JP5633248B2 - Signal processing apparatus, defect detection apparatus, signal processing method, defect detection method, and program - Google Patents

Description

  The present invention relates to a signal processing device, a defect detection device, a signal processing method, a defect detection method, and a program.

  Signals with boundaries may be filtered. In this case, it is difficult to appropriately filter in the vicinity of the boundary. Therefore, conventionally, in the vicinity of the boundary, filtering is performed using only the value inside the boundary by modifying the filter coefficient, or filtering is performed by filling the outside of the boundary with a signal having the same value as the boundary value.

Non-Patent Document 1 Sun Microsystems, "Programming in Java Advanced Imaging" (Chapter 7 Image Enhancement), [online], November 1999, [searched on August 20, 2010], Internet <URL: http: // java.sun.com/products/java-media/jai/forDevelopers/jai1_0_1guide-unc/Image-enhance.doc.html>
Non-Patent Document 2 WIKIPEDIA, "Extrapolation", [online], [searched on August 20, 2010], Internet <URL: http://en.wikipedia.org/wiki/Extrapolation>

  However, when a signal having a gradient at the boundary portion is filtered by the above-described method, the filtered signal is greatly deviated from the original value, and an appropriate result cannot be obtained. For example, a process for detecting a defect on the surface of an inspection object from a difference image between a captured image of the inspection object and an image obtained by low-pass filtering the captured image is known. In such processing, when the above-described filtering is performed, the peripheral portion of the inspection object cannot be appropriately filtered, and the peripheral portion of the inspection object is determined to be a defect.

  In order to solve the above-mentioned problem, in a first aspect of the present invention, a signal processing apparatus for filtering a two-dimensional input signal having a boundary, the two-dimensional extrapolation complementing outside the region of the input signal An extrapolation signal generation unit that generates a signal based on the input signal, a signal addition unit that generates a correction signal obtained by adding the extrapolation signal outside the region of the input signal, a filter unit that filters the correction signal, There is provided a signal processing device, a signal processing method, and a program including an output unit that generates and outputs an output signal obtained by cutting out a region corresponding to the input signal in the filtered correction signal.

  According to a second aspect of the present invention, there is provided a signal processing device for filtering a one-dimensional input signal having a boundary, wherein the signal is a one-dimensional signal that complements outside the region of the input signal, and the value of each position is An extrapolation signal generation unit that generates an extrapolation signal that is a value obtained by inverting the value of the input signal at a position symmetric with respect to the boundary position around the boundary value; and the extrapolation signal outside the area of the input signal. A signal adding unit for generating the added correction signal, a filter unit for filtering the correction signal, a signal obtained by cutting out a region corresponding to the input signal in the filtered correction signal, and generating the generated signal A signal processing device, a signal processing method, and a program are provided.

  It should be noted that the above summary of the invention does not enumerate all the necessary features of the present invention. In addition, a sub-combination of these feature groups can also be an invention.

The structure of the signal processing apparatus 10 which concerns on this embodiment is shown. The processing flow of the signal processing apparatus 10 which concerns on this embodiment is shown. An example of a one-dimensional input signal is shown. An example of the correction signal in which the extrapolation signal is added outside the area of the input signal is shown. 2 shows an example of a correction signal and a signal obtained by low-pass filtering the correction signal. The structure of the defect detection apparatus 30 which concerns on this embodiment is shown. The processing flow of the defect detection apparatus 30 which concerns on this embodiment is shown. An example of the captured image and the boundary position of the inspection object are shown. An example of a corrected image in which an extrapolated image is added outside the region of the captured image is shown. An example of a low-pass filtered corrected image is shown. An example of a difference image obtained by subtracting a low-pass filtered correction image from a captured image is shown. An example of the detection result of a defect is shown. 2 shows an exemplary hardware configuration of a computer 1900 according to the present embodiment.

  Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. In addition, not all the combinations of features described in the embodiments are essential for the solving means of the invention.

