JP4130848B2 - Pixel inspection method and pixel inspection apparatus - Google Patents

Description

  The present invention relates to a pixel inspection method and inspection apparatus for inspecting the quality of a state formed on the surface of an inspection object, and more specifically, a pattern defect or the like by comparing with reference data created in advance. The present invention relates to a pixel inspection method and an inspection apparatus for detecting a pixel.

  Generally, pads, wiring patterns, resists, and the like are formed on the surface of a printed board. The formation state of the pad, wiring pattern, and resist is usually inspected by an inspection apparatus. As an inspection apparatus for inspecting the formation state of the printed circuit board, for example, there is an apparatus described in Patent Document 1 below.

The inspection apparatus described in Patent Document 1 below first captures a plurality of reference patterns, and stores reference data including a luminance upper limit reference value and a luminance lower limit reference value for each pixel of each reference pattern. . When inspecting the inspection object, first, after inspecting the image of the inspection pattern and accurately aligning with the image of the reference pattern, the luminance value of each pixel of the inspection image data is the luminance upper limit reference value of the reference data And whether it is within the range of the luminance lower limit reference value. When the pixel exceeds the reference range, it is determined that the pixel is a defect candidate pixel.
Japanese Patent Laid-Open No. 11-073513

  However, when the surface formation state is inspected using such an inspection apparatus, there are the following problems. That is, as described above, in the method of inspecting the reference pattern and the inspection pattern in correspondence with each other, each pattern must be precisely matched up to the pixel unit, and there is an optical deviation or a mechanical deviation. The case had the problem that false reports would increase. Further, if the resolution is increased in order to perform a precise inspection, it is further difficult to perform alignment in units of pixels, and there is a problem that the inspection accuracy is not improved even if the resolution is increased.

  Therefore, the present invention has been made paying attention to such a problem, and it is not necessary to perform exact alignment in pixel units, and even if there is an optical shift or a mechanical shift, a false report is made. It is an object of the present invention to provide a pixel inspection method and an inspection apparatus that do not cause the above-described problem.

In order to solve the above-mentioned problem, the present invention stores, in advance, an allowable luminance width and a search distance for searching for a corresponding pixel around the pixel position of the inspection object for each pixel of the reference object. A pixel inspection method for inspecting pass / fail of each pixel using the stored allowable luminance width and the search distance, wherein the pixel position of the inspection object corresponding to the pixel position of the reference object is the center. It is determined whether or not there is a pixel within the first allowable luminance width within the first search distance, and the second centered on the pixel position of the reference object corresponding to the pixel position of the inspection object Determining whether there is a pixel within the second allowable luminance width within the search distance, and that there is a pixel within the first allowable luminance width within the first search distance; and Within the search distance The condition that the pixels within the allowable luminance range is present, in which so as to determine the good pixels the pixels corresponding to the pixel position of the reference object.

In this way, it is not necessary to precisely align the reference object and the inspection object to the pixel unit as in the past, and even if the resolution is increased, optical deviations and mechanical deviations are absorbed. It becomes possible to perform inspection with high accuracy. Normally, when only the corresponding pixel of the inspection object is searched based on the reference object, even if an abnormal pixel exists on the inspection object side, the pixel may not be referred to. However, not only based on the reference object, but also on the contrary, the corresponding pixel of the reference object is also searched based on the inspection object, so that the inspection omission of each pixel is eliminated.

  Furthermore, in another invention, the correction process which makes the image of a test object correspond to a reference | standard object is performed before performing the quality determination of such a pixel.

  As an aspect of this correction processing, for example, correction for expanding / contracting an image of an inspection object such as a printed circuit board, correction for rotating an image of the inspection object, or correction for parallel movement, or a predetermined inspection object There are corrections such that the image in the rectangular area substantially matches the corresponding rectangular area of the reference object.

  If such correction processing is performed, the corresponding pixel within the narrow search distance should be found where the search pixel should be found by extending the search distance to the position of the image of the inspection object that has been shifted before correction. Will be able to find out. Further, by narrowing the search distance in this way, it is possible to reduce false information caused by the coincidence of luminance in irrelevant pixels.

