JP5566257B2 - Data generation method and image inspection method - Google Patents

Description

  The present invention relates to a data generation method for extracting a contour of a figure in a binarized image and generating data related to a contour line, and an image inspection method using the data generation method.

  In an image inspection in which an inspection object is inspected using an image obtained by imaging the inspection object with a camera, a contour of a desired figure is extracted from a binarized image in a bitmap format, and the contour line is extracted. Data is generated, and a process for detecting a defect is performed in comparison with design data (design rule) used to generate the inspection object.

  FIG. 25 is a diagram illustrating an example of a bitmap image for a substrate on which wiring is formed. In the bitmap format image obtained by imaging the substrate on which the wiring (that is, the conductor) is formed, the substrate is binarized as “black” and the wiring on the substrate is “white” as shown in FIG. .

  As a method of extracting a contour of a figure in a bitmap image, there is a method of searching for the next contour point using this point as a base point when a certain pixel (bit) on the bitmap image is a contour (for example, a patent) Reference 1).

  FIG. 26 is a diagram for explaining an example of a method for extracting a contour of a figure from a bitmap image according to the conventional technique. The case of extracting a contour of a figure composed of “white” in a bitmap image represented by white and black binary as shown in FIG. 26 is as follows. From the entire bits of the binary bitmap image of “white” and “black”, one “white” point (bit) adjacent to “black” is selected as a starting point, and the starting point is selected. Set to the base point. Next, for example, in the clockwise direction indicated by the arrow in the figure, a “white” point adjacent to this base point and adjacent to “black” is searched, and the detected point is set as a new base point. When such a process is repeatedly executed until the “white” point set as the base point first is returned, an array of base points is obtained. Such an array of base points forms a contour line of a figure composed of “white”. FIG. 26 shows a part of a figure composed of “white” whose contour is to be extracted, but the contour line obtained by the above processing is a closed curve.

  In addition to this, there is a method of tracing the array of the maximum points from the bitmap image from which the set of points having the maximum luminance gradient is extracted by differentiating the image and using this as the contour line.

  In the image inspection, data related to the contour line of the inspection object obtained as described above is generated, and a defect is detected by comparison with the design data used to generate the inspection object.

JP-A-6-223183

  In the above-described conventional technique in which a point detected by searching for a “white” point adjacent to a certain base point and adjacent to “black” is set as a new base point, and the obtained base point array is an outline, When setting the base point to be the start point, it is necessary to search the entire bitmap image for a bit that can be a candidate for the start point, so that the calculation process takes time. In addition, since the next base point cannot be set unless a certain base point is set, it is impossible to apply a plurality of arithmetic processors to one bitmap image, and therefore speeding up by parallel processing is impossible. is there. For example, in the case of a bitmap image of a substrate on which wiring is formed, a “white” bit adjacent to the base point cannot be detected at a location where the line width of the wiring is zero (0). The “next base point” cannot be detected. For this reason, there is a problem that two closed curves are generated and regarded as separate wirings even though the wiring is not actually interrupted.

  Therefore, in view of the above problems, an object of the present invention is to provide a data generation method for generating data related to the contour of a graphic in a bitmap image at high speed and an image inspection method using the data generation method. .

  In order to achieve the above object, in the first aspect of the present invention, a process for generating data related to a contour line of a desired graphic on an inspection object from image data in a bitmap format obtained by imaging the inspection object The data generation method for executing the processing by the arithmetic processing unit is a bit in the image data that represents the center line penetrating the design graphic corresponding to the desired graphic generated from the design data used to generate the inspection object. For each search reference point that is a bit located on the center line on the bitmap image in which the center line is overlapped with the overlay step for superimposing on the map image, the center from the search reference point toward the predetermined search direction A search step for searching for a bit in which a second color different from the first color of the bit located on the line appears and using the detected bit as a contour candidate point , For each search reference point, a step of extracting the one having the shortest distance from the search reference point from the contour candidate points, and confirming the extracted point as a contour point constituting the contour of the desired figure And a line obtained by connecting the contour point and the contact point of the bit having the first color adjacent to the contour point in the order of arrangement of the corresponding search reference points, is determined as the contour line of the desired figure. An output step of outputting data relating to the contour line.

  In the second aspect of the present invention, the image inspection method inspects an inspection object using data related to a contour line of a graphic generated using the data generation method according to the first aspect described above. That is, in the image inspection method according to the second aspect of the present invention, the data relating to the contour line of the graphic output by executing the above-described data generation method by the arithmetic processing unit, and the design contour line for the design graphic Is used to check whether the inspection object has been generated according to the design data.

  In the image inspection method according to the second aspect of the present invention, as processing for generating data related to the design contour line, in the design figure in the design data, each search reference point is directed from the search reference point toward a predetermined search direction. And a search step for design data in which a second color different from the first color of the bit located on the center line appears, and using the detected bit as a design contour candidate point, and each search reference point On the other hand, a design data confirmation step for extracting a design contour candidate point that has the shortest distance from the search reference point and confirming the extracted point as a design contour point constituting the contour of the figure on the design In addition, a line obtained by connecting the design contour point and the contact point of the first color bit adjacent to the design contour point in the order of arrangement of the corresponding search reference points is attached to the design figure. Design data output step for outputting the data related to the design contour line, and data relating to the contour line of the graphic output by executing the data generation method described above by the arithmetic processing device, Inspection that checks whether the object to be inspected is generated according to the design data by comparing the figure outline with the design outline using the data related to the design outline output in the design data output step Steps.

  In the third aspect of the present invention, the data for executing processing for generating data related to the contour line of a desired graphic on the inspection object from the bitmap format image data obtained by imaging the inspection object The generation method includes a step of superimposing a center line penetrating a design figure corresponding to a desired figure generated from the design data used to generate an inspection object on a bitmap image in the image data. And a normal calculation step for calculating the normal of the center line at the position of each bit on the center line, and a normal direction parameter for each bit on the center line on the bitmap image in which the center line is overlaid The weighted average step is a weighted average using a weighting coefficient that becomes the maximum at the search reference point and decreases as the distance from the search reference point increases. And a second color different from the first color of the bit located on the center line from the search reference point along the search line for each search line that is a straight line defined by the weighted average direction parameter. A search step is performed to search for a bit in which a contour appears, and to determine the detected bit as a contour point that forms a contour of a desired figure, and a contour point and a first adjacent to the contour point in order of corresponding search reference points An output step of determining a line obtained by connecting a contact point with a bit having a color as a contour line of a desired figure and outputting data relating to the contour line.

  In the fourth aspect of the present invention, the image inspection method inspects the inspection object using data related to the contour line of the graphic generated using the data generation method according to the third aspect described above. That is, in the image inspection method according to the fourth aspect of the present invention, the data relating to the contour line of the graphic output by executing the above-described data generation method by the arithmetic processing unit, and the design contour line for the designed graphic Is used to check whether the inspection object has been generated according to the design data.

  In the image inspection method according to the fourth aspect of the present invention, as a process of generating data related to the design contour line, the design at the position of each bit on the design center line on the design data bitmap image on which the design center line is overlaid. The design data normal calculation step for calculating the design normal of the center line and the direction parameter of the design normal are maximized at the search reference point set for each bit on the design center line and decrease as the distance from the search reference point increases. For each design search line that is a straight line defined by a weighted average design data weighted average step and a weighted average direction parameter by using a weighting coefficient, from the search reference point toward the design search line. Search for a bit in which a second color different from the first color of the bit located on the center line appears and detect the detected bit. Are determined as design contour points constituting the contour of the figure on the design, and the design contour points and the first color adjacent to the design contour points are arranged in the order of arrangement of the corresponding search reference points. A design data output step of determining a line obtained by connecting the contact point with the bit as a design contour line for a design figure and outputting data relating to the design contour line.

  Each step described above can be realized in the form of a computer program that can be executed by an arithmetic processing unit such as a computer. Creating an apparatus for performing the above processing and a computer program for causing a computer to execute the above processing can be easily implemented by those skilled in the art who understand the following description. Further, it is obvious to those skilled in the art that a computer program that causes a computer to execute the above processing is stored in a recording medium.

  ADVANTAGE OF THE INVENTION According to this invention, the arithmetic processing apparatus, such as a computer, can produce | generate the data regarding the outline of the figure in a bitmap image at high speed and correctly. Unlike the above-described conventional technique for sequentially tracking the base point, parallel processing (so-called multiprocessor parallel processing) can be realized by assigning an arithmetic processing unit to some of the plurality of search reference points. It is possible to generate data related to the contour line of the figure in the map image at high speed.

