JP2014085600A - Microscope - Google Patents

Abstract

Even when a correction process such as gradation conversion and a plurality of captured images captured by changing exposure conditions are combined to generate an observation image, a quick and accurate autofocus process can be executed. Providing a microscope.
An image sensor that has a plurality of pixels that receive light from a sample, captures an image of the sample, and acquires image data; and at least smaller than a predetermined value in a gradation range of luminance values in the image data An image processing unit for generating display image data and focusing image data by performing γ correction using a tone curve on a portion having a luminance value, a display unit for displaying display image data, and image processing And a control unit that performs control for automatically focusing the sample image based on the focus image data that has been γ-corrected by the image processing unit, and the image processing unit is configured to display the display image data displayed on the display unit. The image data for focusing is generated using a γ value smaller than the γ value of the γ correction performed in the above.
[Selection] Figure 1

Description

  The present invention relates to a microscope having a function of forming an image of a sample to be observed and capturing the image.

  2. Description of the Related Art In recent years, in the field of a microscope, an image pickup apparatus such as a digital camera having an autofocus (AF) function is mounted and an image (observation image) captured by the image pickup apparatus is displayed on a display unit. . In AF processing of an image pickup apparatus, a method (contrast AF) in which adjacent pixels in an image pickup device such as a CCD are compared and contrast calculation is performed, and a position where the contrast calculation value is maximized is used as a focus position (contrast AF) has been put into practical use .

  In contrast AF in microscopic observation, imaging is performed while changing the position of a focusing unit such as a stage that moves in the vertical direction (Z direction) by electric control (hereinafter referred to as the Z position), and then from a control unit such as a CPU. A hill-climbing method for acquiring Z position information, registering the Z position information as image position information, and searching for an in-focus position with the maximum contrast value from the result of contrast calculation has been widely put into practical use. In contrast calculation in this hill-climbing method, calculation is generally performed by averaging the difference between adjacent pixels or the square of the difference between adjacent pixels over the entire pixel or a specified range.

  As an example of contrast AF, a technique for performing contrast AF while moving the stage from the AF start position at a fine pitch is disclosed (for example, see Patent Document 1). In this technique, in order to speed up contrast AF, a coarse focus operation with a large stage drive pitch (hereinafter referred to as “Rough scan”) and a fine focus operation with a small stage drive pitch (hereinafter referred to as “Fine scan”). The following two types of AF processing are performed. More specifically, in this technique, after finding a rough focus position by the Rough scan, an accurate focus position is found by the Fine scan.

  For example, the focusing portion is driven in the Z direction, a contrast peak (position exceeding the threshold) is detected by the rough scan, and the in-focus position in the sample Sp is found from the detected peak position by the fine scan. FIG. 13 is a diagram for explaining the conventional contrast AF, and is a diagram illustrating an example of a contrast curve.

  By the way, when the sample to be imaged has a concavo-convex shape, the difference in light reflectance between the reflecting surface and the non-reflecting surface when irradiated with illumination light is large. The part corresponding to the non-reflective surface becomes dark, and when the exposure condition is set according to the non-reflective surface, the part corresponding to the reflective surface of the image becomes bright. As a result, there is a problem that the uneven shape cannot be clearly expressed in the observation image.

  On the other hand, by performing correction processing such as gradation conversion on the captured image, for example, gradation conversion correction (tone curve correction), the uneven shape is generated as a clear image. I was trying to do it. In tone conversion correction (tone curve correction), tone conversion of an input image is performed based on a curve (tone curve) corresponding to a γ value indicating tone response characteristics, and shading correction is performed in the image. In general, correction is performed to brighten dark portions in an image by performing tone curve correction with a γ value of γ> 1.

  As another method for generating a concavo-convex shape as a clear image, a technique for generating an observation image by synthesizing a plurality of captured images captured by changing exposure conditions is known (see, for example, Patent Document 2). ).

JP-A-10-197784 JP 2008-301331 A

  However, a captured image obtained by performing correction processing such as gradation conversion on an image is dark when obtained at a position greatly deviating from the in-focus position, and gradually becomes brighter as it approaches the in-focus position. At this time, the contrast of the image at a position greatly deviating from the in-focus position may be larger than the contrast of the image at a position close to the in-focus position (see FIG. 14). In this case, the contrast of the image at a position greatly deviating from the focus position at the time of contrast AF is erroneously detected as a peak, and as a result, erroneous detection (false focus) of the focus position is caused.

