JP2009222399A - Image gain adjusting device and method, and three-dimensional shape measuring instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problems wherein halation and dark-area-gradation deterioration have occurred, when a dynamic range within the same visual field of an image to be taken has exceeded that of an imaging section conventionally. <P>SOLUTION: An image gain adjusting device controls the gain of each pixel in an image to be taken. The image gain adjusting device includes: an image photographing section for photographing an image by a designated gain; a luminance value discrimination section for discriminating whether the luminance value of each pixel in an image taken by the image photographing section is within a prescribed preset range; and a gain setting section for repeating a series of operation for photographing an image by the image photographing section until the discrimination results of the luminance value discrimination section of all pixels is within a prescribed range by setting the gain in photographing to be the gain of the pixel concerned when the luminance value of each pixel is within a prescribed range and designating a gain in a direction so that the luminance value of the pixel concerned is within a prescribed range, when the luminance value of each pixel is outside a prescribed range. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a gain adjustment technique for capturing an image composed of a plurality of pixels.

  In general, in the inspection process of industrial products, a non-defective product or a defective product is determined by measuring the three-dimensional shape of the product. For example, when inspecting metal parts, it is necessary to inspect various surface patterns, reflectances, shapes, and the like.

Three-dimensional shape measurement methods include a passive measurement method and an active measurement method. As a passive measurement method, for example, there is an SFF (Shape From Focus) method, and a three-dimensional shape is obtained from a change in captured texture. As an active measurement method, for example, there is a pattern projection method. A plurality of images are photographed by projecting light of different phases, and a three-dimensional shape is obtained from a change in phase between the images. Alternatively, a technique of measuring a three-dimensional shape at a time by projecting a fringe pattern having a sinusoidal intensity distribution is also considered (for example, see Patent Document 1).
JP 2005-308439 A

  However, in any of the passive measurement method and the active measurement method, a measurement sensor (for example, a CCD sensor or a CMOS sensor) having a sufficient dynamic range is used in the imaging unit in order to realize highly accurate measurement. There must be. However, a measurement sensor with a wide dynamic range is expensive, and there is a problem that the price of the measurement device increases. Conversely, an inexpensive sensor has a problem that the dynamic range is narrow and the measurement accuracy is deteriorated.

  Further, even when an expensive measurement sensor having a wide dynamic range is used, there is a problem that measurement cannot be performed when the dynamic range allowed by the sensor is exceeded. In this case, it is conceivable to change the shooting conditions so as to be within the dynamic range, but when the brightness difference in the luminance within the same visual field is large, all the pixels included in the same visual field are within the dynamic range of the sensor. There may also be cases where there are no conditions to fit.

  An object of the present invention is to provide an image gain adjusting apparatus and method and a three-dimensional shape measuring apparatus capable of photographing without overexposure or blackout even when the dynamic range of the image to be photographed in the same visual field exceeds the dynamic range of the imaging unit. Is to provide.

  An image gain adjusting apparatus according to the present invention is an image gain adjusting apparatus that controls a gain for each pixel of an image to be captured, and includes an image capturing unit that captures an image with a specified gain and the image capturing unit. A luminance value discriminating unit that discriminates whether or not the luminance value of each pixel of the image is within a predetermined range, and when the luminance value of each pixel is within the predetermined range, the gain at the time of shooting is set to the gain of the pixel If the luminance value of each pixel is outside the predetermined range, a series of operations for capturing an image with the image capturing unit by specifying a gain in a direction in which the luminance value of the pixel is within the predetermined range is performed for all pixels. And a gain setting unit that repeats until the determination result of the luminance value determination unit falls within a predetermined range.

  The three-dimensional shape measuring apparatus according to the present invention measures a three-dimensional shape using an image photographed by the image photographing unit using a gain for each pixel set by the gain setting unit in the image gain adjusting device. It has a measuring part.

  An image gain adjustment method according to the present invention is an image gain adjustment method for controlling the gain of each pixel of an image to be captured, the image capturing procedure for capturing an image with a specified gain, and the image capturing procedure. A luminance value determination procedure for determining whether or not the luminance value of each pixel of the image is within a predetermined range, and if the luminance value of each pixel is within the predetermined range, the gain at the time of shooting is set to the gain of the pixel When the brightness value of each pixel is outside the predetermined range, a series of operations for capturing an image in the image capturing procedure by specifying a gain in a direction in which the brightness value of the pixel is within the predetermined range is performed for all pixels. And a gain setting procedure that is repeated until the determination result of the luminance value determination procedure falls within a predetermined range.