  Further, if the above-described data generation method is used, it is possible to increase the speed of an image inspection method that performs an image inspection based on image data obtained by imaging an inspection object.

It is a flowchart which shows the operation | movement flow of the data generation method by 1st Example of this invention. It is a flowchart which shows the operation | movement flow of the parallel processing performed in the data generation method by 1st Example of this invention. It is a figure which shows an example of the centerline produced | generated in the 1st and 3rd Example of this invention. It is a figure explaining the search of the outline candidate point performed in 1st Example of this invention, and confirmation of an outline point. It is FIG. (1) which illustrates the outline of the figure produced | generated by the data generation method by 1st Example of this invention. It is FIG. (2) which illustrates the outline of the figure produced | generated by the data generation method by 1st Example of this invention. It is FIG. (2) which illustrates the outline of the figure produced | generated by the data generation method by 1st Example of this invention. It is a figure which illustrates the change of the luminance level of the search direction resulting from noise. It is a flowchart which shows the correction process in the search process of the outline candidate point in 1st Example of this invention. It is a flowchart which shows the operation | movement flow of the image inspection method by the 2nd Example of this invention. It is a flowchart which shows the operation | movement flow of the data generation method by 3rd Example of this invention. It is a figure explaining the normal line of the centerline produced | generated in the 3rd Example of this invention. It is a flowchart which shows the operation | movement flow of the parallel processing performed in the data generation method by the 3rd Example of this invention. It is a figure explaining the direction parameter in the data generation method by 3rd Example of this invention. It is FIG. (The 1) which illustrates the weighting coefficient in the data generation method by 3rd Example of this invention. It is FIG. (2) which illustrates the weighting coefficient in the data generation method by 3rd Example of this invention. It is a figure explaining calculation of the weighted average direction parameter in the data generation method by the 3rd example of the present invention. It is a figure explaining the determination of the outline point in the data generation method by 3rd Example of this invention. It is a flowchart which shows the correction process in the search process of the outline candidate point in 3rd Example of this invention. It is a flowchart which shows the operation | movement flow of the image inspection method by the 4th Example of this invention. It is a figure explaining extraction of the outline of the wiring which has a convex part and a crevice in the wiring width direction by the 1st example of the present invention. It is a figure explaining extraction of the outline of the wiring which has a convex part and a crevice in the wiring width direction by the 3rd example of the present invention. It is FIG. (2) explaining extraction of the outline of the wiring which has a convex part and a recessed part in the wiring width direction by 3rd Example of this invention. It is a block diagram which shows the structure of the computer with which the computer program which concerns on the data generation method by the 1st and 3rd Example and the image inspection method by the 2nd and 4th Example operates. It is a figure which shows an example of the bitmap image about the board | substrate with which wiring was formed. It is a figure explaining an example of the method of extracting the outline of a figure from the bitmap image by a prior art.

  FIG. 1 is a flowchart showing an operation flow of a data generation method according to the first embodiment of the present invention. According to the first embodiment of the present invention, the data generation process is executed by an arithmetic processing unit such as a computer in two stages, an offline process and an online process. The off-line process is executed in advance prior to the execution of the on-line process, and is executed on the design data used to generate the inspection object. On the other hand, the online processing is performed on the image data in the bitmap format of the inspection target imaged by the camera. In the present embodiment, the inspection object is a substrate on which wiring is formed, and the figure on the inspection object from which the outline is to be extracted is the wiring on the substrate in the captured image. Note that the present invention can be applied to a substrate other than the substrate on which the inspection object is formed.

  First, before online processing is performed, that is, at the stage of offline processing, in step S101, “in the bitmap image in which the inspection object is imaged” generated from the design data used to generate the inspection object. Data relating to the center line passing through the “designed graphic” corresponding to the “graphic from which the contour line is to be extracted” is created. FIG. 3 is a diagram showing an example of the center line generated in the first and third embodiments of the present invention. For example, when the design figure is a region surrounded by a solid line indicated by reference symbol A, a center line M indicated by a one-dot chain line in FIG.

  In step S101, which is an off-line process, a center line penetrating the design figure is generated in advance, and then the process proceeds to the on-line process. Note that step S101, which is an offline process, does not spend enormous time because a center line can be generated in a single process for the figure even if the figure from which the contour line is to be extracted is complex. . Step S101 is executed by an arithmetic processing unit such as a computer, but may be executed by using, for example, a CAD system that processes design data.

  As online processing, first, in step S201, the image data in the bitmap format of the inspection object imaged by the camera is transferred to an arithmetic processing device such as a computer that executes the data processing method according to the first embodiment of the present invention. Entered. The processing of the following steps S201 to S205 is executed by this arithmetic processing unit. In particular, this arithmetic processing unit is provided with a plurality of arithmetic processors, and the processing of each arithmetic processor is performed independently. If executed, multiprocessor parallel processing in step S300 is possible.

  In step S202, the design bitmap image in the design data used to generate the inspection object and the bitmap image in the bitmap format image data of the inspection object captured by the camera are designed data. The center line that passes through the design figure generated in advance in step S101, which is offline processing, after being aligned on the virtual plane with reference to the predetermined mark defined above, is a bitmap image in the image data. To overlay.

  Next, parallel processing S300 is executed. FIG. 2 is a flowchart showing an operation flow of parallel processing executed in the data generation method according to the first embodiment of the present invention. In step S301, a search reference point is set from the bits located on the center line on the bitmap image in which the center lines are overlaid. The search reference point is a reference point for searching for contour candidate points. Through the processing in step S304, which will be described later, all the bits located on the center line are always employed as search reference points once. As described above, in this embodiment, since a plurality of arithmetic processors are provided in the arithmetic processing unit, the parallel processing S300 is performed by assigning these arithmetic processors to some of the plurality of search reference points existing on the center line. The process of searching for contour candidate points based on the search reference point in (a series of processes from step S301 and steps S302 to S304 described later) can be executed for each arithmetic processor. In the flowchart shown in FIG. 1, the processes from steps S301 to S304 shown in FIG. 2 are collectively shown in step S300. For example, in an arithmetic processing device provided with 100 arithmetic processors, when processing is performed on 10,000 search reference points on the center line, 100 search reference points are assigned to one arithmetic processor. It is done. As a result, the calculation processing time can be reduced to 1/100 compared to the case where the processing is executed for 10,000 search reference points by one calculation processor. Thus, according to the present embodiment, the series of processing from step S301 to S304 is executed in parallel by a plurality of arithmetic processors, so that the arithmetic processing time can be greatly shortened.

  In step S302, for each search reference point set in step S301 on the bitmap image in which the center lines are overlaid, the first bit of the bit located on the center line from the search reference point toward the predetermined search direction. Search for a bit in which a second color different from the color appears. The detected bit is set as a contour candidate point, and data relating to the contour candidate point is temporarily stored in the memory. The “predetermined search direction” in step S302 is the 2n direction (where n is an integer) centered on the search reference point on the bitmap image in which the center lines are superimposed. The greater the magnitude of n, the better the search accuracy.

  FIG. 4 is a diagram for explaining the contour candidate point search and the contour point determination executed in the first embodiment of the present invention. For example, when the figure from which the contour line in the bitmap image obtained by imaging the inspection object is to be extracted is a region surrounded by the solid line indicated by reference symbol B, the center line M indicated by the one-dot chain line in FIG. Taking the case where it is superimposed on B as an example, it is as follows. In the example shown in the figure, n = 8, that is, the search direction is 16 directions indicated by dotted arrows in the drawing. In this embodiment, when an inspection object is a substrate on which wiring is formed and a figure on the inspection object from which a contour line is to be extracted is wired on the substrate in a captured image, on the bitmap image, for example, the substrate is “Black” (corresponding to the “second color”) and the wiring are represented by binary values such as “white” (corresponding to the “first color”). In the example shown in FIG. 4, two search reference points P1 and P2 are set on the center line M, and different arithmetic processors are assigned to the search reference points P1 and P2 to perform parallel processing. At this time, since the search reference points P1 and P2 are located on the center line passing through the design figure corresponding to the figure on the inspection object from which the outline is to be extracted, the color of the bit is “white”. In the example shown in FIG. 4, in the search process of the contour candidate points P1 and P2 in step S205, the adjacent bits are sequentially searched from the search reference points P1 and P2 toward the search direction of 16 directions, respectively. A bit in which “black”, which is a second color different from “white”, which is the first color of the bit located on the line, appears is found. This straight line in the search direction is referred to as a “search line”. The bit when the “black” appears for the first time is set as a contour candidate point. Therefore, 2n contour candidate points existing in the 2n direction (where n is an integer, n = 8 in FIG. 4) with respect to one search reference point are detected.

