Image correction method and image correction device

Abstract

The invention provides an image correction method and an image correction device. The image correction method comprises the following steps: an image acquisition step; a background generation step of generating a plurality of background component images with different degrees of blurring processing for the acquired object image; a selection step for selecting the background component image on the basis of the index values obtained from the plurality of background component images; and an image correction step of generating a corrected object image based on the object image and the background component image.

Description

Technical Field

[0001] The invention relates to an image correction method and an image correction device. Background Art

[0002] Conventionally, a method of acquiring an image of an object captured by a camera device to analyze the object as a target is known. For example, such a method is disclosed in International Publication No. 2019 / 171546.

[0003] The cell image analysis method described in the above-mentioned International Publication No. 2019 / 171546 discloses a structure in which an image of an object is obtained by photographing cells cultured on a culture plate using a photographic device such as a microscope.

[0004] Here, although it is not disclosed in the above-mentioned patent document 1, when cells are cultured using a culture plate (culture container), due to surface tension, the height of the liquid surface of the culture solution increases as it approaches the end of the culture container. When the height of the liquid surface of the culture solution changes, the background of the object image will have uneven brightness. When the background of the object image has uneven brightness, in the correction of the image for reducing the uneven brightness, it is necessary to change the degree (intensity) of the correction process according to the size of the object and the degree of uneven brightness of the image. Therefore, not only does it take labor and time for the operator to set the degree of correction processing one by one, but the degree of correction processing also depends on the experience of the operator who corrects the image. Therefore, an image correction method is sought that can easily perform image correction that suppresses the influence of uneven brightness even when the background of the object image has uneven brightness. Summary of the invention

[0005] The present invention has been made to solve the above-mentioned problems, and one object of the present invention is to provide an image correction method that can easily perform image correction that suppresses the influence of uneven brightness even when uneven brightness occurs in the background of an object image.

[0006] In order to achieve the above-mentioned purpose, the image correction method based on the first aspect of the present invention includes the following steps: an image acquisition step, acquiring an object image reflecting an object as an observation object; a background generation step, for the acquired object image, by performing a blurring process that reduces the difference between the brightness of the object in the object image and the brightness of the part other than the object in a manner of changing the degree of blurring, multiple background component images with different degrees of blurring are generated by extracting the distribution of the brightness component of the background from the object image; a selection step, selecting a background component image based on an index value indicating the degree of blurring obtained from the multiple background component images generated in the background generation step; and an image correction step, generating a corrected object image by correcting the object image in a manner of reducing brightness unevenness based on the object image and the selected background component image.

[0007] An object image correction device based on the second aspect of the present invention comprises: an image acquisition unit, which acquires an object image reflecting an object serving as an observation object; a background generation unit, which generates a plurality of background component images with different degrees of blurring, obtained by extracting the distribution of brightness components of the background from the object image, by performing a blurring process that reduces the difference between the brightness of the object in the object image and the brightness of the portion other than the object in a manner that changes the degree of blurring for the acquired object image multiple times; a selection unit, which selects a background component image based on an index value indicating the degree of blurring obtained from the plurality of background component images generated by the background generation unit; and an image correction unit, which generates a corrected object image obtained by correcting the object image in a manner that reduces brightness unevenness, based on the object image and the selected background component image.

[0008] In the image correction method in the first aspect and the image correction device in the second aspect of the present invention, as described above, the following steps are included: a background generation step, for an acquired object image, by performing a blurring process that reduces the difference between the brightness of the object in the object image and the brightness of the portion other than the object multiple times in a manner that changes the degree of blurring, thereby generating a plurality of background component images with different degrees of blurring obtained by extracting the distribution of the brightness component of the background from the object image; and a selection step, based on an index value indicating the degree of blurring obtained from the plurality of background component images generated in the background generation step, selecting a background component image. Thus, a background component image is automatically selected from the plurality of background component images based on the index value indicating the degree of blurring obtained from the plurality of background component images, so that the object image can be corrected based on the object image and the selected background component image. As a result, even when uneven brightness occurs in the background of the object image, image correction that suppresses the influence of uneven brightness can be easily performed. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a schematic diagram showing the overall structure of the object image correction device according to the first to fourth embodiments.

[0010] Figure 2 It is a schematic diagram used to illustrate an object image.

[0011] Figure 3 This is a schematic diagram for explaining that uneven brightness occurs in the background of an object image due to a culture solution filled in a culture container.

[0012] Figure 4 This is an object image near the end of the culture container, with uneven brightness in the background.

[0013] Figure 5 This is an object image at the center of the culture container with no brightness unevenness in the background.

[0014] Figure 6 This is a flowchart for explaining the processing of the image correction method according to the first embodiment.

[0015] Figure 7 It is a schematic diagram for explaining the method of generating a background component image according to the first to fourth embodiments.

[0016] Figure 8 This is a schematic diagram for explaining the method of acquiring an index value based on a difference image according to the first embodiment.

[0017] Fig. 9 It is a schematic diagram for explaining the method of generating a calibration object image according to the first to fourth embodiments.

[0018] Fig.10 This is a flowchart for explaining the processing of the image correction method according to the second embodiment.

[0019] Fig.11 This is a schematic diagram for explaining the method of selecting a background component image based on a differential value according to the second embodiment.

[0020] Fig.12 This is a flowchart for explaining the processing of the image correction method according to the third embodiment.