  According to the present invention, even when the dynamic range within the same visual field of the image to be captured exceeds the dynamic range of the imaging unit, it is possible to capture an image without whiteout or blackout.

  Embodiments relating to an image gain adjusting apparatus and method and a three-dimensional shape measuring apparatus according to the present invention will be described below.

(First embodiment)
The three-dimensional shape measuring apparatus 100 according to the first embodiment is an apparatus that uses the image gain adjusting apparatus and method according to the present invention.
<Configuration of the three-dimensional shape measuring apparatus 100>
FIG. 1 is an explanatory diagram illustrating a configuration of a three-dimensional shape measuring apparatus 100 according to the first embodiment. The three-dimensional shape measuring apparatus 100 includes a stage 101 on which the inspection object SA is placed, a pattern projection mechanism 102 that projects a predetermined pattern (for example, a grid pattern arranged in black and white in one direction) toward the stage 101, and an imaging mechanism. 103 and a personal computer (personal computer) 104 that performs control of the entire three-dimensional shape measuring apparatus 100, calculation for measuring a three-dimensional shape, display of measurement results, storage of image data, and the like.

  The personal computer 104 includes a main body 104a, a monitor 104b, and a keyboard 104c. The pattern projection mechanism 102 includes a light source 102a, a liquid crystal plate 102b, and a projection optical system 102c. Furthermore, the imaging mechanism 103 includes an imaging unit 103a and an imaging optical system 103b.

  In FIG. 1, a projection control device 105 is connected between the main body 104 a of the personal computer 104 and the pattern projection mechanism 102. The projection control device 105 adjusts the light amount of the light source 102a in accordance with a command from the personal computer 104, displays a predetermined pattern on the liquid crystal plate 102b, and projects it onto the inspection object SA. For example, when the predetermined pattern is a lattice pattern, the projection control device 105 changes the phase of the lattice pattern displayed on the liquid crystal plate 102b and projects it onto the inspection object SA.

  An imaging control device 106 is connected between the main body 104 a of the personal computer 104 and the imaging mechanism 103. The imaging control device 106 inputs an image signal photoelectrically converted by the imaging unit 103 a in response to a command from the personal computer 104, performs gain adjustment, color correction processing, and the like, and outputs image data to the personal computer 104.

  A stage control device 108 is connected between the main body 104 a of the personal computer 104 and the stage mechanism 107. The stage control device 108 controls the stage mechanism 107 in accordance with a command from the personal computer 104. The stage mechanism 107 has a drive unit for moving the stage 101 on which the inspection object SA is placed in a three-dimensional direction (horizontal direction or vertical direction) with respect to the imaging mechanism 103.

  The pattern projection mechanism 102 emits illumination light from the light source 102a, transmits the illumination light parallel to the optical axis direction to the liquid crystal plate 102b, and projects it onto the inspection object SA. The projection optical system 102c that projects the light transmitted through the liquid crystal plate 102b onto the inspection object SA is configured by a combination of a plurality of lenses.

  In response to a command from the personal computer, the projection control device 105 scans the inspection object SA by shifting the phase of the lattice pattern displayed on the liquid crystal plate 102b by every π / 2, for example. Note that the liquid crystal plate 102b may be in a totally transmissive state and project the light emitted from the light source 102a directly onto the inspection object SA. In this case, the uniform illumination light from the light source 102a is irradiated to the inspection object SA from an oblique direction.

  The imaging mechanism 103 forms an image of the lattice pattern light reflected from the inspection object SA on the light receiving surface of the imaging unit 103a by the imaging optical system 103b. The imaging unit 103a is configured by a CCD type or CMOS type image sensor having a plurality of pixels arranged two-dimensionally on the light receiving surface. The gain of the image captured by the imaging unit 103 a is adjusted by the imaging control device 106. Here, the gain adjustment is performed by adjusting the luminance value of the image signal output from the imaging unit 103a with a gain set for each pixel from the personal computer 104. If all the pixels are set to the same gain, the entire image can be taken with the same gain.