  In step S303 of FIG. 2, for each search reference point, the one having the shortest distance from the search reference point is extracted from the plurality of contour candidate points detected in step S302 and temporarily stored in the memory. The extracted points are determined as contour points constituting the contour of the figure. Although there is only one contour candidate point with the shortest distance from the search reference point, the contour candidate point with the shortest distance and the contour candidate point with the shortest distance are in the direction of 180 degrees with reference to the search reference point. The distance between the contour candidate point located in the direction (that is, the direction opposite to the search direction when the contour candidate point of the shortest distance is detected) constitutes the “shortest wiring width” at the search reference point. Will do. Therefore, these two contour candidate points are determined as contour points constituting the contour of the figure (that is, wiring). In the example shown in FIG. 4, contour points Q1 and Q2 are determined for the search reference point P1, and contour points Q3 and Q4 are determined for the search reference point P2.

  In step S304, it is determined whether or not the processing in steps S301 to S303 has been executed for all search reference points. If there is a search reference point that has not yet been processed, the process returns to step S301, and if the process has been executed for all search reference points, the process proceeds to step S203. As described above, since the series of processing from step S301 to step S304 is executed as parallel processing by a plurality of arithmetic processors, "all search reference points" determined in step S304 are one arithmetic operation. It means a plurality of search reference points assigned to the processor.

  In step S203, the contact points between the contour points generated in step S205 and the “white” bits adjacent to the contour points are rearranged in the order of arrangement of the corresponding search reference points on the virtual plane, and these contact points are connected. To do. As described above, the series of processing from step S301 to step S304 is executed as parallel processing by a plurality of arithmetic processors. Therefore, all the generated contour points are re-ordered in the order of search reference points in step S203. It needs to be sorted.

  In step S204, the line obtained by connecting the contacts in step S203 is determined as a contour line, and data relating to the contour line is output. Note that only “white” bits are extracted as contour points, and the points that are far from the search reference point among points where the search line intersects the circumference of the extracted “white” bits, May be used as an outline. Or, only the “black” bit is extracted as the contour point, and the points close to the search reference point among the points where the search line intersects with the extracted “black” bit circumference, It may be a contour line. The output data regarding the contour line may be used, for example, for display on the screen of the display device, or may be used for an image inspection method described as a second embodiment to be described later.

  5 to 7 are diagrams illustrating the contour lines of a graphic generated by the data generation method according to the first embodiment of the present invention. In FIGS. 5 to 7, the figure in which the contour line in the bitmap image obtained by imaging the inspection object is to be extracted is a region surrounded by the solid line indicated by reference symbol B, and the design is superimposed on the bitmap image. A center line M penetrating the figure is represented by a one-dot chain line. In the figure, black squares represent bits. Therefore, a black square on the center line M means a bit that is a search reference point. The black squares located on the solid line indicated by the reference sign B are bits that are defined contour points. When the contact point between the contour point (black) and the “white” bit adjacent to the contour point is obtained and these contact points are connected, the contour line of the figure B is obtained.

  As shown in FIG. 5, the contour points are not arranged at equal intervals in the portion where the wiring is curved. However, when the pitch of the search reference points is sufficiently short, the accuracy problem is Absent.

  Further, as shown in FIG. 6, even if the line width of a part of the wiring that is the graphic B is 0 (zero), the line width is 0 (zero) in the design graphic generated from the design data. Since the center line M also passes through the part of FIG. 6, the wiring sandwiching the part of the line width of 0 (zero) in FIG. 6 is not regarded as a separate wiring as in the case of the prior art.

  Further, as shown in FIG. 7, the contour line can be extracted with high accuracy as the pitch of the search reference point is sufficiently short for the end portion of the wiring as the graphic B as well.

  As described above, according to the contour candidate point search process in step S205, adjacent bits are sequentially searched on the search line from the search reference point toward the predetermined search direction, and the bit located on the center line is searched. A bit in which “black”, which is a second color different from “white”, which is the first color, is found, and a bit when the “black” first appears is used as a contour candidate point. In general, on a bitmap image represented by binary values of white and black, it is possible to determine whether a bit is white or black by detecting a luminance level. In other words, the luminance level of the bit has a level that serves as a boundary for separating whether the bit is white or black. However, if there is a variation in the brightness level in the bitmap image due to some noise when imaging the inspection object, it is possible to accurately determine whether the bit is white or black for the following reason. May not be possible.

FIG. 8 is a diagram illustrating a change in the luminance level in the search direction caused by noise. In FIG. 8, the horizontal axis indicates the position in the search direction on the search line in the contour candidate point search process, and the coordinates thereof are represented by “x”. (In the figure, it represented. By a one-dot chain line) center line of the graphic bit and located at the coordinate x _2. In FIG. 8, the vertical axis indicates the luminance level l, and the luminance level boundary between white and black is represented by l _th . Here, in the captured bitmap image, the color of the bit between the coordinate x ₁ and the coordinate x ₅ is originally “white”, so that the correct contour candidate point of the figure is located at the coordinates x ₁ and x _5. Nevertheless, a case where the luminance level becomes equal to or lower than the boundary level due to the presence of noise between the coordinate x ₃ and the coordinate x ₄ will be described as an example.

In the search processing of the contour candidate points, from the coordinates x _2, 2 directions of -x direction and the + direction is set as the search direction, along the search direction is the color of the bits located at the coordinate x ₂ "White A process of finding a bit in which “black” different from “” appears is executed. When the coordinates x ₂ continue to detect the executed luminance level search processing toward the -x direction, the luminance level is equal to or less than the boundary level l _th at the position of coordinates x _1, and recognition black bits appeared As a result, it is determined that the contour candidate point is located at the coordinate x ₁ . On the other hand, when the search process is executed from the coordinate x ₂ toward the + x direction and the luminance level is detected, the luminance level becomes equal to or less than the boundary level l _th at the position of the coordinate x ₃ , so that a black bit appears. As a result, the contour candidate point is determined to be located at the coordinate x ₂ even though it should be located at the coordinate x ₅ correctly. Such erroneous determination of the contour candidate point results in erroneous recognition of the contour line of the figure.

  Therefore, in order to prevent such erroneous recognition of the contour line, in the present embodiment, it is preferable to execute the following correction processing in the contour candidate point search processing. FIG. 9 is a flowchart showing the correction process in the contour candidate point search process in the first embodiment of the present invention. The contour candidate point search process in the first embodiment of the present invention is as described with reference to FIGS. 2 and 4, and is executed for each search reference point on the bitmap image in which the center lines are superimposed. Is done. The correction process is executed as part of a series of processes in this search process.

  First, in step S401, for a certain search reference point, a bit color is searched from the search reference point toward a predetermined search direction on the search line on the bitmap image in which the center lines are superimposed. In step S402, it is determined whether or not to detect a bit having “black” that is a second color different from “white” that is the first color of the bit located on the center line.

  If it is determined in step S402 that the “black” bit that is the second color has been detected, information regarding the position coordinates of the detected “black” bit that is the second color is stored in the memory, and step S403 is performed. Proceed to When the “black” bit that is the second color is not detected in step S402, the process returns to step S401, and the processes in steps S402 and S401 are repeated until the “black” bit that is the second color is detected. Executed.

  In step S403, a bit color is further searched for in a predetermined search direction on the search line from the position of the detected second color bit. In step S404, it is determined whether or not to detect a bit having the first color “white”.

  If it is determined in step S404 that the “white” bit that is the first color is not detected, the process proceeds to step S405, and the “black” bit that is the second color held in the memory for information regarding the position coordinates. Are determined as contour candidate points and stored in the memory.

  On the other hand, if it is determined in step S404 that the “white” bit that is the first color has been detected, information regarding the position coordinates of the detected “white” bit that is the first color is stored in the memory, Proceed to step S406. In step S406, a bit color is searched for in a predetermined search direction on the search line from the position of the detected “white” bit as the first color. In step S407, it is determined whether or not to detect a bit having “black” as the second color.

  If it is determined in step S406 that the “black” bit that is the second color has been detected, information regarding the position coordinates of the detected “black” bit that is the second color is stored in the memory, and step S403 is performed. Return to. In step S403, a further search is made in the predetermined search direction from the position of the detected second color "black", and the bit color is searched in the predetermined search direction on the search line. Go. After this step S403, the above-described series of processing is executed again.

