JP5953614B2 - Disc discrimination method, disc discrimination device, and disc sorting device - Google Patents

Description

  The present invention relates to a disc discrimination method and disc discriminating apparatus, and more specifically, discriminates the authenticity of a disc by capturing a captured image by capturing a pattern on the front or back surface of the disc and comparing the captured image with a reference image. The present invention relates to a disc discrimination method and a disc discrimination device.

  In addition, the present invention relates to a disk sorting device, and more specifically, to acquire a captured image by capturing a pattern on the front or back surface of the disk, to determine the authenticity of the disk by comparing the captured image with a reference image, The present invention relates to a disk sorting apparatus that sorts disks based on the determination result.

  Note that the disc in this specification is a concept that includes medals and tokens used in gaming machines, and coins as currency.

  Various techniques for picking up a pattern on the front or back surface of a medal or coin and discriminating the denomination or authenticity using the picked-up image have been conventionally proposed. For example, those disclosed in Patent Documents 1 to 3 have been proposed. is there.

  In the image identification method and the image identification device disclosed in Patent Document 1, the uneven pattern of the identification object is read with high resolution, the center position of the object is calculated based on the obtained image data, and the calculated center position is used as a reference. The image data is compressed within a range where the pattern of the object can be identified. Data obtained by rotating the reference image data at various rotation angles is prepared, and the reference image data rotated at the various rotation angles and the compressed image data are collated. Identify the reference image data of the rotation angle that minimizes the cumulative number of inconsistent points obtained by collation, and compare the coincidence points and inconsistency points of the compressed image data with the specified reference image data and a predetermined allowable range A match / mismatch between the compressed image data and the reference image data is identified.

  In the coin identification device of Patent Document 2, the outer diameter and center position of a coin are extracted from image data obtained by reading a coin pattern, and the extracted outer diameter is compared with the pre-recorded outer diameter of an existing coin. By doing so, the denomination of the coin is determined. Based on the extracted center position, the position of the image data is corrected so that the center position of the coin is equal to the center position of the image data, and the image data whose center position is corrected and the primary matching dictionary data are used. Perform rotation matching. When the matching rate exceeds a certain threshold in the rotation matching, the angle is set as the rotation angle of the coin, and the rotation angle of the image data is corrected based on the rotation angle. Pattern matching is performed using the image data with the corrected rotation angle and the secondary matching dictionary to determine whether the coin is true or false.

  In the image discrimination method disclosed in Patent Document 3, rotation angle information is inserted into image data for each rotation angle acquired for each predetermined rotation angle and the data for each rotation angle, and the image data for each angle is stored in an overlapping manner. The reference dictionary is compared with the pixels of the captured image data and the pixels of the reference dictionary, and the captured image is discriminated based on the degree of coincidence of the pixels of the image data for each rotation angle. In addition, the image data for each positional deviation acquired for each predetermined positional deviation and the reference dictionary in which positional deviation information is inserted into the image data for each positional deviation, and the image data for each positional deviation are stored and stored, and the captured image The data pixels and the reference dictionary pixels are collated, and the captured image is discriminated based on the degree of coincidence of the pixels of the image data by positional deviation.

JP-A-9-27056 (FIGS. 1 to 3, paragraph numbers 0015 to 0021) JP-A-10-63911 (FIG. 1, paragraph numbers 0013 to 0018) JP 2006-39732 A (FIGS. 9-12, paragraph numbers 0030, 0038-0043)

  By the way, the pattern on the front surface or the back surface of the disc is formed in a state of being positioned with reference to the center of the disc. However, in the case of a disc such as a game medal or a foreign coin, the positional deviation of the pattern with respect to the center of the disc is large, and the reference image data is rotated at various rotation angles as in the image identification method and image identification device of Patent Document 1 above. Even if collation is performed using the processed data, there is a problem that the discrimination accuracy is insufficient. That is, if the amount of positional deviation of the pattern is large, even if the reference image is rotated with reference to the center of the disc, the pattern is rotated in a state including the positional deviation (in other words, an eccentric state). It becomes a rotated image, and the discrimination accuracy decreases.

  In the coin identification device of Patent Document 2, the center position of the coin is obtained, the position of the image data is corrected so that the center position of the coin and the center position of the image data are equal, and then the rotation angle is obtained by performing rotation matching. The rotation of the image data is corrected at the obtained rotation angle. In this case, the center position of the coin simply coincides with the center position of the image data, and no consideration is given to the positional deviation of the pattern. Therefore, as in the case of Patent Document 1, there is a problem that the discrimination accuracy is insufficient.

  In the image discrimination method of Patent Document 3, in recognizing a rotating coin, data obtained by superimposing image data for each rotation angle is used as a reference dictionary, and the captured image data and the reference dictionary are collated. In this case, since no consideration is given to the positional deviation of the pattern, there is a problem that the discrimination accuracy is insufficient as in the case of Patent Document 1 and Patent Document 2.

  In recognition of a banknote with a large watermark or printing misalignment, data obtained by superimposing misaligned image data is used as a reference dictionary, and the captured image data and the reference dictionary are collated. However, the case where the pattern is misaligned on the rotating disk is not taken into account, and there is still a problem that the discrimination accuracy is insufficient.

The present invention has been made in consideration of the above-described problems of the prior art, and an object of the present invention is to provide a disc discrimination method capable of discriminating with high accuracy even when there is a pattern misalignment with respect to the center of the disc. It is to provide a disc discrimination device.
It is still another object of the present invention to provide a disc sorting apparatus that can discriminate with high accuracy even when there is a misalignment of the pattern with respect to the center of the disc and has high sorting accuracy.
Other objects of the present invention which are not specified here will be apparent from the following description and the accompanying drawings.

  In order to achieve this object, the disc discriminating method, disc discriminating device, and disc sorting device according to the present invention are configured as follows.

In the disc discrimination method of the present invention, a reference image corresponding to a reference disc is prepared, an image of one side of the disc to be discriminated is picked up by an imaging means to obtain a picked-up image, a discriminated image based on the acquired picked-up image and the reference In the disc discriminating method in which the discriminating unit discriminates the authenticity of the discriminating target disc by comparing with an image, (A) generating a first discriminating image based on the captured image of the discriminating target disc, and A step of comparing the discriminated image with the reference image, and (B) generating a plurality of second discriminated images corresponding to images obtained by rotating the first discriminated image at a plurality of different rotation angles. A step of comparing the second image to be discriminated with the reference image, and (C) a plurality of second images obtained by translating one or more selected from the first and second images to be discriminated by coordinate transformation. 3 courtesy Wherein the step of comparing the image with the reference image, wherein the (A), (B) and the authenticity of the determination target disk from the comparison result in the step of (C) is determined, the (A) and ( Three rotation angles are identified from the comparison result between the first and second discriminated images and the reference image in the step B), and the three rotation angles corresponding to the identified three rotation angles in the step (C). The disc discrimination method is characterized in that the comparison is performed only for the third discriminated image .

In the disc discriminating method of the present invention, a first discriminated image is generated based on a captured image of a disc to be discriminated, the first discriminated image and a reference image corresponding to the reference disc are compared, and the first discriminating image is compared. A plurality of second discriminated images corresponding to images obtained by rotating the discriminated images at a plurality of different rotation angles are generated, and the second discriminated image and the reference image are compared. Since the plurality of second discriminated images have different rotation angles with respect to the first discriminating image, even if the pattern of the disc to be discriminated is rotated in the captured image, the rotation is the same as or approximate to the rotation angle. The rotation of the pattern is corrected by comparing the discriminated image having an angle and the rotation direction opposite to the reference image. In other words, the rotational deviation of the pattern is removed or reduced. Further, one or more selected from the first and second discriminated images are translated by coordinate transformation to generate a plurality of third discriminated images, and the third discriminated image and the discriminated image are compared. To do. Thereby, if the direction and the amount of movement in the parallel movement are appropriate, even if the pattern of the disc to be discriminated in the captured image is misaligned, the misalignment is corrected. In other words, the positional deviation is removed or reduced. Therefore, by comparing the first, second, and third discriminated images with the reference image, the influence of both the rotation of the pattern and the positional deviation in the captured image is removed or reduced, and the discrimination accuracy can be improved. .
Furthermore, three rotation angles are specified from the comparison result between the first and second discriminated images and the reference image, and only the third discriminating image corresponding to the specified three rotation angles is compared with the reference image. A comparison is made. In this case, since the number of third images to be compared with the reference image is reduced, there is an advantage that the time required for the determination can be shortened.

  In the present invention, “parallel movement” means that the image moves to an arbitrary coordinate point on the coordinate plane. For example, when the image is formed on the XY plane, the X direction and / or Or moving in the Y direction. The “contrast result” means the degree of difference from the reference image, and is, for example, the degree of difference or similarity to the reference image.

In a preferred example of the disc discrimination method of the present invention, in the step (C), the translation of the first or second discriminated image is repeatedly executed while changing the direction of the translation. In this case, since the correction of the positional deviation can be optimized by changing the direction of the parallel movement, there is an advantage that the discrimination accuracy can be further improved.

In another preferable example of the disc discrimination method of the present invention, the authenticity of the disc to be discriminated (M) is discriminated based on the best comparison result among the comparison results in the steps (A), (B) and (C). To do. In this case, since the true / false determination is made based on the comparison result with the image to be discriminated that has the least influence of both the rotation of the pattern and the positional deviation in the captured image, the discrimination reference value (in other words, the threshold value) is set strictly. There is an advantage that more accurate discrimination is possible.