  FIG. 1 shows a configuration of a signal processing apparatus 10 according to the present embodiment. The signal processing device 10 filters an input signal having a boundary. The input signal may be a one-dimensional signal, a two-dimensional signal such as an image, or a two-dimensional or more multidimensional signal.

  Here, the input signal having a boundary is a signal in which a part of the signal is interrupted without being continuous. In the case of a one-dimensional signal, an input signal having a boundary is, for example, a signal in which at least one end in the minus direction or the plus direction is interrupted. In the case of a two-dimensional signal, an input signal having a boundary is, for example, a signal having a circular boundary such as a circle, a triangle, and a quadrangle.

  The signal processing device 10 includes a boundary position setting unit 12, a boundary value setting unit 14, an extrapolation signal generation unit 16, a signal addition unit 18, a filter unit 20, and an output unit 22. The boundary position setting unit 12 sets the boundary position of the input signal. The boundary value setting unit 14 sets the boundary value of the input signal.

  The extrapolation signal generation unit 16 generates an extrapolation signal that complements the area outside the input signal based on the input signal. As an example, the extrapolation signal generation unit 16 generates an extrapolation signal based on the boundary position set by the boundary position setting unit 12 and the boundary value set by the boundary value setting unit 14.

  The signal adding unit 18 generates a correction signal obtained by adding the extrapolation signal generated by the extrapolation signal generation unit 16 outside the area of the input signal. The filter unit 20 filters the correction signal generated by the signal adding unit 18.

  The output unit 22 cuts out a region corresponding to the input signal in the correction signal filtered by the filter unit 20 and generates a signal. And the output part 22 outputs the cut-out signal as an output signal.

  FIG. 2 shows a processing flow of the signal processing apparatus 10 according to the present embodiment. FIG. 3 shows an example of a one-dimensional input signal. FIG. 4 shows an example of the correction signal obtained by adding the extrapolation signal outside the area of the input signal. FIG. 5 shows an example of a correction signal and a signal obtained by low-pass filtering the correction signal. In each signal waveform shown in FIGS. 3 to 5, the horizontal axis (x axis) represents the position x of the one-dimensional signal, and the vertical axis (y axis) represents the signal value (I (x)). Represent.

  First, in step S11, the signal processing apparatus 10 inputs an input signal to be filtered. In the example of FIG. 3, the signal processing apparatus 10 inputs a one-dimensional signal having a boundary on the left side (minus direction side) of the waveform. The signal processing apparatus 10 may input a one-dimensional signal having a boundary on the right side (plus direction side) of the waveform, or input a one-dimensional signal having a boundary on both the right side and the left side of the waveform. May be.

Subsequently, in step S12, the boundary position setting unit 12 sets a boundary position in the input signal. As an example, the boundary position setting unit 12 detects the position of the end in the region (in the region) where the value of the input signal exists, and sets the detected position as the boundary position. In the example of FIG. 3, the boundary position setting unit 12 sets the left end position (x ₀ ) of the waveform of the one-dimensional signal as the boundary position. The boundary position setting unit 12 may set a position designated by the user as the boundary position.

Subsequently, in step S13, the boundary value setting unit 14 sets a boundary value of the input signal. For example, the boundary value setting unit 14 detects a terminal value in a region (in the region) where the value of the input signal exists, and sets the detected value as a boundary value. In the example of FIG. 3, the boundary value setting unit 14 sets the value (I _b ) at the left end of the one-dimensional signal waveform as the boundary value.

  The boundary value setting unit 14 may set the estimated boundary value, or may set a value obtained by correcting the detected value as the boundary value. The boundary value setting unit 14 may set a value designated by the user as the boundary value.