  On the other hand, if it is determined in step S406 that the “black” bit that is the second color is not detected, the process proceeds to step S405, where the second color is detected in step S402 and retains information regarding the position coordinates. The bit of “black” is determined as a contour candidate point, and this is held in the memory.

  In the contour candidate point search process, by executing the above-described correction process, erroneous recognition of the contour line can be prevented even if noise exists on the captured bitmap image.

For example, in the case where a change in luminance level as shown in FIG. 8 exists on the search line, if the correction process is applied to the search direction in the + direction, the search reference point located at the coordinate x ₂ When the color of the bit is searched along the search direction in the + direction on the search line (step S401), a bit having “black” which is different from “white” which is the color of the bit located at the coordinate x ₂ is obtained. It is detected at the position of coordinates x ₃ (step S402). The position information of the coordinate x ₃ for the bit having “black” is held in the memory. When the bit color is searched from the position of the coordinate x ₃ along the search direction in the + direction on the search line (step S403), the bit having “white” is detected at the position of the coordinate x ₄ . It detects (step S404). Since the bit having “white” is detected at the position of the coordinate x ₄ in this way, the position information of the coordinate x ₄ for the detected bit having “white” is not yet determined for the contour candidate point. Hold on. Next, when the color of the bit is searched from the position of the coordinate x ₄ along the search direction in the + direction on the search line (step S 406), the bit having “black” is detected at the position of the coordinate x ₅ . It detects (step S407). The position information of the coordinate x _{5 for} the detected bit having “black” is newly stored in the memory in place of the position information of the coordinate x ₃ regarding the bit having “black” which has already been detected and held in the memory. is held, the position of the coordinate x _5, along the search direction in the search line + direction, continue to search for the color of the bits (step S403). In the example shown in FIG. 8, there is no bit having “white” beyond the search direction in the + direction on the search line (step S404), so “black” positioned at the coordinate x ₅ held in the memory is displayed. The bits that are included are determined as contour candidate points (step S405). Thereby, the contour candidate point in the search direction in the + direction is determined.

On the other hand, when a change in luminance level as shown in FIG. 8 is present on the search line, if the correction process is applied in the negative search direction, the search reference point located at the coordinate x ₂ is When a bit color is searched along the search direction in the − direction on the search line (step S401), a bit having “black” different from “white” that is the color of the bit located at the coordinate x ₂ is obtained. Then, detection is performed at the position of the coordinate x ₁ (step S402). The position information of the coordinate x ₁ for the bit having “black” is held in the memory. In the example shown in FIG. 8, since there is no bit having “white” beyond the search direction in the − direction on the search line (step S404), “black” located at the coordinate x ₁ held in the memory is displayed. The bits that are included are determined as contour candidate points (step S405). As a result, the candidate contour points in the negative search direction are determined.

  As described above, according to the first embodiment of the present invention, the multiprocessor parallel processing can be realized by assigning the arithmetic processing device to some of the plurality of search reference points, so that the graphic in the bitmap image can be realized. It is possible to generate data relating to the outline of the image at high speed. Moreover, if the correction process is executed in the search process for the contour candidate point, the erroneous recognition of the contour line can be prevented.

  FIG. 10 is a flowchart showing an operation flow of the image inspection method according to the second embodiment of the present invention. An image inspection method according to the second embodiment of the present invention inspects an inspection object using data related to the contour line of a graphic generated using the data generation method according to the first embodiment described above. . According to the second embodiment of the present invention, the data generation process and the image inspection process are divided into two processes, an offline process and an online process, as in the first embodiment, and are executed by an arithmetic processing unit such as a computer. Is done.

  In FIG. 10, steps S101 and S201 to S204 and steps S301 to S304 in the parallel processing S300 are the same as steps S101 and S201 to S204 in the data generation method according to the first embodiment described with reference to FIG. Since it is the same as the process of steps S301 to S304 in the parallel process S300, the description is omitted.

  In this embodiment, before the online processing is executed, that is, in the offline processing stage, the outline of the design figure is captured by the camera with respect to the design data used to generate the inspection object. Steps S102 to S107 are executed according to the same algorithm as the online processing of the bitmap format image data of the inspection object. By using a similar algorithm, the accuracy of the image inspection is ensured. Note that steps S101 to S107, which are offline processes, do not spend much time because even if the figure from which the contour line is to be extracted is complex, it is only necessary to perform one process on the figure. . Steps S101 to S107 are executed by an arithmetic processing unit such as a computer, but may be realized as a new function on a CAD system that processes design data, for example.

  In step S102, a search reference point is set from the bits located on the center line in the design figure in the design data. Note that the search reference points used in the processes in steps S102 to S105 in the offline process are the same as the search reference points used in the processes in steps S301 to S304 in the online process.

  In step S103, in the design figure in the design data, for each search reference point set in step S102, the first color of the bit located on the center line (ie, from the search reference point toward the predetermined search direction) Search for bits in which a second color different from “white”) (ie, “black”) appears. The detected bit is set as a design contour candidate point, and data relating to the design contour candidate point is temporarily stored in the memory. The “predetermined search direction” in step S103 is the same as the “predetermined search direction” in step S302.

  Next, in step S104, for each search reference point, the one having the shortest distance from the search reference point is extracted from the plurality of design contour candidate points detected in step S103 and once stored in the memory. Then, the extracted points are determined as design contour points constituting the contour of the figure on the design. Although there is only one design contour candidate point with the shortest distance from the search reference point, the design contour candidate point with the shortest distance and the design contour candidate point with the shortest distance are 180 on the basis of the search reference point. The distance between the design contour candidate point located in the direction of the degree (that is, the direction opposite to the search direction when the design contour candidate point of the shortest distance is detected) "The shortest width" is formed. Accordingly, these two contour candidate points are determined as contour points that design and configure the contour of the figure (that is, wiring). Thus, the process of step S104 also follows the same algorithm as the process of step S303.

  In step S105, it is determined whether or not the processing in steps S102 to S104 has been executed for all search reference points. If there is a search reference point that has not yet been processed, the process returns to step S102, and if the process has been executed for all search reference points, the process proceeds to step S106. Thus, the process of step S105 also follows the same algorithm as the process of step S304.

  In step S106, the contact points between the design contour points generated in step S104 and the “white” bits adjacent to the design contour points are rearranged in the order of arrangement of the corresponding search reference points on the virtual plane. Connect. Thus, the process of step S106 also follows the same algorithm as the process of step S203.

  In step S107, the line obtained by connecting the contour points in step S106 is determined as a design contour line of a figure (that is, wiring), and data relating to the design contour line is output. Thus, the process in step S107 also follows the same algorithm as the process in step S204.

  In step S205, the data related to the design outline of the design figure in the design data output in step S107 and the data related to the outline of the figure in the image data of the inspection object output in step S204 are used. Inspection processing is executed.

  In step S205, the figure contour in the image data of the inspection object and the design outline for the design figure are collated for each identical search reference point, and the inspection object has been generated according to the design data. Check for no. For example, if the inspection object is a substrate on which wiring is formed and the figure on which the outline on the inspection object is to be extracted is the wiring on the substrate in the captured image, the same search is performed in step S205. Based on whether the line width of the wiring defined by the contour line of the figure in the image data of the inspection object matches the line width of the wiring defined by the design outline at the reference point, the inspection object is It is determined whether or not the data is generated according to the design data. If it is determined that the line widths match, the inspection object is generated according to the design data. If it is determined that the line widths do not match, the inspection object is not generated according to the design data. So it is considered an error. The inspection result is displayed on a screen of a display device, for example.

  As described above, according to the second embodiment of the present invention, with respect to the generation of data related to the contour line, an arithmetic processing unit is allocated to some of the plurality of search reference points, and multiprocessor parallel processing is realized to perform the calculation. Since the processing time is shortened, an image inspection method for performing an image inspection based on image data obtained by imaging an inspection object can also be speeded up. For example, when the inspection target is a substrate on which wiring is formed and the graphic on the inspection target is wiring on the substrate in the captured image, in the image inspection processing, the wiring defined by the contour of the graphic Whether or not the board on which the wiring as the inspection object is formed is generated according to the design data based on whether or not the line width of the wiring and the line width of the wiring defined by the design contour line match. .

