point O, which is the center of the outer circle 38, and the point I, which is the center of the inner circle 40, and the inner circle corresponding to the points P0 and P0 at predetermined positions on the outer circle 38. The intersection with the extension line of the line connecting the point PI on 40 is the vanishing point V.

When a circumferential image is generated from the normalized image 30 after setting the vanishing point V, the line connecting the center point O of the outer peripheral circle 38 and the vanishing point V is set as the center movement locus, and the predetermined angle on the circumferential image is set. The position is the origin of the x-axis of the rectangular image.

The circumference image generation unit 34 generates a circumference image centered on the position of each unit movement amount on the movement locus of the determined center. When generating a circumferential image, the radius is formed according to the ratio of the determined distance from the center to the vanishing point V and the distance from the center O of the outer peripheral circle 38 to the vanishing point V. Generate a circumferential image consisting of each pixel. Specifically, the ratio of the radius of the generated circumferential image to the radius of the outer circle 38 is the distance from the determined center to the disappearance point V and the distance from the center O of the outer circle 38 to the disappearance point V. The radius of the circumferential image to be generated is determined so as to be a ratio, and the circumferential image is generated.

As shown in FIG. 1, the circumferential image generation unit 34 is connected to the development unit 42. The expansion unit 42 assigns a plurality of circumferential images (that is, x-coordinates) along the movement locus (that is, the y-axis direction) generated by the circumferential image generation unit 34 to the xy coordinates to form a rectangle. Generate an image (see FIG. 4B).

(Expanded "rectangular image generation" processing)

FIG. 4A shows a state equivalent to that in which each circumferential image in FIG. 3 is rotated and moved. As shown in FIG. 4 (A), the angle formed by the line connecting the position Ps and the center s on the circumferential image 44 at ts seconds (for example, at the start of cutting) and the X axis of the normalized image is θs. , Θs values are sequentially changed from 0 to 2π (rad) at a predetermined resolution, and pixel information (brightness information) at the coordinate positions of the extracted points Ps is assigned horizontally along the x-axis to form a rectangle. The image is for one line of the image.

Further, as shown in FIG. 4 (A), the angle formed by the line connecting the position Pm on the circumferential image 46 and the center m after tm seconds (for example, at the time of intermediate cutting) and the X axis of the normalized image. Is θm, the value of θm is sequentially changed from 0 to 2π (rad) at a predetermined resolution, and the pixel information (brightness information) of the coordinate position of each extracted point Pm is horizontally assigned along the x-axis. Then, the image becomes one line of the rectangular image.

Further, as shown in FIG. 4 (A), the angle formed by the line connecting the position Pe and the center e on the circumferential image 48 after te seconds (for example, at the end of cutting) and the X axis of the normalized image. Is θe, and the value of θe is sequentially changed from 0 to 2π (rad) at a predetermined resolution, and the pixel information (brightness information) of the coordinate position of each extracted point Pe is horizontally assigned along the x-axis. Then, the image becomes one line of the rectangular image.

As shown in FIG. 4B, the rectangular image 50 can be generated by assigning (expanding) the image of each line to the xy-axis coordinates.

As shown in FIG. 1, the unfolding unit 42 is connected to the magnification correction unit 52. The magnification correction unit 52 executes magnification correction in the y-axis direction of the rectangular image caused by the perspective method. Each magnification along the y-axis is stored in advance in the magnification correction data storage unit 54. The magnification correction data can be constant unless the camera 20 itself is changed or the focal position of the camera 20 is changed.

(Magnification correction processing)

It is difficult to geometrically calculate the degree of change in the magnification from the near side to the large side of the normal image because it is affected by the aberration of the optical system including the camera 20. Therefore, in the present embodiment, a plurality of locus images 56A, 56B, 56C, 56D in which the loci of foreign matter existing on the inner peripheral surface of the cylindrical tube 12A are visualized at different timings (see FIG. 5A). Magnification correction data (or correction formula) is experimentally obtained in advance so that the lengths of all the locus images 56A, 56B, 56C, and 56D on the rectangular image in the y-axis direction are equal to each other, and the magnification correction data is stored. It is stored in the part 54 (see FIG. 1).

By using this magnification correction data (or correction formula) to correct the magnification (magnification ratio) of the rectangular image in the y-axis direction as shown in FIG. 5 (B), the locus images 56A, 56B, 56C, The lengths of 56D in the y-axis direction are equal.

As shown in FIG. 1, the rectangular image 50 (see FIG. 4B) whose magnification has been corrected by the magnification correction unit 52 is synthesized by the composition unit 58 over time. In other words, when a point-shaped foreign substance is present on the inner peripheral surface of the cylindrical tube 12A, the image synthesized by the synthesis unit 58 is represented as a linear locus image in which the point-shaped foreign substance moves (). Hereinafter referred to as an unfolded image).

The compositing unit 58 is connected to the output unit 60 and outputs the synthesized developed image to a predetermined device (for example, a display unit for visual observation, an image analysis device for detecting foreign matter, or the like).

The operation of this embodiment will be described below with reference to the flowchart of FIG.

FIG. 6 shows an image processing control routine executed by the image processing control device 22 shown in FIG. 1 for generating a developed image for observing a foreign object from an image of the inner peripheral surface of the cylindrical tube 12A captured by the camera 20. It is a flowchart which shows.

