JP2006153536A - Mark detection method and apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reliably detect marks applied to lenses to be inspected on the basis of pickup images of the lenses inspected even in the case that the pickup images contain a large number of noise components. <P>SOLUTION: This mark detection apparatus detects a plurality of temporary reference layout marks 4A-4C applied to a lens to be inspected L on the basis of pickup images of the lens to be inspected L (spectacle lens 1) includes an imaging device for imaging the lens to be inspect and acquiring the pickup images. One temporary reference layout mark 4A having a highest precision of matching is searched for and detected by pattern matching from the pickup images. A region in which another temporary reference layout mark 4B in a specific positional relation to the temporary reference layout mark 4A is present is set as a detection region 26. Pattern matching is executed only on the detection region to search for the temporary reference layout mark 4B. In the case that the temporary reference layout mark is not appropriately detected, image enhancement processing is performed on the detection region 26 to search for and detect the temporary reference layout mark 4B by pattern matching. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a mark detection method and apparatus for detecting a plurality of marks provided on a subject from a captured image of the subject (particularly an optical lens such as an eyeglass lens).

  When an unprocessed spectacle lens is attached to a spectacle frame desired by a spectacle wearer, the spectacle lens is trimmed in accordance with the shape of the spectacle frame. At that time, as shown in FIG. 5, edge processing is performed using the fitting point 2 of the spectacle lens 1 as a processing reference point so that the pupil center of the spectacle wearer and the fitting point 2 of the spectacle lens 1 coincide. Since the fitting point 2 of the spectacle lens 1 cannot be directly displayed on the lens surface, in the design of the spectacle lens 1, particularly a progressive power spectacle lens, a predetermined position from a position serving as a design reference (for example, the prism measurement reference point O) is predetermined. A mark called a hidden mark 3 is formed in advance at a position separated by a distance, and the positions of the distance measurement and near distance portions of the spectacle lens 1 from the position of the hidden mark 3, the positions of the fitting points 2, etc. So that it can be derived.

  The temporary reference layout mark 4 indicates a reference when the hidden mark 3 is applied, and is further used as a reference point for positioning in the manufacturing process of the spectacle lens 1. The hidden mark 3 and the temporary reference layout mark 4 are generally referred to as marking marks, and are marked on the lens surface by, for example, a laser marking device. The stamped mark is given so as to minimize the unevenness of the lens surface, and the mark itself is required to be as inconspicuous as possible because of the properties of the spectacle lens 1 as a product. Therefore, the hidden mark 3 and the temporary reference layout mark 4 cannot normally be recognized with the naked eye on the surface of the spectacle lens 1 or the like, and as necessary (for example, by observing from a specific angle). It is given so that it can be recognized. In addition, the code | symbol 8 in FIG. 5 shows the target lens shape of a spectacles frame.

Conventionally, a mark detection method and apparatus for observing and detecting engraved marks such as a hidden mark 3 and a temporary reference layout mark 4 provided on the surface of a spectacle lens has been described in, for example, Patent Document 1 by the present applicant. .
In this mark detection apparatus, the imaging apparatus captures the eyeglass lens 1 as a subject (test lens) having a hidden mark 3 or the like on the surface, and the captured image is captured by the image processing apparatus and the image shown in FIG. Processing is performed to detect the hidden mark 3 and the like.

  That is, the image processing apparatus captures a captured image from an image capturing apparatus such as a CCD camera (S101), binarizes the captured image (S102), performs predetermined filtering (S103), and performs a plurality of filtering from the filtered image. The hidden mark 3 is simultaneously detected. That is, the image processing apparatus first detects the number of hidden marks 3 marked with “O” and counts the number (S104), and then detects the number of hidden marks 3 marked “H” and counts the number (S105).

  The image processing apparatus determines whether or not there are two hidden marks 3 marked ○ in step S104 (S106). If there are not two hidden marks 3 marked ○, this hidden mark marked with ○ 3 is determined to be one (S107). If there is one hidden mark 3 marked with ○, it is determined whether there is one hidden mark 3 marked H counted in step S105. (S108).

If the number of the hidden mark 3 with ◯ is not two or one, or the number of the hidden mark 3 with ◯ is one but the number of the hidden mark 3 with H is not one, the image processing apparatus performs steps S101 to S108. Repeat the process.
When there are two hidden marks 3 marked with ◯, or when both the hidden marks marked with ◯ and H are one, the image processing apparatus uses the hidden mark 3 applied to the spectacle lens 1 as the subject. The detection of the hidden mark 3 is completed by determining that it is properly detected (S109).