  Next, a data processing method according to the third embodiment of the present invention will be described. FIG. 11 is a flowchart showing an operation flow of the data generation method according to the third embodiment of the present invention. According to the third embodiment of the present invention, as in the first embodiment, the data generation process is executed by an arithmetic processing unit such as a computer in two stages of an offline process and an online process. The off-line process is executed in advance prior to the execution of the on-line process, and is executed on the design data used to generate the inspection object. On the other hand, the online processing is performed on the image data in the bitmap format of the inspection target imaged by the camera. In the present embodiment, the inspection object is a substrate on which wiring is formed, and the figure on the inspection object from which the outline is to be extracted is the wiring on the substrate in the captured image. Note that the present invention can be applied to a substrate other than the substrate on which the inspection object is formed.

  That is, as shown in FIG. 11, first, before online processing is executed, that is, at the stage of offline processing, in step S101, the “inspection target” generated from the design data used to generate the inspection target is generated. Data relating to the center line passing through the “designed figure” corresponding to the figure from which the contour line is to be extracted in the bitmap image in which the object is imaged is created. The process for creating data related to the center line is the same as that in the first embodiment described with reference to FIGS. In step S101, which is an off-line process, a center line penetrating the design figure is generated in advance, and then the process proceeds to the on-line process. As in the first embodiment, step S101 is executed by an arithmetic processing device such as a computer, but may be executed by using, for example, a CAD system that processes design data.

  As online processing, first, in step S201, the image data in the bitmap format of the inspection object imaged by the camera is transferred to an arithmetic processing device such as a computer that executes the data processing method according to the third embodiment of the present invention. Entered. The processing of the following steps S201 to S204 and S206 is executed by this arithmetic processing unit. In particular, this arithmetic processing unit is provided with a plurality of arithmetic processors, and the processing of each arithmetic processor is performed. If executed independently, multiprocessor parallel processing in step 500 is possible.

  In step S202, the design bitmap image in the design data used to generate the inspection object and the bitmap image in the bitmap format image data of the inspection object captured by the camera are designed data. The center line that passes through the design figure generated in advance in step S101, which is offline processing, after being aligned on the virtual plane with reference to the predetermined mark defined above, is a bitmap image in the image data. To overlay.

  Next, in step S206, the normal line of the center line at the position of each bit on the center line is calculated on the bitmap image in which the center lines are superimposed. FIG. 12 is a diagram for explaining the normal of the center line generated in the third embodiment of the present invention. Since the bitmap data is digital data, the bit positions on the center line are not on the same line but are discrete values. Therefore, in the present embodiment, first, a line segment connecting two bits on the center line adjacent to the bit is obtained, and a normal line to this line segment is obtained, and this is calculated as the center line method at the bit position on the center line. A line. For example, as shown in FIG. 12, when bits P1, P2, P3, P4 and P5 exist on the center line M, the normal line of the center line at the positions of the bits P2, P3 and P4 is obtained as follows. It becomes like this. The normal line of the center line M at the position of the bit P2 is obtained as a straight line R2 perpendicular to the line segment T2 connecting the bits P1 and P3 adjacent to the bit P2. Further, the normal line of the center line M at the position of the bit P3 is obtained as a straight line R3 perpendicular to the line segment T3 connecting the bits P2 and P4 adjacent to the bit P3. The normal line of the center line M at the position of the bit P4 is obtained as a straight line R4 perpendicular to the line segment T4 connecting the bits P3 and P5 adjacent to the bit P4.

  Next, parallel processing S500 is executed. FIG. 13 is a flowchart showing an operation flow of parallel processing executed in the data generation method according to the third embodiment of the present invention. As shown in FIG. 13, the parallel processing S500 includes steps S501 and S502.

  In step S501, the normal direction parameter is weighted and averaged using a weighting coefficient that becomes maximum at the search reference point set for each bit on the center line and decreases with distance from the search reference point (so-called “weighted average”). Process "). This weighted average process includes the following steps S501-1 to S501-6.

  In step S501-1, a search reference point is set from the bits located on the center line on the bitmap image in which the center lines are superimposed. The search reference point is a reference point for searching for a contour point. Through the processing in step S501-4, which will be described later, all the bits located on the center line are always employed as search reference points once. As described above, in this embodiment, since a plurality of arithmetic processors are provided in the arithmetic processing unit, the parallel processing S500 is performed by assigning these arithmetic processors to some of the plurality of search reference points existing on the center line. The process of searching for candidate points based on the search reference point in (a series of processes in step S501 and step S3502 described later) can be executed for each arithmetic processor. In the flowchart shown in FIG. 11, the processes in steps S501 (S501-1 to S501-6) and S502 shown in FIG. 13 are collectively shown in step S500. For example, in an arithmetic processing device provided with 100 arithmetic processors, when processing is performed on 10,000 search reference points on the center line, 100 search reference points are assigned to one arithmetic processor. It is done. As a result, the calculation processing time can be reduced to 1/100 compared to the case where the processing is executed for 10,000 search reference points by one calculation processor. Thus, according to the present embodiment, as in the first embodiment, the series of processing in steps S501 (S501-1 to S501-6) and S502 are executed in parallel by a plurality of arithmetic processors. Arithmetic processing time can be greatly reduced.

  Next, in step S501-2, a process for setting a section in which a predetermined number of bits continue around the search reference point on the center line is performed. For example, in the example shown in FIG. 12, when the number of consecutive bits in the section is set to 5, for example, if the search reference point is bit P3, the section from bit P1 to bit P5 is set. It should be noted that the number of bits set in the section is only an example, and other numbers such as 10 or 20 may be used. The process of step S501-2 is executed for all set search reference points through the process of step S501-4 described later.

  Next, in step S501-3, the direction parameter of each normal existing in the section is multiplied by the weighting coefficient that becomes maximum at the position of the search reference point corresponding to the section. In step S206 described above, since the normal line of the center line at the position of each bit on the center line is calculated on the bitmap image in which the center lines are overlaid, it is within the section set in step S501-2. At all bit positions on the center line, normals to the center line are calculated. In step S501-3, for each of these normals with respect to the center line, the direction parameter is multiplied by the weighting coefficient that is maximum at the position of the search reference point corresponding to the section. The process of step S501-3 is executed for all the set search reference points through the process of step S501-4 described later.

  The normal direction parameter can be expressed as an angle or direction vector. FIG. 14 is a diagram for explaining direction parameters in the data generation method according to the third embodiment of the present invention. In this embodiment, for the direction parameter of the normal, the direction to be the reference (hereinafter referred to as “reference direction”) is set to a line segment connecting two bits on the center line adjacent to the search reference point. To do. For example, in the example shown in FIG. 14, when the search reference point is set to bit P3, the reference direction of the normal direction parameter is two bits P2 on the center line M adjacent to the search reference point bit P3 and It becomes a line segment T3 connecting P4. As described above, the normal line to the center line is calculated at the position of all the bits on the center line in the section. In the example shown in FIG. 14, each direction parameter of the normal lines R3 and R4 represents the line segment T3. The reference direction is represented by an angle or a direction vector. In FIG. 14, the normal line of the center line M at the position of the search reference point bit P3 is R3, but the normal line R4 of the center line M at the position of the bit P4 is the normal line R3 (or a line parallel thereto). The angle R is shifted from the minute R3 ′) by an angle α.

  The weighting coefficient used in the process of step S501-3 is a value that becomes maximum at the search reference point and decreases as the distance from the search reference point increases. 15 and 16 are diagrams illustrating weighting coefficients in the data generation method according to the third embodiment of the present invention. 15 and 15, the number of consecutive bits in the section is set to 5, for example, and the search reference point is set to bit 3. The weighting coefficient is, for example, a value according to a normal distribution having the maximum probability density at the position of the bit P3 that is the search reference point as shown in FIG. 15, and the position of the bit P3 that is the search reference point as shown in FIG. It is a value according to a triangular function with the maximum probability density. That is, when extracting the outline of the wiring, the weighting coefficient is expressed by a function f (x) with respect to the position x in the wiring traveling direction. Such a weighting coefficient is set for each search reference point, and the direction parameter (angle or direction vector) of each normal existing in the section corresponding to the search reference point is multiplied.

  In step S501-4, it is determined whether or not the processing in steps S501-1 to S501-3 has been executed for all search reference points. If there is a search reference point that has not been processed yet, the process returns to step S501-1, and if the process has been executed for all search reference points, the process proceeds to step S5-1-5. As described above, the series of processes in steps S501 (S501-1 to S501-6) and step S501 are executed as parallel processes by a plurality of arithmetic processors, so that “all” determined in step S501-4 “Search reference point” means a plurality of search reference points assigned to one arithmetic processor.