  In addition, in a method of generating an observation image by combining a plurality of captured images captured by changing exposure conditions, when performing contrast AF, the image acquisition timing must be an interval according to the depth of focus of the imaging device. The peak of contrast cannot be detected. The pitch at the time of scanning depends on the depth of focus of the imaging device. When this pitch is constant, the time required for contrast AF depends on the video signal capture time (frame rate).

  Further, when an observation image is generated by combining a plurality of captured images, there is a problem that processing takes time because a plurality of images are processed. For this reason, reduction of the time required for AF processing has been demanded for the purpose of shortening the processing time.

  The present invention has been made in view of the above, and it is quick even when a plurality of captured images captured by changing a correction process such as gradation conversion and exposure conditions are combined to generate an observation image. An object of the present invention is to provide a microscope capable of executing accurate autofocus processing.

  In order to solve the above-described problems and achieve the object, a microscope according to the present invention condenses light from a sample placed on a stage by an objective lens, and the above-described light is collected based on the collected light. A microscope that generates image data for observation by capturing an image of a sample, the microscope having a plurality of pixels that receive light from the sample, and capturing the image of the sample to acquire image data Γ correction using a tone curve is applied to a portion having a luminance value smaller than a predetermined value in at least the luminance value gradation range in the image data for the element and the sample image acquired by the imaging device. An image processing unit that generates display image data and focusing image data, a display unit that displays the display image data that has been γ-corrected by the image processing unit, and γ correction that is performed by the image processing unit. A control unit that performs control for automatically focusing the image of the sample based on the focused image data, and the image processing unit applies the display image data displayed on the display unit to the display image data. The in-focus image data is generated using a γ value smaller than the γ value of the γ correction applied thereto.

  In the microscope according to the present invention as set forth in the invention described above, the image processing unit generates the focusing image data using the tone curve having a γ value of γ <1.

  In the microscope according to the present invention, in the above invention, the image processing unit has a γ value of a portion having a luminance value greater than or equal to a predetermined value in a gradation range of the luminance value in the image data being γ> 1. The focus image data is generated using an S-shaped tone curve.

  In the microscope according to the present invention as set forth in the invention described above, the control unit resets the γ value after the focusing process is completed.

  The microscope according to the present invention is characterized in that, in the above invention, the control unit resets the γ value to the γ value before the focusing process after the focusing process is completed.

  The microscope according to the present invention condenses the light from the sample placed on the stage by the objective lens, and takes an image of the sample based on the collected light. A microscope for generating data, which includes a plurality of pixels that receive light from the sample, captures an image of the sample, acquires image data, and the sample acquired by the image sensor An image processing unit that performs histogram correction on the image, and a control unit that performs control to automatically focus the image of the sample based on image data that has been histogram corrected by the image processing unit. Features.

  In the microscope according to the present invention as set forth in the invention described above, the control unit synthesizes a plurality of the image signals having different exposure conditions.

  According to the present invention, in the AF process, the contrast is calculated using an image that has been corrected by a value smaller than the γ value of the γ correction performed at the time of display (observation) or that has been subjected to histogram correction. The effect that it is possible to execute a quick and accurate autofocus process even when an observation image is generated by combining a plurality of captured images captured by changing correction processing such as gradation conversion and exposure conditions. Play.

FIG. 1 is a schematic diagram illustrating an overall configuration of a microscope according to the first embodiment of the present invention. FIG. 2 is a flowchart showing AF processing performed by the microscope according to the first embodiment of the present invention. FIG. 3 is a flowchart showing a focusing process performed by the microscope according to the first embodiment of the present invention. FIG. 4 is a diagram for explaining a focusing process performed by the microscope according to the first embodiment of the present invention. FIG. 5 is a diagram showing an example of an image before the correction process is performed in the first embodiment of the present invention. FIG. 6 is a diagram showing an example of an image after the correction process is performed in the first embodiment of the present invention. FIG. 7 is a diagram illustrating an example of an image after a conventional correction process is performed. FIG. 8 is a schematic diagram illustrating an overall configuration of a microscope according to the second embodiment of the present invention. FIG. 9 is a flowchart showing AF processing performed by the microscope according to the second embodiment of the present invention. FIG. 10 is a diagram showing an example of an image after the correction process is performed in the second embodiment of the present invention. FIG. 11 is a diagram showing an example of an image before the correction process is performed in the third embodiment of the present invention. FIG. 12 is a diagram showing an example of an image after the correction process is performed in the third embodiment of the present invention. FIG. 13 is a diagram for explaining conventional contrast AF. FIG. 14 is a diagram for explaining conventional contrast AF.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by the following embodiment. The drawings referred to in the following description only schematically show the shape, size, and positional relationship so that the contents of the present invention can be understood. That is, the present invention is not limited only to the shape, size, and positional relationship illustrated in each drawing.