The disc discriminating apparatus of the present invention holds a reference image corresponding to a reference disc in a reference image holding unit, captures an image of one side of the disc to be discriminated by an imaging unit, acquires a captured image, and images the acquired disc to be discriminated. In the disc discrimination device in which the discriminating unit discriminates the authenticity of the discriminating target disc by comparing the discriminating image based on the image with the reference image, the first discriminating image based on the captured image of the discriminating target disc, and Means for generating a plurality of second discrimination images corresponding to images obtained by rotating the first discrimination image at a plurality of different rotation angles, and one selected from the first and second discrimination images An image moving means for generating a plurality of third discriminated images by translating the above by coordinate transformation, wherein the discriminating means includes the first, second and third discriminated images. By comparison with the reference image and respectively, to determine the authenticity of the determination target disk from the comparison result, said determination means, comparison result between the first and second to-be-determined image and the reference image When the three rotation angles are specified and the third discriminated image and the reference image are compared, only the third discriminating image corresponding to the specified three rotation angles is compared. It is a disk discriminating apparatus characterized by performing

In the disc discriminating apparatus of the present invention, a first discriminated image is generated based on a captured image of a disc to be discriminated, and a plurality of images corresponding to images obtained by rotating the first discriminated image at a plurality of different rotation angles. Means for generating the second discriminated image. In addition, image moving means for generating a plurality of third discriminated images by translating one or more selected from the first and second discriminated images by coordinate transformation is provided. The discriminating unit compares each of the first, second, and third discriminated images with the reference image, and discriminates the authenticity of the disc to be discriminated from the comparison result. Since the plurality of second discriminated images have different rotation angles with respect to the first discriminating image, even if the pattern of the disc to be discriminated is rotated in the captured image, the rotation is the same as or approximate to the rotation angle. The rotation of the pattern is corrected by comparing the discriminated image having an angle and the rotation direction opposite to the reference image. In other words, the rotational deviation of the pattern is removed or reduced. Further, by comparing the third image to be discriminated with the reference image, if the direction and the amount of movement in the parallel movement are appropriate, even if the pattern of the disc to be discriminated in the captured image is misaligned, the position misalignment is achieved. Is corrected. In other words, the positional deviation is removed or reduced. Therefore, by comparing the first, second, and third discriminated images with the reference image, the influence of both the rotation of the pattern and the positional deviation in the captured image is removed or reduced, and the discrimination accuracy can be improved. .
Further, when the three rotation angles are specified from the comparison result between the first and second discriminated images and the reference image, and the third discriminated image and the reference image are compared, the three specified Comparison is performed only on the third image to be discriminated corresponding to the rotation angle. In this case, since the number of third images to be compared with the reference image is reduced, there is an advantage that the time required for the determination can be shortened.

In a preferred example of the disc discriminating apparatus of the present invention, the translation of the first or second discriminated image by the image moving means is repeatedly executed while changing the direction of the parallel movement. In this case, since the correction of the positional deviation can be optimized by changing the direction of the parallel movement, there is an advantage that the discrimination accuracy can be further improved.

In another preferred example of the disk discriminating apparatus of the present invention, the discriminating unit is configured to discriminate the discriminating object based on a best comparison result among the comparison results between the first, second and third discriminated images and the reference image. Determine the authenticity of the disk. In this case, since the true / false determination is made based on the comparison result with the image to be discriminated that has the least influence of both the rotation of the pattern and the positional deviation in the captured image, the discrimination reference value (in other words, the threshold value) is set strictly. There is an advantage that more accurate discrimination is possible.

In the disc discrimination method of the present invention, it is possible to discriminate with high accuracy even when there is a misalignment of the pattern with respect to the center of the disc.
In the disc discriminating apparatus of the present invention, it is possible to discriminate with high accuracy even when there is a misalignment of the pattern with respect to the center of the disc.

It is a schematic front view which shows the medal selection apparatus of Example 1 of this invention. It is a schematic sectional drawing in alignment with the II-II line of the medal selection apparatus of FIG. It is a schematic diagram which shows the state at the time of the imaging timing sensor which comprises the medal selection apparatus of FIG. 1 detecting a medal from which a diameter differs. It is a schematic block diagram of the medal selection apparatus of FIG. It is a block diagram which shows the image process part of the medal selection apparatus of FIG. It is a flowchart for demonstrating operation | movement of the medal selection apparatus of FIG. It is a flowchart which shows the detail of the reference | standard image registration step of FIG. It is a flowchart which shows the detail of the pre-processing step of FIG. It is a flowchart which shows the detail of the image contrast determination step of FIG. FIG. 10 is a flowchart showing details of the image comparison determination step in FIG. 6 and is a continuation of FIG. 9. 10 is a flowchart showing details of a captured image preprocessing step in FIG. 9. It is a flowchart which shows the detail of the parallel movement step of FIG. It is a schematic diagram which shows the movement of the image in the parallel movement step of FIG. It is a flowchart for demonstrating operation | movement of the medal selection apparatus of Example 2 of this invention, and shows the detail of an image contrast determination step. It is a flowchart for demonstrating operation | movement of the medal selection apparatus of Example 2 of this invention, and is a continuation of FIG. It is a flowchart for demonstrating operation | movement of the medal selection apparatus of Example 3 of this invention, and shows the detail of an image contrast determination step. It is a flowchart for demonstrating operation | movement of the medal selection apparatus of Example 3 of this invention, and is a continuation of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

(Constitution)
As an example of the disk sorting device of the present invention, a medal sorting device 100 shown in FIGS. The medal sorting device 100 is used by being incorporated in a game machine or the like. The medal sorting device 100 determines the authenticity of the inserted medals and distributes the fake medal FM to the medal return port 101. The function of guiding to 102 is provided. The medal sorting device 100 includes a main body 103, a medal slot 104, a medal passage 105, a sorting gate 106, a two-dimensional imaging device 120, an imaging timing sensor 111, a medal count sensor 113, a control device 140, a ROM 142, a RAM 143, and a user interface 151. A status indicator 152, a registration switch 153, and a security volume 154.

  The main body 103 is formed with a medal slot 104 and a medal passage 105, and has a function to which a sorting gate 106, a two-dimensional imaging device 120, an imaging timing sensor 111, and a medal count sensor 113 are attached. The main body 103 has a rectangular box shape and is made of resin. In the main body 103, a rectangular imaging window 110 is provided on one side wall of the medal passage 105.

  The medal slot 104 has a function of accepting coins inserted into a slot (not shown) such as a game machine. The medal slot 104 is formed to be shifted to the left end portion of the upper surface of the main body 103 and has a slit-like cross-sectional shape.

  The medal passage 105 has a function of guiding the medal M that is inserted into the medal insertion port 104 and falls or rolls. The medal passage 105 is formed in the main body 103 and has a slit-like cross-sectional shape that is substantially the same as that of the medal insertion slot 104. As shown in FIG. 1, the medal passage 105 includes a vertical medal passage 105 </ b> V that hangs down from the medal insertion slot 104 and an inclined medal passage 105 </ b> S that is inclined downward and obliquely downward to the left. Therefore, the medal M inserted into the medal insertion slot 104 is guided by the guide rail 108 after dropping vertically in the vertical medal passage 105V. As shown in FIG. 1, the guide rail 108 has a guide surface 108 a formed along the guide line GL and is inclined forward and downward in the rolling direction of the medal M. Therefore, the medal M is guided to the right side by the guide rail 108 and rolls on the guide surface 108a of the guide rail 108 to move in the inclined medal path 105S. In other words, in the inclined medal path 105S, the peripheral surface of the medal M contacts the guide rail 108 via the guide line GL, and is guided to the right along the guide line GL while being supported by the guide rail 108. The guide rail 108 may have a shape other than a flat plate. For example, the guide rail 108 may be formed of a rod-shaped body. In this case, the medal M rolls on the guide line GL with its peripheral surface supported by the guide rail 108 while leaning against the guide surface 103a formed on the main body 103 in the inclined medal passage 105S.

  The sorting gate 106 has a sorting plate 109 that is disposed in the inclined medal passage 105S so as to be able to advance and retreat. When the sorting plate 109 enters the inclined medal passage 105S, the rolling medal M is deviated from the guide rail 108 and dropped and returned to the medal return port 101. When the sorting plate 109 leaves the inclined medal passage 105S, the medal M rolls on the guide rail 108 and passes through the sorting gate 106. The distribution plate 109 enters the inclined medal passage 105S by a gate control signal GCS from the control device 140. Normally, the sorting plate 109 is held in a state where it enters the inclined medal passage 105S (that is, the sorting gate 106 is closed).

  The two-dimensional imaging device 120 has a function of capturing an image of one surface of the medal M moving along the medal passage 105 in two dimensions. The two-dimensional imaging device 120 includes a light projecting device 121, a half mirror 122, a condenser lens 123, and an imaging element 124.

  The light projecting device 121 has a function of projecting light onto one surface of the medal M moving through the medal passage 105 via the half mirror 122. The light projecting device 121 is, for example, a surface light projecting device 130. This is because the use of the surface light projecting device 130 enables imaging without the influence of shadows even if the rotation phase of the medal M is different. The surface light projecting device 130 includes a light emitting diode (hereinafter referred to as LED) 131, a light guide 132, a reflection sheet 133, and a diffusion sheet 134.

  The LED 131 is a light source for projecting onto the medal M. A three-color LED is used as the LED 131, and the LED 131 emits white visible light. However, a white LED can be used as the LED 131. As shown in FIG. 2, the LED 131 is disposed so as to face the side end surface of the light guide 132. Therefore, the LED 131 can be disposed in a plane parallel to the medal path 105, and the installation space is small. Note that the position of the LED 131 shown in FIG. 2 is shown for convenience.