  Subsequently, in step S14, the extrapolation signal generation unit 16 generates an extrapolation signal that complements the area outside the input signal based on the input signal. More specifically, the extrapolation signal generation unit 16 is a signal that complements the area outside the input signal, and the value of each position is obtained by converting the value of the input signal at a position symmetrical to the boundary position to the boundary value. An extrapolated signal having a value inverted to the center is generated. That is, the extrapolation signal generation unit 16 generates a signal obtained by inverting the sign of the position around the boundary position with respect to the input signal and inverting the sign of the value around the boundary value as an extrapolation signal.

In the example of FIG. 4, the extrapolation signal generation unit 16 supplements the outside of the left side (minus direction side) region of the input signal with an extrapolation signal (I _m ( x)).

I _m (x) = 2 × I _b −I (2 × x ₀ −x) (1)

In the equation (1), _{I b} represents a boundary value. x ₀ represents the boundary position. I m _(x) represents the value of No. outer挿信at each position x of the left side of the boundary position x ₀ (minus side). I (x) represents the value of the input signal at position x.

That is, in the example of FIG. 4, the extrapolation signal generation unit 16 performs an extrapolation from twice the boundary value (I _b ) (2 × I _b ) to twice the boundary position (X ₀ ) (2 × X ₀ ). The signal [2 × I _b −I (2 × x) obtained by subtracting the value (I (2 × X ₀ −x)) of the input signal at the position (2 × X ₀ −x) obtained by subtracting the position (x) of the insertion signal. ₀₋ x)] is calculated as an extrapolated signal [I _m (x)]. Thereby, the extrapolation signal production | generation part 16 can produce | generate the extrapolation signal connected naturally from the boundary of an input signal outside the area | region of an input signal continuously.

Subsequently, in step S15, the signal adding unit 18 generates a correction signal in which the extrapolation signal generated by the extrapolation signal generation unit 16 is added outside the area of the input signal. That is, the signal adding unit 18 generates a signal obtained by connecting the input signal and the extrapolation signal. In the example of FIG. 4, the signal adding unit 18, in each position of the right side from the boundary position (X ₀₎ (positive direction), the value I (x), and the boundary position (X ₀₎ from the left side (minus At each position (direction side), a correction signal having a value of I _m (x) is generated.

  Subsequently, in step S <b> 16, the filter unit 20 filters the correction signal generated by the signal adding unit 18. In the example of FIG. 5, the filter unit 20 performs low-pass filtering on the correction signal. The filter unit 20 is not limited to low-pass filtering, and may perform other filtering processing.

Subsequently, in step S17, the output unit 22 generates and outputs an output signal obtained by cutting out a region corresponding to the input signal in the filtered correction signal. In the example of FIG. 5, a signal representing the value of each position on the right side (plus direction side) from the boundary position (X ₀ ) in the filtered correction signal is output as an output signal. Thereby, the output part 22 can output the signal of the same range as the case where the input signal which has a boundary is directly filtered.

  According to the signal processing apparatus 10 as described above, even when an input signal having a gradient at the boundary portion is filtered, for example, a signal appropriately filtered at the boundary portion can be output.

In step S14, the extrapolation signal generation unit 16 does not generate an extrapolation signal that complements the entire outside of the area of the input signal, but generates an extrapolation signal that complements a part of the outside of the area. Good. As an example, the extrapolation signal generation unit 16 generates an extrapolation signal that complements an area necessary for calculating a value corresponding to the boundary position (X ₀ ) by filtering processing. In other words, as an example, the extrapolation signal generation unit 16 generates an extrapolation signal that is at least longer than the signal length corresponding to the coefficient length (filter window size) of the filter unit 20. Thereby, extrapolation signal generation part 16 can reduce the amount of operations, the amount of memory, etc. for generating an extrapolation signal.

  FIG. 6 shows a configuration of the defect detection apparatus 30 according to the present embodiment. The defect detection device 30 is a modification of the signal processing device 10 according to the present embodiment, and has substantially the same configuration and function as the signal processing device 10. Accordingly, members having substantially the same configuration and function as members included in the signal processing device 10 are denoted by the same reference numerals, and description thereof will be omitted except for differences.