  In this way, the image captured by the imaging unit 103 a is output to the main body 104 a of the personal computer 104 after gain adjustment, color correction processing, and the like are performed by the imaging control device 106. In the personal computer 104, application software for three-dimensional shape measurement is activated, and the image data input from the imaging control device 106 is analyzed to obtain the three-dimensional shape of the inspection object SA and displayed on the monitor 104b. Alternatively, it is stored in a memory or hard disk built in the main body 104a. The observer operates the three-dimensional shape measuring apparatus 100 using the keyboard 104c while looking at the screen of the monitor 104b of the personal computer 104.

In the present embodiment, the pattern projection method and the SFF method can be selected and used by application software activated on the personal computer 104.
<Measuring method of 3D shape>
Next, a three-dimensional shape measurement method using the pattern projection method and the SFF method will be described.
(Measurement of 3D shape by pattern projection)
In the case of a pattern projection method called a phase shift method, the personal computer 104 instructs the projection control device 105 to shift the phase of the lattice pattern displayed on the liquid crystal plate 102b and project it onto the inspection object SA. The light of the lattice pattern projected onto the inspection object SA on the stage 101 changes to a black and white striped pattern on the inspection object SA. The reflected light of the lattice pattern reflected by the inspection object SA is imaged on the light receiving surface of the imaging unit 103 a by the imaging optical system 103 b of the imaging mechanism 103. The reflected light is photoelectrically converted by the imaging unit 103 a, gain adjusted by the imaging control device 106, and output to the personal computer 104. The image output to the personal computer 104 is a lattice pattern image deformed by the shape of the inspection object SA. Similarly, the phase of the grating pattern displayed on the liquid crystal plate 102b is shifted by π / 2 and projected onto the inspection object SA, and the reflected light of the grating pattern deformed according to the shape of the inspection object SA is output for each phase. The image is taken by the imaging unit 103a. A plurality of pieces of image data captured for each lattice pattern having different phases in this manner are temporarily stored in the memory of the main body 104a of the personal computer 104 or the hard disk. Phase connection is performed from the plurality of pieces of image data, and information on the height direction of the inspection object SA is calculated to obtain the three-dimensional shape of the inspection object SA. Note that the three-dimensional shape measurement method using the phase shift method is a well-known technique and will not be described in detail. However, a plurality of images to be photographed by shifting the phase of the lattice pattern are images that are not blacked out or blown out. It is desirable. For example, when black crushing or whiteout occurs, the phase connection process cannot be performed accurately, and an incorrect three-dimensional shape is measured.
(Measurement of three-dimensional shape by SFF method)
In the case of the SFF method, the personal computer 104 instructs the projection control device 105 to bring the liquid crystal plate 102 b into a totally transmissive state, and projects light onto the inspection object SA on the stage 101. The light reflected by the inspection object SA is imaged on the light receiving surface of the imaging unit 103 a by the imaging optical system 103 b of the imaging mechanism 103. The reflected light is photoelectrically converted by the imaging unit 103 a, gain adjusted by the imaging control device 106, and output to the personal computer 104. The image output to the personal computer 104 is an image of the inspection object SA, but since the inspection object SA has a three-dimensional shape, the focal position differs depending on its height. In the SFF method, the photographing optical system 103b is set to have a shallow depth of field so that the resolution in the height direction is high. The software for three-dimensional shape measurement by the SFF method activated on the personal computer 104 instructs the stage control device 108 to move the stage mechanism 107 up and down in the direction of the optical axis of the imaging optical system 103b, and for each part of the inspection object SA. The height of the stage 101 at which the reflected light is focused is obtained. Since the parts having the same height of the object SA to be inspected are focused at the same stage position, the stage position that is in focus for each part of the object SA to be inspected is determined for each stage position while raising and lowering the stage little by little. The contour lines of the inspection object SA can be drawn, and the three-dimensional shape of the inspection object SA can be obtained. In the case of the SFF method as well, it is desirable that the image to be captured is an image that does not have black crushing or whiteout. For example, when blackout or whiteout occurs, the focal position cannot be obtained accurately, and an incorrect three-dimensional shape is measured.
<Operation of the three-dimensional shape measuring apparatus 100>
Next, the operation of the three-dimensional shape measuring apparatus 100 according to this embodiment will be described. FIG. 2 is a block diagram of the three-dimensional shape measuring apparatus 100. In FIG. 2, the same reference numerals as those in FIG. The block diagram showing the configuration of the main body 104a of the personal computer 104 is functionally drawn including blocks processed by application software that performs three-dimensional shape measurement.