(Embodiment 1)
FIG. 1 is a schematic diagram illustrating an overall configuration of a microscope according to the first embodiment of the present invention. The microscope 1 shown in FIG. 1 has an autofocus (AF) function, and includes a microscope mount 2, a stage 3, a light projection tube 4, an imaging device 5, a control device 6, and a display device 7.

  The microscope mount 2 includes a stage support portion 21 that fixes and supports the stage 3, a light projection tube support portion 22 that supports the light projection tube 4 so as to move up and down, and a drive motor that controls the vertical movement of the light projection tube 4. And a control unit 23.

  The drive motor control unit 23 moves the light projecting tube 4 and the imaging device 5 up and down by driving a drive motor 45 included in the light projecting tube 4 based on the motor drive amount sent from the control device 6.

  The light projecting tube 4 includes an imaging optical system 41, a light source 42, a light source control unit 43, a half mirror 44, and a drive motor 45. The light projecting tube 4 holds the objective lens 8.

  The light emitted from the light source 42 is reflected by the half mirror 44 and applied to the sample Sp placed on the stage 3 via the objective lens 8. On the other hand, the light reflected by the sample Sp passes from the objective lens 8 via the half mirror 44, passes through the imaging optical system 41, is condensed by the image sensor 51, and is photoelectrically converted into an electric signal.

  The drive motor 45 has a function of a drive unit that drives the light projecting tube 4 and the imaging device 5. Hereinafter, the light projecting tube 4 and the imaging device 5 are collectively referred to as a “head portion”.

  The imaging device 5 includes an imaging device 51 such as a CCD or a CMOS, a signal processing unit 52 that performs signal processing such as A / D conversion on a signal acquired by the imaging device 51, and the imaging device 5 (the imaging device 51 and the signal). And an imaging control unit 53 that controls the operation of the processing unit 52).

  The control device 6 includes an input unit 61, a contrast calculation unit 62, an image processing unit 63, a storage unit 64, and a control unit 65. The contrast calculation unit 62 receives image data from the imaging device 5 and performs contrast calculation for calculating a contrast value of the image data.

  The image processing unit 63 performs, for example, white balance (WB) adjustment processing, gain adjustment processing, γ correction processing, D / A conversion processing, format change processing, and the like. The image processing unit 63 combines the target images (image signals having different exposure conditions) when the image generation mode is set to the multiple image combining mode, and generates one observation image. Generate. Hereinafter, with a predetermined value (for example, the median value) in the gradation range of the luminance value in the image as a boundary, a portion having a luminance value smaller than the median value is referred to as a dark portion, and a portion having a luminance value greater than the median value is referred to as a bright portion.

  In the white balance adjustment process, the white balance of the RGB image signal is automatically adjusted. Specifically, the white balance adjustment process automatically adjusts the white balance of the RGB image signal based on the color temperature included in the RGB image signal.

  In the gain adjustment process, the gain of the RGB image signal is adjusted. In the γ correction process, gradation correction (γ correction) of the RGB image signal is performed. At this time, the image processing unit 63 uses different γ values for the image data (display image data) to be displayed on the display device 7 and the image data (focusing image data) used during the focusing process by the control unit 65. Is used to perform γ correction. In the first embodiment, in the γ value for the focusing image data, the γ value indicating the tone response characteristic is set so that the γ value is γ <1 for all inputs. On the other hand, the γ value for the display image data is set to γ> 1, for example. Then, based on the tone curve corresponding to the γ value, tone correction of the image acquired by the imaging device 5 is performed. In the γ correction for the focusing image data, the γ value indicating the tone response characteristic is set so as to satisfy γ <1, but any value including a region where γ <1 can be set.