Japanese Patent Laid-Open No. 2002-1638

  However, in the above-described mark detection apparatus, when the mark detection environment such as the hidden mark 3 in the spectacle lens 1 is good, the mark such as the hidden mark 3 can be detected without any problem, but dust is present on the spectacle lens 1 as the subject. In an environment that tends to adhere, this dust causes a noise component, and the noise component increases in the captured image of the eyeglass lens 1 captured by the imaging device. When a plurality of marks such as the hidden mark 3 are detected simultaneously, the noise component is detected. May be erroneously detected as a mark.

  The object of the present invention has been made in consideration of the above-described circumstances, and even when a picked-up image of a subject has a lot of noise components, the mark applied to the subject is reliably detected from the picked-up image. An object of the present invention is to provide a mark detection method and apparatus.

  A mark detection method according to a first aspect of the present invention is a mark detection method for detecting a plurality of marks provided on a subject from a captured image of the subject, and pattern matching is performed from the captured image of the subject. To find and detect one mark with the highest matching accuracy, and then set the area where there is another mark in a specific positional relationship to this mark as the detection area. To search for and detect the other marks.

  A mark detection method according to a second aspect of the present invention is the mark detection method according to the first aspect of the invention, wherein pattern matching is performed in the detection region where the other mark exists to search for the other mark. If the mark is not detected properly, after performing image enhancement to clarify the contour, brightness, color density, etc. of the captured image, search again for the other marks by pattern matching and detect them. It is characterized by.

  A mark detection method according to a third aspect of the present invention is the mark detection method according to the first or second aspect of the invention, wherein the mark detection order is performed by first searching for and detecting a mark containing a large amount of a curve component, It is characterized by searching for and detecting a mark containing a large amount of linear components.

  A mark detection method according to a fourth aspect of the invention is characterized in that, in the invention according to any one of the first to third aspects, the subject is a spectacle lens, and the mark is a temporary reference layout mark. To do.

  A mark detection apparatus according to a fifth aspect of the present invention is a mark detection apparatus that detects a plurality of marks provided on a subject from a captured image of the subject, and captures the captured image by imaging the subject. The image capturing means to be obtained and the mark having the highest matching accuracy by pattern matching are searched for and detected from the captured image, and an area where another mark having a specific positional relationship with this mark exists is set as a detection area. Image processing means for performing the pattern matching only in the detection area and searching for and detecting the other marks.

  A mark detection apparatus according to a sixth aspect of the present invention is the mark detection device according to the fifth aspect, wherein the image processing means performs pattern matching in a detection region where another mark is present to detect the other mark. If this other mark is not detected properly, image enhancement is performed to clarify the contour, brightness, color density, etc. of the captured image, and then the other mark is searched again by pattern matching. Thus, the detection is performed.

  A mark detection apparatus according to a seventh aspect of the present invention is the mark detection device according to the fifth or sixth aspect, wherein the image processing means first searches for and detects a mark containing a large amount of a curve component, and thereafter a straight line. It is characterized by searching for and detecting a mark containing many components.

  The mark detection apparatus according to an eighth aspect of the invention is characterized in that, in the invention according to any one of the fifth to seventh aspects, the subject is a spectacle lens, and the mark is a temporary reference layout mark. To do.

  According to the first and fourth aspects of the present invention, one mark having the highest matching accuracy is searched and detected from the captured image of the subject by pattern matching, and then a specific positional relationship with respect to this mark is detected. Compared to the case where a plurality of marks are searched and detected at the same time, since the area where other marks exist in the detection area is used as a detection area, pattern matching is performed only in this detection area and the other marks are searched and detected. Particularly, since pattern matching is performed by narrowing down to a specific area and other marks are searched and detected, a plurality of marks can be reliably detected even when the picked-up image of the subject has a lot of noise components.

  According to the second aspect of the present invention, in the detection region where another mark exists, the image enhancement processing also enhances the noise component in the detection region, so that the image enhancement processing is not performed. Thus, by searching for and detecting another mark by pattern matching, it is possible to detect this other mark with high accuracy in a state in which the influence of the noise component is eliminated as much as possible.

  In addition, when other marks are not properly detected, after performing image enhancement processing for clarifying the contour, brightness, color density, etc. of the captured image, the other marks are searched again by pattern matching. By detecting, other marks in the image of the detection area are sharpened with respect to the background, so that these other marks can be reliably searched and detected.