  First, referring to FIG. 2, the operation in the case of a fixed gain in which gain control is not performed by the imaging control device 106 will be described. The operation in this case corresponds to a three-dimensional shape measurement operation that is generally performed. In the main body 104a of the personal computer 104, it is assumed that application software for performing three-dimensional measurement is activated.

  The measurer places the inspection object SA on the stage 101 and inputs a measurement instruction command from the keyboard 104c. Receiving the measurement instruction from the keyboard 104c, the measurement unit 202 outputs an instruction to cause the projection control device 105 to emit the light source 102a and a pattern display instruction to the liquid crystal plate 102b. Next, the measurement unit 202 instructs the control unit 204 to perform shooting with a fixed gain. The control unit 204 that has received an imaging instruction from the measurement unit 202 instructs the imaging control device 106 to capture an image from the imaging unit 103a into the image memory 201 with a fixed gain. Upon receiving an image capturing instruction from the control unit 204, the imaging control device 106 amplifies the image input from the imaging unit 103a with a fixed gain, and captures the image into the image memory 201 of the main body 104a of the personal computer 104. Then, the measurement unit 202 reads the image taken into the image memory 201 and measures the three-dimensional shape of the inspection object SA using the pattern projection method or the SFF method described above. Note that the measurement unit 202 instructs the stage control device 108 as necessary to move the stage 101 and move the imaging position of the inspection object SA.

  Here, in order to make it easy to understand the characteristics of the three-dimensional shape measuring apparatus 100 according to the present embodiment, problems in the case of a fixed gain in which the imaging control apparatus 106 does not perform gain control will be described. In order to simplify the description, the pixel arrangement of the image taken by the imaging unit 103a is from P1, which is composed of four pixels in the horizontal direction X1 to X4 and four pixels in the vertical direction Y1 to Y4, as shown in FIG. It is assumed to be composed of 16 pixels of P16. In general, when shooting an image, the brightness of the entire image is determined and the gain at the time of shooting is determined.Therefore, in the pixel that receives extremely dark subject light or the pixel that receives extremely bright subject light, The dynamic range of 103a may be exceeded. An example of this will be described with reference to FIG. FIG. 4 is an explanatory diagram showing the luminance value for each pixel of the image captured by the 16-pixel imaging unit 103a described in FIG. In FIG. 4, the pixels (X3, Y2) are drawn as extremely dark pixels, and the pixels (X2, Y4) are drawn as extremely bright pixels. FIG. 4A illustrates an image when a pixel other than the pixel (X3, Y2) and the pixel (X2, Y4) is captured with an appropriate gain GA that falls within the dynamic range of the imaging unit 103a. In this case, extremely dark pixels (X3, Y2) are photographed while being blacked out, and extremely bright pixels (X2, Y4) are photographed in a state where whiteout has occurred.

  In this way, in the case of a fixed gain for which gain control is not performed by the imaging control device 106, a blacked out pixel or a whiteout pixel is generated, which affects the case where the measurement unit 202 obtains a three-dimensional shape, There is a problem that an accurate three-dimensional shape cannot be obtained. Therefore, the three-dimensional shape measuring apparatus 100 according to the present embodiment captures a measurement image by performing gain control with the imaging control device 106 so that each pixel of the image to be captured falls within the dynamic range of the imaging unit 103a. It is supposed to be.

  Next, the operation when gain control is performed by the imaging control device 106 will be described in detail with reference to FIG. FIG. 5 is a flowchart showing the operation of the application software of the three-dimensional shape measuring apparatus 100 according to this embodiment. In the main body 104a of the personal computer 104, application software for performing three-dimensional measurement is activated, the inspection object SA is placed on the stage 101, and the measurer has entered a measurement start command from the keyboard 104c. . Further, it is assumed that the gain GA in the case of FIG. 4A described above is set as the default value of the gain set by the gain setting unit 206 in the imaging control apparatus 106. Hereinafter, description will be made in order according to the flowchart of FIG.

  (Step S101) Upon receiving a measurement start command input from the keyboard 104c by the measurer, the three-dimensional shape measurement process is started.

  (Step S102) Gain setting of the imaging control apparatus 106 is performed. Specifically, the control unit 204 sets a default gain GA in the imaging control device 106 from the gain setting unit 206.