  In the D / A conversion process, the RGB image signal after gradation correction is converted into an analog signal. In the format change process, the image signal converted into the analog signal is changed to a predetermined file format and output to the display device 7.

  The storage unit 64 stores a program (application software) that controls the operation of the microscope 1. The storage unit 64 also stores information related to the imaging process (frame rate, exposure time (shutter speed), brightness of the light source 42 (gain), etc.). The storage unit 64 is realized by, for example, a semiconductor memory such as a flash memory, a RAM, and a ROM, a recording medium such as an HDD, MO, CD-R, and DVD-R, and a drive device that drives the recording medium.

  The control unit 65 is configured using a CPU or the like, and comprehensively controls the operation of the microscope 1 as a whole. The control unit 65 performs autofocus for automatically focusing the image of the sample Sp. The control unit 65 writes and stores the maximum value of the calculation result by the contrast calculation unit 62 and the Z coordinate when the maximum value is obtained in the storage unit 64. The control unit 65 transmits an instruction signal for adjusting the brightness of the light source 42 to the light source control unit 43.

  The display device 7 includes a monitor screen for displaying a microscope image or the like corresponding to the display image data, and a microscope operation GUI touch panel. A touch panel is laminated | stacked on a monitor screen, and receives the input signal according to the contact position from the outside.

  In the microscope 1 having the above configuration, when an instruction to perform autofocus (AF) processing is input to the input unit 61 via the touch panel, AF processing is executed under the control of the control unit 65. FIG. 2 is a flowchart illustrating AF processing performed by the microscope 1 according to the first embodiment.

  First, when an instruction to perform autofocus (AF) processing is input, the control unit 65 determines whether or not the currently set mode is the multiple-sheet composition mode (step S101). Here, when the control unit 65 determines that the multiple sheet combining mode is set (step S101: Yes), the control unit 65 turns off the setting of the multiple sheet combining mode (step S102). Thereafter, the control unit 65 proceeds to step S103.

  On the other hand, when it is determined that the setting mode is not the multiple-sheet combining mode (step S101: No), the control unit 65 proceeds to step S103.

  The control unit 65 sets the γ value of the gradation conversion function to γ <1 in a state where the multiple sheet combining mode is not set (step S103). Thereafter, the control unit 65 performs a focusing process described later (step S104). After the focusing process is completed, the control unit 65 resets the γ value to the value before setting in step S103 (step S105).

  Thereafter, the control unit 65 determines whether or not the mode to be set is the multiple-sheet composition mode (step S106). Here, when the mode to be set is the multiple sheet combining mode (step S106: Yes), the control unit 65 turns on the multiple sheet combining mode and ends the process (step S107). On the other hand, when the mode to be set is not the multi-sheet composition mode (step S106: No), the control unit 65 ends the process without resetting the mode.

  Here, the focusing process in step S104 of FIG. 2 will be described with reference to FIGS. FIG. 3 is a flowchart illustrating the focusing process performed by the microscope according to the first embodiment. FIG. 4 is a diagram for explaining a focusing process performed by the microscope according to the first embodiment.

  The control unit 65 sends a signal to the drive motor control unit 23 to drive the drive motor 45 so that the head unit moves to a predetermined start position (step S201). For example, the head unit moves a distance of AF range / 2 toward the Near direction by driving the drive motor 45.

  Next, the control unit 65 outputs an instruction signal for driving the drive motor 45 at a predetermined coarse search pitch to the drive motor control unit 23 (step S202). The head unit moves in the Far direction at a rough search pitch by driving of the drive motor 45.

  Subsequently, the control unit 65 acquires image data captured by the imaging device 5 (step S203), and performs γ correction processing on the image data (step S204). Thereafter, contrast calculation is performed on the image data (focusing image data) that has been subjected to the γ correction processing (step S205). Here, the image data used for the contrast calculation is at least γ-corrected by the image processing unit 63. Thereby, the contrast curve CA by the rough search is obtained.

Thereafter, the control unit 65 determines whether or not a search end condition is satisfied (step S206). The conditional expression for the search end condition is given by the following expression (1).
Contrast calculation peak value × 1/2> current contrast value (1)
Note that another value smaller than 1 may be applied instead of 1/2 of the left side. Further, instead of applying the expression (1) as the search end condition, for example, the search may be ended when the value of the contrast calculation becomes small a predetermined number of times after the peak value is exceeded.