  According to the third aspect of the present invention, since a mark that includes a large amount of curved components is first searched for and detected, and then a mark that includes a large amount of linear components is searched for and detected, it is within the region of the captured image. Since the included noise components include many linear components, detection defects can be suppressed to a low level by first detecting a mark that includes many curve components that are clearly different from the noise components.

  According to the fifth and eighth aspects of the present invention, the image processing means searches for and detects one of the marks with the highest matching accuracy by pattern matching from the captured image of the subject imaged by the imaging means. Since a region where other marks having a specific positional relationship exist as a detection region, pattern matching is performed only in this detection region and the other marks are searched and detected, so a plurality of marks are searched simultaneously. Compared to the case where the detection is performed, the pattern matching is performed by narrowing down to a specific area, and other marks are searched for and detected. Detection can be performed reliably.

  According to the sixth aspect of the present invention, in the detection region where another mark exists, the image enhancement processing also enhances the noise component in the detection region. By searching for and detecting other marks by pattern matching in a state where processing is not performed, these other marks can be detected with high accuracy in a state in which the influence of noise components is eliminated as much as possible.

  In addition, when the other mark is not properly detected, the image processing means performs image enhancement processing for clarifying the outline, brightness, color density, etc. of the captured image, and then performs the other mark by pattern matching. Since another mark in the image of the detection region is sharpened with respect to the background, the other mark can be reliably searched and detected.

  According to the seventh aspect of the present invention, the image processing means first searches for and detects a mark that includes a large amount of curved components, and then searches for and detects a mark that includes a large amount of linear components. Since the noise component included in the image region includes many linear components, detection failure can be suppressed to a low level by first detecting a mark that includes a lot of curve components that are clearly different from the noise component.

The best mode for carrying out the present invention will be described below with reference to the drawings.
FIG. 1 is a layout diagram of an optical system showing an embodiment of a mark detection apparatus according to the present invention.

  The mark detection apparatus 10 shown in FIG. 1 has a plurality of marks, particularly the test lens L, provided on the surface of a test lens L (spectacle lens 1 shown in FIG. 5 in the present embodiment) as a test object. The temporary reference layout mark 4 provided on the peripheral portion is detected by observing the image of the lens L, and as shown in FIG. 1, the illumination optical system 11, the imaging optical system 12, and the image processing The apparatus 25 is comprised. The illumination optical system 11 and the imaging optical system 12 are arranged using a beam splitter (half mirror) 13 so that the optical axis P1 of the illumination optical system 11 and the optical axis P2 of the imaging optical system 12 are the same. ing.

  The illumination optical system 11 is configured by sequentially arranging a light source 14, a condenser lens 15, a pinhole (aperture) 16, a beam splitter 13, an objective lens 17, an imaging lens 18 and a reflective screen 19 on the optical axis P1. Then, the position where the test lens L is placed is set between the objective lens 17 and the imaging lens 18. The light source 14, the condenser lens 15, and the pinhole 16 are referred to as a light source unit 14A.

  The light beam emitted from the light source 14 is collected by the condenser lens 15 and passes through the pinhole 16 to become uniform and efficient illumination light. This illumination light is reflected by the beam splitter 13 and enters the objective lens 17. Since the objective lens 17 is arranged so that the focal position thereof is the position of the pinhole 16 in the light source unit 14A, the range from the objective lens 17 to the position where the test lens L is placed, that is, the book In the embodiment, in the range from the objective lens 17 to the imaging lens 18, the principal ray has a principal ray on the optical axis P <b> 1 of the illumination optical system 11 (that is, coincident with the optical axes of the objective lens 17 and the imaging lens 18). Parallel light becomes parallel. The parallel illumination light is irradiated onto the test lens L, and the light beam emitted from the test lens L reaches the reflective screen 19 via the imaging lens 18, and the temporary reference layout mark 4 of the test lens L, etc. Is projected onto the reflective screen 19.

  The imaging optical system 12 is configured by sequentially arranging an imaging device 20 such as a reflective screen 19, an imaging lens 18, an objective lens 17, a beam splitter 13, and a CCD camera on the optical axis P2. A position where the test lens L is placed between 18 and the objective lens 17 is set.