  (Step S103) An image is taken. Specifically, the control unit 204 instructs the imaging control device 106 to capture an image. Upon receiving an image capture command from the control unit 204, the image capture control device 106 amplifies the image input from the image capture unit 103a with a gain GA and captures the image in the image memory 201 of the main body 104a of the personal computer 104.

  (Step S <b> 104) The luminance value determination unit 205 determines whether the luminance value for each pixel of the image captured in the image memory 201 is within a predetermined range. For example, in the case of FIG. 4A described above, the luminance value determination unit 205 determines whether the luminance value is within a predetermined range for each of the 16 pixels from the pixel (X1, Y1) to the pixel (X4, Y4). Determine whether or not.

  Here, the predetermined range of the luminance value will be described. For example, when the gradation of a pixel is 8 bits in a monochrome image, the image is configured with luminance values from 0 (black side) to 255 (white side). At this time, the blacked out pixels are stuck to a value of 0, and the whiteout pixels are stuck to a value of 255. Therefore, for example, if a luminance value between 1 and 254 is set within a predetermined range, if the luminance value of the pixel is within this range, the image can be taken without being crushed or blown out white. In practice, it is preferable to set the predetermined range of the brightness value to 5 or more and 250 or less in consideration of fluctuation due to noise or the like. Here, it is assumed that the black threshold th1 that is determined to be crushed black is 4, and the white threshold th2 that is determined to be skipped is 251.

  (Step S105) The gain setting unit 206 sets the gain for each pixel in the gain table 207 based on the result determined in step S104. The gain table 207 is a table for storing the gain for each pixel. At the start of the operation, the gain values of all the pixels are reset and are in an undetermined state. For example, when the captured image is FIG. 4A, the luminance value of the pixel (X3, Y2) is 3, and the luminance value of the pixel (X2, Y4) is 253. The luminance values of the other pixels are Suppose that it was in the range of 5 or more and 250 or less. In this case, the determination result in step S104 is that the luminance values of the pixels other than the pixel (X3, Y2) and the pixel (X2, Y4) are within the predetermined range. GA is determined and set in the gain table 207. The state of the gain table 207 at this time is shown in FIG. The gain GA is set for pixels other than the pixels (X3, Y2) and the pixels (X2, Y4), and the gains of the pixels (X3, Y2) and the pixels (X2, Y4) are undetermined.

  (Step S106) It is determined whether or not the gains of all the pixels in the gain table 207 have been determined. If there is a pixel whose gain is undetermined, the process proceeds to step S107, and if there is no pixel whose gain is undetermined, the process proceeds to step S111.

  (Step S107) It is determined whether or not there is a pixel having a luminance value smaller than the black threshold th1. If there is a pixel having a luminance value smaller than the black threshold th1, the process proceeds to step S108. If there is no pixel having a luminance value smaller than the black threshold th1, the process proceeds to step S109.

  (Step S108) A gain larger than the current gain set in the imaging control device 106 is set. For example, since the current gain is the default gain GA, a larger gain GB is obtained. The gain GB is a gain at which a pixel having a luminance value smaller than the black threshold th1 has a luminance value larger than the black threshold th1. When the set gain is obtained, the process returns to step S102.

  For example, returning to step S102, the luminance value of the pixel (X3, Y2) of the image photographed with the gain GB falls within a predetermined range. Therefore, as shown in FIG. The gain of the pixels (X3, Y2) is determined as gain GB. At the time of FIG. 6B, the gain of the pixel (X2, Y4) is undetermined.

  (Step S109) It is determined whether or not there is a pixel having a luminance value greater than the white threshold th2. If there is a pixel with a luminance value greater than the white threshold th2, the process proceeds to step S110, and if there is no pixel with a luminance value greater than the white threshold th2, the process returns to step S102. Actually, since “No” is determined in Step S106, “No” is not determined in both Step S107 and Step S109.

  (Step S110) A gain smaller than the current gain set in the imaging control device 106 is set. For example, since the current gain is the default gain GA, a smaller gain GC is obtained. The gain GC is a gain at which a pixel having a luminance value larger than the white threshold th2 has a luminance value smaller than the white threshold th2. When the set gain is obtained, the process returns to step S102.