  In this embodiment, the light guide 132 has a rectangular thin plate shape made of resin from the viewpoint of low cost, and the surface thereof is arranged in parallel with the medal passage 105. The resin exhibits a milky white color due to being transparent or mixed with a diffusing material. When the diffusion material is mixed, the diffusion sheet 134 becomes unnecessary. The light guide 132 can also be constituted by a glass substrate. In this embodiment, the light guide 132 is opposed to the imaging window 110.

  The reflection sheet 133 has a function of preventing light from diffusing from the light guide 132 to the opposite side of the medal path 105 and reflecting it to the medal path 105 side. The reflection sheet 133 is in close contact with the surface of the light guide 132 located on the opposite side of the medal path 105. Note that a silver screen may be deposited on the light guide 132 instead of the reflection sheet 133.

  The diffusion sheet 134 has a function of uniformly diffusing light projected from the surface of the light guide 132 on the medal path 105 side. Therefore, the projection light from the LED 131 guided by the light guide 132 or reflected by the reflection sheet 133 is made a uniform light amount over the entire surface by the diffusion sheet 134 and is projected toward the medal path 105. The As a result, uniform light is projected onto the medal M. The projection light projected from the diffusion sheet 134 is projected at a right angle to the medal path 105, in other words, the medal M moving through the medal path 105. This is because an optical shadow due to the unevenness of the surface of the medal M is not created. Since the light guide 132, the reflection sheet 133, and the diffusion sheet 134 are thin, the light projecting device 121 can be downsized.

  The half mirror 122 has a function of reflecting part of light and transmitting part of light. Specifically, the light projection from the light projection device 121 is transmitted, and the reflected light from the medal M is reflected. In other words, the half mirror 122 projects the light from the light projecting device 121 at a right angle to the medal M in the medal path 105 and reflects the reflected light from the medal M in a direction parallel to the medal path 105. Let In this embodiment, the half mirror 122 is formed by depositing chromium on a thin transparent resin. This is for cost reduction. However, chromium may be plated on the glass plate. The half mirror 122 is disposed on the side of the imaging window 110 so as to be positioned at the lower left as the distance from the medal path 105 increases by 45 degrees with respect to the surface of the medal path 105. Specifically, the half mirror 122 is inclined at an angle of 45 degrees with respect to the medal path 105 in the lower left region of the inclined medal path 105S. The longitudinal axis LL of the half mirror 122 is arranged in a direction inclined at a predetermined angle with respect to the travel line DL of the medal M in the facing medal path 105 (which is a slightly inclined horizontal line because it is opposed to the inclined medal path 105S). Has been.

  The condensing lens 123 has a function of condensing the light reflected by the half mirror 122 into a predetermined small range. The condensing lens 123 is a convex lens having a predetermined refractive index due to the above function, and is disposed on the left side of the half mirror 122 (lower left diagonal in FIG. 1) in the main body 103 and is equal to or smaller than the half mirror 122. It has a diameter. It is preferable to devise the shape of the light projecting device 121 and reduce the size of the condenser lens 123. This is for cost reduction and miniaturization.

  The image sensor 124 has a function of capturing an image condensed by the condenser lens 123. The image sensor 124 is disposed on the left side of the condenser lens 123 (in the diagonally lower left in FIG. 1). For the image pickup element 124, a CCD image sensor or a CMOS image sensor is employed for miniaturization.

  The imaging timing sensor 111 has a function of detecting the timing at which the medal M rolling on the medal path 105 faces the imaging window 110. The imaging timing sensor 111 is disposed in the inclined medal passage 105S downstream of the imaging window 110, and takes an image when the center of the medal M reaches above the longitudinal axis LL of the half mirror 122 (in other words, on a reference line BL described later). The timing sensor 111 is arranged so as to detect the medal M. Therefore, the imaging timing sensor 111 outputs a timing signal TS indicating the timing at which the medal M can be optimally imaged as a detection signal for the medal M.

  As the imaging timing sensor 111, it is preferable to use a photoelectric sensor that can detect the position of the medal M more accurately. In this embodiment, the imaging timing sensor 111 is a photoelectric sensor 112 including a light emitting unit 112a, a light receiving unit 112b, and a prism 112c. The light emitting unit 112a, the light receiving unit 112b, and the prism 112c are arranged so that the light emitted from the light emitting unit 112a is incident on the light receiving unit 112b via the prism 112c, and the medal M blocks the light emitted from the light emitting unit 112a. Is configured to be detected. In other words, the detection axis DAL for detecting the medal M is formed by the axis of the light emitted from the light emitting unit 112a (that is, the optical axis LA), and the medal M crosses the detection axis DAL by the peripheral surface of the medal M. Detected.

  The detection axis DAL is preferably arranged in a direction substantially perpendicular to the progress line DL of the medal M when viewed from a direction perpendicular to the imaging window 110 (a direction from the front side to the back side in FIG. 1). In other words, the detection axis DAL is preferably arranged in a direction substantially perpendicular to the guide line GL of the guide rail 108 in the inclined medal path 105S. This is because the detection axis DAL crosses the inclined medal path 105S at the shortest distance, and the imaging timing sensor 111 can be installed most efficiently. That is, since the area required for installation of the imaging timing sensor 111 is minimized when viewed from a direction perpendicular to the guide line GL, there is an advantage that the medal sorting device 100 can be downsized. However, the angle of the detection axis DAL with respect to the guide line GL is not limited to 90 degrees, and can be appropriately set according to the shape of the medal path 105 and the arrangement of the imaging timing sensor 111.

Note that the light receiving unit 1 1 2b of the imaging timing sensor 111 can also be disposed at a position facing the light emitting unit 1 1 2a with the inclined medal passage 105S interposed therebetween. In that case, the prism 1 1 2c is unnecessary.

  The imaging window 110 includes a rectangular opening in a plan view provided on one side wall of the inclined medal path 105S, and has a function of demarcating an imaging area of the medal M rolling on the inclined medal path 105S. As shown in FIG. 3, the height H of the imaging window 110 (in other words, the length of the long side LS) is formed wider than the diameter of the maximum diameter selection target medal M1. This is for acquiring information on the diameter of the medal M in the vertical direction. The width W of the imaging window 110 (in other words, the length of the short side SS) is formed to be slightly smaller than the diameter of the minimum diameter selection target medal M3. The rolling medal M is prevented from coming off the inclined medal path 105S, and the lateral size of the half mirror 122 is restricted, and the half mirror 122 that is inclined with respect to the medal path 105 at an angle of 45 degrees is separated. This is to regulate the amount and reduce the size of the device. However, by providing other pop-out prevention means, the width W of the imaging window 110 can be made larger than the diameter of the medal M.

  When the bisector of the angle ANG formed by the guide line GL of the guide rail 108 and the detection axis DAL of the imaging timing sensor 111 when viewed from the direction perpendicular to the imaging window 110 is the reference line BL, the length of the imaging window 110 The imaging window 110 is arranged so that the side is parallel to the reference line BL. In other words, the imaging window 110 extends along the reference line BL. The longitudinal axis LL of the half mirror 122 is parallel to the reference line BL, and is arranged at a predetermined distance from the reference line BL in a direction perpendicular to the imaging window 110. In other words, the longitudinal axis LL and the reference line BL are arranged so as to overlap each other when viewed from a direction perpendicular to the imaging window 110.

  The medal count sensor 113 has a function of detecting the medal M that has passed through the sorting gate 106. One or a plurality of medal count sensors 113 are provided at the end of the inclined medal passage 105S downstream of the sorting gate 106. In this embodiment, one medal count sensor 113 is provided. The medal count sensor 113 outputs a medal detection signal DS for detecting the medal M determined to be a genuine medal TM. Therefore, the number of accepted genuine medals TM can be determined by counting the medal detection signal DS. As the medal count sensor 113, a photoelectric or magnetic sensor is used. In this embodiment, the medal count sensor 113 is a photoelectric sensor 114 having a light emitting unit 114a and a light receiving unit 114b. The light emitting unit 114a and the light receiving unit 114b are arranged so that the light emitted from the light emitting unit 114a enters the light receiving unit 114b, and the medal M detects the passage of the medal M by blocking the light emitted from the light emitting unit 114a. Has been.

  The control device 140 controls the operation of the imaging device 124 and the LED 131 based on the timing signal TS output from the imaging timing sensor 111 and receives the captured image signal IS output from the imaging device 124 to determine the authenticity of the medal M. It has a function of discriminating and selecting the medal M rolling on the medal passage 105 by controlling the opening and closing of the sorting gate 106 based on the discrimination result. The control device 140 also has a function of counting the number determined as the genuine medal TM based on the medal detection signal DS output from the medal count sensor 113. The control device 140 is constituted by, for example, a microcomputer 141 that operates based on a predetermined program. The control device 140 includes an image processing unit 160 that executes various image processes. Details of the image processing unit 160 will be described later.

  The ROM 142 has a function of storing a program and data for operating the control device 140. As shown in FIG. 5, the ROM 142 includes a reference image holding unit 171 that holds a later-described reference image.

  The RAM 143 has a function of temporarily storing data necessary during the operation of the control device 140. As illustrated in FIG. 5, the RAM 143 includes a captured image storage unit 172 that stores a captured image of the medal M captured by the two-dimensional imaging device 120, and a processed image storage unit that stores an image generated by the image processing unit 160. 173.

