JP2006177737A - Image processing device, microscope device, inspection device, and image processing program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To adjust the quantity of light properly in a short time by a simplified device constitution. <P>SOLUTION: An image processing part 110 of this inspection device 1 adjusts the brightness of an image acquired by a camera and displays it on a monitor 54. A brightness information calculation means calculates the brightness in a reference domain of the image when the image acquired by the camera is displayed on the monitor 54. A dimming table shows a relation between the quantity of incident light into the camera and a dimming level adjusted by control of the quantity of incident light. A dimming level changing quantity calculation means calculates the changing quantity of the dimming level to the image based on the brightness and the dimming table. A light quantity control information generation means compares the changing quantity of the dimming level with the present dimming level, and generates light quantity control information relative to the quantity of light to be changed. A control circuit 23 controls the quantity of the incident light into the camera based on the light quantity control information. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a technique for appropriately setting the amount of light of an image captured in a microscope or an inspection apparatus that inspects a defect to be inspected.

  In an inspection device that inspects flat panel display (FPD) substrates, such as liquid crystal panels and plasma display panels, and semiconductor wafers, the inspection target is imaged by the imaging device, and the captured image is displayed on a monitor or the like. I do. In a microscope apparatus equipped with an imaging device, an observation image formed by a microscope can be acquired as an image by the imaging device. In these inspection apparatuses and microscope apparatuses, the brightness is appropriately adjusted so that an image captured using the mounted imaging apparatus can be easily inspected and observed by a user or the like, and then displayed on a monitor or the like. In the following description, the process for adjusting the brightness of the image display screen is referred to as a dimming process.

  As a general dimming process, it is determined whether or not the brightness of an image is within a predetermined range. If the luminance is out of the predetermined range, the amount of light output from the lighting device is determined within the predetermined range. There is a method of repeatedly performing the process of changing one step at a time in a direction to approach the inside. This process is shown in the flowchart of FIG.

  In the dimming process shown in FIG. 15, the effective maximum brightness is obtained from the brightness of the image, and the effective maximum brightness is an appropriate value according to the magnitude relationship between the value and the bright part threshold value and the dark part threshold value. The light quantity level is adjusted so that it falls within the target brightness range. The effective maximum luminance value is defined as the maximum value among the luminances in which the frequency occupies 1% or more of the entire distribution with respect to the luminance of all pixels constituting the image. The target luminance range is a range of luminance values that are greater than or equal to the dark portion threshold and less than or equal to the bright portion threshold. The bright threshold value in the target luminance range means that when displaying an image on a display means such as a monitor, if a pixel with high luminance exceeds the value among pixels that form the image, the image is too bright and inspected. For example, 225 is set as the bright threshold value in a 256-gradation image. The dark area threshold value in the target luminance range is that, when displaying an image, if pixels with high luminance fall below that value, the image is too dark and affects inspection and observation. For example, 180 or the like is set as the dark portion threshold value in an image with 256 gradations.

  First, in step S101, the process proceeds to step S102, step S108, or step S112 depending on the result of comparing the effective maximum luminance value of the image with the bright part threshold value and the dark part threshold value. Of the processes shown in FIG. 15, steps S102 to S107 show processes when the effective maximum brightness is less than the dark part threshold value, and steps S108 to S111 show the effective maximum brightness as the bright part threshold. Step S112 is a process in the case where the effective maximum brightness is not less than the dark part threshold value and not more than the bright part threshold value, that is, a process in the case where the target brightness range is included.

  For example, when the effective maximum luminance is less than the dark part threshold value, it is determined in step S102 whether or not a value corresponding to the process of “darkening” the light amount is stored in the immediately preceding control flag. Here, the control flag is a flag set during the previous dimming process, and stores a value indicating the content of the previous dimming process. If the dimming process for “darkening” the amount of light has been performed in the previous process, the process proceeds to step S103 without performing the dimming process, and “OK (no dimming)” is set as the control flag. The process ends. If the “darkening” process has not been executed in the previous dimming process, the process proceeds to step S104, and whether the light amount level is set to the maximum value among the values that can be set by the inspection apparatus or the microscope apparatus. Determine whether. If the light amount level has already been set to the maximum value, no further dimming processing can be performed, so the control flag is set to “OK” in step S105, and the processing ends. If the light amount level is not the maximum value in step S104, the light amount level is increased by one step in step S106, the control flag is set to “brighten” in step S107, and the process ends.

  When the effective maximum luminance is larger than the bright part threshold value, the process proceeds to step S108. In the processing after step S108 shown in FIG. 15, before reducing the light amount level, it is determined whether or not the minimum value that can be set by the apparatus is already set (step S108), and the minimum value is set. If the light is not dimmed, the control flag is set to “OK” (step S109) and the process is terminated. If it is possible to set the light amount level to be smaller, the light amount level is decreased by one step (step S110), the control flag is set to “darken” (step S111), and the process ends.

  As described above, when the effective maximum luminance is not included in the target luminance range, the light amount is changed step by step under predetermined conditions (steps S106 and S110). After changing the amount of light by one step, the dimming process of FIG. 15 is executed again, and the process of increasing or decreasing the amount of light by one step is repeated until the effective maximum luminance is included in the target luminance range.

  As a method for shortening the time required and appropriately adjusting the amount of light, the relationship between the output level of the voltage from the illuminating device and the level of the amount of light incident on the imaging device is obtained from the transmittance of the ND filter. A method using a look-up table (hereinafter, dimming table) for dimming processing showing the relationship is disclosed (for example, Patent Document 1). In the dimming method using the dimming table, the output of the lighting device corresponding to the maximum value is obtained from the maximum value of the incident light amount in a predetermined area of the image by the dimming table, and the value obtained by the lighting device from the dimming table Adjust to output with.

As other light control methods, a method of controlling the shutter speed and aperture of the camera and a method of controlling the amount of illumination light are used. For example, a method for adjusting the amount of incident light to the imaging device by rotating a pair of polarizing plates relatively around the optical axis is disclosed (for example, Patent Document 2). Of the two polarization components orthogonal to each other with respect to the incident light, a pair of polarizations so that the amplitude transmittance for one polarization component is 1 and the amplitude transmittance for the other polarization component is 0.6 or more and 0.8 or less. The plate is arranged in the optical axis direction. The pair of polarizing plates are rotated relative to each other around the optical axis, and the light amount is adjusted by changing the transmittance. Since the transmittance varies in a relatively wide range depending on the combination of the amplitude transmittances of the polarizing plates, it is suitable for adjusting the light amount in a wider range.
JP 2001-91469 A (Summary, FIGS. 1, 3 and 4, paragraphs 0026 to 0031) JP 2002-169195 A (summary, FIG. 1, paragraph 0006)

  In the method of adjusting the light amount step by step as in the conventional dimming process, it is necessary to repeat the process of FIG. 15 a plurality of times until the light amount is adjusted to an appropriate light amount. For this reason, when the brightness of the image is greatly deviated from the above target brightness range, it takes time until the screen is adjusted to the desired brightness.

  In the method of setting the control amount of the amount of illumination light with reference to the dimming table described in Patent Document 1, the time required for the dimming process is shortened, but in the dimming table, the range of the corresponding light amount is widened. In order to achieve this, it is necessary to prepare a plurality of ND filters having different transmittances. Since the dimming table is created by a plurality of ND filters having different transmittances, an algorithm for determining the configuration of the dimming table and the output of illumination becomes complicated.