  For example, returning to step S102, the brightness value of the pixel (X2, Y4) of the image captured with the gain GC falls within a predetermined range. Therefore, as shown in FIG. The gain of the pixels (X2, Y4) is determined as the gain GC. At the time of FIG. 6C, the gains of all the pixels in the gain table 207 are determined.

  (Step S111) Since the gains of all the pixels in the gain table 207 have been determined, the gain setting unit 206 supplies the gain for each pixel of the image captured by the imaging unit 103a to the imaging control device 106 according to the gain table 207. Set.

  (Step S112) An image for measuring a three-dimensional shape is taken. Specifically, the control unit 204 instructs the imaging control device 106 to capture an image. Upon receiving an image capture command from the control unit 204, the imaging control device 106 amplifies the signal input from the imaging unit 103a with the gain set in the gain table 207, and the image memory of the main body 104a of the personal computer 104. 201.

  (Step S113) Three-dimensional shape measurement processing is performed. The three-dimensional shape measurement method uses the pattern projection method or the SFF method described above. The measured three-dimensional shape data is stored in a storage device 203 such as a hard disk of the personal computer 104. Alternatively, the measurement result is displayed on the monitor 104b.

  (Step S114) The three-dimensional shape measurement process is terminated.

  In the above description, a case where a single image is taken to measure a three-dimensional shape has been described. However, depending on a three-dimensional shape measurement method, a plurality of images need to be taken. In this case, the measurement unit 202 captures a plurality of images by repeating the processing from step S102 to step S112. In step S113, the measurement unit 202 uses a plurality of images captured with appropriate gains to obtain a three-dimensional shape. Perform measurement processing. Here, the processing from step S102 to step S112 is a part corresponding to the image gain adjusting apparatus and the image gain adjusting method according to the present invention.

  Next, a case where a plurality of images are captured using the phase shift method described above will be described. Here, four images taken by shifting the phase every π / 2 are processed to measure a three-dimensional shape. In this case, the projection control device 105 controls the liquid crystal plate 102b so as to shift the phase of the lattice pattern projected onto the inspection object SA by π / 2 in response to a command from the personal computer 104. At this time, every time the phase of π / 2 is shifted, the processing from step S102 to step S112 in the flowchart of FIG. 5 is repeated, and four images having different phases for every π / 2 photographed with an appropriate gain. Get. As shown in FIG. 7, the four captured images correspond to a1 to a4 that are different for each phase. An image IM1, an image IM2, an image IM3, and an image IM4 illustrated in FIG. 8A are examples of four images having different phases for each π / 2.

  At this time, the image IM1, the image IM2, the image IM3, and the image IM4 are photographed with different gains. Therefore, when obtaining a three-dimensional shape, it is necessary to normalize the luminance value of each image. . For example, it is assumed that the image IM1 is an image photographed with the gain of FIG. In this case, the normalization process is a process of dividing the luminance value of each pixel by the gain of each pixel. Actually, in order to simplify the process, a normalization table of 1 / gain is used for the images IM1 and IM2. , Image IM3, image IM4 are preferably provided for every four images and calculated. In this case, for example, each pixel of the image IM1 photographed with the gain shown in FIG. 6C only needs to be multiplied by the coefficient of the normalization table as shown in FIG.

  After performing the normalization processing, when phase concatenation processing is performed on four images (image IM1, image IM2, image IM3, image IM4) having different phases for every π / 2, a three-dimensional image as shown in FIG. A shape is obtained. A detailed description of the phase shift method will be omitted.

  As described above, the three-dimensional shape measuring apparatus 100 according to the present embodiment captures a plurality of gain images with the imaging unit 103a and the imaging control device 106, and the brightness of each pixel of the image captured with the brightness value determination unit 205. It is determined whether or not the value is within a predetermined range, and the gain setting unit 206 specifies a gain in a direction in which the luminance value of each pixel is within the predetermined range so that the luminance value of all the pixels is within the predetermined range. Since the gain of each pixel is set, even if the dynamic range within the same visual field of the image to be captured exceeds the dynamic range of the imaging unit, an appropriate image can be captured without causing blackout or whiteout. In particular, the three-dimensional shape measuring apparatus 100 can measure a three-dimensional shape without causing a measurement error due to black crushing or whiteout.