  The defect detection device 30 inputs a captured image obtained by capturing the surface of the inspection object as an input image, and detects a defect on the surface of the inspection object from the input captured image. The defect detection device 30 includes an input unit 32, a boundary position setting unit 12, a boundary value setting unit 14, an extrapolation signal generation unit 16, a signal addition unit 18, a filter unit 20, and a difference image generation unit 34. And a detection unit 36.

  The input unit 32 inputs a captured image obtained by capturing the inspection object. The boundary position setting unit 12 sets the boundary position of the inspection object in the captured image. The boundary value setting unit 14 sets the boundary value of the inspection object in the captured image.

  The extrapolation signal generation unit 16 generates an extrapolated image that complements the outside of the region of the captured image based on the boundary position and boundary value of the extrapolated image. The signal adding unit 18 generates a corrected image in which the extrapolated image is added outside the captured image area. The filter unit 20 performs low-pass filtering on the corrected image.

  The difference image generation unit 34 generates a difference image representing the difference between the captured image input by the input unit 32 and the corrected image subjected to low-pass filtering. The detection unit 36 analyzes the difference image and detects a defect of the inspection object.

  FIG. 7 shows a processing flow of the defect detection apparatus 30 according to the present embodiment. FIG. 8 shows an example of a captured image and the boundary position of the inspection object. FIG. 9 shows an example of a corrected image in which an extrapolated image is added outside the region of the captured image. FIG. 10 shows an example of a low-pass filtered corrected image. FIG. 11 shows an example of a difference image obtained by subtracting a low-pass filtered correction image from a captured image. FIG. 12 shows an example of a defect detection result.

  First, in step S21, the input unit 32 inputs a captured image obtained by imaging the surface of the inspection object. In the example of FIG. 8, the input unit 32 inputs a captured image obtained by capturing an image of the surface of a circular inspection object placed on an observation platform.

  Subsequently, in step S22, the boundary position setting unit 12 sets the boundary position in the captured image. In the example of FIG. 8, the boundary position setting unit 12 sets the peripheral portion of the inspection object shown in the captured image as the boundary position. As an example, the boundary position setting unit 12 sets, as the boundary position, a circular boundary line connecting portions where the luminance in the captured image changes greatly, as indicated by a dotted line in FIG.

  Subsequently, in step S23, the boundary value setting unit 14 sets a boundary value in the captured image. In the example of FIG. 8, the boundary value setting unit 14 sets the pixel value of the peripheral portion of the inspection object shown in the captured image as the boundary value. As an example, the boundary value setting unit 14 sets a pixel value on a circular boundary indicated by a dotted line in FIG. 8 as a boundary value.

  The boundary value setting unit 14 may calculate the boundary value by averaging the values along the tangential direction of the boundary of the captured image. For example, in the example of FIG. 8, the boundary value is calculated by averaging the pixel values along a circular boundary line representing the position of the peripheral portion of the inspection object.

  Subsequently, in step S24, the extrapolation signal generation unit 16 generates an extrapolated image that complements the outside of the region of the captured image based on the captured image. More specifically, the extrapolation signal generation unit 16 calculates an extrapolated image in which the value of each pixel position is a value obtained by inverting the value of the captured image at a pixel position symmetric with respect to the boundary position around the boundary value. Generate.

  In this case, the extrapolation signal generation unit 16 generates the value of each pixel position of the extrapolated image based on the value of the captured image at the symmetric pixel position across the boundary line connecting the boundary positions. That is, the extrapolation signal generation unit 16 is an extension of the normal line obtained by dropping the value of each pixel position of the extrapolated image from the pixel position to the boundary line, and is the same as the distance from the pixel position to the boundary line. It generates based on the value of the captured image at the pixel position of the distance.