  In the method of dimming using a polarizing plate described in Patent Document 2, the transmittance of the polarizing plate varies from element to element. For this reason, the amount of light to be controlled varies depending on the characteristics of the polarizing plate used. As an example, when one visible light polarizing plate (polarizing filter) having a structure in which a thin polarizing film is sandwiched between two glasses, variation with respect to the average transmittance is about ± 10%. When such a polarizing plate is used, there is a problem that light control is not performed according to an algorithm for setting an optimal light amount.

  An object of the present invention is to realize appropriate light amount adjustment in a short time with a simplified apparatus configuration.

  In order to solve the above-described problem, in the image processing apparatus according to the present invention, which displays the image obtained from the imaging device on the display screen, the brightness of the image obtained from the imaging device is adjusted and displayed on the display screen. A luminance information calculation unit that calculates luminance information based on luminance in a predetermined region of the image, a light amount incident on the imaging device, and a relationship between a dimming level adjusted by the control of the incident light amount. A dimming level change amount calculating means for calculating a dimming level change amount for the image based on the look-up table shown, the luminance information and the look-up table; and a dimming level change amount; Light intensity control information generating means for comparing the current light control level and generating light intensity control information for the light intensity to be changed, and controlling the incident light intensity to the imaging device based on the light intensity control information Configuration to which a that control means.

  Preferably, determination means for determining whether or not the value of the luminance information is included in a predetermined range, the luminance information calculation means includes first luminance information in the first region of the image. And the second luminance information in the second region is calculated, and the dimming level change amount calculating means determines that the value of the first luminance information is not within the predetermined range by the determining means Is configured to calculate the amount of change in dimming level for the image based on the second luminance information and the lookup table.

  Preferably, the luminance information calculation unit calculates the updated luminance information in the predetermined area after the incident light amount is controlled by the control unit, and based on the updated luminance information and the lookup table. Comparing means for comparing the estimated luminance, and lookup table updating means for updating the lookup table based on the comparison result of the comparing means.

Preferably, the luminance information includes a maximum luminance value or a minimum luminance value in the predetermined area.
Preferably, the determination unit defines a reproduction area where the gradation of the image is reproduced, and determines whether the luminance information is included in the range of the reproduction area. Furthermore, the second area may be an area different from the first area, and the second luminance information may be a maximum luminance value or a minimum luminance value in the second area. The look-up table update means may update the look-up table using a least square method. Alternatively, the lookup table update means may update the lookup table using an offset between the updated luminance information after the luminance is controlled and the luminance estimated based on the lookup table. Good.

  Preferably, the light amount control information includes light amount control information about the imaging device and light amount control information about an illumination device that irradiates an imaging target of the imaging device. Alternatively, the light amount control information includes information related to the exposure time of the imaging device.

  The present invention is not limited to the above image processing apparatus. An image processing program for causing a computer to execute the microscope apparatus, the inspection apparatus, and the image processing method provided with the image processing apparatus is also included in the present invention.

  According to the present invention, the dimming process is appropriately performed based on the lookup table showing the relationship between the incident light quantity and the dimming level for adjusting the light quantity using the luminance of the image. The time required can be shortened. In order to correct the look-up table by comparing the theoretical value obtained from the look-up table with the actual measurement value, the light is adjusted by the look-up table adapted to the actual operation, and the image is dimmed to the appropriate brightness in a short time. Is done.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the drawings.
<Embodiment 1>
FIG. 1 is a configuration diagram of an inspection apparatus including an image processing apparatus according to the present embodiment. The inspection apparatus 1 includes a microscope 100 and a computer 53 that processes an image of the microscope 100. The memory of the computer 53 stores a program for executing various processes according to the present embodiment. The inspection apparatus 1 is used, for example, for inspecting an inspection target using an image of the inspection target obtained from the microscope 100. The microscope 100 can observe ultraviolet rays and includes a visible light optical system using epi-illumination and an ultraviolet light optical system using ultraviolet illumination.

  In the microscope 100, the revolver 2 is arranged in correspondence with the stage 21 on which the inspection target is placed. For example, five objective lenses 3 are attached to the revolver 2. For example, among the five objective lenses 3, one is a lens for ultraviolet light, and the other is a lens for visible light. The revolver 2 is rotatably mounted, and is selectively switched so that a desired lens among the plurality of objective lenses 3 is positioned on the optical axis 4 by the rotation of the motor M1.

  A specimen 29 to be inspected is placed on the stage 21. The stage 21 is mounted so as to be movable in a plane direction perpendicular to the z-axis in FIG. 1, and can be driven in the z direction by a motor M2. By moving the stage 21 in the z direction, the in-focus position is determined with respect to the specimen 29 placed on the stage 21.

The motors M1 and M2 are driven by the drive circuit 22 that has received a command from the control circuit 23, and signals are fed back to the control circuit 23 in accordance with the recognition result of the sensor S1.
The visible light optical system in the microscope 100 reflects light from the visible illumination light source 5 for observation of visible light by the half mirror 25 through the illumination system lens 6 and irradiates the specimen 29 through the objective lens 3 for visible light. . The light reflected by the specimen 29 passes through the objective lens 3 and passes through the half mirror 25. The transmitted light forms an enlarged image at the image position 9 via the dichroic mirror 26 and the imaging lens 7 and is visually observed by the lens binocular unit 8. Note that the dichroic mirror 26 used in the present embodiment has a characteristic of transmitting visible light and reflecting ultraviolet light.

  A shutter 10 that is a light blocking member is disposed in front of the visible illumination light source 5 in the direction of the light path. The shutter 10 is driven by a motor M3, and the light from the visible illumination light source 5 is opened during visible light observation, the motor M3 is turned off during ultraviolet light observation, and the shutter 10 is shielded by a spring (not shown). The motor M <b> 3 is controlled to be turned on / off by the drive circuit 22 that has received a command from the control circuit 23.

  On the other hand, the ultraviolet light optical system reflects deep ultraviolet (hereinafter referred to as DUV) light from an ultraviolet illumination light source 11 for observing ultraviolet light by an ultraviolet light half mirror 41 through an illumination system lens 12 and a light reduction unit 102. Further, the light is reflected by the ultraviolet light mirror 42 and the dichroic mirror 26. The reflected light is applied to the specimen 29 through the half mirror 25 and the objective lens 3 for ultraviolet light. The light reflected by the specimen 29 passes through the objective lens 3 and passes through the half mirror 25. The transmitted light is reflected by the dichroic mirror 26, passes through the imaging lens 14, the ultraviolet light mirror 42, passes through the ultraviolet light half mirror 41, and passes through the imaging lens 14, and the imaging position of the ultraviolet light observation TV camera 15. 16 is imaged.

  Similarly to the visible illumination light source 5, a shutter 13, which is a light shielding member, is also arranged on the front surface of the ultraviolet illumination light source 11 in the light path direction. The shutter 13 is driven by a motor M4, and opens the DUV light from the ultraviolet illumination light source 11 when observing ultraviolet light, turns off the power of the motor M4 when observing visible light, and shields the shutter 13 with a spring (not shown). The motor M4 is controlled to be turned on / off by the drive circuit 22 that has received a command from the control circuit 23. When the power source of the motor M3 is damaged and the motor M4 is stopped, the shutter 10 is shielded by a spring. The light reduction unit 102 is configured to be able to adjust the light amount of the ultraviolet illumination light source 11 stepwise by a combination of a plurality of light reduction filters, and to be capable of dimming processing.