  In the imaging device 20, the optical aperture surface (not shown) of the imaging lens built in the imaging device 20 is disposed at the focal position of the objective lens 17. Thus, in the range from the objective lens 17 to the position where the lens L is placed, that is, in the present embodiment, the range from the objective lens 17 to the imaging lens 18, the principal ray is the principal ray. The parallel light is parallel to the twelve optical axes P2 (that is, coincident with the optical axes of the objective lens 17 and the imaging lens 18). With this arrangement, the light receiving surface of the imaging device 20 and the reflective screen 19 become conjugate, and the image of the test lens L projected on the reflective screen 19 is reflected, and the imaging lens 18, the test lens L, the objective The light passes through the lens 17 and the beam splitter 13 and forms an image on the light receiving surface (CCD element surface) of the imaging device 20.

  The imaging magnification of the lens L to be imaged by the imaging device 20 is a field-of-view range corresponding to the entire surface of the lens L (for example, a field-of-view range of 82 mm when the diameter of the lens L is 80 mm). The magnification that can be secured on the light receiving surface of the imaging lens 20 (for example, a 1/2 inch size CCD element surface), and this magnification is realized by adjusting the arrangement positions of the imaging device 20 and the objective lens 17.

  The light source 14 is, for example, an LED that emits red light or near-infrared light in order to project a mark such as the temporary reference layout mark 4 of the lens L to be examined and obtain a sharp image. Further, the beam splitter 13 having a transmittance to reflectance ratio of 7: 3 is used. Further, the reflection type screen 19 is configured by attaching a reflection sheet coated with fine particles such as glass and aluminum in order to increase the reflectance. The reflective screen 19 is rotated at a high speed (for example, 3400 rpm) by the motor 21 in order to make the surface brightness and background uniform, and reflects the image of the lens L in this state.

  The imaging lens 18 is a lens (convex lens) having a positive focal length, and is disposed between the mounting position of the test lens L and the reflective screen 19 as described above. As shown in FIG. 2, the imaging lens 18 has a function of condensing the light beam that has passed through the lens L to be examined. In particular, when the test lens L is a negative power lens, the light beams A and B (light beam A is parallel light, the light beam B will be described later; the same applies hereinafter) that have passed through the test lens L are spread by the influence of the negative power. The diverging rays A and B are collected by the imaging lens 18 and projected onto the reflection type screen 19. The imaging lens 18 is arranged close to the position where the test lens L is placed, so that most of the divergent light after passing through the test lens L is captured and condensed. The imaging lens 18 and the reflective screen 19 are preferable in that they can be set to an optimum size, and the distance M between the imaging lens 18 and the position where the lens L is placed is set to 13 mm, for example.

  By the way, generally, when the subject lens L is photographed from above the subject lens L (eyeglass lens 1) using an imaging device and the image of the subject lens L is observed, the peripheral portion of the image of the subject lens L is observed. A shadow S (FIG. 5) is generated. When this shadow S occurs, the temporary reference layout mark 4 provided on the periphery of the lens L to be tested cannot be recognized by the shadow S, and the position thereof may not be detected.

Thus, the cause of the shadow S occurring in the peripheral portion of the lens L (eyeglass lens 1) can be considered as follows.
First, if the light beam incident on the test lens L from the light source is diverging light, the test lens L is a negative power lens (lens having a negative focal length) with a thick edge (edge) as shown in FIG. As described above, the light beam C incident on the edge portion of the test lens L is refracted by the first surface 5 of the test lens L and travels through the test lens L, and then the second surface 6 of the test lens L. It is considered that the shadow S is generated as a result of total reflection that reaches the edge surface 7 of the lens L and cannot be emitted to the outside of the lens L.

  Further, when the test lens L is a negative power lens and a light beam incident on the edge portion of the test lens L is emitted from the test lens L, the emitted light beam is influenced by the negative power of the negative power lens. It is considered that the shadow S is generated as a result of not spreading to the reflection type screen.

  On the other hand, in the mark detection apparatus 10 of the present embodiment, the principal ray of the light beam traveling between the objective lens 17 and the imaging lens 18 shown in FIG. 1 is the optical axis P1 of the illumination optical system 11 and the imaging optical system 12. Since the parallel light is incident on the test lens L from the objective lens 17, even if the test lens L is a minus power lens having a thick edge (edge), the parallel light is parallel to the optical axis P2. As shown in FIG. 2, the light ray A that has entered the edge portion of the test lens L is refracted by the first surface 5 of the test lens L and travels through the test lens L. Since the total reflection at the second surface 6 is reduced and the light is easily emitted outside the lens L, the light beam can be passed through the edge portion of the negative power lens. Therefore, even when the test lens L is a negative power lens, the shadow S (FIG. 5) generated in the peripheral portion of the image of the test lens L is reduced.