  The user interface 151 has a function of electrically connecting to a main body device (not shown) such as a game machine in which the medal sorting device 100 is incorporated. By connecting the main device to the medal sorting device 100 via the user interface 151, a desired signal can be input / output to / from the main device.

  The status indicator 152 has a function of displaying the operation status of the medal sorting device 100. The status indicator 152 is composed of, for example, a plurality of LEDs (not shown) having different emission colors, and the light emission of these LEDs is controlled by the control device 140, whereby various states (for example, the medal sorting device 100) (for example, Normal operation, error occurrence, etc.) are notified. As the status indicator 152, a display device such as a liquid crystal panel can be used.

  The registration switch 153 is used in registration of a reference image, which will be described later, and has a function of instructing the control device 140 to start and end registration.

  The security volume 154 has a function of setting a reference value for discriminating from the fake medal FM in the medal sorting device 100. The control device 140 determines the authenticity of the medal M based on the reference value set by the security volume 154.

  Next, the image processing unit 160 will be described with reference to FIG. The image processing unit 160 includes a center extraction unit 161, an edge enhancement unit 162, a binarization unit 163, an expansion / contraction unit 164, a size conversion unit 165, an image rotation unit 166, an image movement unit 167, and a determination unit 168. .

  The center extraction unit 161 has a function of extracting the center position of the medal M in the captured image based on the captured image held in the captured image holding unit 172 of the RAM 143. In other words, the coordinate value indicating the center of the medal M in the captured image is calculated. As will be described later, since the center of the medal M is located on the reference line BL, one of the peripheral edges of the medal M on the straight line corresponding to the reference line BL is detected in the captured image, and the distance between the peripheral edges is detected. The midpoint is the center position of the medal M. A known method may be used for extracting the center position. For example, one edge and the other edge of the medal M are detected for each line extending in the vertical axis (Y-axis) direction in the captured image, and the distance between both edges in the line where the distance between the detected edges is the maximum. Is the center position of the medal M. However, the method of extracting the center position on the reference line BL is much simpler and easier than the known method, and the time required for extracting the center position can be shortened. In addition, a diameter sensor that detects the diameter of the medal M may be provided, and the center position of the medal M may be calculated based on the detected diameter. In this case, on the straight line corresponding to the reference line BL, a point that is separated from the guide line GL by a value that is ½ of the diameter (that is, radius) may be the center of the medal M. There is no need for detection, and the time required to extract the center position can be further shortened.

  The edge enhancement unit 162 has a function of enhancing edges in the captured image held in the captured image holding unit 172. Edge emphasis is a process for sharpening an image by making the density gradient of the contour portion of the image steep. Edge enhancement can be performed by subtracting the second derivative from the original image (Laplacian filter) or by using an unsharp mask.

  The binarization unit 163 has a function of binarizing the image whose edge is enhanced by the edge enhancement unit 162. Binarization is processing for converting a grayscale image into a binary image. In binarization, when a pixel value (that is, luminance) is equal to or higher than a predetermined threshold, the pixel value is set to “1”, and otherwise, the pixel value is set to “0”.

  The dilation / contraction unit 164 expands the image binarized by the binarization unit 163 and replaces it with white if there is even one pixel around the pixel of interest, and one pixel around the pixel of interest. However, if there is a black pixel, it has a function of repeatedly executing contraction processing to replace it with black. By repeatedly executing the expansion process and the contraction process, noise is removed from the binarized image and a pattern defect (particularly, a linear pattern defect) is repaired.

  The size conversion unit 165 has a function of reducing the image size of the image expanded and contracted by the expansion / contraction unit 164. The size conversion is performed using a known affine transformation at a predetermined reduction rate with reference to the coordinate origin (X = 0, Y = 0).

  The image rotation unit 166 has a function of rotating the captured image held in the captured image holding unit 172 or the image expanded / contracted by the expansion / contraction unit 164. The rotation is performed at a predetermined rotation angle using a known affine transformation and using the medal center position extracted by the center extraction unit 161 as a reference.

  The image moving unit 167 has a function of translating the image whose size has been converted by the size converting unit 165. The parallel movement is performed in a predetermined direction and a moving distance using a known affine transformation. In other words, the entire image is translated based on the movement distance (for example, 1 pixel in the X axis direction and 0 pixel in the Y axis direction) indicated by the pixels.

  The image processing unit 160 includes a center extraction unit 161, an edge enhancement unit 162, a binarization unit 163, an expansion / contraction unit 164, a size conversion unit 165, an image rotation unit 166, an image moving unit 167, and a determination unit 168. As long as it has the above functions, it may be configured by either hardware or software. It is possible to make a part of the hardware and the rest software. In the present embodiment, the entire image processing unit 160 is configured by hardware advantageous for increasing the processing speed.

  In the medal sorting device 100 having the above-described configuration, the medal M moves obliquely downward along the guide line GL while being supported by the guide rail 108 in the inclined medal path 105S, and the circumferential surface on the traveling direction side of the medal M is the imaging timing. When the sensor 111 is positioned on the detection axis DAL of the sensor 111 (that is, the optical axis LA of the photoelectric sensor 112), the medal M is detected as having reached a predetermined position (that is, the imaging position) of the imaging window 110. Therefore, when the medal M reaches the imaging position, the peripheral surface of the medal M is positioned on the detection axis DAL regardless of the diameter of the medal M. On the other hand, since the peripheral surface of the medal M is guided along the guide line GL by the guide rail 108, when the medal M reaches the imaging position, the peripheral surface of the medal M is positioned on the guide line GL. That is, as shown in FIG. 3, the outer circumferences of the maximum diameter medal M1, the intermediate diameter medal M2, and the minimum diameter medal M3 are in contact with the detection axis DAL and the guide line GL when viewed from the direction perpendicular to the imaging window 110. It becomes. This means that the centers C1, C2, and C3 of the medals M1, M2, and M3 are located on the bisector of the angle formed by the guide line GL and the detection axis DAL when viewed from the direction perpendicular to the imaging window 110. To do. Therefore, by setting the bisector as the reference line BL and extending the imaging window 110 along the reference line BL, the entire pattern formed on one surface of the medal M having a different diameter can be obtained. An image can be easily and reliably captured. Therefore, easy and reliable discrimination and selection are possible. In other words, since the diameter range of the medal M that can image the entire pattern is widened, the diameter range that can be discriminated and selected is widened. In addition, in the direction perpendicular to the reference line BL when viewed from the direction perpendicular to the imaging window 110, the width W of the imaging window 110 can be set without considering the movement of the center position even for medals M having different diameters. The width W of the imaging window 110 can be made relatively small. In other words, it is not necessary to increase the imaging area in accordance with the shift or shift of the center position of the medal M. Therefore, the medal sorting device 100 can be reduced in size. In addition, since a plurality of imaging timing sensors 111 are not required, the cost is low and no complicated adjustment is required, which can be easily realized. Further, when the center position of the medal M serving as a reference for image discrimination is obtained, the center position exists on the reference line BL, so that the center position can be extracted simply and easily, and the processing time required for discrimination is shortened. The In other words, the time required for sorting is shortened, and faster sorting becomes possible.

  The shape of the imaging window 110 is a rectangle having a long side LS and a short side SS, and the imaging window 110 is arranged so that the long side LS of the rectangle is substantially parallel to the reference line BL. In general, since the imaging device 124 has a rectangular effective imaging surface, the use efficiency of the imaging surface in the imaging device 124 can be improved by making the imaging window 110 rectangular.

  The imaging window 110 is arranged so as to be symmetric with respect to the reference line BL when viewed from a direction perpendicular to the imaging window 110. In other words, the imaging window 110 is arranged so that the central axis in the short side direction of the imaging window 110 overlaps the reference line BL. Accordingly, if the time difference from the detection of the medal M by the imaging timing sensor 111 to the imaging of the medal M by the image sensor 124 is negligible, the center of the medal M is arranged at the center of the rectangular short side in the imaging window 110. Therefore, the entire pattern can be imaged more efficiently.

  A photoelectric sensor 112 is used as the imaging timing sensor 111, and the optical axis LA of the photoelectric sensor 112 forms a detection axis DAL. Therefore, since the medal M is detected by light having high directivity and linearity, detection accuracy can be improved.

(Operation)
Next, the operation of the medal sorting device 100 will be described with reference to FIGS. Hereinafter, the processing of the control device 140 will be mainly described.

  First, as shown in FIG. 6, initialization is performed in step S1. In initialization, the frame rate of the image sensor 124, the sensitivity of the imaging timing sensor 111 and the medal count sensor 113, and the like are set.

  In the next step S2, it is determined whether or not to register a reference image. That is, it is determined whether or not the registration switch 153 is turned on. When the registration switch 153 is on, the process proceeds to step S3, and registration of a reference image described later is executed. If the registration switch 153 is off, the process proceeds to step S4.

  In step S4, it is determined whether or not the imaging timing sensor 111 is turned on. In other words, it is determined whether or not the medal M rolling on the medal passage 105 has reached the imaging position. When the medal M is inserted into the medal insertion slot 104, the inserted medal M falls in the vertical medal path 105V and then rolls in the inclined medal path 105S, and the imaging timing sensor 111 is turned on. That is, the imaging timing sensor 111 is turned on in response to the insertion of the medal M into the medal insertion slot 104. If the imaging timing sensor 111 is on, the process proceeds to step S5. When the medal M is not inserted into the medal insertion slot 104, the imaging timing sensor 111 is kept off, and Step S4 is repeatedly executed. In other words, the standby state is maintained until the medal M is inserted into the medal insertion slot 104.