  Furthermore, in this case, the extrapolation signal generation unit 16 takes, as an example, a captured image of pixels around a symmetric pixel position with a boundary position with respect to the pixel position as a value of each pixel position in the extrapolated image. Calculate based on the value of. For example, when there is no pixel at the corresponding pixel position, the extrapolation signal generation unit 16 complements the values of the pixels around the pixel position and generates the value of the pixel position. Thereby, the extrapolation signal production | generation part 16 can produce | generate the value of each pixel of an extrapolation image with sufficient precision.

  Subsequently, in step S25, the signal adding unit 18 generates a corrected image in which the extrapolated image generated by the extrapolated signal generating unit 16 is added outside the region of the captured image. In the example of FIG. 9, the signal adding unit 18 generates a corrected image in which an image outside the region of the inspection object in the captured image is replaced with an extrapolated image.

  Subsequently, in step S26, the filter unit 20 performs low-pass filtering on the corrected image generated by the signal adding unit 18. In the example of FIG. 10, the filter unit 20 applies a Gaussian filter to the corrected image. The Gaussian filter is defined by the following equation (2).

  The filter unit 20 performs low-pass filtering on the corrected image by calculating the convolution of the Gaussian filter expressed in Equation (2) and the corrected image. In Expression (2), μ is the center of the filter, and f (x) is maximum when x = μ. Σ represents the spread of the filter.

  Subsequently, in step S <b> 27, the difference image generation unit 34 generates a difference image representing a difference between the captured image input by the input unit 32 and the corrected image subjected to low-pass filtering by the filter unit 20. The difference image of FIG. 11 is an image obtained by subtracting the low-pass filtered corrected image shown in FIG. 10 from the captured image shown in FIG.

  Subsequently, in step S <b> 28, the detection unit 36 analyzes the difference image generated by the difference image generation unit 34 and detects a defect of the inspection object. In the example of FIG. 12, the detection unit 36 binarizes the difference image shown in FIG. 11 with a predetermined threshold value, and sets a portion having a value of 1 (white point in the figure) as a defect. Identify.

  According to the defect detection apparatus 30 as described above, low-pass filtering can be appropriately applied at the boundary portion of the inspection object. Therefore, according to the defect detection device 30, it is possible to accurately detect defects on the surface of the inspection object.

  FIG. 13 shows an example of a hardware configuration of a computer 1900 according to the present embodiment. A computer 1900 according to this embodiment is connected to a CPU peripheral unit having a CPU 2000, a RAM 2020, a graphic controller 2075, and a display device 2080 that are connected to each other by a host controller 2082, and to the host controller 2082 by an input / output controller 2084. Input / output unit having communication interface 2030, hard disk drive 2040, and CD-ROM drive 2060, and legacy input / output unit having ROM 2010, flexible disk drive 2050, and input / output chip 2070 connected to input / output controller 2084 With.

  The host controller 2082 connects the RAM 2020 to the CPU 2000 and the graphic controller 2075 that access the RAM 2020 at a high transfer rate. The CPU 2000 operates based on programs stored in the ROM 2010 and the RAM 2020 and controls each unit. The graphic controller 2075 acquires image data generated by the CPU 2000 or the like on a frame buffer provided in the RAM 2020 and displays it on the display device 2080. Instead of this, the graphic controller 2075 may include a frame buffer for storing image data generated by the CPU 2000 or the like.

  The input / output controller 2084 connects the host controller 2082 to the communication interface 2030, the hard disk drive 2040, and the CD-ROM drive 2060, which are relatively high-speed input / output devices. The communication interface 2030 communicates with other devices via a network. The hard disk drive 2040 stores programs and data used by the CPU 2000 in the computer 1900. The CD-ROM drive 2060 reads a program or data from the CD-ROM 2095 and provides it to the hard disk drive 2040 via the RAM 2020.