  In addition, since the imaging lens 18 is arranged between the mounting position of the test lens L and the reflection type screen 19, the light ray A traveling from the test lens L to the reflection type screen 19 by this imaging lens 18. And B can be condensed. For this reason, when the test lens L is a negative power lens, it is possible to suppress the light beam that has passed through the negative power lens from spreading and diverging by the condensing function of the imaging lens 18. When the lens L is a minus power lens, the shadow S generated in the peripheral portion of the image of the lens L to be measured is reduced.

  Further, since the imaging lens 18 is arranged close to the mounting position of the test lens L, the test lens L is a negative power lens, and light rays A and B that have passed through the negative power lens spread. Even if the light diverges, most of the light flux can be captured and collected by the imaging lens 18, and the divergence can be suppressed and guided to the reflective screen 19. Also from this point, when the test lens L is a negative power lens, the shadow S generated in the peripheral portion of the image of the test lens L is reduced.

  When the test lens L is a plus power lens, since the edge of the lens is thin, the light beam passes through the edge of the test lens L well, and a shadow S is formed on the periphery of the image of the test lens L. The temporary reference layout mark 4 and the like applied to the peripheral portion can be detected well by observing the image of the lens L to be tested. Similarly, when the test lens L is a negative power lens, the shadow S generated in the peripheral portion of the image of the test lens L is reduced as described above. The provisional reference layout mark 4 and the like can be detected well.

  As shown in FIG. 1, since the imaging lens 18 is disposed between the mounting position of the test lens L and the reflective screen 19, this negative power is used when the test lens L is a negative power lens. Even if the light beam that has passed through the lens spreads and diverges as indicated by light rays A and B in FIG. 2, the divergence of this light beam can be suppressed by the condensing action of the imaging lens 18, and the amount of light beam that reaches the reflective screen 19 Can be suppressed. For this reason, the image of the lens L (minus power lens) is brightened.

  When the imaging lens 18 is disposed close to the position where the test lens L is placed, most of the luminous flux that has spread and diverged through the test lens L (minus power lens) is focused on the imaging lens. 18 can capture and condense and suppress the divergence of the light, so that it is possible to further suppress a decrease in the amount of light flux reaching the reflective screen 19, and an image of the lens L (minus power lens) can be obtained. It becomes even brighter.

  When the test lens L is a plus power lens, the image of the test lens L is bright due to the condensing action of the lens itself, but when the test lens L is a negative power lens as described above, the test lens L is also bright. The image of the lens L can be brightened. For this reason, the difference in brightness of the image of the test lens L generated when the test lens L is a minus power lens and a plus power lens is reduced.

  When the imaging lens 18 is arranged close to the position where the test lens L is placed, especially when the test lens L is a negative power lens, the divergence of the light beam that has passed through the test lens L is diverged. Since it is further suppressed, the imaging lens 18 and the reflective screen 19 are reduced in size.

  The light beam traveling between the objective lens 17 and the imaging lens 18 shown in FIG. 1 becomes parallel light whose principal ray is parallel to the optical axis P1 of the illumination optical system 11 and the optical axis P2 of the imaging optical system 12. The illumination optical system 11 and the imaging optical system 12 can be an afocal optical system. For this reason, even if the test lens L changes its position in the optical axis direction between the objective lens 17 through which the parallel light passes and the imaging lens 18, the imaging magnification of the image of the test lens L taken by the imaging device 20 is It becomes constant. Since the depth of field of the imaging device 20 is deep, the focus of the image of the test lens L is also appropriate. Therefore, even if the test lens L has different thicknesses between the plus power lens and the minus power lens, and even if there is a slight misalignment in the set position of the test lens L, the imaging device 20 performs the test. The image of the lens L is clearly captured at the same imaging magnification.

  As shown in FIG. 1, the image of the surface of the test lens L is projected on the reflective screen 19 through the test lens L, reflected by the reflective screen 19, and imaged through the test lens L. Captured by the device 20. Therefore, even if the test lens L is a lens with an astigmatism axis and the image projected on the reflective screen 19 is distorted by the astigmatism axis, the image on the surface of the test lens L is the test lens. Since it passes through L twice and reaches the imaging device 20, the distortion of the image due to the astigmatic axis is canceled out, and an image without distortion is taken by the imaging device 20.