  In the next step S5, the control device 140 outputs a lighting control signal LCS to the LED 131, and the LED 131 is turned on for a short time (that is, flashed) based on the lighting control signal LCS. Thereby, diffused light is emitted from the light projecting device 121 toward the imaging window 110, and the medal M facing the imaging window 110 is projected.

  In the next step S6, the control device 140 outputs an imaging control signal ICS to the imaging device 124, and the imaging device 124 images the medal M based on the imaging control signal ICS. In other words, the captured image of the medal M is acquired by the two-dimensional imaging device 120. The image sensor 124 outputs a captured image signal IS including the acquired captured image to the control device 140. The control device 140 transfers the captured image included in the supplied captured image signal IS to the RAM 143 via the bus line BS shown in FIG. The RAM 143 stores and holds the sent captured image in the captured image holding unit 172.

  Note that the captured image acquired in step S6 is one of the front and back surfaces of the medal M to be selected. Therefore, when the patterns of the front and back surfaces of the medal M are different, it is necessary to compare with the respective reference images on the front and back surfaces of the reference medal SM described later. In the present embodiment, description will be made assuming that the patterns of the front and back surfaces of the medal M are different.

In the next step S7, image comparison determination is executed. In the image comparison determination, the image processing unit 160 of the control device 140 performs predetermined processing on the captured image held in the captured image holding unit 172 to generate a determination target image, and the determination unit of the image processing unit 160 168 compares the reference image held in the reference image holding unit 171 of the ROM 142 with the generated image to be discriminated, and the authenticity of the medal is discriminated based on the comparison result. In other words, when the comparison result with the reference image satisfies a predetermined reference, it is determined that they match (authentic medal TM), and in other cases, it is determined that they do not match (false medal FM). Details of the image comparison determination in step S7 will be described later.

  In the next step S8, it is determined whether or not it is determined to match in the image comparison determination in step S7. In other words, it is determined whether or not a genuine medal is determined. If it is determined that they match (that is, if they are determined to be genuine medals), the process proceeds to step S9. If it is determined that they do not match (that is, if they are determined to be false medals), the process returns to step S2.

  In step S9, the control device 140 outputs a gate control signal GCS to the sorting gate 106, the sorting plate 109 leaves the medal path 105, and the sorting gate 106 is opened. As a result, the genuine medal TM rolling on the inclined medal passage 105S passes through the sorting gate 106 and is introduced into the main device (not shown) via the medal receiving port 102. In other words, the medal M inserted into the medal insertion slot 104 is determined as the genuine medal TM and is selected as the genuine medal TM by the distribution gate 106.

  In the next step S10, it is determined whether or not the medal count sensor 113 is turned on. When the medal count sensor 113 is off, step S11 is repeatedly executed. In other words, the medal count sensor 113 is in a standby state. When the genuine medal TM is selected in step S9, the medal count sensor 113 is turned on by the genuine medal TM that has passed the sorting gate 106, and the process proceeds to step S12.

  In step S11, the control device 140 outputs a gate control signal GCS to the sorting gate 106, the sorting plate 109 enters the medal path 105 and the sorting gate 106 is closed, and the process returns to step S2.

  If it is determined in step S8 that they do not match (that is, if they are determined to be fake medals), the closed state of the distribution gate 106 is maintained, so that the medals M rolling on the medal path 105 are allocated to the distribution gate 106. Cannot be passed, and is distributed to the medal return port 101. In other words, the medal M is selected as a fake medal FM and released from the medal return port 101.

(Register reference image)
Next, reference image registration executed in step S3 of FIG. 6 will be described with reference to FIG. The registration of the reference image is performed by acquiring images of the front and back surfaces of a medal (hereinafter referred to as a reference medal SM) serving as a reference for authenticity determination by the two-dimensional imaging device 120. As the reference medal SM, it is preferable to use an unused medal M in order to improve the discrimination accuracy, but a used medal M may be used. In the reference image registration of FIG. 8, registration setting is made in the first step S21. In the registration setting, for example, it is selected whether the image to be registered is the front side or the back side of the medal M.

  In the next step S22, it is determined whether or not the registration is completed. The end of registration is determined by whether or not the registration switch 153 is turned off. When the registration switch 153 is turned off, the process returns to step S2 of FIG. 6, and when the registration switch 153 is not turned off, the process proceeds to step S23.

  In step S23, as in step S4 of FIG. 6, it is determined whether or not the imaging timing sensor 111 is turned on. When the reference medal SM is inserted into the medal insertion slot 104 and the imaging timing sensor 111 is turned on, the process proceeds to step S24. When the imaging timing sensor 111 is off, step S23 is repeatedly executed. In other words, the standby state is maintained until the reference medal SM is inserted into the medal insertion slot 104.

  In the next step S24, as in step S5 of FIG. 6, the control device 140 outputs the lighting control signal LCS to the LED 131, and the LED 131 is lit (that is, flashed) for a short time based on the lighting control signal LCS. Thereby, diffused light is emitted from the light projecting device 121 toward the imaging window 110, and the reference medal SM facing the imaging window 110 is projected.

  In the next step S25, as in step S6 of FIG. 6, the control device 140 outputs the imaging control signal ICS to the imaging device 124, and the imaging device 124 images the reference medal SM based on the imaging control signal ICS. In other words, the captured image of the reference medal SM is acquired by the two-dimensional imaging device 120. The image sensor 124 outputs a captured image signal IS including the acquired captured image to the control device 140. The control device 140 stores and holds the captured image included in the supplied captured image signal IS in the captured image holding unit 172 of the RAM 143.

  In the next step S <b> 26, the image processing unit 160 of the control device 140 performs preprocessing on the captured image held in the captured image holding unit 172. As shown in FIG. 8, the preprocessing is performed in the order of center extraction, edge enhancement, binarization, expansion / contraction, and size conversion. First, in step S <b> 41, the center extraction unit 161 extracts the center position of the reference medal SM in the captured image held in the captured image holding unit 172. The extracted coordinate value of the center position is stored in the RAM 143.

  In the next step S <b> 42, the edge enhancement unit 162 executes edge enhancement processing on the captured image held in the captured image holding unit 172. The edge-enhanced image is held in the processed image holding unit 173 of the RAM 143.

  In subsequent step S43, the binarizing unit 163 binarizes the edge-enhanced image held in the processed image holding unit 173. The binarized image is held in the processed image holding unit 173.

  Thereafter, in step S <b> 44, the expansion / contraction unit 164 executes expansion / contraction processing on the binarized image held in the processed image holding unit 173. By the expansion / contraction process, noise of the binarized image is removed, pattern defects are repaired, and the like. The expanded / contracted image is held in the processed image holding unit 173.

  Further, in step S45, the size converting unit 165 executes a process of converting the size of the expanded / contracted image held in the processed image holding unit 173. By the size conversion process, the expanded / contracted image is reduced to reduce the number of pixels. The size-converted image is held in the processed image holding unit 173. Thus, the preprocessing of step S26 in FIG. 7 is completed.

  In step S27 of FIG. 7, the data is stored in the ROM 142. That is, the pre-processed captured image is transferred from the RAM 143 to the ROM 142 via the bus line BS, and is stored and held in the reference image holding unit 171 as a reference image. After step S27 ends, the process returns to step S21, and the above steps S21 to S27 are repeatedly executed. Accordingly, a plurality of reference images can be registered for each of the front and back surfaces of the reference medal SM.

  In registering the reference image, a surface number k that specifies either the front surface or the back surface of the reference medal SM is set. That is, “0” is set as the face number k in the reference image corresponding to the surface of the reference medal SM. Similarly, “1” is set as the face number k in the reference image corresponding to the back face of the reference medal SM. The reference image holding unit 171 stores and holds the surface number k together with a plurality of reference images. Thereby, based on the surface number k, it is possible to distinguish the front-side reference image and the back-side reference image in the reference medal SM.

(Image contrast judgment)
Next, the image comparison determination in step S7 in FIG. 6 will be described with reference to FIG. First, in step S51 of FIG. 9, preprocessing of the captured image of the selection target medal (in other words, the determination target medal) M acquired in step S6 of FIG. 6 is executed. In the pre-processing executed in step S54, as shown in FIG. 11, steps S41 to S44 that are the same as those in FIG. 8 are executed, whereby center extraction, edge enhancement, binarization, expansion / contraction processing are performed. Made. In other words, the image that has not been subjected to the size conversion in step S45 in FIG. 8 is stored and held in the processed image holding unit 173 of the RAM 143 as a preprocessed image.

  In the next step S52, the preprocessed image held in the processed image holding unit 173 is stored and held in the captured image holding unit 172 of the RAM 143. In other words, the captured image held in the captured image holding unit 172 is replaced with the preprocessed image.

  In the next step S53, the control device 140 sets “0” for the surface number k described above. As a result, a comparison is first made with the reference image corresponding to “k = 0” (in other words, the reference image on the surface of the reference medal SM).

  In the next step S54, the reference image having the surface number k is selected from the plurality of reference images held in the reference image holding unit 171 of the ROM 142.

  In the next step S55, the control device 140 sets “0” to the rotation angle θ. In other words, the rotation angle θ is initialized (that is, reset).

  In the next step S56, the same size conversion process as that in step S45 of FIG. 8 is performed on the preprocessed image held in the captured image holding unit 172. The size-converted image is stored and held in the processed image holding unit 173 as a discriminated image.

  In the next step S <b> 57, image comparison for comparing the reference image held in the reference image holding unit 171 with the discrimination target image held in the processed image holding unit 173 is executed. In the image comparison, the selected reference image and the image to be discriminated are compared in pixel units, and the difference degree DF is calculated by counting the number of pixels having different pixel values.