  The input / output controller 2084 is connected to the ROM 2010, the flexible disk drive 2050, and the relatively low-speed input / output device of the input / output chip 2070. The ROM 2010 stores a boot program that the computer 1900 executes at startup and / or a program that depends on the hardware of the computer 1900. The flexible disk drive 2050 reads a program or data from the flexible disk 2090 and provides it to the hard disk drive 2040 via the RAM 2020. The input / output chip 2070 connects the flexible disk drive 2050 to the input / output controller 2084 and inputs / outputs various input / output devices via, for example, a parallel port, a serial port, a keyboard port, a mouse port, and the like. Connect to controller 2084.

  A program provided to the hard disk drive 2040 via the RAM 2020 is stored in a recording medium such as the flexible disk 2090, the CD-ROM 2095, or an IC card and provided by the user. The program is read from the recording medium, installed in the hard disk drive 2040 in the computer 1900 via the RAM 2020, and executed by the CPU 2000.

  A program that is installed in the computer 1900 and causes the computer 1900 to function as the signal processing device 10 includes a boundary position setting module, a boundary value setting module, an extrapolation signal generation module, a signal addition module, a filter module, and an output module. Is provided. These programs or modules work with the CPU 2000 or the like to make the computer 1900 into the boundary position setting unit 12, the boundary value setting unit 14, the extrapolation signal generation unit 16, the signal addition unit 18, the filter unit 20, and the output unit 22, respectively. Make it work.

  The information processing described in these programs is read by the computer 1900, whereby the boundary position setting unit 12 and the boundary value setting unit 14 are specific means in which the software and the various hardware resources described above cooperate. , Function as extrapolation signal generation unit 16, signal addition unit 18, filter unit 20 and output unit 22. And the specific signal processing apparatus 10 according to the intended purpose is constructed | assembled by implement | achieving the calculation or processing of the information according to the intended purpose of the computer 1900 in this embodiment by these specific means.

  A program that is installed in the computer 1900 and causes the computer 1900 to function as the defect detection apparatus 30 includes an input module, a boundary position setting module, a boundary value setting module, an extrapolation signal generation module, a signal addition module, and a filter. A module, a difference image generation module, and a detection module; These programs or modules work on the CPU 2000 or the like to change the computer 1900 into the input unit 32, the boundary position setting unit 12, the boundary value setting unit 14, the extrapolation signal generation unit 16, the signal addition unit 18, the filter unit 20, and the difference. It functions as the image generation unit 34 and the detection unit 36, respectively.

  The information processing described in these programs is read into the computer 1900, whereby the input unit 32, the boundary position setting unit 12, the boundary, which are specific means in which the software and the various hardware resources described above cooperate. It functions as the value setting unit 14, extrapolation signal generation unit 16, signal addition unit 18, filter unit 20, difference image generation unit 34, and detection unit 36. And the specific defect detection apparatus 30 according to the use purpose is constructed | assembled by implement | achieving the calculation or processing of the information according to the use purpose of the computer 1900 in this embodiment by these specific means.

  As an example, when communication is performed between the computer 1900 and an external device or the like, the CPU 2000 executes a communication program loaded on the RAM 2020 and executes a communication interface based on the processing content described in the communication program. A communication process is instructed to 2030. Under the control of the CPU 2000, the communication interface 2030 reads transmission data stored in a transmission buffer area or the like provided on a storage device such as the RAM 2020, the hard disk drive 2040, the flexible disk 2090, or the CD-ROM 2095, and sends it to the network. The reception data transmitted or received from the network is written into a reception buffer area or the like provided on the storage device. As described above, the communication interface 2030 may transfer transmission / reception data to / from the storage device by a DMA (direct memory access) method. Instead, the CPU 2000 transfers the storage device or the communication interface 2030 as a transfer source. The transmission / reception data may be transferred by reading the data from the data and writing the data to the communication interface 2030 or the storage device of the transfer destination.