  As shown in FIG. 1, when the auxiliary lens 22 having a positive focal length is detachably disposed between the objective lens 17 and the position where the test lens L is placed, the test lens L It becomes possible to make the light beam incident on the beam into convergent light. As shown in FIG. 2, the convergent light beam B is incident on the test lens L and travels through the test lens L. Then, the total reflection on the second surface 6 of the test lens L is performed. Compared to the light beam A, the number of light beams decreases, and the light beam can be more easily emitted out of the lens L, and the function of allowing the light beam to pass through the edge portion of the negative power lens, which is the lens L, is increased. For this reason, in particular, even in the case of a test lens L (negative power lens) having an intensity number, the shadow S (FIG. 5) generated on the periphery of the image is further reduced, and further, for example, a test with a large aperture of about φ80 mm. Even with the lens L (minus power lens), the shadow S generated at the periphery of the image is further reduced. The attachment / detachment of the auxiliary lens 22 is appropriately selected in consideration of the lens power, the aperture, and the like of the test lens L as described above.

  As described above, the image of the lens L (eyeglass lens 1) photographed by the imaging device 20 is photoelectrically converted by the imaging device 20 into an image signal, and is taken into the image processing device 25 shown in FIG. The image processing device 25 performs image processing as will be described later, and detects a plurality of temporary reference layout marks 4 from a captured image of the lens L (glasses lens 1). The position of the hidden mark 3 is calculated from the detected positions of the plurality of temporary reference layout marks 4.

  That is, as shown in FIG. 5, the hidden mark 3 is on the straight line E connecting the temporary reference layout marks 4A and 4B marked with ○ among the temporary reference layout marks 4, and further × If the intersection point between the straight line E and the straight line E drawn perpendicularly to the straight line E from the temporary reference layout mark 4C marked with the straight line E is O, they are provided at equidistant positions on both sides from the intersection point O. The intersection point O is the prism measurement reference point described above.

  An image processing procedure for detecting the temporary reference layout mark 4 performed by the image processing device 25 will be described below with reference to FIGS. 3 and 4.

  The image processing device 25 fetches the captured image of the lens L (eyeglass lens 1) from the imaging device 20 (S1), searches the captured image for the temporary reference layout mark 4 with a circle by pattern matching, and the matching accuracy is high. The highest temporary reference layout mark 4A is detected (S2). This pattern matching is performed by searching and detecting from the captured image of the lens L a pattern similar to a pre-registered pattern characteristic (in this embodiment, a pattern shape characteristic). This is an image processing method for displaying similarity (reliability) similar to the above pattern as a numerical value. The reliability is a percentage value indicating the approximate level of the pattern to be searched against the pre-registered pattern features. For example, if half of the pattern to be searched is unclear, The property becomes 50% or less.

  The image processing apparatus 25 determines whether or not the temporary reference layout mark 4A detected by the pattern matching is one and the reliability of the detected temporary reference layout mark 4A is 90% or more (S3). . The image processing device 25 detects a plurality of provisional reference layout marks 4A, or if the reliability of one detected provisional reference layout mark 4A is less than 90%, determines that there is a detection failure. Then, the detection of the temporary reference layout mark 4 is finished.

  If the detected temporary reference layout mark 4A is one and the reliability of the detected temporary reference layout mark 4A is 90% or more, the image processing device 25 has a specific position with respect to the temporary reference layout mark 4A. Other temporary reference layout marks 4B having a relationship, that is, other temporary reference marks located at positions facing the temporary reference layout mark 4A with respect to the image center of the lens L as shown in FIG. The area where the layout mark 4B exists is set as the detection area 26, and the detection area by pattern matching is narrowed down to the detection area 26 (S4). The image processing apparatus 25 performs the above-described pattern matching only in the detection area 26 (pattern matching performed without performing image enhancement processing described later), and searches for and detects the temporary reference layout mark 4B (S5). .

  The image processing apparatus 25 determines whether there is one temporary reference layout mark 4B detected by the pattern matching and the reliability of the detected temporary reference layout mark 4B is 90% or more (S6). When the temporary reference layout mark 4B is not properly detected, that is, the image processing apparatus 25 detects a plurality of detected temporary reference layout marks 4B, or the reliability of one detected temporary reference layout mark 4B is 90. If it is less than%, image enhancement processing is performed only for this detection area 26 (S7).

  This image enhancement process is an image processing technique that makes the image easy to see by clarifying the contour, brightness, color density, and the like of the captured image in the detection region 26. In the present embodiment, this image enhancement process is a process for sharpening the temporary reference layout mark 4B by enhancing the density gradient between the temporary reference layout mark 4B and the background in the captured image in the detection region 26. .