  The similarity may be calculated instead of the difference DF. In that case, the similarity is calculated by counting the number of pixels with matching pixel values.

In the next step S58, it is determined whether or not the difference DF calculated in step S57 is equal to or less than a predetermined threshold value. If below the threshold, it is determined that a match at step S59, the flow returns to step S 7 of FIG. If the dissimilarity DF exceeds the threshold value, the process proceeds to step S60.

  In step S60, it is determined whether or not the rotation angle θ is “0”. If “θ = 0”, the process proceeds to step S62, and if “θ ≠ 0”, the process proceeds to step S61.

  In step S62 and the next step S63, a minimum dissimilarity DFm indicating the minimum value of the dissimilarity DF and a minimum dissimilarity rotation angle θm that minimizes the dissimilarity DF are set. That is, the current dissimilarity DF is set as the minimum dissimilarity DFm in step S62, and the current rotation angle θ is set as the minimum dissimilarity rotation angle θm in step S63. The set minimum difference DFm and minimum difference rotation angle θm are stored in the RAM 143.

  When “θ = 0” in step S60, the dissimilarity DF calculated in step S57 is set as the minimum dissimilarity DFm, and “0” is set as the minimum dissimilarity rotation angle θm.

  If “n ≠ 0” in step S60, it is determined in step S61 whether or not the difference DF calculated in step S57 is less than the minimum difference DFm. In the case of “DF <DFm”, that is, when the difference DF calculated in step S55 is smaller than the already set minimum difference DFm, the process proceeds to step S62, and the minimum difference DFm is updated. When “DF ≧ DFm”, the process proceeds to step S64, and the current minimum difference DFm is maintained as it is.

  In the next step S64, a value obtained by adding the rotation angle increment θd to the current rotation angle θ is set as a new rotation angle θ. In other words, the rotation angle θ is updated. In this embodiment, θd is set so that a total of 64 discriminated images including the discriminated image of “θ = 0” can be obtained when the image is rotated once. In this case, θd is “5.625 °”.

  In the next step S65, it is determined whether or not the rotation angle θ updated in step S64 is “360 °” or more. If “θ <360 °”, the process proceeds to step S66, the preprocessed image held in the captured image holding unit 172 is rotated by the image rotation unit 166 at the rotation angle set in step S64, and then the process returns to step S56. . Thereby, steps S56 to S64 are repeatedly executed until it is determined in step S58 that the dissimilarity DF is equal to or less than the threshold value or the rotation angle θ is equal to or greater than “360 °”. In other words, the reference image is compared with a plurality of discriminated images having different rotation angles including the case of “θ = 0”. Each discriminated image with “θ ≠ 0” corresponds to an image obtained by rotating the discriminating image with “θ = 0” at different rotation angles θ.

  If “θ ≧ 360 °” in step S65, the process proceeds to step S67 in FIG. 10, and “0” is set as the rotation angle count m. The rotation angle count number m is held in the RAM 143.

  In the next step S68, it is determined whether or not the rotation angle count number m is equal to “0”. If “m = 0”, the minimum dissimilarity rotation angle θm is set as the rotation angle θ in step S69, and then the process proceeds to step S73. If “m ≠ 0”, the process proceeds to step S70.

  In step S70, it is determined whether or not the rotation angle count number m is equal to “1”. In the case of “m = 1”, “θm−θd” obtained by subtracting the rotation angle increment θd from the minimum difference rotation angle θm is set as the rotation angle θ in step S71, and then the process proceeds to step S73. If “m ≠ 1”, in step S72, “θm + θd” obtained by adding the rotation angle increment θd to the minimum difference rotation angle θm is set as the rotation angle θ, and then the process proceeds to step S73.

  In step S73, the preprocessed image held in the captured image holding unit 172 is rotated by the image rotation unit 166 at the rotation angle set in any of steps S69, S71, and S72, and then proceeds to step S74 and rotated. The size of the preprocessed image is converted by the size conversion unit 165.

  In the next step S75, “0” is set to the image movement count number n. In other words, the image movement count number n is initialized (that is, reset).

  In the next step S76, the parallel movement process of FIG. 12 is executed. In the parallel movement process of FIG. 12, the discrimination target image held in the processed image holding unit 173 of the RAM 143 is translated in a predetermined direction corresponding to the image movement count number n. The parallel image to be discriminated is held in the processed image holding unit 173 of the RAM 143. That is, in step S91, it is determined whether or not the image movement count is “0”. If “n = 0”, the image to be determined is moved by one pixel in the upper right direction (the position of FIG. 13A). After the movement to P1, that is, each “+1” pixel movement in the X-axis direction and the Y-axis direction), the process returns to step S76 in FIG. If “n ≠ 0”, the process proceeds to step S92 to determine whether or not the image movement count number n is “1”. In the case of “n = 1”, the discriminated image is moved upward by one pixel in step S99 (moved to position P2 in FIG. 13B, that is, moved by “+1” pixel in the Y-axis direction), and then FIG. Return to step S76. If “n ≠ 1”, the process proceeds to step S93 to determine whether or not the image movement count number n is “2”. In the case of “n = 2”, the image to be discriminated is moved by one pixel in the upper left direction in step S100 (moved to position P3 in FIG. 13C), that is, “−1” in the X-axis direction and “+1” in the Y-axis direction. After “pixel movement”, the process returns to step S76 in FIG. If “n ≠ 2”, the process proceeds to step S94 to determine whether or not the image movement count number “3” is “3”. In the case of “n = 3”, after the image to be discriminated is moved one pixel to the left (moved to position P4 in FIG. 13D, that is, “−1” pixel moved in the X-axis direction) in step S101, The process returns to step S76 in FIG. When “n ≠ 3”, the process proceeds to step S95, and it is determined whether or not the image movement count number n is “4”. In the case of “n = 4”, the image to be discriminated is moved by one pixel to the right (moved to the position P5 in FIG. 13E, that is, “+1” pixels are moved in the X-axis direction) in step S102. Returning to step S76 of FIG. In the case of “n ≠ 4”, the process proceeds to step S96, and it is determined whether or not the image movement count number n is “5”. In the case of “n = 5”, the image to be discriminated is moved by one pixel in the lower right direction (moved to a position P6 in FIG. 13F), that is, “+1” in the X-axis direction and “−1” in the Y-axis direction. After “pixel movement”, the process returns to step S76 in FIG. If “n ≠ 5”, the process proceeds to step S97 to determine whether the image movement count number n is “6”. In the case of “n = 6”, the discriminated image is moved downward by one pixel in step S104 (moved to position P7 in FIG. 13G, that is, moved by “−1” pixel in the Y-axis direction). Returning to step S76 of FIG. In the case of “n ≠ 6”, the process proceeds to step S105, in which the image to be discriminated is moved by one pixel to the lower left (moved to position P8 in FIG. 13H, that is, each “−1” in the X-axis direction and Y-axis direction. After the pixel movement), the process returns to step S76 in FIG. In FIG. 13, for the sake of convenience, the movement distance is shown large to clearly show the direction of parallel movement.

  After execution of step S76 in FIG. 10, “1” is added to the current image movement count number n in step S77, and a new image movement count number n is set. In other words, the image movement count number n is updated.

  In the next step S78, it is determined whether or not the data image movement count number n is “8” or more. If the image movement count number n is not “8” or more (that is, “n <8”), the process proceeds to step S79, and the reference image held in the reference image holding unit 171 is similar to step S57 in FIG. An image comparison that compares the image to be determined held in the processed image holding unit 173 is executed to calculate the dissimilarity DF.

In the next step S80, similarly to step S 58 in FIG. 9, the difference degree DF calculated in step S79 whether or not a predetermined threshold value or less is determined. If it is equal to or smaller than the threshold value, it is determined in step S81 that they match, and the process returns to step S7 in FIG. When the dissimilarity DF exceeds the threshold value, the process returns to step S76, and steps S76 to S79 are repeatedly executed. That is, the comparison between the image to be discriminated and the plurality of reference images is repeatedly executed while changing the direction of the parallel movement.

  When the image movement count number n is “8” or more in step S78 (that is, when “n ≧ 8”), the process proceeds to step S82, where the new rotation angle count number m is set to “1”. "M + 1" is added.

  In the next step S83, it is determined whether or not the rotation angle count m is “2” or less. If “m ≦ 2”, the process returns to step S68, and steps S68 to S82 are repeatedly executed.

  As a result, the minimum difference rotation angle θm from which the minimum difference DFm can be obtained from the comparison result between the plurality of discriminated images having different rotation angles including “θ = 0” and the reference image is specified as the first rotation angle. The angle “θm−θd” obtained by subtracting the rotation angle increment θd from the minimum difference rotation angle θm is specified as the second rotation angle, and the angle “θm + θd” obtained by adding the rotation angle increment θd to the minimum difference rotation angle θm is the third. The rotation angle is specified, and only the discriminated image corresponding to the specified first to third rotation angles is translated and compared with the reference image. Therefore, it is possible to reduce the time required for the determination as compared to the case where the parallel movement is performed for all of the plurality of determination target images having different rotation angles.

  If “m> 2” in step S83, the process proceeds to step S84, where “1” is added to the current surface number k, and a new surface number k is set.

  In the next step S85, it is determined whether or not the surface number k is “2” or more. When the surface number k is less than “2” (that is, “k <2”), the process returns to step S52 of FIG. In other words, the processing of steps S52 to S84 is executed again with “k = 1” set. That is, a comparison with the reference image on the back surface of the reference medal SM is performed. When the surface number k is “2” or more (that is, “k ≧ 2”), it is determined that there is a mismatch in step S86, and the process returns to step S7 in FIG.