  The control circuit 23 has a timer for measuring the irradiation time of the DUV light, and issues a command to the drive circuit 22 when the irradiation time of the DUV light irradiating the specimen 29 reaches an arbitrary set time. In response to the command, the motor M4 is driven, the shutter 13 is closed, and the irradiation of the DUV light onto the specimen 29 is shielded by the ultraviolet light shielding means 23a.

  The ultraviolet light shielding unit 23a shields the DUV light so that the specimen 29 is not irradiated with the DUV light other than the ultraviolet light observation of the specimen 29, that is, during the visible light observation. Further, the ultraviolet light shielding means 23a integrates the lighting time of the ultraviolet illumination light source 11 during visible light observation, and when this lighting time reaches the irradiation time of DUV light set in an ultraviolet light shielding window (not shown), A command is issued to the drive circuit 22. By this command, the motor M4 is driven, the shutter 13 is closed, and the irradiation of the specimen 29 with DUV light is shielded. Further, the ultraviolet light shielding unit 23 a shields the irradiation of the specimen 29 with the DUV light that irradiates the specimen 29. These functions of the ultraviolet light shielding means 23 a may be directly incorporated in the control circuit 23 or may be executed by an instruction from the computer 53.

  The UV light observation TV camera 15 is connected to a capture board 52 via a camera controller 51. A computer 53 having a monitor 54 is connected to the capture board 52. In FIG. 1, the capture board 52 and the computer 53 are drawn separately, but in reality, the capture board 52 is built in the computer 53 or is inserted into the slot of the computer 53.

  The capture board 52 has an interface function for displaying an image on the monitor 54 via the computer 53. The computer 53 is connected to the control circuit 23 of the microscope 100 via the cable 55. The control circuit 23 incorporates an interface circuit such as RS232C or GPIB, and the interface circuit enables communication between the control circuit 23 of the microscope 100 and the computer 53. When the “login” signal transmitted from the computer 53 is received by the control circuit 23 via the cable 55, the control circuit 23 drives the motors M1 to M4 of each part.

  An image processing unit 110 that executes image processing such as light control processing is connected to the camera controller 51, the capture board 52, and the computer 53. Alternatively, the image processing unit 110 may be built in the computer 53.

  The image processing unit 110 receives various types of information for controlling the amount of light incident on the image sensor of the camera (imaging device) from the camera controller 51, and also stores various types of information for controlling the amount of illumination light of the microscope 100 by the computer 53. Receive from. The computer 53 stores various programs for executing the dimming process according to the present embodiment in the memory. A CPU (not shown) reads a predetermined program from the memory and executes a flowchart described below, whereby the illumination light quantity of the microscope 100 is appropriately controlled.

  Note that the information received by the image processing unit 110 from the camera controller 51 is information about the shutter speed, aperture, exposure time, and the like, for example. The information received from the computer 53 is information related to the control of the dimming unit 102 acquired by the drive circuit 22 and the control circuit 23, for example.

  The image processing unit 110 acquires image information related to the brightness of an image acquired from the capture board 52 in addition to information received from the camera controller 51 and the computer 53. Based on this information, the image processing unit 110 calculates a light amount change amount necessary to adjust the image to an appropriate brightness, and controls the camera light amount and the illumination light amount to execute the dimming process. To do. The change amount of the camera light amount is transmitted to the camera controller 51, and the change amount of the illumination light amount is transmitted to the control circuit 23 and the drive circuit 22 via the computer 53.

  In FIG. 1, the image processing unit 110 is configured to operate only during ultraviolet light observation, but is not limited thereto. For example, a dimming unit having the same configuration as the dimming unit 102 is disposed between the illumination system lens 6 and the half mirror 25, and this dimming unit is controlled by the drive circuit 22 and the control circuit 23, so that it is visible. It can also be operated in light observation.

  FIG. 2 is a block diagram of the image processing unit 110. The image processing unit 110 includes an image capturing unit 501, a current light amount reading unit 502, a luminance information calculation unit 503, a designated area information storage unit 504, a dimming level change amount calculation unit 505, a dimming level-light amount lookup table (LUT). ) A storage unit 506, a dimming level-light amount LUT update unit 507, a light amount control information generation unit 508, and a dimming level change amount calculation setting information storage unit 509.

  The image capturing unit 501 captures image data acquired from the capture board 52. The current light amount reading unit 502 reads the light amount based on the information regarding the light amount acquired from the computer 53 and the camera controller 51. The luminance information calculation unit 503 calculates the luminance in a predetermined area of the image based on the image information captured by the image capturing unit 501. The designated area information storage unit 504 stores information such as a reference area indicating a predetermined area of an image designated by a user or the like via the computer 53 or the like. The dimming level change amount calculation unit 505 calculates a light amount to be changed, that is, a dimming level change step, from the luminance obtained by the luminance information calculation unit 503. The dimming level-light amount lookup table storage unit 506 stores a lookup table for managing the relationship between the light amount and the dimming level. The dimming level-light amount LUT update unit 507 updates the lookup table. The light quantity control information generation unit 508 creates information about the light quantity to be controlled from the current light quantity and dimming level changing step, and gives the information to the computer 53 and the camera controller 51. The dimming level change amount calculation setting information storage unit 509 stores information necessary for calculating the dimming level change step based on the information received from the computer 53.

  In the image processing apparatus according to the present embodiment, in order to adjust the brightness of an image, the amount of light is changed with reference to the luminance of the image captured from the capture board 52, and an image having a desired brightness is obtained. In the following, a dimming process in which the image processing apparatus changes the light amount of the inspection apparatus 1 based on the brightness (luminance) of the image captured from the capture board 52 to adjust the image to an appropriate brightness will be described.

  FIG. 3 is a diagram for explaining the relationship between the light quantity of the camera and the illumination light quantity from the illumination light source of the microscope. In the figure, the vertical axis represents the camera control level, and the horizontal axis represents the illumination control level. Here, the control level is a unit of the amount of light that can be controlled by the inspection apparatus 1. The larger the control level, the larger the amount of light.

  In the graph of FIG. 3, the total light amount level, that is, the dimming level is obtained by adding the camera control level value on the vertical axis and the illumination control level value on the horizontal axis. For example, when the light control level is -24, the camera control level is -12 and the illumination control level is -12. If the light control level is adjusted by one step larger to -23, the camera control level becomes -8 and the illumination control level becomes -15.

  FIG. 4 is a diagram for explaining the relationship between the light control level and the amount of light when actually changed based on the light control level. The vertical axis represents the output light quantity relative value, and the horizontal axis represents the light control level. The output light amount relative value is defined, for example, as 1 for the light amount at the minimum light control level. In the present embodiment, the output light amount relative value is associated with a change in light amount of +1/4 EV (Exposure Value, exposure value) with a change in light control level of +1 step. Here, the change of the exposure value + 1 EV corresponds to a double increase in the amount of light.

Assuming that the current light amount is Y and the light amount (change amount) when the dimming level is changed by X steps is Y ′, the relationship between Y and Y ′ is expressed as follows using X.
Y ′ = Y × 2 ^ (X / 4) (1)
When formula (1) is arranged with respect to X, formula (2) is obtained.

  When the γ characteristic of the camera that captures the image is linear (γ = 1.0), the formulas (1) and (2) hold even if the light amount Y is replaced with the luminance of the image. That is, it is possible to perform the light control process by changing the light control level based on the luminance value of the image.