In step 100, it is determined whether or not imaging has been started. If a negative determination is made in step 100, the routine ends.

If an affirmative determination is made in step 100, the process proceeds to step 102, and the image capturing unit 24 captures the image captured by the camera 20.

In the next step 104, the normalization process is executed. That is, the distortion (ellipse) generated in the captured image is normalized and converted into a circle (see FIG. 2).

In the next step 106, the vanishing point V is specified from the normalized image, and then the process proceeds to step 108 to determine the center movement locus of the plurality of circumferential images extracted from the normalized image based on the vanishing point V. The y-axis is determined by doing so (see FIG. 3).

In the next step 110, the cutout range to be observed is determined, and then the process proceeds to step 112, and the coordinates of each position of the circumferential image from the vanishing point V and the center of each circumferential image within the cutout range. (X coordinate) is specified (see FIG. 4 (A)), and the process proceeds to step 114.

In step 114, the circumferential image within the cutout range is expanded to generate a rectangular image (see FIG. 4B, and the process proceeds to step 116.

In step 116, the magnification correction data is read out, the process proceeds to step 118, the magnification correction is executed on the developed rectangular image (see FIG. 5), and the process proceeds to step 120.

In step 120, the rectangular image after the magnification correction is combined, then the process proceeds to step 122, the image is output to a predetermined device, and the process proceeds to step 124.

In step 124, it is determined whether or not the imaging of the camera 20 is completed, and if a negative determination is made, the process returns to step 102 and the above steps are repeated. If an affirmative decision is made in step 124, this routine ends.

In the present embodiment, a cylindrical tube has been described as an example of the tubular tube, but the observation target may be the inner peripheral surface of a polygonal tubular body having an axis.

Further, although the camera 20 is used to manufacture the cylindrical tube 12A by the tube material manufacturing apparatus 10, the camera 20 may be in a position where the inner peripheral surface of the resin pipe 12B as a product is imaged and observed. ..

Further, when generating a rectangular image to be developed, the images from the start of imaging to the end of imaging at a predetermined position may be combined, or the composition may be continued to develop the entire inner peripheral surface of the observation target. The image information may be obtained.

10 Pipe material manufacturing equipment 12 Raw material 14 Storage unit 16 Extrusion block 16A Guideway 16B Supply side end face 16C Discharge side end face 12A Cylindrical pipe 18 Post-processing unit 12B Resin pipe 20 Camera 16D Through hole 20A Wiring 22 Image processing control device 24 Image capture unit 26 Conversion part 28 Approximate ellipse 30 Normalized image 32 Disappearance point identification part 34 Circumferential image generation part 36 Center movement locus determination part 38 Outer circle 40 Inner circumference circle 42 Expansion part 44 Circumference image 46 Circumference image 48 Circumference image 50 Rectangular image 52 Magnification correction unit 54 Magnification correction data storage unit 56A, 56B, 56C, 56D Trajectory image 58 Composite unit 60 Output unit

Claims (7)

An annular image showing the inner peripheral surface of the tubular body extending from the predetermined position along the axial direction is imaged by an imaging means installed at the predetermined position with the axis of the tubular body as the optical axis.
An image processing device that develops a circular image captured by the imaging means to generate a rectangular image.
A specific means for identifying a vanishing point in perspective from a circular image captured by the imaging means, and
The distance from the center to the disappearance point and the circumference of the outermost edge are centered on each point along a straight line from the center of the circumference of the outermost edge of the annular image captured by the imaging means to the disappearance point. An extraction means for extracting a plurality of circumferential images consisting of each pixel on the circumference formed by a radius corresponding to the ratio of the center to the disappearance point.
Generation to generate the rectangular image by assigning each circumferential image extracted by the extraction means to a coordinate plane having a direction along the circumference as the x-axis and a direction along the axis as the y-axis. Means and
An image processing device having. The image processing apparatus according to claim 1, wherein the rectangular image is an image obtained by cutting out a part of the annular image captured by the imaging means in a direction along an axis. The specific means
A point of interest is set on the circumference of the outermost edge of the circular image, and the point of interest is set.
Find the center point of the outermost circumference and the center point of the inner circumference of the circular image.
Find the point on the inner circumference that corresponds to the point of interest.
An extension of the line connecting the center point of the outermost circumference and the center point of the inner circumference of the annular image, the point of interest, and a point on the inner circumference corresponding to the point of interest. Identify the point where the extension of the line connecting with and the intersection is as the vanishing point.
The image processing apparatus according to claim 1 or 2, wherein the image processing apparatus is characterized by the above. The image processing apparatus according to any one of claims 1 to 3, further comprising a conversion means for correcting distortion of the circular image captured by the imaging means and converting the circular image into a regular circular image. The image processing apparatus according to any one of claims 1 to 4, further comprising a correction means for correcting a magnification in the axial direction of the rectangular image. The image processing apparatus according to any one of claims 1 to 5, further comprising a compositing means for synthesizing a plurality of rectangular images generated by the generating means. Computer,
Operate as the image processing apparatus according to any one of claims 1 to 6.
Image processing control program.

Images