  In the medal sorting device 100 according to the first embodiment described above, the reference image holding unit 171 that holds the reference image corresponding to the reference medal SM, and the two-dimensional image that captures the picked-up image by capturing the front or back surface of the medal M to be selected. The discrimination unit that discriminates the authenticity of the medal M by comparing the discrimination image based on the captured image of the medal M acquired by the imaging device 120 and the two-dimensional imaging device 120 with the reference image held in the reference image holding unit 171. 168 and a distribution gate 106 that distributes medals M according to authenticity based on the determination result by the determination unit 168.

  The image processing unit 160 performs predetermined image processing on a captured image acquired by the two-dimensional imaging apparatus. The image processing unit 160 rotates an image by coordinate conversion and an image by coordinate conversion. Is included. The image processing unit 160 generates a discriminated image (hereinafter, referred to as a first critical image) based on the captured image of the discriminating target disk, and rotates the first discriminated image at a plurality of different rotation angles. A plurality of discriminated images (hereinafter referred to as second discriminated images) corresponding to the images are generated. Then, the determination unit 168 compares each of the first, second, and third images to be determined with the reference image, and determines the authenticity of the determination target disk from the comparison result.

  Since the plurality of second discriminated images have different rotation angles with respect to the first discriminating image, even if the pattern of the disc to be discriminated is rotated in the captured image, the rotation is the same as or approximate to the rotation angle. The rotation of the pattern is corrected by comparing the discriminated image having an angle and the rotation direction opposite to the reference image. In other words, the rotational deviation of the pattern is removed or reduced. Further, by comparing the third image to be discriminated with the reference image, if the direction and the amount of movement in the parallel movement are appropriate, even if the pattern of the disc to be discriminated in the captured image is misaligned, the position misalignment is achieved. Is corrected. In other words, the positional deviation is removed or reduced. Therefore, by comparing the first, second, and third discriminated images with the reference image, the influence of both the rotation of the pattern and the positional deviation in the captured image is removed or reduced, and the discrimination accuracy can be improved. .

  Further, the minimum difference rotation angle θm that provides the minimum difference DFm from the comparison result of the plurality of discriminated images having different rotation angles including “θ = 0” and the reference image is specified as the first rotation angle, and the minimum The angle “θm−θd” obtained by subtracting the rotation angle increment θd from the difference rotation angle θm is specified as the second rotation angle, and the angle “θm + θd” obtained by adding the rotation angle increment θd to the minimum difference rotation angle θm is the third rotation. The angle is specified, and only the discriminated image corresponding to the specified first to third rotation angles is translated and compared with the reference image. Therefore, the time required for determination can be shortened compared to the case where parallel movement is performed for all of the plurality of images to be determined. Therefore, the discrimination speed is improved and high-speed sorting becomes possible.

  14 and 15 show image comparison processing in the medal sorting device according to Embodiment 2 of the present invention. The medal sorting device according to the second embodiment selects a selection medal (in other words, a discrimination target medal) based on the best comparison result among the comparison results of the plurality of discriminated images and the reference image by rotation and translation in the image comparison determination. The difference from the medal sorting device 100 of the first embodiment is that the authenticity of M is determined. Other than that, it is the same as the medal sorting device 100 of the first embodiment. For this reason, only the image comparison determination process will be described here. Further, the same steps as the image comparison determination process in the medal sorting device 100 of the first embodiment are denoted by the same reference numerals as those in FIGS. 9 and 10 and the description thereof is omitted.

  The image comparison determination process of FIGS. 14 and 15 is executed in step S7 of FIG. 6 in the same manner as the medal sorting device 100 of the first embodiment. First, the same steps S51 to S57 as in the first embodiment are executed, so that the discriminated image of “θ = 0” and the reference image of “k = 0” are compared, and the dissimilarity DF is calculated. In the present embodiment, after execution of step S57, the same steps S60 to S66 as in the first embodiment are executed without executing step S58 of FIG. Thereby, a plurality of discriminated images having different rotation angles including the case of “θ = 0” are compared with the reference image, and the minimum difference DFm and the minimum difference angle θm with the best comparison result are stored in the RAM 143. Retained.

  Further, as shown in FIG. 15, by performing the same steps S67 to S79 as in the first embodiment, the discriminated image corresponding to the first rotation angle is translated, and the translated discriminated image and “ The difference image DF is calculated by comparing with the reference image of “k = 0”. In this embodiment, after execution of step S79, step S80 of FIG. 10 is not executed, and it is determined in step S201 whether or not the difference DF calculated in step S79 is less than the minimum difference DFm. In the case of “DF <DFm”, that is, when the dissimilarity DF calculated in step S79 is smaller than the minimum dissimilarity DFm already set, the process proceeds to step S202, and the minimum dissimilarity DFm is updated. When “DF ≧ DFm”, the process returns to step S76, and the current minimum difference DFm is maintained as it is. As a result, the discriminated image translated in the eight directions shown in FIGS. 13A to 13H is compared with the reference image of “k = 0”, and the minimum difference DFm as the best comparison result is obtained. It is set and held in the RAM 143.

  When the image movement count number n is “8” or more in step S78 (that is, when “n ≧ 8”), steps S82 and S83 are executed as in the first embodiment to obtain a new rotation angle count number m. After “m + 1” obtained by adding “1” to the current rotation angle count number m is set, it is determined whether the rotation angle count number m is “2” or less. If “m ≦ 2”, the process returns to step S68 as in the first embodiment. Thereby, steps S68 to S79, S201, S202, and S82 are repeatedly executed.

  In the above-described medal sorting device of the second embodiment, substantially the same effect as that of the first embodiment can be obtained. That is, even if the pattern of the disc to be discriminated is rotated in the captured image, the discriminating image having the same or approximate rotation angle as that of the rotation angle and having the reverse rotation direction is compared with the reference image. The pattern rotation is corrected. In other words, the rotational deviation of the pattern is removed or reduced. If the direction and amount of translation are appropriate, even if the pattern of the disc to be discriminated in the captured image is misaligned, the misalignment is corrected. In other words, the positional deviation is removed or reduced. Therefore, the influence of both the rotation of the pattern and the positional deviation in the captured image is removed or reduced, and the discrimination accuracy can be improved. Further, since only the image to be discriminated corresponding to the specified rotation angle is translated and compared with the reference image, the time required for the determination can be shortened. Therefore, the discrimination speed is improved and high-speed sorting becomes possible.

  Further, authenticity is determined based on the minimum difference DFm that provides the best comparison result. In other words, true / false determination is made based on the comparison result in which the influences of both the rotation of the pattern and the positional deviation in the image to be determined are the least. Therefore, the reference value (in other words, the threshold value) for determination can be set stricter than in the case of the first embodiment, so that more accurate determination is possible, and thus more accurate selection is possible.

  16 and 17 show image comparison processing in the medal sorting device according to Embodiment 3 of the present invention. The medal sorting device according to the third embodiment compares a plurality of discriminated images having different rotation angles including “θ = 0” in the image comparison determination with the reference image while performing parallel movement, and the obtained comparison result. This is different from the medal sorting device 100 of the first embodiment in that the authenticity of the sorting target medal (in other words, the discrimination target medal) M is determined based on the best comparison result. Other than that, it is the same as the medal sorting device 100 of the first embodiment. For this reason, only the image comparison determination process will be described here.

  First, in step S301 in FIG. 16, as in step S51 in FIG. 9, preprocessing of the captured image of the selection target medal (in other words, the determination target medal) M acquired in step S6 in FIG. 6 is executed. An image that has been subjected to center extraction, edge enhancement, binarization, and expansion / contraction processing is stored and held in the processed image holding unit 173 of the RAM 143 as a preprocessed image.

  In the next step S302, the preprocessed image held in the processed image holding unit 173 is stored and held in the captured image holding unit 172 of the RAM 143, as in step S52 of FIG.

  In the next step S303, “0” is set to the surface number k, and in the subsequent step S304, the reference image of the surface number k is selected, and the process proceeds to step S305.

  In step S305 and step S306, “0” is set for the rotation angle θ and the image movement count number n, respectively. In other words, the rotation angle θ and the image movement count number n are initialized (that is, reset).

  In the next step S307, the size conversion process is performed on the preprocessed image held in the captured image holding unit 172, as in step S56 of FIG. The size-converted image is stored and held in the processed image holding unit 173 as a discriminated image.

  In the next step S308, as in step S57 of FIG. 9, an image comparison that compares the reference image held in the reference image holding unit 171 and the image to be determined held in the processed image holding unit 173 is executed. The degree DF is calculated.

  In the next step S309, it is determined whether or not the image movement count number n is “0”. In other words, in step S309, it is determined whether or not parallel movement is being performed. If “n = 0” in which the parallel movement is not executed, the process proceeds to step S310. If “n ≠ 0” in which the parallel movement is executed, the process proceeds to step S311.

  In step S310, it is determined whether or not θ is “0”. If “θ = 0”, the process proceeds to step S312. If “θ ≠ 0”, the process proceeds to step S311.

  In step S312, the minimum difference DFm indicating the minimum value of the difference DF is set. If “n = 0” is determined in step S309 and “θ = 0” is determined in step S310, the difference DF calculated in step S308 is set as the minimum difference DFm. The set minimum difference DFm is stored in the RAM 143.