According to the present invention, it is not necessary to precisely align the reference object and the inspection object to the pixel unit, and even if the resolution is increased, the optical object and the mechanical object can be absorbed to perform an accurate inspection. Will be able to do. Also, usually, when only the corresponding pixel of the inspection object is searched based on the reference object, even if an abnormal pixel exists on the inspection object side, the pixel may not be referred to. In addition to using the reference object as a base, the corresponding pixel of the reference object is also searched based on the inspection object, so that the inspection omission of each pixel is eliminated.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an outline of the pixel determination process in the present embodiment, and shows an example of determining the presence or absence of a corresponding pixel of the inspection object 11 based on the image of the reference object 10. is there. FIG. 2 shows a functional block diagram of the inspection apparatus 1 according to the present embodiment. FIGS. 3 and 4 show a correction process for the entire image of the inspection object 11 and the rectangular area image by the correction processing means 6. This is an example. FIG. 5 shows a flow of generating reference data in this inspection method, and FIG. 6 shows a flow of inspection processing.

  The inspection apparatus 1 in this embodiment includes an imaging unit 2 that captures a surface image of an inspection object 11 such as a printed circuit board, and a storage unit 5 that stores reference data of the reference object 10. When determining the quality of each pixel of the inspection object 11, first, correction processing is performed so that the image of the imaged inspection object 11 substantially matches the image of the reference object 10. When determining the quality of each pixel of the inspection object 11 subjected to the correction process, first, the pixel position of the inspection object 11 corresponding to each pixel position of the reference object 10 is specified, and the pixel position is the center. It is determined whether there is a pixel within the allowable luminance width within the first search distance. Also, conversely, within the allowable luminance width within the second search distance centered on the pixel position of the reference object 10 (that is, the original pixel position) corresponding to the pixel position of the inspection object 11. It is determined whether a pixel exists. When pixels included in the allowable luminance width exist within each search distance, the pixel existing at the pixel position of the reference object is determined as a good pixel. Hereinafter, a specific configuration of the inspection apparatus 1 will be described in detail.

  As shown in FIG. 2, the pixel inspection apparatus 1 includes an imaging unit 2, a preprocessing unit 3, an image memory 30, a reference data generation unit 4, a storage unit 5, a correction processing unit 6, a pixel determination unit 7, a cluster determination. Means 8 and output means 9 are provided.

  The imaging unit 2 captures a surface image of the reference object 10 or the inspection object 11 at the time of inspection. In this embodiment, the surface image is acquired with 256 gray scales. The image pickup means 2 includes an irradiation device that irradiates light from an oblique direction, a CCD camera that acquires reflected light from directly above, and the like. The reference object 10 is used to generate data (reference data) that serves as a reference when inspecting the inspection object 11, and has already been determined to be non-defective by visual inspection or other inspection devices. It is.

  The preprocessing unit 3 performs A / D conversion on the image of the reference object 10 or the inspection object 11 captured by the imaging unit 2 and stores the image in the image memory 30.

  The reference data generation unit 4 generates reference data from the image of the reference object 10 captured by the imaging unit 2. This reference data includes data relating to the entire shape of the reference object 10, data relating to a plurality of rectangular areas inside the reference object 10, and data relating to pixels. The data related to the overall shape is data such as the length and width of the printed circuit board, the data related to the rectangular area is data such as the pattern image in the rectangular area, and the data related to each pixel is the brightness and tolerance of the pixel. Data such as luminance width and search distance. Among the data regarding this pixel, the allowable luminance width indicates a difference between the upper limit value and the lower limit value of the luminance of the pixel to be inspected, and the search distance is within the allowable luminance width with a predetermined pixel position as the center. It indicates the distance to search for pixels. The allowable luminance width and the search distance are set for each pixel. For example, the allowable luminance width is set to be large for a portion where the luminance change is large, such as a silk edge, a pad edge, or a wiring pattern edge. Similarly, for the search distance, the search distance is set to be large for a portion where the luminance change is large, such as a silk edge, a pad edge, or a wiring pattern edge. These allowable luminance widths and search distances are automatically set. An upper limit value of the allowable luminance width and search distance is set manually in advance, and the standard deviation of each pixel of the plurality of reference objects 10 is set. To be determined. Specifically, for a portion where there is almost no luminance change, the allowable luminance width is set to ± 10 and the search distance is set to 1 pixel, and for a portion where the luminance change is large, the allowable luminance width is ± 30 and the search distance is 3 Set as pixel. The allowable luminance width and the search distance are not limited to these values.

  The storage unit 5 stores the reference data generated by the reference data generation unit 4.