  In step S501-5, the sum of the direction parameters of each normal multiplied by the weighting coefficient in step S501-3 is calculated. Next, in step S501-6, the weighted average direction parameter is calculated by dividing the sum calculated in step S501-5 by the number of bits existing in the section. FIG. 17 is a diagram for explaining the calculation of the weighted average direction parameter in the data generation method according to the third embodiment of the present invention. In the example shown in FIG. 17, a case will be described in which the number of consecutive bits in a section is set to 5, for example, and the weighting coefficient is a value according to a normal distribution having the maximum probability density at the position that is the search reference point. By executing the processing of S501-1 to S501-4 as described above, all the bits positioned on the center line are always adopted as search reference points once, and a corresponding weight is assigned to each search reference point. A group of direction parameters for each normal multiplied by a coefficient is calculated. For example, regarding the normal line at the position of bit P3, the direction parameter thereof follows the weighting coefficient according to the normal distribution D1 when the search reference point is set to bit P1, and the normal distribution D2 when the search reference point is set to bit P2. Weighting coefficient, weighting coefficient according to normal distribution D3 when the search reference point is set to bit P3, weighting coefficient according to normal distribution D4 when the search reference point is set to bit P4, and search reference point when bit P5 is set Weighting coefficients according to the normal distribution D5 are respectively multiplied in step S501-3, and then these five types of multiplication results are added in step S501-5 to calculate the sum. “5” which is the number of consecutive bits In, dividing the sum calculated in step S501-5. As a result, the weighted average direction parameter is calculated for the bit P3. Thus, in step S501-6, the sum calculated in step S501-5 is divided by the number of bits existing in the section. In the example of FIG. 17, the number of bits existing in the section is set to 5 and divided by “5”. However, for example, if the number of bits existing in the section is set to 10, division by “10” is performed. If the number of bits existing in the section is set to 20, division by "20" is performed.

  As described above, the straight line defined by the direction parameter of each normal that is weighted and averaged generated in step S501-6 is used as a “search line” in order to determine the contour point in step S502. In step S502, for each search line that is a straight line defined by the direction parameter of each normal line subjected to the weighted average, the first color of the bit located on the center line from the search reference point along the search line Searches for a bit in which a different second color appears, and determines the detected bit as a contour point constituting the contour of the desired figure.

  FIG. 18 is a diagram for explaining determination of contour points in the data generation method according to the third embodiment of the present invention. For example, when the figure from which the contour line is to be extracted in the bitmap image obtained by imaging the inspection object is a region surrounded by the solid line indicated by reference symbol B, the center line M indicated by the one-dot chain line in FIG. Taking the case where it is superimposed on B as an example, it is as follows. The normals of the center line M at each position of the bits P2 and P3 are R2 and R3, respectively. In the present embodiment, the normal line R2 at the position of the bit P2 of the center line M is set to R2 ″ by the weighted average (weighted average) process for the normal direction parameter in step S501 (steps S501-1 to S501-6). The normal line R3 at the position of the bit P3 of the center line M is changed to R3 ″, and the direction of the straight line is changed. When the center line M is bent sharply, the direction of the normal line at the corresponding position of the bit on the center line changes abruptly compared to the direction of the normal line in the vicinity thereof, but in this embodiment, in step S501. Since the normal direction parameter in (Steps S501-1 to S501-6) is weighted average, the direction does not change abruptly between search lines adjacent to each other.

  In this embodiment, as in the first embodiment, when the inspection object is a substrate on which wiring is formed, and a figure on the inspection object whose contour is to be extracted is wired on the substrate in the captured image, a bitmap is used. On the image, for example, the substrate is represented by binary values such as “black” (corresponding to the “second color”) and the wiring “white” (corresponding to the “first color”). For example, as shown in FIG. 18, the adjacent bits are sequentially searched from the bits P1, P2, P3 and P4 toward the corresponding search lines R1, R2 ″, R3 ″ and R4, respectively. A bit in which “black”, which is a second color different from “white”, which is the first color of the bit located on the line, appears is found. The bit when the “black” appears for the first time is taken as the contour point.

  After the contour point is generated in step S502, the process proceeds to step S203 in FIG. In step S203, the contour points generated in step S502 and the contact points of the “white” bits adjacent to the contour points are rearranged in the order of arrangement of the corresponding search reference points on the virtual plane, and these contact points are connected. To do. As described above, since the series of processing in step S501 (that is, steps S501-1 to S501-6) and step S302 is executed as parallel processing by a plurality of arithmetic processors, all the generated contour points are processed in this step. In S203, the search reference points need to be rearranged in the order of arrangement.

  In step S204, the line obtained by connecting the contacts in step S203 is determined as a contour line, and data relating to the contour line is output. Note that only “white” bits are extracted as contour points, and the points that are far from the search reference point among points where the search line intersects the circumference of the extracted “white” bits, May be used as an outline. Or, only the “black” bit is extracted as the contour point, and the points close to the search reference point among the points where the search line intersects with the extracted “black” bit circumference, It may be a contour line. The output data regarding the contour line may be used, for example, for display on the screen of the display device, or may be used for an image inspection method described as a fourth embodiment to be described later.

  Also in the third embodiment of the present invention, as in the case of the first embodiment, in order to prevent erroneous recognition of the contour line due to the presence of noise in the bitmap image, the contour point search process is as follows. It is preferable to execute a correction process. FIG. 19 is a flowchart showing the correction processing in the contour point search processing in the third embodiment of the present invention. The contour point search process in the third embodiment of the present invention is as described with reference to FIGS. 11 to 18 and is executed for each search reference point on the bitmap image in which the center lines are superimposed. The The correction process is executed as part of a series of processes in this search process.

  First, in step S601, for a certain search reference point, a bit color is searched from the search reference point toward the direction along the search line on the search line on the bitmap image in which the center lines are superimposed. In step S602, it is determined whether or not to detect a bit having “black” that is a second color different from “white” that is the first color of the bit located on the center line.

  If it is determined in step S602 that the “black” bit that is the second color has been detected, information regarding the position coordinates of the detected “black” bit that is the second color is stored in the memory, and step S603 is performed. Proceed to If the “black” bit that is the second color is not detected in step S602, the process returns to step S601, and the processes of steps S602 and S601 are repeated until the “black” bit that is the second color is detected. It is.

  In step S603, the color of the bit is further searched from the position of the detected second color bit toward the direction along the search line on the search line. In step S604, it is determined whether or not to detect a bit having “white” as the first color.

  If it is determined in step S604 that the bit of “white” that is the first color is not detected, the process proceeds to step S605, and the bit of “black” that is the second color that is held in the memory for information regarding the position coordinates. Are determined as contour points and stored in the memory.

  On the other hand, if it is determined in step S604 that the “white” bit that is the first color is detected, information about the position coordinates of the detected “white” bit that is the first color is stored in the memory. The process proceeds to step S606. In step S606, the search is further performed in the direction along the search line from the position of the detected “white” bit as the first color, and the color of the bit is searched in the predetermined search direction on the search line. To go. In step S607, it is determined whether or not to detect a bit having “black” as the second color.

  If it is determined in step S606 that the “black” bit that is the second color has been detected, information regarding the position coordinates of the detected “black” bit that is the second color is stored in the memory, and step S603 is performed. Return to. In step S603, a further search is made in the direction along the search line from the position of the detected second color "black" bit, and the color of the bit is searched in the predetermined search direction on the search line. To go. After this step S603, the above-described series of processing is executed again.

  On the other hand, if it is determined in step S606 that the “black” bit as the second color is not detected, the process proceeds to step S605, where the second color is detected in step S602 and retains information on the position coordinates. The “black” bit is determined as a contour point and held in the memory.

  In the contour point search processing, by executing the above-described correction processing, erroneous recognition of the contour line can be prevented even if noise exists on the captured bitmap image. A specific example of this correction processing is as described with reference to FIG.

  As described above, according to the third embodiment of the present invention, it is possible to realize multiprocessor parallel processing by assigning an arithmetic processing unit to some of the plurality of search reference points. It is possible to generate data relating to the outline of the image at high speed. Further, if the correction process is executed in the contour point search process, erroneous recognition of the contour line can be prevented.

  FIG. 20 is a flowchart showing an operation flow of the image inspection method according to the fourth embodiment of the present invention. An image inspection method according to a fourth embodiment of the present invention inspects an inspection object using data relating to the contour line of a graphic generated using the data generation method according to the third embodiment described above. . According to the fourth embodiment of the present invention, the data generation process and the image inspection process are divided into two processes, an offline process and an online process, as in the third embodiment, and are executed by an arithmetic processing unit such as a computer. Is done.