  When the search condition is satisfied in step S206 (step S206: Yes), the control unit 65 proceeds to step S207. On the other hand, when the search condition is not satisfied in step S206 (step S206: No), the control unit 65 returns to step S202.

  In step S207, the control unit 65 calculates a fine search start position that is a position returned by a predetermined distance Dp in the Near direction from the detected peak position (detected peak position) (step S207).

  Subsequently, the control unit 65 sends a signal to the drive motor control unit 23 to drive the drive motor 45 to move the head unit to the fine search start position calculated in step S207 (step S208).

  Thereafter, the control unit 65 transmits a signal to the drive motor control unit 23 to drive the drive motor 45 at a predetermined fine search pitch (step S209). Thereafter, the control unit 65 acquires image data captured by the imaging device 5 (step S210), and performs contrast calculation (step S211). Here, the image data used for the contrast calculation is at least γ-corrected by the image processing unit 63. Thereby, a contrast curve CB by fine search is obtained.

  Subsequently, the control unit 65 determines whether or not the search end condition of the above formula (1) is satisfied (step S212). As a result of the determination, if the search end condition is satisfied (step S212: Yes), the head portion is moved to the detection peak position (step S213), and a series of focusing processes is ended. On the other hand, when the search condition is not satisfied in step S211 (step S212: No), the control unit 65 returns to step S209.

Here, when the maximum luminance value is I _MAX , x is the luminance value of the image data input to the image processing unit 63, and y is the luminance value of the image data output from the image processing unit 63, the γ value is It is preferably set with reference to equation (2).

FIG. 5 is a diagram illustrating an example of an image before the correction process is performed in the first embodiment. FIG. 6 is a diagram illustrating an example of an image after the correction processing is performed in the first embodiment. FIG. 7 is a diagram illustrating an example of an image after a conventional correction process is performed. 5 to 7, (a) shows an actually captured image, and (b) shows that the γ value is γ = 1 (FIG. 5), γ <1 (FIG. 6), and γ> 1 (FIG. 7). (C) is a straight line connecting point A ₀ and point B ₀ and a straight line connecting point A ₁ and point B _{1 in} (a). FIG. 4 is a pixel-signal intensity graph (luminance profile) showing the signal intensity output from each pixel on the straight line connecting the point A ₂ and the point B ₂ .

  The image γ-corrected with γ <1 shown in FIG. 6A becomes clearer than the image before correction shown in FIG. 5A (an image γ-corrected with γ = 1). Yes. Further, it can be seen that the brightness profile in FIG. 6C has a larger difference between the peak and the dark part than the brightness profile in FIG. As a result, an image in which noise in the dark portion is reduced can be obtained from an image that has been γ corrected with γ <1. As a result, it is possible to prevent the contrast from becoming unnecessarily large even when imaging is performed at a position deviating from the focal position.

  On the other hand, the image γ-corrected with γ> 1 shown in FIG. 7A is clearer than the image before correction shown in FIG. 5A (an image γ-corrected with γ = 1). However, in the luminance profile of FIG. 7C, the intensity change in the dark part is large and the noise in the dark part is large compared to the luminance profile of FIG.

  According to the first embodiment described above, in the AF process, the contrast is calculated using an image that has been set to γ <1 and subjected to γ correction, so that the image is taken at a position that is out of the focus position. Even if it is a case where the contrast is suppressed from becoming unnecessarily large, and an observation image is generated by combining a plurality of captured images captured by changing correction processing such as gradation conversion and exposure conditions, A quick and accurate autofocus process can be executed.

  In the first embodiment of the present embodiment, it has been described that the contrast is calculated using an image that has been subjected to γ correction by setting γ <1 in the AF processing. However, the γ value at the time of the AF processing is the observation image. It is sufficient that it is smaller than the γ value at the time of display (observation).

(Embodiment 2)
FIG. 8 is a schematic diagram illustrating an overall configuration of the microscope 1a according to the second embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the component same as the structure demonstrated in FIG. The microscope 1a according to the second embodiment includes a control device 6a including an image processing unit 63a and a control unit 65a instead of the control device 6 described above.