The correction processing unit 6 performs correction processing for making the image of the inspection object 11 imaged by the imaging unit 2 substantially coincide with the reference object 10. An example of the correction of the entire image in this correction processing is shown in FIG. In FIG. 3, a solid line portion shaded with diagonal lines indicates the reference object 10, and a broken line indicates the inspection object 11. As shown in FIG. 3, when the inspection object 11 is smaller than the reference object 10 (FIG. 3A), correction processing is performed to enlarge the entire shape by δ _x and δ _y . Also, if the inspection object 11 is rotated by also [delta] _theta than reference object 10 performs correction processing as rotated by that angle. Further, when the inspection object 11 is displaced in parallel with the reference object 10, a correction process is performed in which the inspection object 11 is translated by the amount of the displacement. These correction processes are effective when, for example, the inspection object 11 is not fixed at a regular position on the stage, or when there is an error in the dimensions of the inspection object 11.

  Next, another aspect of this correction processing is shown in FIG. FIG. 4A shows an example of a rectangular area where the reference object 10 is located, and FIG. 4B shows a rectangular area at the same position of the inspection object 11. In an actual product, as shown in FIG. 4B, the pad or wiring pattern of the inspection object 11 may be displaced in a predetermined direction from the pad or wiring pattern of the reference object 10 or the like. In such a case, the parallel movement correction process is performed so that the image in the rectangular area of the inspection object 11 substantially matches the reference object 10. By performing these correction processes, the pad and the wiring pattern of the inspection object 11 substantially coincide with the pad and the wiring pattern of the reference object 10, and the allowable luminance can be obtained without increasing the search distance too much. A corresponding pixel within the width can be found. That is, originally, it is possible to find a corresponding pixel with a narrow search distance where the search pixel must be found by extending the search distance to the corresponding position of the image before correction. By narrowing the search distance in this way, it is possible to prevent an irrelevant pixel that happens to have the same brightness to be determined as a “corresponding pixel”.

  The pixel determination means 7 determines whether or not a pixel corresponding to each pixel position of the reference object 10 exists in the inspection object 11. The first pixel determination means 70 and the second pixel determination means 70 are as follows. The pixel determination means 71 is provided.

  First, the first pixel determination means 70 specifies the pixel position of the inspection object 11 corresponding to each pixel position of the reference object 10 based on the reference object 10 and searches centering on this pixel position. It is determined whether or not there is a pixel within the allowable luminance width with respect to the luminance of the pixel of the reference object 10 within the distance. In this determination, if there is even one pixel within the allowable luminance width within the search distance, it is determined as “good pixel”, and conversely, when no pixel within the allowable luminance width exists within the search distance. Are determined to be “bad pixels”. In general, if the reference object 10 and the inspection object 11 are completely matched by the correction processing means 6, the pixel existing at the position of the inspection object 11 corresponding to the pixel position of the reference object 10 may be inspected. . However, in reality, there are optical shifts and mechanical shifts, so that it is difficult to make them completely coincide with each other, and when the resolution is increased, there is a possibility that the shift is several pixels. For this reason, if there is an almost identical luminance within the search distance, it is determined as “good pixel” as a primary determination. The determination result by the first pixel determination means 70 is visually displayed on a display device or the like. For example, in the portion determined as “defective pixel”, an “x” mark or the like is displayed on the image of the reference object 10. Indicates.

  In contrast, the second pixel determination unit 71, on the contrary, allows the luminance of the pixel of the inspection object 11 to be within a search distance centered on the pixel position of the reference object 10 based on the inspection object 11. It is determined whether there is a pixel within the luminance width. Also in this determination, if there is even one pixel within the allowable luminance width within the search distance, it is determined as “good pixel”, and conversely, there is no pixel within the allowable luminance width within the search distance. Are determined to be “bad pixels”. When the determination process based on the inspection object 11 is performed, an image of the inspection object 11 after the above-described correction process is used. Then, the pixel position of the reference object 10 corresponding to the position (the center position of the first search distance) of the inspection object 11 after the correction process is specified, and the allowable luminance width / search distance at the pixel position is determined. It is read out from the storage means 5 and it is determined whether or not a pixel within the allowable luminance width with respect to the luminance of the inspection object 11 exists on the reference object 10 within the search distance. Normally, if the reference processing object 10 and the inspection object 11 can be completely matched by the correction processing means 6, only the pixel existing at the position of the inspection object 11 corresponding to the pixel position of the reference object 10 is inspected. good. However, in reality, there are optical shifts and mechanical shifts, so that it is difficult to make them completely coincide with each other, and when the resolution is increased, there is a possibility that the shift is several pixels. For this reason, if there is a pixel having substantially the same luminance within the search distance, it is determined as “good pixel” as a secondary determination. Similar to the first determination result, the second determination result is visually displayed on the display device, overwritten on the determination image by the first pixel determination means 70, and determined as a “bad pixel”. An “x” mark or the like is shown in the part.