  If “n ≠ 0” in step S309 or “θ ≠ 0” in step S310, it is determined in step S311 whether or not the difference DF calculated in step S308 is less than the minimum difference DFm. . In the case of “DF <DFm”, that is, when the difference DF calculated in step S308 is smaller than the already set minimum difference DFm, the process proceeds to step S312 and the minimum difference DFm is updated. If “DF ≧ DFm”, the process proceeds to step S313, and the current minimum difference DFm is maintained as it is.

  In step S313, as in step S76 in FIG. 10, the parallel movement process in FIG. 12 is executed on the discrimination target image held in the processed image holding unit 173. The parallel image to be discriminated is stored and held in the processed image holding unit 173.

  In the next step S314, “1” is added to the current image movement count number n, and a new image movement count number n is set. In other words, the image movement count number n is updated.

  In the next step S315, it is determined whether or not the image movement count number n is “8” or more. When the image movement count number n is not “8” or more (that is, when “n <8”), the process returns to step S308, and the above steps S308 to S314 are repeatedly executed. That is, the discriminated image translated in step S313 is stored and held in the processed image holding unit 173 of the RAM 143, and the difference DF is calculated with respect to the reference image in step S308. In other words, the calculation of the degree of difference based on the comparison between the discriminated image to be translated and the reference image is repeatedly executed while changing the direction of translation. Then, the minimum value of the calculated differences is set as the minimum difference. When the image movement count number n is “8” or more (that is, when “n ≧ 8”), the process proceeds to step S316 in FIG.

In step S 316, a value obtained by adding the rotation angle increment θd to the current rotation angle theta is set as a new rotation angle theta. In other words, the rotation angle θ is updated.

  In the next step S317, it is determined whether or not the rotation angle θ updated in step S316 is “360 °” or more. When “θ <360 °”, the process proceeds to step S318, and the preprocessed image held in the captured image holding unit 172 is rotated at the updated rotation angle θ. Thereafter, the process returns to step S306 in FIG. 16, and steps S306 to S316 are repeatedly executed. Thus, each of the plurality of discriminated images having different rotation angles θ is compared with the reference image while being translated while changing the direction of translation, and the difference DF is calculated as a comparison result. Then, the calculated minimum value of the difference DF is set as the minimum difference DFm.

  If “θ ≧ 360 °” in step S317, the process proceeds to step S317 to determine whether or not the minimum difference DFm is equal to or less than a predetermined threshold value. If the minimum difference degree DFm is equal to or smaller than the threshold value, a match is determined in step S320, and the process returns to step S7 in FIG. In other cases (in other words, when the minimum difference DFm exceeds the threshold value), the process proceeds to step S321, "1" is added to the current surface number k, and a new surface number k is set.

  In the next step S322, it is determined whether or not the surface number k is “2” or more. If the surface number k is less than “2” (ie, “k <2”), the process returns to step S304 in FIG. In other words, the processes in steps S304 to S321 are executed again with “k = 1” set. That is, a comparison with the reference image on the back surface of the reference medal SM is performed. When the surface number k is “2” or more (that is, “k ≧ 2”), it is determined that there is a mismatch in step S323, and the process returns to step S8 in FIG.

  In the medal sorting device of the third embodiment described above, similarly to the first embodiment, even if the pattern of the disc to be discriminated is rotated in the captured image, the rotation angle is the same as or approximate to the rotation angle, and The rotation of the pattern is corrected by comparing the discriminated image whose rotation direction is opposite with the reference image. In other words, the rotational deviation of the pattern is removed or reduced. If the direction and amount of translation are appropriate, even if the pattern of the disc to be discriminated in the captured image is misaligned, the misalignment is corrected. In other words, the positional deviation is removed or reduced. Therefore, the influence of both the rotation of the pattern and the positional deviation in the captured image is removed or reduced, and the discrimination accuracy can be improved.

  As in the case of the second embodiment, authenticity is determined based on the minimum difference DFm that provides the best comparison result. In other words, true / false determination is made based on the comparison result in which the influences of both the rotation of the pattern and the positional deviation in the image to be determined are the least. In addition, the image to be discriminated corresponding to all the rotation angles is translated and compared with the reference image. Therefore, it is possible to set the determination reference value (in other words, the threshold value) more strictly than in the second embodiment. Thereby, the accuracy of discrimination and sorting is further improved.

(Modification)
In addition, this invention is not limited to the said Example, A various change is possible. For example, the similarity can be obtained instead of the dissimilarity DF, and the similarity can be quantified as a comparison result. In this case, a genuine medal may be determined when the similarity is equal to or greater than a predetermined threshold, and a false medal may be determined when the similarity is less than the threshold. In addition, when the patterns of the front and back surfaces of the selection target medal M are the same, it is possible to apply by omitting the processing related to the surface number n. Furthermore, by appropriately setting the face number k, the present invention can be applied to a plurality of denomination medals M each having a different pattern.

  In the above embodiment, in the image comparison determination, the captured image of the selection target medal M is not converted in size but is stored in the captured image holding unit 172 as a preprocessed image, and the stored preprocessed image is rotated before and after the rotation. Although the size conversion is performed, the captured image may be rotated. In that case, since the preprocessing of FIG. 8 is performed on the captured image before and after the rotation of the captured image, the time required for the image comparison determination increases as compared with the above-described embodiment.

  In the above embodiment, a medal having a concavo-convex pattern has been described as an example, but the present invention can also be applied to a disk having a pattern formed by printing or the like. In the above embodiment, the game medal is described as an example, but the present invention can be applied to other types of disks such as coins and tokens. Even in that case, the same effect can be obtained, and it is particularly effective in preventing fraud.

  The present invention can be suitably used for a disk processing apparatus such as a game machine, a vending machine, and a payment machine, and is particularly suitable for an apparatus that processes a plurality of types of disks having different diameters.

100 medal sorting device 101 medal return port 102 medal receiving port 103 main body 103a guide surface 104 medal insertion port 105 medal passage 105S inclined medal passage 105V vertical medal passage 106 sorting gate 108 guide rail (guide body)
108a Guide surface 109 Distribution plate 110 Imaging window 111 Imaging timing sensor 112 Photoelectric sensor 112a Light emitting unit 112b Light receiving unit 112c Prism 113 Medal count sensor 114 Photoelectric sensor 114a Light emitting unit 114b Light receiving unit 120 Two-dimensional imaging device 121 Light projecting device 122 Half mirror 123 Condensing lens 124 Image sensor 130 Area projector 131 LED
132 Light Guide 133 Reflective Sheet 134 Diffusion Sheet 140 Controller 141 Microcomputer 142 ROM
143 RAM
151 User Interface 152 Status Indicator 153 Registration Switch 154 Security Volume 160 Image Processing Unit 161 Center Extraction Unit 162 Edge Enhancement Unit 163 Binarization Unit 164 Expansion / Shrinkage Unit 165 Size Conversion Unit 166 Image Rotation Unit 167 Image Movement Unit 168 Discrimination Unit 171 Reference image holding unit 172 Captured image holding unit 173 Processed image holding unit BS Bus line M Medal M1, M2, M3 Medal FM Fake medal SM Reference medal TM True medal BL Reference line DAL Detection axis GL Guide line LA Optical axis LL Longitudinal axis LS Long side SS Short side DF Dissimilarity DFm Minimum dissimilarity DL Progress line DS Medal detection signal DS Medal detection signal GCS Gate control signal ICS Imaging control signal IS Captured image signal LCS Lighting control signal TS Timing signal

Claims (2)

Discrimination is performed by preparing a reference image corresponding to the reference disc, capturing an image of one side of the disc to be discriminated by an imaging unit, and comparing the discriminated image based on the acquired captured image with the reference image. In the disc discrimination method, wherein the means discriminates the authenticity of the disc to be discriminated,
(A) generating a first discriminated image based on a captured image of the discriminating target disk, and comparing the first discriminated image with the reference image;
(B) generating a plurality of second discrimination images corresponding to images obtained by rotating the first discrimination image at a plurality of different rotation angles, and comparing the second discrimination image with the reference image. And a process of
(C) a step of comparing a plurality of third discriminated images obtained by translating one or more selected from the first and second discriminated images by coordinate transformation and the reference image;
Including
The true / false of the disc to be discriminated is determined from the comparison results in the steps (A), (B) and (C) ,
Three rotation angles are specified from the comparison results between the first and second discriminated images and the reference image in the steps (A) and (B), and the specified 3 is determined in the step (C). A disc discrimination method characterized in that comparison is performed only for the third discriminated image corresponding to one rotation angle . A reference image corresponding to a reference disk is held in a reference image holding unit, an image of one side of a disc to be discriminated is picked up by an imaging unit, a picked-up image is acquired, and a discriminated image based on the acquired captured image of the disc to be discriminated and the In the disc discriminating apparatus in which the discriminating unit discriminates the authenticity of the disc to be discriminated by comparing with a reference image.
Means for generating a plurality of second discriminated images corresponding to images obtained by rotating the first discriminating image based on the captured image of the discriminating target disk and the first discriminating image at a plurality of different rotation angles, respectively. , Image moving means for generating a plurality of third discriminated images by translating one or more selected from the first and second discriminated images by coordinate transformation;
The discriminating means compares each of the first, second and third discriminated images with the reference image, discriminates the authenticity of the disc to be discriminated from the comparison result ;
When the discrimination means specifies three rotation angles from the comparison result between the first and second discrimination images and the reference image, and compares the third discrimination image and the reference image. A disc discriminating apparatus characterized in that a comparison is performed only for the third discriminated image corresponding to the specified three rotation angles .

Images