[0021] Fig.13 This is a schematic diagram for explaining the method of selecting a background component image based on the standard deviation according to the third embodiment.

[0022] Fig.14 This is a flowchart for explaining the processing of the image correction method according to the fourth embodiment.

[0023] Fig.15 This is a schematic diagram for explaining a configuration for acquiring an index value using a power spectrum image according to the fourth embodiment. DETAILED DESCRIPTION

[0024] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

[0025] Reference Figure 1 Next, an image correction method using the object image correction device 100 according to the first embodiment will be described.

[0026] (Structure of object image correction device)

[0027] like Figure 1 As shown, the object image correction device 100 includes an image acquisition unit 1, a control unit 5, a display unit 6, and an input receiving unit 7. The control unit 5 includes a background generation unit 2, a selection unit 3, and an image correction unit 4. The object image correction device 100 is an example of an "image correction device" in the claims.

[0028] The image acquisition unit 1 is configured to acquire an object image 10. In the first embodiment, the object image 10 is a cell 20 (see Figure 2 Specifically, the object image 10 is taken when the culture container 30 (refer to Figure 3 ) of the culture solution 31 (reference Figure 3 ) is obtained by culturing cells 20 in a conditioned medium. In the first embodiment, the image acquisition unit 1 is configured to acquire the object image 10 from a device that captures the object image 10, such as a microscope 8 equipped with an imaging device. The image acquisition unit 1 includes, for example, an input / output interface.

[0029] The background generation unit 2 is configured to generate a background 21 (see FIG. 1 ) extracted from the object image 10. Figure 3 ) is obtained by analyzing the distribution of the brightness components of the background component image 12 (refer to Figure 7 ). The background generation unit 2 performs filtering processing (blurring processing) on ​​the object image 10 to reduce the difference in brightness between the cells 20 as the subject in the object image 10 and the background 21 as the portion other than the object. In addition, when performing filtering processing on the object image 10, the background generation unit 2 generates a plurality of background component images 12 using a plurality of filters with different filter sizes. In addition, the details of the processing by which the background generation unit 2 generates the background component images 12 will be described later.

[0030] The selection unit 3 is configured to select a background component image 12 from among the plurality of background component images 12, the index value indicating the degree of blur obtained based on the brightness value of each background component image in the plurality of background component images 12 generated by the background generation unit 2 being smaller than a predetermined threshold value. In addition, details of the process of the selection unit 3 selecting one background component image 12 from among the plurality of background component images 12 will be described later.

[0031] The image correction unit 4 generates a corrected object image 14 by correcting the object image 10 to reduce brightness unevenness based on the object image 10 and the background component image 12 selected by the selection unit 3. The details of the process of generating the corrected object image 14 by the image correction unit 4 will be described later.

[0032] The control unit 5 is configured to control the object image correction device 100, and includes a background generation unit 2, a selection unit 3, and an image correction unit 4 as control blocks. In addition, the control unit 5 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), a GPU (Graphics Processing Unit), or an FPGA (Field-Programmable Gate Array) configured for image processing, etc. In addition, the control unit 5 is configured to control the display unit 6 to display the object image 10, the correction object image 14, etc.

[0033] The display unit 6 is configured to display the object image 10 acquired by the image acquisition unit 1 and the corrected object image 14 generated by the image correction unit 4. The display unit 6 includes a display device such as a liquid crystal monitor, for example.

[0034] The input receiving unit 7 is configured to receive an operation input by an operator. The input receiving unit 7 includes, for example, an input device such as a mouse and a keyboard.

[0035] (Object Image)

[0036] Reference Figure 2The object image 10 is described below. In the first embodiment, the object image 10 is an image showing the existing cell 20. In addition, in the first embodiment, the object image 10 is a microscope image captured by a microscope 8 equipped with an imaging device. The object image 10 is an image obtained by capturing a cell 20 having differentiation ability with respect to the cell 20. For example, the cell 20 includes an iPS cell (induced Pluripotent Stem Cell), an ES cell (Embryonic Stem Cell), and the like.

[0037] (Uneven background brightness due to culture solution)

[0038] Next, refer to Figure 3 to Figure 5 The case where the background 21 of the object image 10 may have uneven brightness due to the culture solution 31 is described. In the first embodiment, the image in which the background 21 of the object image 10 has uneven brightness is set as the object image 10a (refer to Figure 4 ), the image of the object image 10 in which the background 21 does not have uneven brightness is set as the object image 10b (refer to Figure 5 ).

[0039] like Figure 3 As shown, the cells 20 are cultured in a culture solution 31 filled in a culture container 30. The height of the liquid surface 31a of the culture solution 31 gradually changes near the end 40 of the culture container 30 due to surface tension. Figure 3 In the example shown, the height of the liquid surface 31a of the culture solution 31 increases as it approaches the end 30a of the culture container 30. In this case, due to the difference in the height of the culture solution 31, Figure 4 As shown in the object image 10a, the background 21 has uneven brightness. In addition, the object image 10a is an image of the cells 20 including the vicinity 40 of the end of the culture container 30. Figure 4 In the object image 10 a shown, uneven brightness of the background 21 is expressed by adding hatching lines at different intervals. Figure 3 The object image 10a shown is an example of uneven brightness in which the brightness value (pixel value) of the background 21 decreases from the left side to the right side of the image. The vicinity 40 of the end of the culture container 30 refers to both the position of the end 30a of the culture container 30 itself and the vicinity of the position of the end 30a of the culture container 30.