  Finally, the pixel determination means 7 indicates that there is at least one pixel within the allowable luminance width within the search distance of the inspection object 11, and within the allowable luminance width within the search distance of the reference object 10. On the condition that at least one pixel exists, the pixel existing at the pixel position of the reference object 10 is determined as a good pixel. Conversely, when there is no pixel within the allowable luminance width within the search distance of the inspection object 11, or when there is no pixel within the allowable luminance width within the search distance of the reference object 10, A pixel present at the pixel position of the reference object 10 is determined as a defective pixel.

  Based on the size of the pixel group of the reference object 10 determined as “defective pixel” by the pixel determining means 7, the cluster determining means 8 determines whether or not the inspection object 11 is a defective product as a whole. judge. This pass / fail determination is determined as a defective product when there are a predetermined number or more of adjacent pixels determined as “defective pixels”.

  The output means 9 outputs the determination result by the cluster determination means 8 so that it can be notified. At this time, since it is necessary to inform the user which part is a defective cluster, the position of the cluster determined to be a defective cluster by the cluster determination means 8 is visually output to the display device.

  Next, a method for inspecting the inspection object 11 using the inspection apparatus 1 configured as described above will be described.

  <Standard data generation flow>

  First, FIG. 5 shows a flowchart for generating reference data when inspecting the inspection object 11. When generating reference data, first, a plurality of reference objects 10 prepared in advance are set on a stage (not shown) of the inspection apparatus 1 and an image of the surface is acquired using the imaging means 2 (step S1). ). When a predetermined number or more of images of the reference object 10 are captured, data relating to the entire area, data relating to the rectangular area, and data relating to pixels are generated for each reference object 10 (step S2), and a plurality of reference objects are generated. For the object 10, an average value of data relating to the entire area, an average value of data relating to the rectangular area, an average value of data relating to pixels, a standard deviation value, and the like are calculated (step S3). Next, the upper limit value of the allowable luminance width and the upper limit value of the search distance are manually input (step S4). This input may be input in advance before step S1 instead of this step.

  Then, after the calculation of the average value and the standard deviation value in step S3, for the pixel having the largest standard deviation value, the upper limit value of the allowable luminance width and the upper limit value of the search distance that are input previously are set. For a pixel having a small standard deviation value, the allowable luminance width and the search distance are set small (step S5). Then, the set data is stored in the storage means 5 as reference data (step S6).

  <Inspection flow of inspection object 11>

  Next, a flowchart for inspecting the inspection object 11 is shown in FIG. First, when inspecting the inspection object 11, the inspection object 11 is set on the stage of the inspection apparatus 1, and an image of the surface is acquired using the imaging means 2 (step T <b> 1). This captured image may be misaligned depending on how it is set on the stage, and may be different from the state of the image of the reference object 10 stored in the storage unit 5. . Therefore, correction processing is performed to make the image states substantially coincide (step T2). In this correction process, first, the entire shape is corrected. Specifically, three corner points on the inspection object 11 are extracted, and the vertical and horizontal lengths, rotation angles, parallel movement distances, and the like of the inspection object 11 are calculated from the three points. Then, based on these vertical and horizontal lengths, rotation angles, parallel movement distances, etc., correction processing is performed so that the entire image of the inspection object 11 substantially matches the entire image of the reference data.

  Next, a rectangular area correction process is performed. When this rectangular area correction processing is performed, the image of the inspection object 11 is translated so that the image of the predetermined rectangular area of the reference object 10 and the image of the corresponding rectangular area of the inspection object 11 substantially coincide. .

  And after these correction processes are complete | finished, it is determined whether the pixel which exists in each position of the reference | standard object 10 is a good pixel. In this determination, first, the position, luminance, allowable luminance width, and search distance of each pixel of the reference object 10 are read from the storage means 5 (step T3). Then, the pixel position of the inspection object 11 corresponding to the read pixel position is specified, and within the allowable luminance width with respect to the luminance of the pixel of the reference object 10 within the search distance around the pixel position. It is determined whether there is a luminance pixel (step T4). This determination is performed by the first pixel determination means 70. Here, when no pixel within the allowable luminance width exists within the search distance, the pixel at the pixel position of the reference object 10 is determined as a “bad pixel” (step T8).