  5A and 5B are diagrams illustrating the relationship between the dimming level and the luminance of the image. The vertical axis represents the luminance, and the horizontal axis represents the dimming level. In the present embodiment, the luminance having the maximum value is used in a predetermined region that refers to luminance (hereinafter referred to as a reference region). This luminance value is the effective maximum luminance value in this embodiment.

  5A and 5B are obtained from the relationship of FIG. For example, when the dimming level changes by +4 steps, the amount of change in the amount of light that changes in accordance with the change in the dimming level corresponds to +1 EV, that is, twice the amount before the change, based on the definition of the relative value of the output light amount. At this time, theoretically, the brightness of the image is double that before the change.

  In contrast to the theoretical value, the dimming level actually varies depending on the amount of light as shown in FIG. Therefore, the change in the luminance of the image with respect to the amount of change in the dimming level also differs in the range of the dimming level that can reproduce the gradation depending on, for example, the reflectance of the inspection object. FIG. 5A shows the relationship between the light control level and the luminance when the reflectance of the object to be inspected is high, such as a mirror. FIG. 5B shows the relationship between the light control level and the luminance when the reflectance of the object to be inspected is low, such as glass. In FIG. 5A, the brightness is adjusted so that the gradation of the image can be reproduced even when the dimming level is small, that is, when the amount of light is small. However, when the dimming level is increased, the luminance is extremely increased. That is, the image becomes too bright and “whiteout” appears on the image. On the other hand, in FIG. 5B, compared with FIG. 5A, unless the light control level is increased (the amount of light is increased), the image is too dark and “blackout” appears on the image.

  As shown in FIGS. 5A and 5B, the dimming level for making the image appropriate brightness varies depending on the reflectance of the object to be inspected. Therefore, in the dimming process according to the present embodiment, the dimming process is performed based on the brightness when the image is displayed on the monitor 54, that is, the magnitude of the luminance of the image.

  FIG. 6 is a schematic diagram for explaining the relationship between the luminance of an image and the amount of change in the amount of light adjusted by the dimming process. The vertical axis represents the amount of light to be changed, that is, the dimming level changing step, and the horizontal axis represents the luminance level of the image. In FIG. 6, the characteristic of the dimming level changing step with respect to the luminance level is represented by a thick solid line.

  The entire image luminance level is divided into three areas of “blackout range B”, “tone reproduction range G”, and “overexposed range W” according to the magnitude of luminance. Among them, in the gradation reproduction range G, the maximum value and the minimum value at which the brightness is determined to be appropriate for the effective maximum luminance are set as the bright portion threshold ThTL and the dark portion threshold ThTD, respectively. A range between the dark portion threshold ThTD and the bright portion threshold ThTL is defined as a target luminance range T. On the monitor 54, the brightness is too dark because the brightness is too dark and the gradation is lost, and the threshold value for determining that the brightest part of the image is blacked out is the gradation reproduction dark part threshold ThGD. The threshold value at which the gradation is lost and it is determined that the brightest part of the image is overexposed is the gradation reproduction bright part threshold ThGL.

  When the image luminance level takes a value within the target luminance range T, the dimming level changing step is 0, that is, the dimming level is not changed. The target luminance range T represents a range where the luminance is determined to be an appropriate value, and details will be described later. When the image luminance level takes a value outside the target luminance range T, the dimming level changing step is set according to the amount of deviation of the luminance level from the target luminance range T. When the luminance level is darker than the target luminance range T, the dimming level changing step takes a positive value. That is, the light is adjusted in the direction of increasing the brightness of the image. When the luminance level is brighter than the target luminance range T, the dimming level changing step takes a negative value. That is, the light is adjusted in the direction of decreasing the brightness of the image. The absolute value of the dimming level changing step increases as the effective maximum luminance deviates greatly from the target luminance range T.

  If the luminance level of the image is in the blacked out range B or overexposed range W, and the gradation cannot be reproduced accurately, the dimming level changing step for adjusting the luminance level to the target luminance range T is not necessarily appropriate. Cannot be calculated. This is particularly the case when the luminance level is close to the minimum or maximum luminance value reproduced on the monitor 54. In this case, the dimming level changing step is set uniformly. For example, it is assumed that the image is reproduced with 256 gradations. When the luminance level of the image is in the blackout range B, a dimming level changing step is set such that the luminance level is increased to four times that before dimming, for example. When the brightness level of the image is in the overexposure range W, for example, a dimming level changing step is set such that the brightness level is darkened to 1/4 times that before dimming.

  In the light control process according to the present embodiment, the light control level is changed based on the luminance level by using the relationship shown in FIG. FIG. 7 is a diagram showing a dimming level model when the dimming level is set based on the relationship between the luminance level of the image and the dimming level changing step. The vertical axis represents the dimming level, and the horizontal axis represents the luminance level of the image.

  FIG. 7 shows the luminance level LumX of the actual image. Here, the luminance level LumX is the above-described effective maximum luminance. Further, the light amount corresponding to one step of light control level is “LumEv”. Here, the unit of LumEv is EV. For example, when LumEV = 1, the brightness of the image is + 1EV, that is, doubled when the light control level changes by +1 step. When the light control level is changed by −1 step, the brightness of the image is −1 EV, that is, ½ times.

In the present embodiment, the target brightness (referred to as LumObj) in the light control process is set as the following expression (3), assuming an intermediate value in the target brightness range.
LumObj = (ThTD + ThTL) / 2 (3)
The luminance level LumX is set to the target luminance LumObj by the dimming process. Assuming that the dimming level changing step at this time is StX, the target luminance LumObj and the actual luminance level LumX are expressed by the relational expression (4).

LumObj = LumX × 2 ^ (StX × LumEv) (4)
Equation (4) is derived from the fact that the brightness is increased by (2 ^ LumEv) by changing the dimming level by one step. When the equation (4) is solved for the dimming level changing step StX, it is expressed as the following equation (5). From equation (5), it can be seen that the dimming level changing step StX in the dimming process is calculated from the luminance level LumX of the input image, the target luminance LumObj, and the unit light quantity LumEv of one step.

  In FIG. 7, the relationship between the image luminance level LumX and the light control level is indicated by a curve. The curve is indicated by a solid line for a region corresponding to the gradation reproduction range G, and by a broken line for a region corresponding to the outside of the gradation reproduction range G. In the example of FIG. 7, since the luminance level LumX is on the darker side than the target luminance range T, the amount of light is controlled to be bright in order to adjust the light to the target luminance. That is, the dimming level changing step StX> 0, and control is performed to increase the amount of light. This is also clear from the fact that the numerator> the denominator of the logarithm of the logarithm in the right side of the equation (5).

  On the other hand, when the luminance level LumX is on the brighter side than the target luminance range T, the amount of light is controlled to darken the image. That is, the dimming level changing step StX <0, and control is performed so as to reduce the light amount. Since the numerator is smaller than the denominator of the logarithm of the formula (5), the same applies to the fact that the formula (5) is derived.

  When the luminance level LumX is in the blacked out range B or overexposed range W, the control for increasing or decreasing the light amount by the constant dimming level changing step is performed regardless of the value of the luminance level LumX. Since it is as having demonstrated with reference to, it abbreviate | omits here.