[0040] In addition, if Figure 5As shown in the figure, the height of the liquid surface 31a of the culture solution 31 is constant in the central part 41 of the culture container 30. When the height of the liquid surface 31a of the culture solution 31 is constant, the background 21 does not have uneven brightness. That is, as shown in the object image 10b, in the image of the cells 20 including the central part 41 of the culture container 30, the background 21 does not have uneven brightness. In addition, the object image 10b is an image of only the cells 20 in the central part 41 of the culture container 30.

[0041] (Processing of image correction method)

[0042] Next, refer to Figure 1 as well as Figure 6 to Figure 9 The method of correcting the object image 10 by the image correction method of the first embodiment is described below. Figure 6 As shown, in the first embodiment, the image correction method includes an image acquisition step S1, a background generation step S2, a selection step S3 and an image correction step S4.

[0043] (Object image acquisition)

[0044] In the first embodiment, first, as step S1, an object image 10 is acquired. Specifically, the image acquisition unit 1 acquires the object image 10 captured by the microscope 8 or the like equipped with an imaging device, for example, by using communication. Then, the process proceeds to step S2.

[0045] (Generation of background component image)

[0046] Next, as step S2, the background generating unit 2 obtains the background component image 12 based on the object image 10a. Figure 7 The method of generating the background component image 12 by the background generating unit 2 is described. In the first embodiment, the background generating unit 2 generates the background component image 12 by extracting the distribution of the brightness component of the background 21 from the object image 10a by filtering the object image 10a acquired by the image acquiring unit 1. Specifically, the background generating unit 2 generates the background component image 12 by applying a median filter to the object image 10a. In the first embodiment, the background generating unit 2 blurs the image in such a way as to reduce the difference in brightness between the cell 20 as the subject of the object image 10a and the background 21 as the portion other than the cell 20.

[0047] In addition, the filtering process of the median filter is used to obtain the median value of the pixel values ​​of each pixel in an area (filter) set to a predetermined size with the focus pixel as the center. Specifically, the filtering process of the median filter is used to obtain the pixel values ​​of each pixel in the filter with the focus pixel as the center, and arrange them in the order of pixel values ​​to obtain the median value. Then, the obtained median value is set as the pixel value of the focus pixel. The focus pixel is changed to perform this process on each pixel of the object image 10a. Therefore, the processing load of the filtering process of the median filter increases.

[0048] Therefore, in the first embodiment, the background generating unit 2 (see Figure 1 ) by Figure 7 The object image 10a in which the background 21 shown in (A) has uneven brightness is reduced to generate Figure 7 Specifically, the background generation unit 2 generates the reduced object image 10c by performing a reversible compression process on the object image 10a. In the first embodiment, the background generation unit 2 generates the reduced object image 10c by, for example, reducing the object image 10a to 1 / 8 of its size.

[0049] Then, if Figure 7 As shown in (C), the background generating unit 2 generates a reduced background component image 11 by filtering the reduced object image 10c after reduction. In the first embodiment, the background generating unit 2 applies a median filter to the reduced object image 10c, which is an image obtained by reducing the object image 10a. The reduced background component image 11 is an image obtained by extracting the brightness unevenness (background component) of the background 21 through filtering. In the reduced background component image 11, the position of the cell 20 in the object image 10a is represented by a dotted line. In addition, Figure 7 The reduced background component image 11 shown in (C) is an example in which the blurring process is performed to such an extent that the cells 20 and the background 21 cannot be clearly distinguished.

[0050] Then, if Figure 7 As shown in (D), the background generating unit 2 generates the background component image 12 by enlarging the reduced background component image 11. Specifically, the background generating unit 2 enlarges the reduced background component image 11 so that the size of the background component image 12 becomes the same as the size of the object image 10a. In the first embodiment, for example, the background generating unit 2 generates the background component image 12 by enlarging the reduced background component image 11 to 8 times the size.

[0051] Furthermore, in the background generation step S2, a plurality of median filter sizes are applied to the reduced object image 10c. Thus, the background generation unit 2 generates a plurality of reduced background component images 11, and enlarges each of the plurality of reduced background component images 11 to generate a plurality of background component images 12. For example, in the first embodiment, Figure 8 As shown in the upper part of , a plurality of background component images 12a to 12c are acquired. In addition, the larger the filter size, the stronger the blurring degree (blurring processing intensity) can be. Then, the process proceeds to step S3.

[0052] (Background component image selection)

[0053] In step S3, the selection unit 3 selects one background component image 12c from the plurality of background component images 12a to 12c. Figure 8 The configuration of the background generating unit 2 selecting the background component image 12c will be described. The selecting unit 3 performs a process of obtaining the difference in the brightness value of each background component image among the plurality of background component images 12a to 12c generated by the background generating unit 2. At this time, the difference in the brightness value of two adjacent background component images 12a to 12c with different blurring intensities among the background component images 12a to 12c with different blurring intensities due to the difference in filter size is obtained. Specifically, a differential image 13b obtained by obtaining the difference in the brightness value of the background component images 12a and 12b is obtained. In addition, a differential image 13c obtained by obtaining the difference in the brightness value of two adjacent background component images 12b and 12c with different blurring intensities is obtained. In addition, the selecting unit 3 is configured to select the background component image 12c based on the fact that the index value indicating the degree of blurring obtained from all the acquired differential images 13 including the differential images 13b and 13c is less than a predetermined threshold value.