  After performing the image enhancement processing on the detection area 26, the image processing apparatus 25 performs pattern matching only on the detection area 26 to search for and detect the temporary reference layout mark 4B (S8).

  The image processing apparatus 25 determines whether there is one temporary reference layout mark 4B detected by pattern matching and the reliability of the detected temporary reference layout mark 4B is 90% or more (S9). If a plurality of temporary reference layout marks 4B are detected or the reliability of one detected temporary reference layout mark 4B is less than 90%, the image processing device 25 determines that the detection is defective, and this At that time, the detection of the temporary reference layout mark 4 is finished.

  In steps S6 and S9, the image processing apparatus 25 detects one temporary reference layout mark 4B, and if the detected temporary reference layout mark 4B has a reliability of 90% or more, the detected temporary reference layout mark 4B is detected. As shown in FIG. 3C, other temporary reference layout marks 4C having a specific relationship with 4A and 4B, that is, orthogonal to a straight line E connecting the temporary reference layout mark 4A and the temporary reference layout mark 4B, Further, an area where another temporary reference layout mark 4C exists at a position passing through the center of the image is set as a detection area 27, and as shown in FIG. 3B, the detection area by pattern matching is narrowed down to the detection area 27 (S10). ).

  The image processing apparatus 25 searches and detects the temporary reference layout mark 4C by performing pattern matching (pattern matching performed without performing image enhancement processing) only in the detection region 27 (S11).

  The image processing device 25 determines whether or not there is one temporary reference layout mark 4C detected by the pattern matching and the reliability of the detected temporary reference layout mark 4C is 90% or more (S12). . When the temporary reference layout mark 4C is not properly detected, that is, the image processing device 25 detects a plurality of temporary reference layout marks 4C, or the reliability of one detected temporary reference layout mark 4C is less than 90%. In this case, the above-described image enhancement process is performed only on the detection area 27 (S13).

  In this image enhancement process, in the captured image in the detection region 27, the density gradient is enhanced between the temporary reference layout mark 4C and the background, and the temporary reference layout mark 4C is sharpened. In a state where the image enhancement processing has been performed, the image processing device 25 performs pattern matching only on the detection area 27 to search for and detect the temporary reference layout mark 4C (S14).

  The image processing device 25 determines whether or not there is one temporary reference layout mark 4C detected by this pattern matching and the reliability of the detected temporary reference layout mark 4C is 90% or more (S15). . The image processing device 25 determines that the detection is defective if a plurality of temporary reference layout marks 4C are detected or if the reliability of one detected temporary reference layout mark 4C is less than 90%. Then, the detection of the temporary reference layout mark 4 is finished.

  In step S12 and S15, the image processing apparatus 25 detects one temporary reference layout mark 4C, and when the reliability of the detected temporary reference layout mark 4C is 90% or more, FIG. As shown, a straight line F is dropped vertically from the detected temporary reference layout mark 4C to a straight line E connecting the detected temporary reference layout mark 4A and the temporary reference layout mark 4B, and an intersection of the straight line E and the straight line F is shown. The position of O is detected, and the detection of the temporary reference layout mark is completed (S16).

  In the image processing procedure for detecting the temporary reference layout mark, the pattern matching method is used to search for and detect the temporary reference layout mark with a circle and then to detect the temporary reference layout mark with an X mark. . The reason for this is that the mark ○ has a shape containing a lot of curved components, whereas the mark x has a shape containing a lot of straight components, and the noise component contained in the area of the captured image of the lens L has a lot of straight components. This is because it is easier to detect the ◯ mark, which has many components that are clearly different from the noise component, and to suppress the detection failure.

With the configuration as described above, the following effects (1) to (3) are achieved according to the above embodiment.
(1) The image processing device 25 searches for one mark (temporary reference layout mark 4A) having the highest matching accuracy by pattern matching from the captured image of the lens L (glasses lens 1) captured by the imaging device 20. An area where the temporary reference layout mark 4B having a specific positional relationship with the temporary reference layout mark 4A exists is set as a detection area 26, and pattern matching is performed only on the detection area 26, and the temporary reference layout mark 4B is searched for and detected, and an area in which another temporary reference layout mark 4C having a specific positional relationship with the temporary reference layout marks 4A and 4B exists is set as a detection area 27, and a pattern is formed only in the detection area 27. Matching is performed to search and detect the temporary reference layout mark 4C. Therefore, compared with the case where a plurality of temporary reference layout marks 4A, 4B, and 4C are simultaneously searched and detected, pattern matching is performed by focusing on the detection areas 26 and 27, and the temporary reference layout marks 4B and 4C are respectively searched. Therefore, even if the picked-up image of the lens L (eyeglass lens 1) has a large amount of noise components, the plurality of temporary reference layout marks 4A, 4B, 4C can be reliably detected.