  FIG. 8 is a flowchart of the basic operation of the dimming process, and FIG. 9 is a flowchart of the dimming process when the luminance level is outside the gradation reproduction range G. The processing shown in FIGS. 8 and 9 is executed by a predetermined program stored in the memory of the computer 53. The light control processing in the image processing apparatus according to the present embodiment will be described with reference to the flowcharts of FIGS.

  When the luminance level of the reference area of the image is included in the gradation reproduction range G, the basic operation process of FIG. 8 is executed. First, in step S1, it is determined whether or not the reference luminance level, that is, the value of the effective maximum luminance is included in the target luminance range T. If the luminance level is less than the dark portion threshold ThTD, within the target luminance range T, and exceeds the bright portion threshold ThTL, the process proceeds to steps S2, S14, and S15, respectively.

  If the effective maximum brightness is less than the dark portion threshold ThTD, that is, the brightness level of the image is dark, and it is determined that dimming is necessary to make the image brighter, the dimming level is changed from the dimming table in step S2. Step n (corresponding to StX in FIG. 7) is calculated. In step S3, the immediately preceding control flag is determined. Here, the control flag is a flag that is set when the previous dimming process is executed. In the previous dimming process, any process of increasing, decreasing, or not processing the light amount is performed. A predetermined value indicating whether or not is executed is stored.

  If the control flag is other than “darken”, the process proceeds to step S9 without performing the process. If the control flag is “darken”, it is determined in step S4 whether or not the calculated dimming level changing step n is greater than one.

  Satisfying the condition of step S3 means that the image is too dark as a result of performing the process of darkening the image in the immediately previous dimming process, so that the image is going to be brightened in the dimming process to be performed in the future. I understand. Therefore, if the condition of step S53 is satisfied, it is determined in step S4 whether or not the dimming level changing step is n> 1, and if yes, the image darkened in the previous dimming process is determined in step S5. The dimming level changing step is set to n = 1 so that the image is not brightened rapidly in the current process. In step S6, the dimming level is increased by one step. In step S7, the control flag is set to “brighten”, and the process ends.

  If No in step S4, that is, if the dimming level changing step is n = 1, the effective maximum luminance is outside the target luminance range T but is in a close position. When dimming at a position close to the target luminance range T, the luminance of the image does not enter the target luminance range T by one-step dimming, and values alternately below the dark portion threshold ThTD and above the bright portion threshold ThTL. Could be taken. In order to end the process of alternately repeating “brightening” and “darkening” the control flag, in step S8, the control flag is set to “OK”, and the process ends without performing dimming.

  If the determination of the control flag in step S3 is No, the process proceeds to step S9 to determine whether or not the dimming level is the maximum value. Here, the maximum value of the light control level is the maximum value of the amount of light that can be adjusted by the inspection apparatus 1. If Yes in step S9, that is, if the dimming level is the maximum value, the control flag is set to “OK” in step S10, and the process ends without performing dimming.

  If No in step S9, that is, if the dimming level can still be raised, the dimming level is increased by n steps in step S11. If the dimming level exceeds the maximum value in step S12, clipping is performed to the maximum value. In step S13, the control flag is set to “brighten”, and the process ends.

  If it is determined in step S1 that the effective maximum luminance exceeds the bright part threshold value, that is, the luminance level of the image is bright, and it is necessary to perform dimming so that the image becomes darker, in step S15, the same as step S2 Then, n of the dimming level changing step is calculated from the dimming table. In step S16, it is determined whether or not the immediately preceding control flag is “brighten”. If Yes in step S16, it is further determined in step S17 whether or not n in the dimming level changing step is greater than 1.

  Satisfying the condition of step S17 means that the image has become too bright as a result of performing the process of brightening the image in the immediately preceding dimming process, so that the image is being darkened in the next dimming process. Therefore, when this condition is satisfied (Yes in step S17), the dimming level changing step is set to n = 1 in step S18. If the condition is not satisfied, no particular processing is performed. In step S19, the dimming level is decreased by n steps, and in step S20, the control flag is set to “darken” and the process ends.

  If No in step S16, the process proceeds to step S21 to determine whether the dimming level is the minimum value. Here, the minimum value of the light control level is the minimum value of the amount of light that can be adjusted by the inspection apparatus 1. If YES in step S21, that is, if the dimming level is the minimum value, the control flag is set to “OK” in step S22, and the process ends without performing dimming.

  If NO in step S21, that is, if the dimming level can still be lowered, the dimming level is decreased by n steps in step S23. In step S24, if the dimming level is below the minimum value, clipping is performed to the minimum value, and in step S25, the control flag is set to “darken”, and the process ends.

If the effective maximum luminance value is within the target luminance range T in step S1, the control flag is set to “OK” in step S14, and the process ends without performing dimming.
With the dimming process of FIG. 8, n of the dimming level changing step is determined according to the luminance level of FIG. 6, and the dimming level is appropriately adjusted. However, as described with reference to FIG. 6, when the luminance level is in the overexposure range W or the underexposure range B, control for increasing or decreasing the light amount by a predetermined level is executed. When the brightness level of the image is far from the target brightness range T, such as overexposure or blackout occurs, the brightness of the image is adjusted by the process of FIG. In the present embodiment, the process of FIG. 9 is executed before the dimming process based on the luminance level of the reference area shown in FIG.

  FIG. 9 is a flowchart of the light control processing when overexposure or underexposure occurs. First, in step S31, it is determined whether or not the maximum luminance value (RYmax) of the reference region is larger than the gradation reproduction bright portion threshold ThGL that is used as a reference when determining the occurrence of overexposure. judge. FIG. 6 shows the gradation reproduction bright portion threshold ThGL. In No, it progresses to the process after step S39. In the case of Yes, in step S32, the minimum luminance value (RYmin) of the reference area is calculated. Here, the maximum luminance value RYmax of the reference region matches the above effective maximum luminance.

  In step S33, it is determined whether or not the minimum luminance value RYmin of the reference area is included in the gradation reproduction range G shown in FIG. If included, in step S34, the dimming level is controlled so that the luminance is decreased until RYmin reaches the blackening level (tone reproduction dark part threshold ThGD in FIG. 6), and the process ends.

  If RYmin is outside the gradation reproduction range G, the process proceeds to step S35. In the following processing, processing is executed based on the luminance level in a region (second region) different from the reference region.

  In step S35, the minimum luminance value NRYmin in the second region is calculated. In step S36, it is determined whether or not the obtained NRYmin is included in the gradation reproduction range G. If it is included, in step S37, the dimming level is controlled so that the luminance is decreased until NRYmin reaches the blacked-out level, and the process ends. If not included, in step S38, the light control level is controlled so that the luminance is reduced by a predetermined level X, and the process is terminated.

  When the maximum brightness value RYmax of the reference area is in the overexposure range, it is appropriate to darken the image to determine the appropriate value of the brightness RYmin of the reference area and the brightness in the area other than the reference area. Judgment is made based on the minimum value NRYmin. If neither the RYmin nor the NRYmin is included in the gradation reproduction range G, it is determined that the gradation of the entire image cannot be reproduced, and the dimming level is adjusted so that the image becomes dark by a predetermined step X. Lighted. For example, when the gradation of the image is 256 gradations, X = −2 is set, and the light is adjusted so that the luminance is darkened to ¼ (−2 EV).