[0054] Specifically, the average value of the brightness value of the entire image is obtained for each of the differential images 13 including the differential images 13b and 13c, to obtain the differential value as the index value. Figure 6 As shown, the difference value obtained from the difference image 13b is "8", and the difference value obtained from the difference image 13c is "4". Moreover, when the difference value is smaller than the specified threshold value, the background component image 12c with a larger filter size is selected from the background component images 12b and 12c used to generate the difference image 13c. The specified threshold value based on which the selection is based can be arbitrarily changed by setting, but it is "5" in this first embodiment. In addition, when there are multiple difference images 13 with difference values ​​smaller than the specified threshold value, the difference image 13 with the largest difference value is used to select the background component image 12. Thereafter, the process enters step S4.

[0055] (Generation of Corrected Object Image)

[0056] In step S4, the image correction unit 4 generates a corrected object image 14 by correcting the object image 10a so as to reduce brightness unevenness, based on the object image 10a and the background component image 12c selected by the selection unit 3. Fig. 9 The structure for generating the calibration object image 14 is described below. Fig. 9 As shown, the image correction unit 4 subtracts the background component image 12c from the object image 10a. In addition, when the background component image 12c is subtracted from the object image 10a, the pixel value of the entire image sometimes becomes smaller and the contrast of the image is reduced. Therefore, in the first embodiment, the image correction unit 4 generates the corrected object image 14 by adding a prescribed brightness value after subtracting the background component image 12c from the object image 10a. The prescribed pixel value is, for example, a value of half the grayscale of the pixel value of the object image 10a. In the first embodiment, the background generation unit 2 adds 128 as the prescribed pixel value when the pixel value of the object image 10a is 256 grayscales.

[0057] like Fig. 9 As shown, the brightness unevenness of the background 21 of the calibration object image 14 is reduced. Fig. 9 The calibration object image 14 shown expresses that the brightness unevenness of the background 21 is reduced by not adding hatching to the background 21 .

[0058] As described above, even when the object image 10a has brightness unevenness, the object image correction device 100 selects an appropriate background component image 12c to correct the image, thereby obtaining a corrected object image 14 with reduced brightness unevenness.

[0059] (Effects of this embodiment)

[0060] The image correction method of the first embodiment includes the following steps: an image acquisition step S1, acquiring an object image 10a showing a cell 20 as an observation object; a background generation step S2, for the acquired object image 10a, generating a plurality of background component images 12a~12c with different degrees of blurring obtained by extracting the distribution of the brightness component of the background 21 from the object image 10a by performing a blurring process that reduces the difference between the brightness of the cell 20 in the object image 10a and the brightness of the background 21 as a part other than the cell 20 multiple times in a manner changing the degree of blurring; a selection step S3, selecting a background component image 12c based on an index value indicating the degree of blurring obtained from the plurality of background component images 12a~12c generated in the background generation step S2; and an image correction step S4, generating a corrected object image 14 obtained by correcting the object image 10a in a manner to reduce brightness unevenness based on the object image 10a and the selected background component image 12c. Thus, the background component image 12c is automatically selected from the plurality of background component images 12a to 12c based on the index value indicating the degree of blurring obtained from the plurality of background component images 12c, so that the object image 10a can be corrected based on the object image 10a and the selected background component image 12c. As a result, even when the background 21 of the object image 10a has uneven brightness, image correction can be easily performed to suppress the influence of uneven brightness.

[0061] In the first embodiment, the index value is obtained based on the brightness values ​​of the plurality of background component images 12a to 12c, and in the selection step S3, one background component image 12c corresponding to the index value smaller than the predetermined threshold value is selected from the plurality of background component images 12a to 12c generated in the background generation step S2. Thus, the background component image 12c whose index value based on the brightness values ​​of the plurality of background component images 12a to 12c is smaller than the predetermined threshold value is automatically selected. That is, since the background component image 12c obtained by sufficiently performing the blurring process is automatically selected, the object image 10a can be corrected based on the object image 10a and the selected background component image 12c obtained by sufficiently performing the blurring process. As a result, the image correction can be easily and appropriately performed on the object image 10a so as to suppress the influence of uneven brightness.

[0062] In the first embodiment, in the selection step S3, when there are a plurality of index values ​​smaller than the predetermined threshold value among the plurality of background component images 12a to 12c generated in the background generation step S2, one background component image 12c corresponding to the index value having the largest value among the index values ​​having the largest value is selected. Thus, even when a plurality of index values ​​having the largest value among the index values ​​having the largest value are acquired, a more appropriate background component image 12c can be selected. Here, the degree of blurring of the background component image 12 corresponding to the index value having the largest value among the index values ​​... As a result, it is possible to more appropriately select the background component image 12 used when performing image correction on the object image 10 a so as to suppress the influence of uneven brightness.