  The CPU 2000 is all or necessary from among files or databases stored in an external storage device such as a hard disk drive 2040, a CD-ROM drive 2060 (CD-ROM 2095), and a flexible disk drive 2050 (flexible disk 2090). This portion is read into the RAM 2020 by DMA transfer or the like, and various processes are performed on the data on the RAM 2020. Then, CPU 2000 writes the processed data back to the external storage device by DMA transfer or the like. In such processing, since the RAM 2020 can be regarded as temporarily holding the contents of the external storage device, in the present embodiment, the RAM 2020 and the external storage device are collectively referred to as a memory, a storage unit, or a storage device. Various types of information such as various programs, data, tables, and databases in the present embodiment are stored on such a storage device and are subjected to information processing. Note that the CPU 2000 can also store a part of the RAM 2020 in the cache memory and perform reading and writing on the cache memory. Even in such a form, the cache memory bears a part of the function of the RAM 2020. Therefore, in the present embodiment, the cache memory is also included in the RAM 2020, the memory, and / or the storage device unless otherwise indicated. To do.

  In addition, the CPU 2000 performs various operations, such as various operations, information processing, condition determination, information search / replacement, etc., described in the present embodiment, specified for the data read from the RAM 2020 by the instruction sequence of the program. Is written back to the RAM 2020. For example, when performing the condition determination, the CPU 2000 determines whether the various variables shown in the present embodiment satisfy the conditions such as large, small, above, below, equal, etc., compared to other variables or constants. When the condition is satisfied (or not satisfied), the program branches to a different instruction sequence or calls a subroutine.

  Further, the CPU 2000 can search for information stored in a file or database in the storage device. For example, in the case where a plurality of entries in which the attribute value of the second attribute is associated with the attribute value of the first attribute are stored in the storage device, the CPU 2000 displays the plurality of entries stored in the storage device. The entry that matches the condition in which the attribute value of the first attribute is specified is retrieved, and the attribute value of the second attribute that is stored in the entry is read, thereby associating with the first attribute that satisfies the predetermined condition The attribute value of the specified second attribute can be obtained.

  The program or module shown above may be stored in an external recording medium. As the recording medium, in addition to the flexible disk 2090 and the CD-ROM 2095, an optical recording medium such as DVD or CD, a magneto-optical recording medium such as MO, a tape medium, a semiconductor memory such as an IC card, and the like can be used. Further, a storage device such as a hard disk or RAM provided in a server system connected to a dedicated communication network or the Internet may be used as a recording medium, and the program may be provided to the computer 1900 via the network.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

  The order of execution of each process such as operations, procedures, steps, and stages in the apparatus, system, program, and method shown in the claims, the description, and the drawings is particularly “before” or “prior to”. It should be noted that the output can be realized in any order unless the output of the previous process is used in the subsequent process. Regarding the operation flow in the claims, the description, and the drawings, even if it is described using “first”, “next”, etc. for convenience, it means that it is essential to carry out in this order. It is not a thing.

DESCRIPTION OF SYMBOLS 10 Signal processing apparatus, 12 Boundary position setting part, 14 Boundary value setting part, 16 Extrapolation signal generation part, 18 Signal addition part, 20 Filter part, 22 Output part, 30 Defect detection apparatus, 32 Input part, 34 Difference image generation Part, 36 detection part, 1900 computer, 2000 CPU, 2010 ROM, 2020 RAM, 2030 communication interface, 2040 hard disk drive, 2050 flexible disk drive, 2060 CD-ROM drive, 2070 input / output chip, 2075 graphic controller, 2080 display Device, 2082 Host controller, 2084 I / O controller, 2090 Flexible disk, 2095 CD-ROM

Claims (11)