  In the case of No in step S31, the process proceeds to step S39, where the maximum luminance value RYmax of the reference area is smaller than the gradation reproduction dark part threshold ThGD that is used as a reference when determining that blackout occurs. Determine whether or not. FIG. 6 shows the gradation reproduction dark part threshold ThGD. In No, it progresses to step S44, performs the normal light control process in case RYmax is contained in the gradation reproduction range G shown by FIG. 8, and complete | finishes a process. In the case of Yes, the process after step S40 is performed. In the processing after step S40, the processing is executed based on the luminance level in a region different from the reference region used in steps S31 and S39. Here, the other area may be the same area as the second area used in the processing after step S35, or may be another third area. In the present embodiment, the same second area as that used in step S35 is used.

  In step S40, the maximum luminance value NRYmax in the second region is calculated. In step S41, it is determined whether or not the obtained NRYmax is included in the gradation reproduction range G. If not included, the dimming level is controlled to increase the luminance by a predetermined level Y in step S43, and the process is terminated. If it is included, the dimming level is controlled so that the luminance is increased until NRYmax reaches the overexposure level in step S42, and the process ends.

  When the maximum luminance value RYmax of the reference region is in the blackout range B, it is determined how much the image should be brightened based on the maximum luminance value NRYmax in a region other than the reference region. When NRYmax is not included in the gradation reproduction range G, it is determined that gradation reproduction has not been performed for the entire image, and the light adjustment level is adjusted so that the image is brightened by a predetermined step Y. For example, Y = 2 is set, and dimming is performed so that the luminance is four times as bright (+2 EV).

  Even when the reference region is the entire image, the processing of FIG. 9 can be similarly executed by setting the values of the luminance information NRYmin and NRYmax for other regions other than the reference region to 0. . If NRYmin and NRYmax are set to 0, the determination in step S36 and step S41 is inevitably determined as No, and the process proceeds to step S38 and step S43, respectively, and the reference area is a partial area of the image. Similarly, the processing of FIG. 9 is realized.

  When the inspection target is inspected with the image on the monitor 54, the reflectance may vary depending on the portion of the inspection target. By appropriately specifying the region to be inspected using the above-mentioned dimming method, the dimming process suitable for the inspection is performed. For example, it is assumed that the object to be inspected has two current lines that are not in contact with the left and right, arranged in the vertical direction, has a defect so as to straddle between them, and is short-circuited between the left and right current lines.

  10A and 10B are examples in which a specific area is used as a reference area. In FIG. 10A, the central part of the image shown in white is the reference area, and the part shown by surrounding shading is the other area. On the other hand, in FIG. 10B, the peripheral portion of the image shown in white is the reference region, and the portion shown in the middle shade is the other region.

  FIG. 10C and FIG. 10D show the target areas of the light control processing in the case where the inspection target is the white block shown in FIGS. 10A and 10B, respectively. In FIG. 10C, the vicinity of the center of the image is adjusted to an appropriate brightness by the dimming process, which is suitable for obtaining an image displayed in detail with respect to the short-circuited portion. On the other hand, in FIG. 10D, since the peripheral area of the image is adjusted to an appropriate brightness by the dimming process, it is suitable for obtaining an image displayed in detail with respect to the wiring (pattern) of the two current lines. ing. In this way, the light control processing suitable for the inspection is performed by appropriately setting the reference region for the inspection target.

  For example, when the detailed position of the defect to be inspected is already known and the defect is to be examined in detail, the defect portion is specified in detail by designating the reference area as shown in FIG. 10A. An image suitable for examination can be obtained. On the other hand, when the position of the defect is not known in detail, the defect portion is extracted by comparing the defect image with an image of the same pattern without the defect. In this case, by designating the reference area as shown in FIG. 10B, the pattern portion is displayed with appropriate brightness, and therefore, it can be used to extract a portion different from the normal pattern as a defect.

  10A and 10B are examples in which a reference area is specified, but the present invention is not limited to this. For example, as described above, the entire image may be used as the reference area. Information about the reference area is stored in the designated area information storage unit 504 in FIG. For example, in the case of a rectangular reference area, the coordinate value may be information such as the upper left and lower right position coordinates of the rectangular portion. For example, the reference area may be represented by a logical value such as “1”, and other than the reference area may be represented by a logical value such as “0”. Further, the reference area is not limited to one type. For example, as shown in FIG. 10A and FIG. 10B, it has a plurality of reference areas, and according to the contents of the inspection, etc., to select which reference area to use for the dimming process according to an instruction from the computer 53 Also good.

  As described above, even if the dimming process is performed based on the dimming level changing step calculated from the dimming table, the dimming level after the dimming process is not necessarily changed as shown in FIG. Absent. This is due to a quantization error in gradation of the acquired image, a quantization error in a mechanism that is driven when the amount of light is changed, and the like. The gradation quantization error is an error that occurs when, for example, the gradation is discretized in 256 levels. The quantization error in the mechanism that is driven when the amount of light is changed is, for example, an error due to a loss of accuracy that is equal to or less than the drive amount corresponding to one pulse in the stepping motor.

  Comparing the dimming level as an estimated value theoretically obtained from the dimming table with the dimming level after actually executing the dimming process, and correcting the dimming table based on the deviation amount . In the present embodiment, the dimming table characteristics are updated using the least square method.

  FIG. 11 is a diagram for explaining a method for correcting a shift in light control level. The vertical axis represents the light control level, and the horizontal axis represents the luminance level of the image. In FIG. 11, the dimming table characteristic before correction is represented by CF, and the effective maximum luminance in the reference area is represented by PS1.

  FIG. 12 is a flowchart of processing for correcting the light control table according to the present embodiment. The processing shown in FIG. 12 is executed by a predetermined program stored in the memory of the computer 53.

  First, in step S51, the reference luminance value PS1 is obtained from the current input image that is the subject of the dimming process. Here, as described above, PS1 is the maximum luminance value in the reference region, and corresponds to the effective maximum luminance.

  Next, in step S52, a target luminance value PS2 is determined, and a dimming level changing step for dimming the reference luminance value PS1 to the target luminance value PS2 is calculated based on the current dimming table characteristic CF. The light quantity is changed based on the calculated dimming level changing step. In step S53, an image after actually changing the amount of light is acquired, and a reference luminance value PS3, which is the maximum luminance value of the reference region, is obtained.

  Finally, in step S54, the target luminance value PS2 is compared with the reference luminance value PS3. If the difference between the two is a predetermined value or more, the dimming table characteristic CF in step S52 is corrected by the least square method, and the new dimming table characteristic CF ′ is used for the subsequent dimming process.

The least square method applied in the present embodiment in order to update the dimming table characteristics will be described.
Formula (1) representing the dimming table characteristics is generalized, and the reference luminance value PS1 of the input image is changed to y (0), and the reference luminance value PS2 of the image when the dimming level is changed by n steps from y (0). When y (n) is a light amount change at the light control level of one step, x is expressed by the following equation (6).

y (n) = y (0) × 2 ^ (n × x) (6)
The light quantity change x corresponds to a change of (x−EV).
When the equation (6) is logarithmically transformed and replaced with Y = log (y (n)), B = log (y (0)), A = x and X = n × log2, as shown in the following equation: Expressed as a linear function.

Y = B + A × X (7)
From the equation (6), data for P X and Y are obtained. Here, P pieces of data are calculated by using a plurality of dimming level changing n steps. When the sum of P pieces of data X and Y is represented by Σ, A and B are represented by the following equations (8) and (9) by solving equation (7) by the least square method, respectively.