[0063] In the first embodiment, in the image correction method of selecting one background component image 12a to 12c corresponding to an index value smaller than a predetermined threshold value, it is preferred that in the selection step S3, the brightness value difference images 13a to 13c are generated based on two adjacent background component images 12a to 12c having different degrees of blurring among the plurality of background component images 12a to 12c having different degrees of blurring, the difference value as the index value is obtained from the difference image 13, and one background component image 12c used for generating the difference image 13c having a difference value smaller than a predetermined difference value threshold value is selected. Thus, the background component image 12c having a difference value as a quantitative value based on the brightness values ​​of the plurality of background component images 12a to 12c having a difference value smaller than the difference value threshold value is automatically selected, and the object image 10a can be corrected based on the object image 10a and the background component image 12c corresponding to the difference image 13c having a small difference value. As a result, it is possible to easily and appropriately perform image correction on the object image 10 in such a way as to suppress the influence of uneven brightness by using the background component image 12 c automatically selected based on the difference value.

[0064] In the first embodiment, the blurring process is a filter process for performing correction processing by filtering the object image 10a, and the size of the filter used to change the degree of blurring is changed in various ways to generate a plurality of background component images 12a to 12c with different degrees of blurring. Thus, a plurality of background component images 12a to 12c with different degrees of blurring can be generated according to the size of the filter size. As a result, the image correction for suppressing the influence of uneven brightness can be performed on the object image 10a using the background component image 12c selected from the plurality of background component images 12a to 12c generated according to the size of the filter size.

[0065] In the first embodiment, the filter used in the filtering process in the background generation step S2 is a median filter, and a plurality of background component images 12a to 12c are generated from the object image 10a by using the median filter. Here, when a Gaussian filter or a mean filter is applied as the filtering process, the brightness component of the background 21 may not be accurately acquired due to stray light with extremely high pixel values ​​or foreign matter with extremely low brightness values. Therefore, by applying a median filter that performs smoothing using the median value of the brightness value of each pixel in a predetermined area, it is possible to acquire a background component image 12 that accurately acquires the brightness component of the background 21 even when stray light or foreign matter is mixed. As a result, it is possible to use the accurate background component image 12c when correcting the brightness unevenness of the background 21, and thus it is possible to acquire a corrected object image 14 that accurately corrects the brightness unevenness of the background 21.

[0066] [Second embodiment]

[0067] Next, the image correction method of the second embodiment is described. The device structure of the object image correction device 100 used in the image correction method of the second embodiment is the same as Figure 1 In the second embodiment, the object image correction device 100 shown in FIG. Fig.10 The selection step S3a shown is a case where the selection unit 3 performs differentiation processing on the brightness value of each of the plurality of background component images 12a to 12c. In the second embodiment, description of points common to the first embodiment will be omitted.

[0068] In the second embodiment, Fig.10 In step S3a shown in FIG. 1 , the selection unit 3 is configured to perform differential processing on the brightness value of each of the plurality of background component images 12a to 12c generated by the background generation unit 2. Specifically, Fig.11As shown, a Sobel filter (an example of a differential filter) is applied to the brightness values ​​of the background component images 12a to 12c in both the vertical and horizontal directions of the image to obtain a differential image, and the average value of the brightness value of the differential image is obtained as a differential value. For example, in the second embodiment, the differential value obtained from the background component image 12a is "10", the differential value obtained from the background component image 12b is "6", and the differential value obtained from the background component image 12c is "4". The prescribed threshold value based on which the selection is based can also be arbitrarily changed by setting, but in the second embodiment, it is "5". Moreover, when the differential value is smaller than the prescribed threshold value "5", the background component image 12c based on which the differential value was obtained is selected. Thereafter, the process enters step S4 to generate the corrected object image 14.

[0069] (Effects of the Second Embodiment)

[0070] Next, the effects of the second embodiment will be described.

[0071] In the image correction method of the second embodiment, in the selection step S3a, a differential value as an index value is obtained based on the brightness value of each background component image in a plurality of background component images 12a to 12c having different degrees of blur processing, and one background component image 12c corresponding to a differential value smaller than a predetermined differential value threshold is selected. Thus, a background component image 12c having a differential value as a quantitative value based on the brightness values ​​of the plurality of background component images 12a to 12c smaller than the differential value threshold is automatically selected, so that the object image 10a can be corrected based on the object image 10a and the selected background component image 12c having a small differential value. As a result, the image correction of the object image 10a in a manner that suppresses the influence of uneven brightness can be easily and appropriately performed using the background component image 12c automatically selected based on the differential value.

[0072] In addition, other effects of the second embodiment are the same as those of the above-mentioned first embodiment.

[0073] [Third Embodiment]

[0074] Next, the image correction method of the third embodiment is described. The device structure of the object image correction device 100 used in the image correction method of the third embodiment is similar to Figure 1 In the third embodiment, the object image correction device 100 shown in FIG. Fig.12 In the selection step S3b shown, the selection unit 3 obtains the value of the standard deviation for the brightness value of each of the plurality of background component images 12a to 12c. In the third embodiment, description of points common to the first and second embodiments will be omitted.

[0075] In a third embodiment, Fig.12 In step S3b shown in FIG. Fig.13 As shown in FIG. 1 , a process is performed to obtain the value of the standard deviation for the brightness value of each of the plurality of background component images 12a to 12c generated by the background generation unit 2. Specifically, the brightness values ​​of the background component images 12a to 12c are applied to the following formula to obtain the standard deviation. In the following formula, the image size is M×N, src(i, j) is the brightness value of the position (i, j) of the image, and μ represents the average value of the brightness value.