  In FIG. 20, the processes in steps S101, S201 to S204 and S206 and steps S501 (S501-1 to S501-6) and S502 in the parallel process S500 are the third implementation described with reference to FIGS. Since this is the same as steps S101, S201 to S204 and S206 and steps S501 (S501-1 to S501-6) and S502 in the parallel processing S500 in the data generation method according to the example, the description will be omitted.

  In this embodiment, before the online processing is executed, that is, in the offline processing stage, the outline of the design figure is captured by the camera with respect to the design data used to generate the inspection object. Steps S102 and S106 to S110 are executed according to the same algorithm as the online processing of the bitmap format image data of the inspection object. By using a similar algorithm, the accuracy of the image inspection is ensured. Note that steps S101, 102 and S106 to S110, which are offline processes, can be performed for a long time because even if the figure from which the contour line is to be extracted is complex, it is only necessary to perform one process on the figure. Never spend. Steps S101, 102, and S106 to S110 are executed by an arithmetic processing unit such as a computer, but may be realized as a new function on a CAD system that processes design data, for example.

  In step S102, a search reference point is set from the bits located on the center line in the design figure in the design data. Note that the search reference points used in steps S102, S108, S109, and S110 in the offline processing are the same as the search reference points used in steps S501-1 to S501-4 in the online processing. .

  Next, in step S108, the design normal of the design center line at the position of each bit on the design center line is calculated on the design data bitmap image in which the design center line penetrating the design figure is superimposed. This design normal calculation processing follows the same algorithm as the normal calculation processing in step S206.

  In step S109, the direction parameter of the design normal is weighted and averaged using a weighting coefficient that becomes maximum at the search reference point set for each bit on the design center line and decreases as the distance from the search reference point increases. This joining average process follows the same algorithm as the weighted average process in step S501.

  Next, in step S110, for each design search line, which is a straight line defined by the direction parameter of the weighted average design normal, the bit located on the center line from the search reference point toward the design search line. A bit in which a second color different from the first color appears is searched, and the detected bit is determined as a design contour point constituting the contour of the figure on the design. In the design outline determination process, the outline point determination process in step S502 follows the same algorithm.

  In step S106, on the virtual plane, the design contour points determined in step S110 and the contact points between the “white” bits adjacent to the design contour points are rearranged in the arrangement order of the corresponding search reference points, and these contact points are arranged. Connect. Thus, the process of step S106 also follows the same algorithm as the process of step S203.

  In step S107, the line obtained by connecting the contour points in step S106 is determined as a design contour line of a figure (that is, wiring), and data relating to the design contour line is output. Thus, the process in step S107 also follows the same algorithm as the process in step S204.

  In step S205, the data related to the design outline of the design figure in the design data output in step S107 and the data related to the outline of the figure in the image data of the inspection object output in step S204 are used. Inspection processing is executed.

  In step S205, the figure contour in the image data of the inspection object and the design outline for the design figure are collated for each identical search reference point, and the inspection object has been generated according to the design data. Check for no. For example, if the inspection object is a substrate on which wiring is formed and the figure on which the outline on the inspection object is to be extracted is the wiring on the substrate in the captured image, the same search is performed in step S205. Based on whether the line width of the wiring defined by the contour line of the figure in the image data of the inspection object matches the line width of the wiring defined by the design outline at the reference point, the inspection object is It is determined whether or not the data is generated according to the design data. If it is determined that the line widths match, the inspection object is generated according to the design data. If it is determined that the line widths do not match, the inspection object is not generated according to the design data. So it is considered an error. The inspection result is displayed on a screen of a display device, for example.

  As described above, according to the fourth embodiment of the present invention, with respect to the generation of data related to the contour line, an arithmetic processing unit is assigned to some of the plurality of search reference points to realize multiprocessor parallel processing. Since the processing time is shortened, an image inspection method for performing an image inspection based on image data obtained by imaging an inspection object can also be speeded up. For example, when the inspection target is a substrate on which wiring is formed and the graphic on the inspection target is wiring on the substrate in the captured image, in the image inspection processing, the wiring defined by the contour of the graphic Whether or not the board on which the wiring as the inspection object is formed is generated according to the design data based on whether or not the line width of the wiring and the line width of the wiring defined by the design contour line match. .

  Subsequently, a comparison between the first embodiment and the third embodiment will be described. FIG. 21 is a diagram for explaining extraction of the outline of a wiring having a convex portion and a concave portion in the wiring width direction according to the first embodiment of the present invention. FIGS. 22 and 23 are diagrams illustrating the extraction of the outline of a wiring having a convex portion and a concave portion in the wiring width direction according to the third embodiment of the present invention. As shown in FIG. 21, when there is a recess in the width direction of the wiring, the outline of the wiring can be extracted in both the first and third embodiments of the present invention. However, in the first embodiment of the present invention, search directions are provided in a plurality of directions, contour candidate points are searched along these directions, contour candidate points constituting the shortest distance are determined as contour points, and contour lines are extracted. Therefore, when the width of the wiring projection direction (longitudinal direction) is particularly narrow, the contour line may not be extracted accurately as shown in FIG. 21 depending on how the search direction is selected. . On the other hand, according to the third embodiment, the contour line is determined using the search line obtained by weighted average (weighted average) of the normals of the center line for the search of the contour point. Even if the width in the wiring traveling direction (longitudinal direction) is narrow, the contour line can be accurately extracted as shown in FIG. Further, as shown in FIG. 23, when extracting a contour line of a wiring having a convex part and a concave part in the wiring width direction, the contour line is accurately drawn even if the bit of the center line M is shifted in the wiring width direction. Can be extracted.

  Each step in the data generation method according to the first and third embodiments and the image inspection method according to the second and fourth embodiments is realized in the form of a computer program that can be executed by an arithmetic processing unit such as a computer. Is done. FIG. 24 is a block diagram showing a configuration of a computer on which a computer program according to the data generation method according to the first and third embodiments and the image inspection method according to the second and fourth embodiments operates.

  As shown in FIG. 24, the computer program is stored in a storage medium 10 (external storage medium such as a flexible disk or CD-ROM). For example, the computer program is installed in a computer having the following configuration and installed in the computer program. The data generation method according to the first embodiment or the image inspection method according to the second embodiment operates.

  The CPU 11 controls the entire computer. The CPU 11 is connected to a ROM 13, a RAM 14, an HD (hard disk device) 15, an input device 16 such as a mouse and a keyboard, an external storage medium drive device 17, and a display device 18 such as an LCD, CRT, plasma display, and organic EL via a bus 12. Is connected. The control program for the CPU 11 is stored in the ROM 13.

  Computer programs according to the data generation methods according to the first and third embodiments and the image inspection methods according to the second and fourth embodiments are installed from the storage medium 10 to the HD 15. The RAM 14 has a work area for the CPU 11 to execute various arithmetic processes. The HD 15 stores input data, final data, OS (operating system), and the like in advance.

  First, when the computer is turned on, the CPU 11 reads the control program from the ROM 10 and further reads the OS from the HD 15 to start this OS. As a result, the computer is ready to install the computer program relating to the data generation method according to the first and third embodiments and the image inspection method according to the second and fourth embodiments from the storage medium 10.

  Next, the storage medium 10 is loaded into the external storage medium drive device 17, a control command is input from the input device 16 to the CPU 11, the computer program stored in the storage medium 10 is read, and stored in the HD 15 or the like. That is, the computer program is installed in the computer.

  Thereafter, when the computer program is started, the computer executes each process in the data generation method according to the first and third embodiments and the image inspection method according to the second and fourth embodiments. The “data regarding the contour line” or “the result of the image inspection performed on the image data obtained by imaging the inspection object” obtained as a result of the processing is stored in the HD 15 so that it can be used later, or The result may be used for visual display on the display device 18.

  24, the computer program stored in the storage medium 10 is installed in the HD 15. However, the present invention is not limited to this, and the computer program may be installed in the computer via an information transmission medium such as a LAN. Alternatively, it may be installed in advance in the HD 15 built in the computer.

  The present invention uses a technique for extracting a contour line of a desired figure in a bitmap image obtained by imaging an inspection object with a camera, and a bitmap image obtained by imaging the inspection object with a camera. It can be used for techniques for inspecting inspection objects. The inspection object includes a substrate on which wiring is formed.