  Similar to the image processing unit 63 described above, the image processing unit 63a performs, for example, white balance (WB) adjustment processing, gain adjustment processing, γ correction processing, D / A conversion processing, format change processing, and the like. The image processing unit 63a generates a single observation image by combining the target images when the image generation mode is set to the multiple image combining mode. When performing γ correction on the focusing image data, the image processing unit 63a performs correction processing using an S-shaped tone curve in which γ <1 on the dark side and γ> 1 on the bright side.

  The control unit 65a is configured using a CPU or the like, and comprehensively controls the operation of the entire microscope 1a. The control unit 65a performs autofocus for automatically focusing the image of the sample Sp. The control unit 65a writes and stores the maximum value of the calculation result by the contrast calculation unit 62 and the Z coordinate when the maximum value is obtained in the storage unit 64. The control unit 65 transmits an instruction signal for adjusting the brightness of the light source 42 to the light source control unit 43.

  In the microscope 1a, when an instruction to perform AF processing is input to the input unit 61 via the touch panel, the AF processing is executed under the control of the control unit 65a. FIG. 9 is a flowchart illustrating AF processing performed by the microscope 1a according to the second embodiment.

  First, when an instruction to perform AF processing is input, the control unit 65a determines whether or not the currently set mode is a multiple-sheet composition mode (step S301). Here, when the control unit 65a determines that the multiple-sheet combining mode is set (step S301: Yes), the control unit 65a turns off the setting of the multiple-sheet combining mode (step S302). Thereafter, the controller 65a proceeds to step S303.

  On the other hand, when it is determined that the setting mode is not the multiple-sheet combining mode (step S301: No), the control unit 65a proceeds to step S303.

  The controller 65a sets the tone conversion function graph to an S-shaped tone curve in a state where the multiple-sheet composition mode is not set (step S303). After that, the control unit 65a performs the above-described focusing process using the focusing image data that has been subjected to the γ correction by the S-shaped tone curve (step S304).

  After the focusing process is completed, the control unit 65a resets the γ value (gradation conversion function graph) to the value before the setting in step S303 (step S305).

  Thereafter, the control unit 65a determines whether or not the mode to be set is the multi-sheet composition mode (step S306). Here, when the mode to be set is the multiple-sheet combining mode (step S306: Yes), the control unit 65a turns on the multiple-sheet combining mode and ends the process (step S307). On the other hand, when the mode to be set is not the multi-sheet composition mode (step S306: No), the control unit 65a ends the process without resetting the mode.

FIG. 10 is a diagram illustrating an example of an image before the correction process is performed in the second embodiment. Here, FIG. 10A shows an actually captured image, and FIG. 10B is a graph showing a signal input / output relationship when the tone conversion function graph is an S-shaped tone curve. FIG. 10C is a pixel-signal intensity graph (luminance profile) showing the signal intensity output from each pixel on the straight line connecting the point A ₃ and the point B ₃ in FIG.

  The image that has been γ-corrected with the S-shaped tone curve shown in FIG. 10A is clearer than the image before correction shown in FIG. 5A (an image that has been γ-corrected with γ = 1). It has become. Further, in the luminance profile of FIG. 10C, it can be seen that the difference between the peak and the dark portion is larger than that of the luminance profile of FIG. As a result, an image in which noise in the dark portion is reduced can be obtained from an image that has been γ-corrected with an S-shaped tone curve. As a result, it is possible to prevent the contrast from becoming unnecessarily large even when imaging is performed at a position deviating from the focal position.

  According to the second embodiment described above, in the AF process, the contrast is calculated using an image that has been γ-corrected with an S-shaped tone curve. Even when there is an unnecessary increase in contrast, it is quick even when generating an observation image by combining multiple captured images captured by changing correction processing such as gradation conversion and exposure conditions. In addition, accurate autofocus processing can be executed.

  Further, according to the above-described second embodiment, γ correction is performed by the S-shaped tone curve to reduce the noise in the dark part, and the brightness value in the bright part is increased, so that the position deviated from the in-focus position. The contrast at the in-focus position can be increased. Thereby, false focusing can be suppressed.

(Embodiment 3)
FIG. 11 is a diagram showing an example of an image before the correction process is performed in the third embodiment of the present invention. FIG. 12 is a diagram illustrating an example of an image after the correction process is performed in the third embodiment. 11 and 12, (a) shows an actually captured image, and (b) shows a straight line connecting point A ₁₀ and point B _{10 in} (a) and points A ₄ and B ₄ . It is a pixel-signal intensity graph (luminance profile) indicating the signal intensity output by each pixel on the connecting line, and (c) is a luminance value indicating the frequency of each luminance value in the pixel-signal intensity graph shown in (b). It is a frequency graph (histogram). In the third embodiment, the image processing unit 63 or 63a of the first and second embodiments described above performs histogram correction on the focusing image data instead of γ correction.