[0076]

[0077] For example, in the third embodiment, the standard deviation obtained from the background component image 12a is "10", the standard deviation obtained from the background component image 12b is "6", and the standard deviation obtained from the background component image 12c is "4". The predetermined threshold value based on which the selection is made can also be arbitrarily changed by setting, but is "5" in the third embodiment. Moreover, when the value of the standard deviation is smaller than the predetermined standard deviation threshold value "5", the background component image 12c based on which the standard deviation was obtained is selected. After that, the process proceeds to step S4 to generate the corrected object image 14.

[0078] (Effects of the Third Embodiment)

[0079] Next, the effects of the third embodiment will be described.

[0080] In the image correction method of the third embodiment, in the selection step S3b, a standard deviation as an index value is obtained based on the brightness value of each background component image in a plurality of background component images 12a to 12c having different degrees of blur processing, and one background component image 12c corresponding to a standard deviation smaller than a predetermined threshold value is selected. Thus, a background component image 12c having a standard deviation as a quantitative value based on the brightness values ​​of the plurality of background component images 12a to 12c smaller than the standard deviation threshold value is automatically selected, and the object image 10a can be corrected based on the object image 10a and the selected background component image 12c having a small standard deviation. As a result, the object image 10a can be easily and appropriately corrected in such a way as to suppress the influence of uneven brightness using the background component image 12c automatically selected based on the standard deviation.

[0081] In addition, other effects of the third embodiment are the same as those of the first and second embodiments described above.

[0082] [Fourth Embodiment]

[0083] Next, the image correction method of the fourth embodiment is described. The device structure of the object image correction device 100 used in the image correction method of the fourth embodiment is similar to Figure 1 In the fourth embodiment, the object image correction device 100 shown in FIG. Fig.14 In the selection step S3c shown, the selection unit 3 generates power spectrum images 15a to 15c based on the brightness values ​​of each background component image in the plurality of background component images 12a to 12c, and selects one background component image 12c using a specific value as an index value based on the power spectrum images 15a to 15c. In addition, in the fourth embodiment, descriptions of points common to the first to third embodiments are omitted.

[0084] In the fourth embodiment, Fig.14 In step S3c shown in FIG. Fig.15 As shown, Fourier transform is performed on each of the multiple background component images 12a to 12c generated by the background generation unit 2 to obtain power spectrum images 15a to 15c. The power spectrum images 15a to 15c are images in which the vertical y axis and the horizontal x axis of the image are both expressed in frequency. The selection unit 3 obtains a specific value for each of the power spectrum images 15a to 15c, and the specific value is the average value of the brightness value on the circumference at a specific frequency. For example, in the fourth embodiment, the specific value obtained from the power spectrum image 15a is "10", the specific value obtained from the power spectrum image 15b is "6", and the specific value obtained from the power spectrum image 15c is "4". The prescribed threshold value based on which the selection is made can also be arbitrarily changed by setting, but in the fourth embodiment, it is "5". Moreover, when the specific value is smaller than the prescribed threshold value "5", the background component image 12c based on which the specific value is obtained is selected. Thereafter, the process enters step S4 to generate the calibration object image 14.

[0085] (Effects of the Fourth Embodiment)

[0086] Next, the effects of the fourth embodiment will be described.

[0087] In the image correction method of the fourth embodiment, in the selection step S3c, by performing Fourier transform processing on each of the plurality of background component images 12a to 12c having different degrees of blur processing, power spectrum images 15a to 15c representing the intensity of the spectrum corresponding to the frequency component are generated, a specific value which is the average of the brightness values ​​of the power spectrum images 15a to 15c at a specific frequency is obtained as an index value, and one background component image 12c used for generating the power spectrum image 15c having a specific value smaller than a predetermined specific value threshold is selected. Thus, the background component image 12c having a specific value as a quantitative value based on the brightness values ​​of the plurality of background component images 12a to 12c which is smaller than the specific value threshold is automatically selected, and the object image 10a can be corrected based on the object image 10a and the selected background component image 12c. As a result, the image correction can be easily and appropriately performed on the object image 10a so as to suppress the influence of brightness unevenness using the background component image 12c automatically selected based on the specific value.

[0088] In addition, other effects of the fourth embodiment are the same as those of the first to third embodiments described above.

[0089] [Modifications]

[0090] The embodiments disclosed herein are illustrative in all aspects and should not be construed as limiting. The scope of the present invention is indicated by the claims rather than the description of the embodiments described above, and includes all modifications (variations) within the meaning and scope equivalent to the claims.

[0091] For example, in the first to fourth embodiments, the object in the object image 10 is shown as a cell 20, but the present invention is not limited thereto. An object image 10a showing an arbitrary subject to be observed may be acquired to generate the corrected object image 14.

[0092] In the first to fourth embodiments, the image acquisition unit 1 acquires the object image 10, but the present invention is not limited thereto. For example, the background generation unit 2 may acquire the object image 10 acquired in advance by the image acquisition unit 1 and stored in a storage unit (not shown).

[0093] In the first to fourth embodiments, the object image 10 is an example of an image captured by the microscope 8, but the present invention is not limited thereto. The object image 10 may be an image showing an object, and may be an image captured by using an SPM (Scanning Probe Microscope). Even when an image is captured by using an SPM, the object image 10 may be tilted due to, for example, a tilt of the stage on which the cell 20 is mounted. Figure 4 Since uneven brightness occurs as in the object image 10a shown in the figure, it is also effective to apply the image correction method of the present invention.