  Here, the light quantity change x, that is, A at the dimming level in one step is obtained from the equation (8). The obtained A is applied to the exponent part of equation (1). With this application, for example, when the exponent part becomes larger than the designed value, the change in the light amount at the light control level in one step, that is, the value on the left side of the equation (1) becomes large. When the exponent part becomes smaller than the designed value, the change in the light amount at the light control level in one step, that is, the value Y on the left side of the equation (1) becomes smaller.

  If there is no data that deviates greatly from the theoretical characteristics, the correction process has a relatively small influence on the dimming table, and the dimming table characteristics can be corrected with the entire influence minimized. In the present embodiment, by changing this x, the registered value of the light amount corresponding to each light control level is changed.

  The above-described correction of the dimming table characteristics may be performed every time the dimming process is performed on the image referred to in the inspection process. In the initial setting before the start of inspection, a sample substrate or the like may be prepared in advance, and the dimming table characteristics may be corrected in advance. By correcting the dimming table in advance using the object to be inspected, the dimming table that has already been corrected can be used when performing inspection, and it is necessary to correct the dimming table during inspection. As a result, tact time is improved.

  As described above with reference to FIGS. 11 and 12, the theoretically derived luminance value after dimming is compared with the luminance value obtained from the actual dimming process, and the dimming table characteristics are corrected. As a result, the dimming process can be performed using the dimming table in accordance with the object to be inspected to be imaged by the inspection apparatus 1, the configuration of the inspection apparatus 1, and the like.

  In the inspection apparatus 1 according to the present embodiment, in order to change the light amount based on the calculated dimming level changing step, for example, a method by controlling the light amount of the camera or the light amount of the illumination system of the microscope is controlled. There is a method. Control information is defined as, for example, the shutter opening time of the camera and the angle of the deflection beam splitter (PBS) used in the illumination system of the microscope for controlling the amount of light.

  FIG. 13A is a diagram for explaining the relationship between the shutter opening time of the camera, which is control information, and the light control level set by the control information. In FIG. 13A, the shutter release time, which is control information, is plotted on the vertical axis, the dimming level set by the shutter open time is plotted on the horizontal axis, and the vertical axis is a logarithmic axis.

  When dimming according to the shutter opening time of the camera, as shown in FIG. 13A, the logarithm of the shutter opening time and the dimming level of the camera have a linear relationship. Also, in the shutter opening time region where the camera control light control level takes a positive value, the shutter opening time is longer than 1/30 second of the frame rate. For this reason, the shutter opening time is controlled with a finer light control level so that the accuracy does not deteriorate.

  FIG. 13B is a diagram for explaining the relationship between the angle of the PBS, which is control information, and the light control level set by the control information. In FIG. 13B, the angle of PBS, which is control information, is plotted on the vertical axis, and the dimming level set by the PBS angle is plotted on the horizontal axis. Note that the PBS is disposed in the dimming unit 102 of FIG. 1 and changes the amount of illumination light by rotating in the range of 0 ° to 90 ° around the illumination optical axis of the ultraviolet illumination light source 11.

  As shown in FIG. 13B, the amount of light output from the illumination system is adjusted by changing the angle of the PBS. Based on the relationship of FIG. 13B, the amount of light can be finely adjusted by control information about the illumination system.

  As described above, in the present embodiment, even if the image to be dimmed is significantly different from the target brightness, or even when overexposure or blackout occurs, the dimming table Based on the characteristics, the light can be adjusted to an appropriate brightness in a short time. Furthermore, even if the dimming table characteristics have an error between the theoretical characteristics and the actual one, it is possible to adjust the brightness to an appropriate brightness in a short time by correcting the deviation. It is said.

  Note that although the inspection apparatus has been described in the present embodiment, the present invention is not limited to this. The same operation and effect can be obtained even with a program that executes the above-described light control processing, a recording medium that stores the program, a microscope apparatus that includes the program, an image processing apparatus, and the like.

<Embodiment 2>
In the first embodiment, the least square method is used when correcting the dimming table characteristics. However, in the second embodiment, the dimming table characteristics are corrected only for regions different between the theoretical value and the actual value. It differs in the point to do. Hereinafter, differences from the first embodiment will be mainly described.

  FIG. 14 is a diagram for explaining a method for correcting the relationship between the luminance level of the image and the dimming level in the present embodiment. In FIG. 14, the vertical axis represents the luminance level of the image, and the horizontal axis represents the dimming level. In FIG. 14, a part of the graph of FIG. 5A is indicated by a solid line, and a graph indicating the relationship between the actual light control level and the luminance is indicated by a broken line.

  As shown in FIG. 14, there is a difference between a theoretical value represented by a black rhombus and an actual measurement value represented by a white square for a certain dimming level. It is assumed that processing for reducing the influence of noise is performed by applying an averaging filter to a local region of an image before obtaining an actual measurement value. When the influence of noise is small, the influence due to the difference between the theoretical value and the actual measurement value is small if the luminance is small, and the influence due to this difference is large if the luminance is large. Therefore, in the present embodiment, each dimming level is corrected based on the difference between the luminance estimated from the designed dimming table characteristics and the actual luminance.

  At the dimming level X, the luminance derived from the design (before correction) dimming table characteristics is estimated luminance Yest (X), and the actual luminance value obtained by actual dimming processing is Ymea (X). The correction coefficient (offset coefficient) Cor (X) is defined by the following equation (10).

Cor (X) = (Ymea (X) -Yes (X)) / Yes (X) (10)
The offset coefficient Cor (X) represents the ratio of the difference in the actually measured luminance value Ymea (X) with respect to the luminance Yest (X) estimated from the dimming table. When the actual measurement value Ymea (X) of the luminance is larger than the estimated luminance Yest (X), Cor (X)> 0. On the other hand, when the measured luminance value Ymea (X) is smaller than the estimated luminance Yest (X), Cor (X) <0. For example, Yes (X) = 100. At this time, if Ymea (X) = 103, Cor (X) = 0.03 from the equation (10). If Ymea (X) = 97, then Cor (X) = − 0.03. If Ymea (X) = 100 and the theoretical value and the actual measurement value match, then Cor (X) = 0.

  In the present embodiment, the dimming process is performed by sequentially converting the luminance using the offset coefficient Cor (X). For example, assume that the dimming level changing step is calculated for the luminance Y1 (XX) of the image acquired at the dimming level XX. In this case, when referring to the dimming table characteristics, the luminance is converted into Y2 (XX) as shown in the following equation (11) using the offset coefficient Cor (XX) at the dimming level XX.

Y2 (XX) = Y1 (XX) × (1-Cor (XX)) (11)
The luminance Y1 (XX) is corrected to Y2 (XX) so as to substantially match the designed dimming table characteristics by the equation (11). For example, Y1 (XX) = 103 and Cor (XX) = 0.03. At this time, Y2 (XX) = 99.91 is obtained from the equation (11). When Y1 (XX) = 97 and Cor (XX) = − 0.03, Y2 (XX) = 99.91 is obtained. In this way, correction is performed so as to substantially match the original design value of 100.

  When calculating the dimming level changing step, the target luminance Jobj is necessary. When the dimming level determined by the dimming level changing step is X ′, the target luminance Job (X ′) at this time is It can be estimated from the following equation (12).