(Second Embodiment)
Next, a three-dimensional shape measuring apparatus according to the second embodiment will be described. The three-dimensional shape measuring apparatus according to the present embodiment has the same configuration as the three-dimensional shape measuring apparatus 100 described in the first embodiment. The flowchart of FIG. 5 is different from the first embodiment. FIG. 10 is a flowchart showing the operation of the application software of the three-dimensional shape measuring apparatus 100 according to this embodiment. The same processing steps as those in FIG. 5 are performed. The difference from FIG. 5 of the first embodiment is that step S115 is provided between step S106 and step S107, and the processing content of step S113 for performing the measurement process is changed. Hereinafter, only the parts different from FIG. 5 in the flowchart of FIG. 10 will be described.

  (Step S115) It is determined whether or not the gain setting unit 206 has performed the process of changing the gain and repeating the imaging (the process from step S102 to step S110 in FIG. 5) a predetermined number of times. If the predetermined number of times has been performed, the process proceeds to step S111. If the predetermined number of times has not been performed, the process proceeds to step S107. The predetermined number indicates the number of times the gain is changed in step S108 or step S110 when the determination result in step S106 is “No”, and is set in advance in the measurement unit 202, the storage device 203, or the like. For example, when the process for increasing the gain in step S108 and the process for decreasing the gain in step S110 are performed once, it is necessary to set the predetermined number to at least twice.

  (Step S113b) Basically, the three-dimensional shape measurement process is performed in the same manner as in step S113 of FIG. 5, but the three-dimensional shape measurement process is performed even when the gains of all the pixels are not determined in step S106. In this case, with reference to the gain table 207, the pixel position where the gain is undetermined is not measured, but the three-dimensional shape measurement process is performed by interpolation from the luminance values of the surrounding pixels. Or you may make it show to the monitor 104b that the part cannot be measured. For example, a pixel position that cannot be measured on the inspection object SA displayed on the monitor 104b may be flashed and displayed in red to alert the measurer.

  As described above, in addition to the effect of the first embodiment, the three-dimensional shape measurement apparatus 100 according to the present embodiment rounds up the measurement even when the gains of all the pixels of the image to be captured cannot be determined easily. It can be carried out. Further, since error information is displayed on the monitor 104b for the pixels for which an appropriate gain could not be determined, the measurer can be alerted.

(Third embodiment)
Next, a three-dimensional shape measuring apparatus according to the third embodiment will be described. The three-dimensional shape measuring apparatus according to the present embodiment has basically the same configuration as the three-dimensional shape measuring apparatus 100 described in the first embodiment. The difference from the first embodiment is not only the gain adjustment but also the exposure conditions and the amount of illumination light.

  In the case of the present embodiment, in the flowchart of FIG. 5 of the first embodiment, gain adjustment is performed and exposure conditions and illumination light quantity are adjusted. For example, in step S102 of FIG. 5, the gain of the imaging control device 106 is set, the exposure conditions (shutter speed, aperture, etc.) for shooting an image with the imaging unit 103a, and the light source 102a of the pattern projection mechanism 102 Sets the amount of light emitted by. The setting of the exposure condition is commanded from the measuring unit 202 of the personal computer 104 to the imaging control device 106, and the setting of the light amount is commanded from the measuring unit 202 of the personal computer 104 to the projection control device 105. Further, as in the case of the gain setting in step S102 in FIG. 5, default values are set in advance for the exposure conditions and the light amount. Similarly, in step S108 and step S110 in FIG. 5, the gain is adjusted and the exposure condition and the amount of illumination light are adjusted.

  In this way, even when the gain cannot be adjusted only by gain adjustment, it is possible to adjust more widely than in the case of the first embodiment by adjusting the exposure conditions and the amount of illumination light, and an image that is not crushed or blown out white. Can be taken.

  Although the present embodiment has been described based on the flowchart of FIG. 5 of the first embodiment, the present invention can be similarly applied to the flowchart of FIG. 10 described in the second embodiment. In particular, in the case of the flowchart of FIG. 10 of the second embodiment, the exposure conditions and the amount of illumination light may be changed when the gains of all the pixels cannot be set even after performing the predetermined number of times in step S115. In this case, in the flowchart of FIG. 10, when the determination result in step S115 is “Yes”, a process for changing the exposure condition and the amount of illumination light may be inserted, and after this process, the process may return to step S102.

  As described above, according to each embodiment, according to the present invention, even when the dynamic range within the same visual field of the image to be captured exceeds the dynamic range of the imaging unit, an image without whiteout or blackout is captured. be able to.