[0094] In the first to fourth embodiments described above, an example is shown in which one background component image 12c corresponding to an index value smaller than a predetermined threshold value is selected from the plurality of background component images 12a to 12c generated in the background generation step S2 in the selection steps S3 and S3a to S3c, but the present invention is not limited thereto. In the selection step S3, one background component image 12 corresponding to an index value equal to a predetermined threshold value may be selected from the plurality of background component images 12 generated in the background generation step S2.

[0095] In addition, in the first to fourth embodiments, examples are shown in which three background component images 12a to 12c are generated by blurring using filter sizes of different sizes, but the present invention is not limited thereto. The generated background component images 12 may be any number as long as there are two or more, and blurring may be performed using a plurality of filter sizes of different sizes depending on the number of background component images 12 generated.

[0096] In addition, in the above-mentioned first to fourth embodiments, an example of a structure in which the background generating unit 2 generates the background component image 12 by applying a median filter to the object image 10a is shown, but the present invention is not limited to this. For example, the background generating unit 2 can also be configured to generate the background component image 12 by applying a Gaussian filter or a mean filter to the object image 10a. However, in the case where the background generating unit 2 generates the background component image 12 by applying a Gaussian filter or a mean filter, sometimes the components of the background 21 cannot be accurately obtained due to stray light with extremely high pixel values ​​or foreign matter with extremely low pixel values. Therefore, the background generating unit 2 is preferably configured to generate the background component image 12 by applying a median filter.

[0097] In the first to fourth embodiments, the background generating unit 2 generates the background component image 12 by reducing the object image 10a and applying a filter to the reduced object image 10c, but the present invention is not limited thereto. The background generating unit 2 may also be configured to generate the background component image 12 by applying a blurring process to the object image 10a without reducing the object image 10a.

[0098] In the first to fourth embodiments, the background generating unit 2 performs correction processing on the object image 10a having uneven brightness in the background 21 to generate the corrected object image 14, but the present invention is not limited thereto. The background generating unit 2 may be configured to perform correction processing on the object image 10a regardless of whether the background 21 has uneven brightness.

[0099] In the first to fourth embodiments, an example of a structure in which the corrected object image 14 is generated by subtracting the background component image 12 from the object image 10a by the background generating unit 2 is shown, but the present invention is not limited thereto. For example, the background generating unit 2 may generate the corrected object image 14 by dividing the object image 10a by the background component image 12. Any method may be used for generating the corrected object image 14 by the background generating unit 2.

[0100] In the first to fourth embodiments, an example of a structure in which the background generating unit 2 generates the corrected object image 14 by subtracting the background component image 12 from the object image 10a and adding a predetermined brightness value is shown, but the present invention is not limited thereto. For example, the background generating unit 2 may be configured to generate the corrected object image 14 without adding a predetermined brightness value after subtracting the background component image 12 from the object image 10a.

[0101] [Way]

[0102] Those skilled in the art will appreciate that the above-described exemplary embodiments are specific examples of the following aspects.

[0103] (Item 1)

[0104] An image correction method comprises the following steps:

[0105] An image acquisition step of acquiring an object image showing the object to be observed;

[0106] A background generation step, for the acquired object image, by performing a blurring process that reduces the difference between the brightness of the object in the object image and the brightness of the portion other than the object in a manner of changing the degree of blurring process multiple times, thereby generating a plurality of background component images with different degrees of blurring process, obtained by extracting the distribution of the brightness component of the background from the object image;

[0107] A selecting step of selecting one of the background component images based on an index value indicating a degree of blurring obtained from the plurality of background component images generated in the background generating step; and

[0108] The image correction step generates a corrected object image by correcting the object image in a manner that reduces brightness unevenness based on the object image and the selected background component image.

[0109] (Item 2)

[0110] According to the image correction method described in item 1,

[0111] The index value is obtained based on the brightness values ​​of the multiple background component images,

[0112] In the selection step, one of the background component images corresponding to the index value smaller than a predetermined threshold value is selected from the plurality of background component images generated in the background generation step.

[0113] (Item 3)

[0114] According to the image correction method described in item 2,

[0115] In the selection step, when there are multiple index values ​​smaller than a prescribed threshold value, one of the background component images generated in the background generation step that corresponds to the largest index value among the index values ​​smaller than the prescribed threshold value is selected.

[0116] (Item 4)

[0117] According to the image correction method described in item 2,

[0118] In the selection step, a difference image of brightness values ​​is generated based on two adjacent background component images with different degrees of blur processing among the multiple background component images with different degrees of blur processing, a difference value serving as the index value is obtained based on the difference image, and one of the background component images for generating the difference image whose difference value is smaller than a prescribed difference value threshold is selected.

[0119] (Item 5)

[0120] According to the image correction method described in item 2,

[0121] In the selection step, a differential value serving as the index value is obtained based on the brightness value of each of the plurality of background component images having different degrees of blur processing, and one of the background component images corresponding to the differential value that is smaller than a prescribed differential value threshold is selected.

[0122] (Item 6)

[0123] According to the image correction method described in item 2,

[0124] In the selection step, the standard deviation as the index value is obtained based on the brightness value of each of the multiple background component images with different degrees of blur processing, and one of the background component images corresponding to the standard deviation smaller than a specified standard deviation threshold is selected.