A signal processing device for filtering a two-dimensional input signal representing an image of an inspection object having a boundary,
An outer interpolation signal generating unit that generates based two-dimensional No. outer挿信to complement the region outside the region of the inspection object in the input signal to the input signal,
A signal adding unit that generates a correction signal by adding the extrapolation signal outside the region in the input signal;
A filter unit for filtering the correction signal;
An output unit that generates and outputs an output signal obtained by cutting out a region corresponding to the input signal in the filtered correction signal;
With
The outer interpolation signal generating unit, said a signal that complements an area outside in the input signal, the value of each position, the input signal at the positions symmetrical with respect to the boundary position wherein a peripheral portion of the object A signal processing device that generates an extrapolated signal that is a value obtained by inverting the value of around the boundary value. The signal processing apparatus according to claim 1, wherein the extrapolation signal generation unit generates a value at each position of the extrapolation signal based on a boundary value averaged along a tangential direction of a boundary of the input signal. The signal processing device generates an extrapolated image as the extrapolated signal;
The extrapolation signal generation unit generates a value of each pixel position in the extrapolated image based on the value of the input image at a symmetrical position across a boundary line connecting the boundaries of the input image. The signal processing apparatus as described. The extrapolation signal generation unit calculates a value of each pixel position in the extrapolated image based on pixel values of pixels around a symmetric position with a boundary position sandwiched with respect to the pixel position. Signal processing equipment. 5. The signal processing device according to claim 1, wherein the extrapolation signal generation unit generates an extrapolation signal that is at least longer than a signal length corresponding to a coefficient length of the filter unit. A signal processing apparatus for filtering a one-dimensional input signal having a boundary where a part of the signal is not continuous and the end is interrupted ,
A one-dimensional signal that complements an area outside in the input signal, outside the value of each position, a value obtained by inverting the value of the input signal around a boundary value at the position symmetrical with respect to the boundary position An extrapolation signal generator for generating an interpolation signal;
A signal adding unit that generates a correction signal by adding the extrapolation signal outside the region in the input signal;
A filter unit for filtering the correction signal;
An output unit that generates a signal obtained by cutting out a region corresponding to the input signal in the filtered correction signal, and outputs the generated signal as an output signal;
A signal processing apparatus comprising: An input unit for inputting a captured image obtained by imaging the inspection object;
The signal processing device according to any one of claims 1 to 5, wherein the correction signal to which the extrapolation signal is added outside the region of the inspection object is low-pass filtered.
A difference image generation unit that generates a difference image between the captured image and the low-pass filtered image;
A detection unit for analyzing the difference image and detecting a defect of the inspection object;
A defect detection apparatus comprising: A signal processing method for filtering a two-dimensional input signal representing an image of an inspection object having a boundary,
And generating, based the two-dimensional No. outer挿信to complement the region outside the region of the inspection object in the input signal to the input signal,
Generating a correction signal by adding the extrapolation signal outside the region in the input signal;
Filtering the correction signal;
Generating and outputting an output signal obtained by cutting out a region corresponding to the input signal in the filtered correction signal, and
The outer interpolation signal is a signal for complementing the area outside in the input signal, the value of each position, the value of the input signal at the positions symmetrical with respect to the boundary position is peripheral portion of the object A signal processing method that is a value obtained by inverting the centering on the boundary value. A signal processing method for filtering a one-dimensional input signal having a boundary where a part of the signal is not continuous and the end is interrupted ,
A one-dimensional signal that complements an area outside in the input signal, outside the value of each position, a value obtained by inverting the value of the input signal around a boundary value at the position symmetrical with respect to the boundary position Generate the interpolated signal,
Generate a correction signal by adding the extrapolation signal outside the region in the input signal,
Filtering the correction signal;
A signal processing method for generating a signal obtained by cutting out a region corresponding to the input signal in the filtered correction signal, and outputting the generated signal as an output signal. Input a captured image of the inspected object,
According to the signal processing method of claim 8, low-pass filtering a region including the inspection object in the captured image as the input signal,
Generating a difference image between the captured image and the low-pass filtered image;
A defect detection method for detecting a defect of the inspection object by analyzing the difference image.   A program that causes a computer to function as the apparatus according to any one of claims 1 to 7.