It is a lineblock diagram of three-dimensional shape measuring device 100 concerning each embodiment. It is a block diagram of the three-dimensional shape measuring apparatus 100 according to each embodiment. It is explanatory drawing which shows the pixel arrangement example of the imaging part 103a. It is explanatory drawing which shows an example of the image image | photographed with a different gain. It is a flowchart which shows the measurement process of 1st Embodiment. It is explanatory drawing which shows an example of the gain table. It is explanatory drawing which shows a phase shift method. It is explanatory drawing which shows the example of a picked-up image of a phase shift method. It is explanatory drawing which shows an example of a normalization table. It is a flowchart which shows the measurement process of 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Three-dimensional shape measuring apparatus 101 ... Stage 102 ... Pattern projection mechanism 102a ... Light source 102b ... Lattice pattern 102c ... Projection optical system 103a ... Imaging part 103b ... Imaging Optical system 104 ... PC 104a ... main body 104b ... monitor 104c ... keyboard 105 ... projection control device 106 ... imaging control device 107 ... stage mechanism 108 ... stage control device 201 ... Image memory 202 ... Measurement unit 203 ... Storage device 204 ... Control unit 205 ... Luminance value determination unit 206 ... Gain setting unit 207 ... Gain table SA ... Inspected object

Claims (5)

An image gain adjustment device that controls gain for each pixel of an image to be captured,
An image capturing unit that captures an image with a specified gain;
A luminance value determining unit that determines whether or not the luminance value of each pixel of the image captured by the image capturing unit is within a predetermined range set in advance;
When the luminance value of each pixel is within the predetermined range, the gain at the time of shooting is set as the gain of the pixel. When the luminance value of each pixel is outside the predetermined range, the luminance value of the pixel is set to be within the predetermined range. An image gain comprising: a gain setting unit that repeats a series of operations for capturing an image with the image capturing unit by specifying a gain until the determination result of the luminance value determination unit for all pixels falls within a predetermined range. Adjustment device. The image gain adjusting device according to claim 1,
The luminance value determining unit determines whether or not the luminance value of each pixel of the image captured by the image capturing unit is within the dynamic range of the image capturing unit;
The gain setting unit sets the gain at the time of shooting as the gain of the pixel when the luminance value of each pixel is within the dynamic range, and the gain of the pixel when the luminance value of each pixel is smaller than the dynamic range. In the direction of increasing, or when the luminance value of each pixel is larger than the dynamic range, a series of operations for capturing images by designating the image capturing unit in the direction of decreasing the gain of the pixel is performed for all pixels. An image gain adjustment device, wherein the determination is performed until the determination result of the luminance value determination unit falls within a predetermined range. A three-dimensional shape measuring apparatus having the image gain adjusting apparatus according to claim 1,
A three-dimensional shape measuring apparatus, comprising: a measuring unit that measures a three-dimensional shape using an image photographed by the image photographing unit using a gain for each pixel set by the gain setting unit. An image gain adjustment method for controlling a gain for each pixel of an image to be captured,
An image capture procedure to capture an image with a specified gain;
A luminance value determining procedure for determining whether or not the luminance value of each pixel of the image captured in the image capturing procedure is within a predetermined range set in advance;
When the luminance value of each pixel is within the predetermined range, the gain at the time of shooting is set as the gain of the pixel. When the luminance value of each pixel is outside the predetermined range, the luminance value of the pixel is set to be within the predetermined range. A gain setting procedure that repeats a series of operations for capturing an image in the image capturing procedure by specifying a gain until the determination result of the luminance value determining procedure for all pixels falls within a predetermined range. Adjustment method. The image gain adjustment method according to claim 4,
The luminance value determining procedure determines whether or not the luminance value of each pixel of the image captured in the image capturing procedure is within the dynamic range of the image capturing procedure,
In the gain setting procedure, when the luminance value of each pixel is within the dynamic range, the gain at the time of shooting is set as the gain of the pixel, and when the luminance value of each pixel is smaller than the dynamic range, the gain of the pixel is A series of operations for capturing an image by designating each of the image capturing procedures in the direction of increasing or in the direction of decreasing the gain of the pixel when the luminance value of each pixel is larger than the dynamic range. An image gain adjustment method comprising repeating the determination until the determination result of the luminance value determination procedure falls within a predetermined range.

Images