Job (X ′) = Job × Cor (X ′) (12)
Reference is made to whether or not the obtained Job (X ′) is within the target luminance range. Take. By appropriately increasing or decreasing the dimming level changing step, it is possible to suppress the influence of the deviation of the dimming table characteristics on the dimming process. Unlike the first embodiment, the present embodiment can be applied even when the characteristic cannot be modeled as a mathematical expression. In other words, even when there is a local area where the deviation between the dimming table characteristics and the actual measurement values is large, the correction method according to this embodiment can be applied to affect the entire dimming table. The dimming table is appropriately corrected at a position where there is a deviation while keeping it to a minimum.

  Note that the correction method using the offset coefficient in the present embodiment may be executed every time the light control process is performed. Further, in the initial setting before the dimming process is executed, the dimming table may be corrected in advance using an object to be inspected.

  As described above, in the microscope apparatus according to the present embodiment, the light adjustment table is appropriately corrected even when there is a local deviation between the light adjustment table and the actual measurement value. The light can be adjusted to the appropriate brightness over time.

  Although the inspection apparatus has been described in the present embodiment, the present invention is not limited to this, but is the same as in the first embodiment. The same operation and effect can be obtained even with a program that executes the above-described light control processing, a recording medium that records the program, a microscope apparatus that includes the program, and an image processing apparatus.

It is a block diagram of the inspection apparatus provided with the image processing apparatus which concerns on this embodiment. It is a block diagram of an image processing part. It is a figure explaining the relationship between the light quantity of a camera, and the illumination light quantity from the illumination light source of a microscope. It is a figure explaining the relationship between the light control level when the light control level is actually changed based on the light control level. It is FIG. (1) explaining the relationship between a light control level and the brightness | luminance of an image. It is FIG. (2) explaining the relationship between a light control level and the brightness | luminance of an image. It is a schematic diagram explaining the relationship between the brightness | luminance of an image, and the variation | change_quantity of the light quantity adjusted by a light control process. It is the figure which showed the model of the light control level. It is a flowchart about the basic operation | movement of a light control process. It is a flowchart of the light control process in case a luminance level is outside a gradation reproduction range. It is an example (the 1) which makes a specific area | region a reference area. It is an example (the 2) which makes a specific area | region a reference area. It is an example (the 1) of the image which showed the specific area | region as the reference area with respect to the to-be-inspected object. It is an example (the 2) of the image which showed the specific area | region as the reference area with respect to the to-be-inspected object. It is a figure explaining the method of correct | amending the shift | offset | difference of a light control level. 3 is a flowchart of processing for correcting a light control table according to the first embodiment. It is a figure explaining the relationship between the shutter opening time of a camera, and the light control level set by the shutter opening time. It is a figure explaining the relationship between the angle of a polarizing beam splitter, and the light control level set by the angle of a polarizing beam splitter. FIG. 10 is a diagram illustrating correction of a relationship between an image luminance level and a dimming level in the second embodiment. It is a flowchart of the conventional light control process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inspection apparatus 52 Capture board 53 Computer 54 Monitor 100 Microscope 102 Dimming part 110 Image processing part (image processing apparatus)

Claims (13)

In an image processing apparatus for adjusting the brightness of an image obtained from an imaging device and displaying it on a display screen,
Luminance information calculation means for calculating luminance information based on luminance in a predetermined region of the image when the image obtained from the imaging device is displayed on the display screen;
A look-up table showing the relationship between the amount of light incident on the imaging device and the dimming level adjusted by controlling the amount of incident light;
A dimming level change amount calculating means for calculating a dimming level change amount for the image based on the luminance information and the lookup table;
A light amount control information generating means for comparing the amount of change of the light control level with the current light control level and generating light amount control information for the light amount to be changed;
An image processing apparatus comprising: control means for controlling the amount of light incident on the imaging device based on the light amount control information. Determination means for determining whether or not the value of the luminance information is included in a predetermined range;
Further comprising
The luminance information calculating means calculates first luminance information in a first region of the image and second luminance information in a second region;
When the determination unit determines that the value of the first luminance information is not within the predetermined range, the dimming level change amount calculation unit is based on the second luminance information and the lookup table. The image processing apparatus according to claim 1, wherein an amount of change in light control level for the image is calculated. The luminance information calculating unit calculates the updated luminance information in the predetermined region after the incident light amount is controlled by the control unit;
A comparison means for comparing the updated luminance information with the luminance estimated based on the lookup table;
The image processing apparatus according to claim 1, further comprising a lookup table update unit that updates the lookup table based on a comparison result of the comparison unit. The image processing apparatus according to claim 1, wherein the luminance information includes a maximum luminance value or a minimum luminance value in the predetermined area. The said determination means defines the reproduction area where the gradation of an image is reproduced, and determines whether the said brightness | luminance information is contained in the range of the said reproduction area. Image processing device. The second region is a region different from the first region, and the second luminance information is a maximum luminance value or a minimum luminance value in the second region. Item 3. The image processing apparatus according to Item 2. The image processing apparatus according to claim 3, wherein the look-up table update unit updates the look-up table using a least square method. The look-up table updating means updates the look-up table using an offset between the updated luminance information after the luminance is controlled and the luminance estimated based on the lookup table. The image processing apparatus according to claim 3. The image processing according to claim 1, wherein the light amount control information includes light amount control information about the imaging device and light amount control information about an illumination device that irradiates an imaging target of the imaging device. apparatus. The image processing apparatus according to claim 1, wherein the light amount control information includes information related to an exposure time of the imaging apparatus. In a microscope apparatus that acquires an image of an object to be inspected through a microscope with an imaging device, and adjusts the brightness of the image obtained from the imaging device and displays it on a display screen.
Luminance information calculation means for calculating luminance information based on luminance in a predetermined region of the image when the image obtained from the imaging device is displayed on the display screen;
A look-up table showing the relationship between the amount of light incident on the imaging device and the dimming level adjusted by controlling the amount of incident light;
A dimming level change amount calculating means for calculating a dimming level change amount for the image based on the luminance information and the lookup table;
A light amount control information generating means for comparing the amount of change of the light control level with the current light control level and generating light amount control information for the light amount to be changed;
A microscope apparatus comprising: control means for controlling the amount of light incident on the imaging device based on the light amount control information. In an inspection apparatus that acquires an image to be inspected with an imaging apparatus, adjusts the brightness of the image obtained from the imaging apparatus and displays the image on a display screen for inspection,
Luminance information calculation means for calculating luminance information based on luminance in a predetermined region of the image when the image obtained from the imaging device is displayed on the display screen;
A look-up table showing the relationship between the amount of light incident on the imaging device and the dimming level adjusted by controlling the amount of incident light;
A dimming level change amount calculating means for calculating a dimming level change amount for the image based on the luminance information and the lookup table;
A light amount control information generating unit that compares the amount of change of the light control level with the current light control level and generates light amount control information for the light amount to be changed;
An inspection apparatus comprising: control means for controlling the amount of light incident on the imaging device based on the light amount control information. In an image processing program for causing a computer to execute a process of adjusting the brightness of an image obtained from an imaging device and displaying it on a display screen,
Calculating luminance information based on luminance in a predetermined region of the image when the image obtained from the imaging device is displayed on the display screen;
Based on the luminance information and a look-up table showing the relationship between the amount of incident light to the imaging device and the amount of dimming adjusted by controlling the amount of incident light, the amount of change in the dimming level for the image is calculated. Calculate
Compare the amount of change in the dimming level with the current dimming level, and generate light amount control information for the amount of light to be changed,
An image processing program for executing processing for controlling the amount of light incident on the imaging device based on the light amount control information.