  (2) The image processing apparatus 25 performs image enhancement processing for clarifying the contour, brightness, color density, etc. of the captured image in each of the detection areas 26, 27 where the temporary reference layout marks 4B, 4C exist. Later, the temporary reference layout marks 4B and 4C are searched for and detected by pattern matching. Therefore, by performing image enhancement processing, the temporary reference layout marks 4B and 4C in the respective images of the detection areas 26 and 27 are detected. Since the background is sharpened, the temporary reference layout marks 4B and 4C can be reliably searched and detected.

  (3) Since the image enhancement process also enhances noise components in the detection areas 26 and 27, the image processing apparatus 25 temporarily performs pattern matching before performing the enhancement process, without performing the image enhancement process. By searching for and detecting the reference layout marks 4B and 4C and performing the image enhancement process only when the temporary reference layout marks 4B and 4C are not properly detected by this pattern matching, these temporary reference layout marks 4B and 4C are obtained. Can be detected with high accuracy in a state in which the influence of the noise component is eliminated as much as possible.

As mentioned above, although this invention was demonstrated based on the said embodiment, this invention is not limited to this.
For example, the mark such as the temporary reference layout mark 4 in the above embodiment may be any mark such as a mark formed by transfer using a mold or a mark formed in a convex shape or a concave shape by a laser or the like. .

  In the above-described embodiment, the case where the lens L to be examined is the spectacle lens 1 has been described. However, an optical lens used in a telescope, a microscope, or the like may be used.

1 is a layout diagram of an optical system showing an embodiment of a mark detection apparatus according to the present invention. It is sectional drawing which expands and shows the to-be-tested lens and imaging lens of FIG. FIG. 6 is an operation diagram illustrating a procedure for detecting a temporary reference layout mark executed by the image processing apparatus of FIG. 1. 3 is a flowchart showing a procedure for detecting a temporary reference layout mark executed by the image processing apparatus of FIG. 1. It is a top view which shows the spectacle lens as a test lens of FIG. 1 with the mark given to the surface. It is a flowchart which shows the conventional mark detection method.

Explanation of symbols

1 Eyeglass lens (subject)
4, 4A, 4B, 4C Temporary reference layout mark 10 Mark detection device 20 Imaging device 25 Image processing device 26, 27 Detection area L Test lens

Claims (8)

A mark detection method for detecting a plurality of marks provided on a subject from a captured image of the subject,
From the captured image of the subject, one mark having the highest matching accuracy is detected and detected by pattern matching, and then an area in which another mark having a specific positional relationship with this mark exists is detected. A mark detection method, wherein the pattern matching is performed only on the detection area to search for and detect the other marks.   In the detection area where the other mark exists, pattern matching is performed to search for the other mark, and when the other mark is not properly detected, the contour, brightness, and color density of the captured image are detected. The mark detection method according to claim 1, wherein after performing image enhancement processing to clarify the above, the other marks are searched again by pattern matching and detected.   3. The detection order of the marks according to claim 1 or 2, wherein a mark including a large amount of curved components is first searched and detected, and thereafter a mark including a large amount of linear components is searched and detected. Mark detection method.   4. The mark detection method according to claim 1, wherein the subject is a spectacle lens, and the mark is a temporary reference layout mark. A mark detection apparatus for detecting a plurality of marks provided on a subject from a captured image of the subject,
Imaging means for imaging the subject to obtain a captured image;
Search for and detect one mark with the highest matching accuracy by pattern matching from the captured image, and set the detection area as the area where other marks that have a specific positional relationship with this mark exist. Image processing means for searching for and detecting the other marks by performing the pattern matching;
A mark detection apparatus comprising:   The image processing means searches for the other mark by performing pattern matching in a detection region where another mark exists, and when the other mark is not properly detected, the contour, brightness, 6. The mark detection apparatus according to claim 5, wherein after performing image enhancement processing for clarifying color intensity, the other mark is searched again and detected by pattern matching.   7. The mark according to claim 5, wherein the image processing means searches for and detects a mark containing a large amount of curve components first, and then searches for and detects a mark containing a lot of straight line components. Detection device.   8. The mark detection apparatus according to claim 5, wherein the subject is a spectacle lens, and the mark is a temporary reference layout mark.

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