  Next, after the first pixel determination is completed, the pixel of the reference object 10 corresponding to the pixel position of the inspection object 11 is based on the image of the inspection object 11 after the correction process. It is determined whether or not there is a pixel within the allowable luminance width within the search distance centered on the position. However, for each pixel of the inspection object 11, data such as an allowable luminance width and a search distance is not stored, and therefore the allowable luminance width of the pixel position of the reference object 10 corresponding to the pixel position of the inspection object 11. Or search distance. Specifically, first, an allowable luminance width and a search distance of the pixel position of the reference object 10 corresponding to the pixel position of the inspection object 11 are read (step T5). Based on the read allowable luminance width and the search distance, pixels within the allowable luminance width with respect to the luminance of the inspection object 11 exist within the search distance with the pixel position of the corresponding reference object 10 as the center. It is determined whether or not to perform (step T6). This determination is performed by the second pixel determination unit 71. If there is no luminance pixel within the allowable luminance width within the search distance, the pixel at the pixel position of the reference object 10 is determined as a “bad pixel”. (Step T8).

  On the other hand, when it is determined as “good pixel” in step T4 and “good pixel” is determined in step T6, the pixel corresponding to the pixel position of the reference object 10 is determined as “good pixel” (step T7). ).

  If all the pixels have been inspected (step T9; Yes), the number of adjacent defective pixels among the pixels of the reference object 10 determined as “defective pixels” by the pixel determining means 7 is next. When there are more than a predetermined number of defective pixels (step T10), the inspection object 11 outputs that it is a defective product (step T11), while the number of all adjacent defective pixels Is less than the predetermined number, an output indicating that the product is non-defective is output (step T12).

  As described above, according to the embodiment, for each pixel of the reference object 10, the allowable luminance width and the search distance for searching the corresponding pixel of the inspection object 11 with the pixel position as the center are stored in advance. When determining the quality of each pixel of the inspection object 11, the first search distance within the first search distance centered on the pixel position of the inspection object 11 corresponding to each pixel position of the reference object 10 is used. Since it is determined whether or not there is a pixel within the allowable luminance range, it is not necessary to accurately align the reference object and the inspection object to the pixel unit as in the past, and even if the resolution is increased, it is optical. This makes it possible to perform inspections with high accuracy by absorbing mechanical deviations and mechanical deviations.

  Further, when performing the inspection in this way, conversely, within the search distance centered on the pixel position of the reference object 10 corresponding to the pixel position of the inspection object 11, the luminance of the inspection object 11 is reversed. It is determined whether or not there is a pixel within the allowable luminance width. If there is a pixel within the allowable luminance width within the search distance, the pixel corresponding to the pixel position of the reference object 10 is determined to be good. Since it is determined as a pixel, it is possible to eliminate an inspection omission for each pixel of the inspection object 11 and to perform an inspection with high accuracy.

  Further, before such pixel determination is performed, the entire shape of the inspection object 11 is corrected, and the correction process for each rectangular area is performed to convert the image of the inspection object 11 into the image of the reference object 10. Since it was made to almost match, the corresponding pixel within the narrow search distance should be found where the search distance should be found by expanding the search distance to the position of the image of the inspection object shifted before correction. You will be able to find out. By narrowing the search distance in this way, it is possible to prevent the occurrence of false information due to the coincidence of luminance in irrelevant pixels.

  In addition, this invention is not limited to the said embodiment, It can implement in a various aspect.

  For example, in the above-described embodiment, the printed circuit board has been described as an example of the inspection object 11. However, the present invention is not limited thereto, and liquid crystal panels, characters, figures, symbols, and the like attached to the surface of the article are inspection objects. Also good.

  In the above embodiment, the first search distance and the second search distance, and the first allowable luminance width and the second allowable luminance width are set to the same value. Different values may be set.

  Furthermore, in the above embodiment, the allowable luminance width and the search distance are set for each pixel, but all may be set to a common allowable luminance width and search distance. In the above embodiment, the first allowable luminance width and the first search distance are described separately from the second allowable luminance width and the second search distance, but these are the same. May be.

  In addition, in the above-described embodiment, the correction processing means 6 performs the correction process for the entire shape and the correction process for each rectangular area. However, the present invention is not limited to this, and the inspection object 11 and the reference object 10 Any correction processing method may be used as long as the positions are substantially matched. In the above description, correction processing for a rectangular area is given as an example of correction processing for each area. However, the correction processing is not necessarily limited to a rectangular area, and correction processing for various areas may be performed.