[0125] (Item 7)

[0126] According to the image correction method described in item 2,

[0127] In the selection step, a power spectrum image representing the intensity of the spectrum corresponding to the frequency component is generated by performing Fourier transform processing on each of the multiple background component images with different degrees of blur processing, a specific value is obtained as the index value, and one of the background component images used to generate the power spectrum image whose specific value is smaller than a specified specific value threshold is selected, wherein the specific value is the average of the brightness values ​​of the power spectrum image at a specific frequency.

[0128] (Item 8)

[0129] According to the image correction method described in item 1,

[0130] The blurring process is a filtering process for performing correction processing by applying filtering to the object image, and the size of the filter for changing the degree of the blurring process is varied in a plurality of ways to generate a plurality of the background component images having different degrees of blurring process.

[0131] (Item 9)

[0132] According to the image correction method described in item 8,

[0133] The filter used in the filtering process in the background generating step is a median filter, and the background component image is extracted from the object image by using the median filter to generate a plurality of the background component images.

[0134] (Item 10)

[0135] An image correction device, comprising:

[0136] an image acquisition unit that acquires an object image showing an object to be observed;

[0137] A background generating unit, for the acquired object image, generating a plurality of background component images having different degrees of blurring by extracting the distribution of the brightness component of the background from the object image, by performing blurring processing for reducing the difference between the brightness of the object in the object image and the brightness of the portion other than the object in a manner of changing the degree of blurring processing a plurality of times in a manner of changing the degree of blurring processing;

[0138] a selection unit that selects one of the background component images based on an index value indicating a degree of blurring obtained from the plurality of background component images generated by the background generation unit; and

[0139] An image correction unit generates a corrected object image by correcting the object image so as to reduce brightness unevenness based on the object image and the selected background component image.

Claims

1. An image correction method, comprising the following steps: An image acquisition step of acquiring an object image showing the object to be observed; A background generation step, for the acquired object image, by performing a blurring process that reduces the difference between the brightness of the object in the object image and the brightness of the portion other than the object in a manner of changing the degree of blurring process multiple times, thereby generating a plurality of background component images with different degrees of blurring process, obtained by extracting the distribution of the brightness component of the background from the object image; A selecting step of selecting one of the background component images based on an index value indicating a degree of blurring obtained from the plurality of background component images generated in the background generating step; as well as The image correction step generates a corrected object image by correcting the object image in a manner that reduces brightness unevenness based on the object image and the selected background component image.

2. The image correction method according to claim 1, wherein: The index value is obtained based on the brightness values ​​of the multiple background component images, In the selection step, one of the background component images corresponding to the index value smaller than a predetermined threshold value is selected from the plurality of background component images generated in the background generation step.

3. The image correction method according to claim 2, wherein: In the selection step, when there are multiple index values ​​smaller than a prescribed threshold value, one of the background component images generated in the background generation step that corresponds to the largest index value among the index values ​​smaller than the prescribed threshold value is selected.

4. The image correction method according to claim 2, wherein: In the selection step, a difference image of brightness values ​​is generated based on two adjacent background component images with different degrees of blur processing among the multiple background component images with different degrees of blur processing, a difference value serving as the index value is obtained based on the difference image, and one of the background component images for generating the difference image whose difference value is smaller than a prescribed difference value threshold is selected.

5. The image correction method according to claim 2, wherein: In the selection step, a differential value serving as the index value is obtained based on the brightness value of each of the plurality of background component images having different degrees of blur processing, and one of the background component images corresponding to the differential value that is smaller than a prescribed differential value threshold is selected.

6. The image correction method according to claim 2, wherein: In the selection step, the standard deviation as the index value is obtained based on the brightness value of each of the multiple background component images with different degrees of blur processing, and one of the background component images corresponding to the standard deviation smaller than a specified standard deviation threshold is selected.

7. The image correction method according to claim 2, wherein: In the selection step, a power spectrum image representing the intensity of the spectrum corresponding to the frequency component is generated by performing Fourier transform processing on each of the multiple background component images with different degrees of blur processing, a specific value is obtained as the index value, and one of the background component images used to generate the power spectrum image whose specific value is smaller than a specified specific value threshold is selected, wherein the specific value is the average of the brightness values ​​of the power spectrum image at a specific frequency.

8. The image correction method according to claim 1, wherein: The blurring process is a filtering process for performing correction processing by applying filtering to the object image, and the size of the filter for changing the degree of the blurring process is varied in a plurality of ways to generate a plurality of the background component images having different degrees of blurring process.

9. The image correction method according to claim 8, wherein: The filter used in the filtering process in the background generating step is a median filter, and the background component image is extracted from the object image by using the median filter to generate a plurality of the background component images.

10. An image correction device, comprising: an image acquisition unit that acquires an object image showing an object to be observed; A background generating unit, for the acquired object image, generating a plurality of background component images having different degrees of blurring by extracting the distribution of the brightness component of the background from the object image, by performing blurring processing for reducing the difference between the brightness of the object in the object image and the brightness of the portion other than the object in a manner of changing the degree of blurring processing a plurality of times in a manner of changing the degree of blurring processing; a selection unit that selects one of the background component images based on an index value indicating a degree of blurring obtained from the plurality of background component images generated by the background generation unit; as well as An image correction unit generates a corrected object image by correcting the object image so as to reduce brightness unevenness based on the object image and the selected background component image.

Images