  The histogram-corrected image shown in FIG. 12A is clearer than the uncorrected image shown in FIG. 11A. In addition, it can be seen that the peak of the peak is flattened in the luminance profile of FIG. 12B compared to the luminance profile of FIG. In addition, in the histogram of FIG. 12C, it can be seen that the frequency of the luminance value is flattened as compared with the histogram of FIG. Thereby, an image in which noise in a dark part is reduced can be obtained by an image subjected to histogram correction. As a result, it is possible to prevent the contrast from becoming unnecessarily large even when imaging is performed at a position deviating from the focal position.

  According to the third embodiment described above, since the contrast is calculated using the image subjected to the histogram correction in the AF process, the contrast is obtained even when the image is taken at a position out of the focus position. Quick and accurate autofocus processing even when generating an observation image by combining correction images such as tone conversion and changing the exposure conditions and combining multiple captured images to suppress unnecessary increase Can be executed.

  Further, according to the third embodiment described above, the contrast at the in-focus position can be increased by performing histogram correction to increase the brightness value of the bright part. Thereby, false focusing can be suppressed.

  In the above-described embodiment, an erecting microscope has been described as an example. For example, an inverted microscope that performs AF processing to capture a sample image of a sample, an imaging function that captures a sample, and an image are displayed. The present invention can also be applied to an imaging apparatus having a display function to be performed, such as a video microscope.

  As described above, the microscope according to the present invention is useful for executing a quick and accurate autofocus process.

DESCRIPTION OF SYMBOLS 1,1a Microscope 2 Microscope mount 3 Stage 4 Projection tube 5 Imaging device 6, 6a Control device 7 Display device 8 Objective lens 21 Stage support part 22 Projection tube support part 23 Drive motor control part 41 Imaging optical system 42 Light source 43 Light source control unit 44 Half mirror 45 Drive motor 51 Imaging element 52 Signal processing unit 53 Imaging control unit 61 Input unit 62 Contrast calculation unit 63, 63a Image processing unit 64 Storage unit 65, 65a Control unit Sp sample

Claims (7)

A microscope that collects light from a sample placed on a stage by an objective lens and generates image data for observation by capturing an image of the sample based on the collected light,
An image sensor that has a plurality of pixels that receive light from the sample, captures an image of the sample, and acquires image data;
For the display, the image of the sample acquired by the imaging device is subjected to γ correction using a tone curve for a portion having a luminance value smaller than a predetermined value in the gradation range of the luminance value in the image data. An image processing unit for generating image data and in-focus image data;
A display unit that displays the display image data that has been γ-corrected by the image processing unit;
A control unit that performs control to automatically focus the image of the sample based on the focusing image data that has been γ-corrected by the image processing unit;
With
The image processing unit generates the focusing image data using a γ value smaller than a γ value of γ correction performed on the display image data displayed on the display unit. microscope.   The microscope according to claim 1, wherein the image processing unit generates the focusing image data using the tone curve having a γ value of γ <1.   The image processing unit uses the S-shaped tone curve in which a γ value of a portion having a luminance value equal to or higher than a predetermined value in a gradation range of luminance values in the image data is γ> 1, and the image for focusing is used. The microscope according to claim 1, wherein data is generated.   The microscope according to claim 1, wherein the control unit resets the γ value after the focusing process is completed.   The microscope according to claim 4, wherein the control unit resets the γ value to the γ value before the focusing process after the focusing process is completed. A microscope that collects light from a sample placed on a stage by an objective lens and generates image data for observation by capturing an image of the sample based on the collected light,
An image sensor that has a plurality of pixels that receive light from the sample, captures an image of the sample, and acquires image data;
An image processing unit that performs histogram correction on the image of the sample acquired by the imaging device;
A control unit that performs control to automatically focus the image of the sample based on image data that has been histogram-corrected by the image processing unit;
A microscope comprising:   The microscope according to claim 1, wherein the control unit synthesizes a plurality of the image signals having different exposure conditions.