The figure which shows the outline | summary of the inspection processing method in one embodiment of this invention Functional block diagram of the inspection apparatus in the same form The figure which shows the outline | summary of the process of the whole correction | amendment in the same form The figure which shows the outline | summary of the process of correction | amendment of the rectangular area in the same form The figure which shows the production | generation flow of the reference data in the form The figure which shows the flow of the inspection process in the same form

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Inspection apparatus 2 ... Imaging means 3 ... Pre-processing means 4 ... Reference data generation means 5 ... Storage means 6 ... Correction processing means 7 ... Pixel determination means 8 ... Cluster determination means 9 ... output means 10 ... reference object 11 ... inspection object 70 ... first pixel determination means 71 ... second pixel determination means

Claims (4)

For each pixel of the reference object, an allowable luminance width and a search distance for searching for a corresponding pixel centered on the pixel position of the inspection object are stored in advance, and the stored allowable luminance width and the search are stored. A pixel inspection method for inspecting the quality of each pixel using a distance,
It is determined whether there is a pixel within a first allowable luminance width within a first search distance centered on the pixel position of the inspection object corresponding to the pixel position of the reference object, and the inspection object It is determined whether there is a pixel within the second allowable luminance width within the second search distance centered on the pixel position of the reference object corresponding to the pixel position of the object, and within the first search distance Corresponding to the pixel position of the reference object provided that there is a pixel within the first allowable luminance width and that there is a pixel within the second allowable luminance width within the second search distance. A pixel inspection method in which a pixel is determined to be a good pixel. For each pixel of the reference object, an allowable luminance width and a search distance for searching for a corresponding pixel centered on the pixel position of the inspection object are stored in advance, and the stored allowable luminance width and the search are stored. A pixel inspection method for inspecting the quality of each pixel using a distance,
The image of the inspection object is corrected in correspondence with the reference object, and the first search distance is centered on the pixel position of the inspection object after the correction processing corresponding to the pixel position of the reference object. It is determined whether or not there is a pixel within the allowable luminance width, and the second is within a second search distance centered on the pixel position of the reference object corresponding to the pixel position of the inspection object after the correction process. Determine whether there is a pixel within the allowable brightness range, and that there is a pixel within the first allowable brightness range within the first search distance, and a second within the second search distance. A pixel inspection method in which a pixel corresponding to a pixel position of the reference object is determined as a good pixel on condition that a pixel within an allowable luminance width exists. Imaging means for imaging the inspection object, storage means for storing a permissible luminance width in advance for each pixel of the reference object, and a search distance for searching for a corresponding pixel around the pixel position of the inspection object; A pixel inspection apparatus comprising: a pixel determination unit that inspects pass / fail of each pixel using a stored allowable luminance width and a search distance, wherein the pixel determination unit includes:
First pixel determination for determining whether or not there is a pixel within a first allowable luminance width within a first search distance centered on the pixel position of the inspection object corresponding to the pixel position of the reference object Means,
Second pixel determination for determining whether a pixel within a second allowable luminance width exists within a second search distance centered on the pixel position of the reference object corresponding to the pixel position of the inspection object With means,
When the first pixel determination unit and the second pixel determination unit determine that there is a pixel within each allowable luminance width within each search distance, a pixel corresponding to the pixel position of the reference object is determined. A pixel inspection device for determining a good pixel. Imaging means for imaging the inspection object, and storage means for storing in advance a permissible luminance width and a search distance for searching for a corresponding pixel around the pixel position of the inspection object for each pixel of the reference object Correction processing means for correcting the image of the inspection object in correspondence with the reference object, pixel determination means for inspecting pass / fail of each pixel using the allowable luminance width and the search distance stored in the storage means, A pixel inspection apparatus comprising:
It is determined whether or not there is a pixel within the first allowable luminance width within a first search distance centered on the pixel position of the inspection object after the correction processing corresponding to the pixel position of the reference object. A pixel determination means;
A first determination is made as to whether or not there is a pixel within the second allowable luminance width within a second search distance centered on the pixel position of the reference object corresponding to the pixel position of the inspection object after the correction process. Two pixel determination means,
When the first pixel determination unit and the second pixel determination unit determine that there is a pixel within each allowable luminance width within each search distance, a pixel corresponding to the pixel position of the reference object is determined. A pixel inspection device for determining a good pixel.

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