10 recording medium 11 CPU
12 bus 13 ROM
14 RAM
15 Hard Disk Device 16 Input Device 17 External Storage Medium Drive Device 18 Display Device

Claims (20)

A data generation method in which processing for generating data related to a contour line of a desired figure on an inspection target is executed by an arithmetic processing unit from image data in a bitmap format in which the inspection target is captured,
A superposition step of superimposing a center line penetrating a design figure corresponding to the desired figure generated from the design data used to generate the inspection object on a bitmap image in the image data; ,
For each search reference point that is a bit located on the center line on the bitmap image in which the center line is overlaid, the bit located on the center line from the search reference point toward a predetermined search direction. Searching for a bit in which a second color different from the first color appears, and using the detected bit as a contour candidate point;
For each of the search reference points, a candidate having the shortest distance from the search reference point is extracted from the contour candidate points, and the extracted point is confirmed as a contour point constituting the contour of the desired graphic Steps,
A line obtained by connecting the contour point and the contact point of the bit having the first color adjacent to the contour point in the arrangement order of the corresponding search reference points is determined as the contour line of the desired figure. An output step for outputting data relating to the contour line;
A data generation method comprising:   2. The data generation method according to claim 1, wherein the predetermined search direction is a 2n direction (where n is an integer) centered on the search reference point on the bitmap image on which the center line is superimposed.   The search step and the determination step are executed independently for each arithmetic processor in the arithmetic processing unit assigned to some search reference points among the search reference points. Data generation method. The searching step includes
On the bitmap image in which the center line is overlaid, for each of the search reference points, a search is performed from the search reference point toward a predetermined search direction, and the first color of the bit located on the center line and A first determination step of determining whether to detect bits having different second colors;
If it is determined in the first determination step that the bit of the second color has been detected, the first color is further searched from the detected bit of the second color toward the predetermined search direction. A second determination step for determining whether or not to detect the bits having;
If it is determined in the second determination step that the bit of the first color is not detected, a candidate point determination step of determining the bit of the second color detected immediately before as the contour candidate point;
If it is determined that the first color bit is detected in the second determination step, the second color is further searched from the detected first color bit toward the predetermined search direction. A third determination step for determining whether or not to detect the bits having;
Have
If it is determined in the third determination step that the second color bit has been detected, the search and determination processing in the second determination step is further executed,
The data generation according to any one of claims 1 to 3, wherein when it is determined that the second color bit is not detected in the third determination step, candidate point determination processing in the candidate point determination step is executed. Method.   The data generation method according to any one of claims 1 to 4 is executed by the arithmetic processing device, and the data relating to the contour line of the desired graphic and the design contour line regarding the design graphic are output. And an inspection step of checking whether or not the inspection object is generated according to the design data by comparing the contour line of the desired figure with the design contour line using the data. Image inspection method. In the design figure in the design data, for each of the search reference points, a second color different from the first color of the bit located on the center line from the search reference point toward a predetermined search direction A search step for design data that searches for a bit in which is detected and uses the detected bit as a design contour candidate point;
For each search reference point, the design contour point that extracts the shortest distance from the search reference point from the design contour candidate points, and the extracted point constitutes the contour of the figure on the design A design data confirmation step to be confirmed as
A line obtained by connecting the design contour point and the contact point of the bit having the first color adjacent to the design contour point in the arrangement order of the corresponding search reference points is obtained with respect to the design figure. A design data outline step for confirming the design outline and outputting data related to the design outline;
An image inspection method according to claim 5. A data generation method in which processing for generating data related to a contour line of a desired figure on an inspection target is executed by an arithmetic processing unit from image data in a bitmap format in which the inspection target is captured,
A superposition step of superimposing a center line penetrating a design figure corresponding to the desired figure generated from the design data used to generate the inspection object on a bitmap image in the image data; ,
A normal calculation step for calculating a normal of the center line at the position of each bit on the center line on the bitmap image in which the center line is overlaid,
A weighted average step of weighting and averaging the normal direction parameter using a weighting factor that is maximized at a search reference point set for each of the bits on the center line and decreases with distance from the search reference point;
For each search line that is a straight line defined by the weighted averaged direction parameter, the second color different from the first color of the bit located on the center line along the search line from the search reference point A step of searching for a bit in which the color of the color appears, and determining the detected bit as a contour point constituting the contour of the desired graphic;
A line obtained by connecting the contour point and the contact point of the bit having the first color adjacent to the contour point in the arrangement order of the corresponding search reference points is determined as the contour line of the desired figure. An output step for outputting data relating to the contour line;
A data generation method comprising: The weighted average step includes
Sequentially setting each bit on the centerline as the search reference point;
Executing, for each search reference point, a process of setting a section in which a predetermined number of the bits continue around the search reference point on the center line;
A multiplication step for executing a process for multiplying each normal section by a process of multiplying a direction parameter of each normal existing in the section and the weighting coefficient that is maximized at the position of the search reference point corresponding to the section. ,
An adding step of calculating a sum of each of the direction parameters multiplied by the weighting factor;
A division step of calculating the weighted averaged direction parameter by dividing the sum by the predetermined number;
The data generation method according to claim 7.   9. The data generation method according to claim 7, wherein the weighting coefficient is a value according to a normal distribution having a maximum probability density at the position of the search reference point.   The data generation according to claim 7, wherein, in the normal line calculating step, the normal line of the center line at the bit position is a normal line to a line segment connecting two bits on the center line adjacent to the bit. Method.   The direction parameter is an angle or a direction vector defined with a line segment connecting two bits on the center line adjacent to the search reference point as a reference direction. Data generation method.   The said determination step is performed independently for every arithmetic processor in the said arithmetic processing unit allocated to some search reference points of each said search reference points. The data generation method described. The confirmation step includes
On the bitmap image in which the center line is overlaid, for each search line, a search is performed from the search reference point along the search line, from the search reference point along the search line, and on the center line. A first determination step of determining whether or not to detect a bit having the second color different from the first color of the bit located;
If it is determined in the first determination step that the bit of the second color has been detected, the bit having the first color is further searched along the search line from the detected bit of the second color. A second determination step of determining whether or not to detect
A contour point determining step for determining the bit of the second color detected immediately before as the contour point when it is determined in the second determining step that the bit of the first color is not detected;
If it is determined in the second determination step that the bit of the first color has been detected, the bit having the second color is further searched along the search line from the detected bit of the first color. A third determination step for determining whether or not to detect
Have
If it is determined in the third determination step that the second color bit has been detected, the search and determination processing in the second determination step is further executed,
The data generation according to any one of claims 7 to 12, wherein when it is determined that the second color bit is not detected in the third determination step, a contour point determination process in the contour point determination step is executed. Method.   The data generation method according to claim 1, further comprising a center line generation step of generating the center line using design data used to generate the inspection object.   The data generation method according to claim 1, further comprising a display step of displaying an image based on the data relating to the contour line on a screen of a display device.   The overlaying step includes an alignment step of aligning a design bitmap image in the design data and a bitmap image in the image data with reference to a predetermined mark defined on the design data. The data generation method according to claim 1 or 7.   The inspection object is a substrate on which wiring is formed, and the desired graphic on the inspection object is the wiring on the substrate in a captured image. The data generation method according to claim 1.   Data relating to the contour of the desired graphic output by the execution of the data generation method according to any one of claims 7 to 13 and a design contour for a design graphic And an inspection step of checking whether or not the inspection object is generated according to the design data by comparing the contour line of the desired figure with the design contour line using the data. Image inspection method. Design data normal calculation for calculating the design normal of the design center line at the position of each bit on the design center line on the design data bit map image on which the design center line penetrating the design figure is superimposed Steps,
A weighted average for design data that is weighted using a weighting coefficient that maximizes the direction parameter of the design normal at a search reference point set for each bit on the design center line and decreases with distance from the search reference point. Steps,
For each design search line that is a straight line defined by the weighted averaged direction parameter, the first color of the bit located on the center line from the search reference point toward the design search line Searching for a bit in which the different second color appears, and confirming the detected bit as a design contour point constituting the contour of the figure on the design;
A line obtained by connecting the design contour point and the contact point of the bit having the first color adjacent to the design contour point in the arrangement order of the corresponding search reference points is obtained with respect to the design figure. A design data output step for confirming the design contour line and outputting data related to the design contour line;
An image inspection method according to claim 18. The inspection object is a substrate on which wiring is formed, and the desired figure on the inspection object is the wiring on the substrate in a captured image,
In the inspection step, the inspection object is designed based on whether or not the line width of the wiring defined by the outline of the desired graphic matches the line width of the wiring defined by the design contour. 20. The image inspection method according to any one of claims 5, 6, 18 and 19, wherein it is determined whether the data is generated according to data.

Images