Imaging device, imaging method, and program

Abstract

To provide an imaging device, an imaging method and a program that acquire a photographed image having on-axis chromatic aberrations more suppressed.SOLUTION: An imaging device 10 comprises: an imaging optical system 12; an imaging element 16 which acquires a photographed image, a memory 8 which stores chromatic aberration correction information corresponding to an image height of the photographed image in a sagittal direction and a tangential direction of the photographed image for correcting on-axis chromatic aberrations of the imaging optical system 12; a drive device 20 which moves the imaging optical system 12 in an optical-axis direction; and a processor 40. The processor 40 acquires a correction object area, reads the corresponding chromatic aberration correction information out of the memory based upon the image height in the correction object area, and determines an imaging position corresponding to a wavelength band of the imaging element based upon the chromatic aberration correction information.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an imaging device, an imaging method, and a program. [Background technology]

[0002] Generally, light incident on an imaging optical system contains a plurality of different wavelengths. In such cases, the imaging optical system forms images corresponding to the wavelengths of the incident light at different positions along the optical axis of the imaging optical system (axial chromatic aberration).

[0003] The technology described in Patent Document 1 involves taking multiple images while changing the relative distance between the imaging optical system and the imaging element, and then combining the multiple images obtained to obtain an image with reduced axial chromatic aberration. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-85774 Summary of the Invention

[0005] One embodiment of the technique of the present disclosure provides an imaging device, an imaging method, and a program that can acquire a captured image in which axial chromatic aberration is further suppressed. [Means for solving the problem]

[0006] An imaging device according to one aspect of the present invention includes an imaging optical system, an imaging element that acquires a captured image, a memory that stores chromatic aberration correction information for correcting axial chromatic aberration of the imaging optical system, the chromatic aberration correction information corresponding to the image height in the sagittal and tangential directions in the captured image, a drive device that moves the imaging optical system in the optical axis direction, and a processor, in which the processor acquires an area to be corrected, reads the corresponding chromatic aberration correction information from the memory based on the image height of the correction area, and determines an imaging position corresponding to the wavelength band of the imaging element based on the chromatic aberration correction information.

[0007] Preferably, the processor causes the drive device to move the lens group of the imaging optical system to an imaging position, and causes the imaging element to acquire a photographed image.

[0008] Preferably, the wavelength bands include a first color wavelength band, a second color wavelength band, and a third color wavelength band, and the processor determines, based on the chromatic aberration correction information, imaging positions: a first lens position that is the position of the lens group when imaging the first color wavelength band, a second lens position that is the position of the lens group when imaging the second color wavelength band, and a third lens position that is the position of the lens group when imaging the third color wavelength band, and causes the imaging element to acquire a first captured image that is an image of the first color wavelength band at the first lens position, a second captured image that is an image of the second color wavelength band at the second lens position, and a third captured image that is an image of the third color wavelength band at the third lens position.

[0009] Another aspect of the present invention is an imaging device that includes an imaging optical system, an imaging element that acquires a captured image, a drive device that moves the imaging optical system in the optical axis direction, and a processor, in which the processor acquires an area to be corrected, scans the lens group using the drive device, acquires contrast information in the sagittal direction and tangential direction of the wavelength band in the area to be corrected, and determines an imaging position corresponding to the wavelength band of the imaging element based on the contrast information.

[0010] Preferably, the processor causes the driving device to move the imaging optical system to the imaging position and causes the imaging element to acquire the captured image.

[0011] Preferably, the wavelength bands include a first color wavelength band, a second color wavelength band, and a third color wavelength band, and the processor determines, based on the contrast information, imaging positions: a first lens position which is the position of the lens group when imaging the first color wavelength band, a second lens position which is the position of the lens group when imaging the second color wavelength band, and a third lens position which is the position of the lens group when imaging the third color wavelength band, and causes the imaging element to acquire a first captured image which is an image of the first color wavelength band at the first lens position, a second captured image which is an image of the second color wavelength band at the second lens position, and a third captured image which is an image of the third color wavelength band at the third lens position.

[0012] Preferably, the wavelength band relates to the spectral characteristics of the imaging element.

[0013] Preferably, the processor acquires a captured image for each spectral characteristic and generates a separate captured image from the captured image.

[0014] Preferably, the processor calculates the sagittal contrast and the tangential contrast of the area to be corrected, calculates an area contrast ratio between the sagittal contrast and the tangential contrast, and determines the imaging position based on the area contrast ratio.

[0015] Preferably, the processor determines the imaging position by assigning different weights to the sagittal direction and the tangential direction based on the area contrast ratio.

[0016] Preferably, the processor accepts input of the correction target area based on an area selection instruction from a user.

[0017] Preferably, the processor detects a contrast area including a portion having a contrast equal to or greater than a first threshold value in the captured image, and receives an input of the contrast area as the area to be corrected.

[0018] Preferably, the processor performs face detection processing and receives an input of a face-detected area as the area to be corrected.

[0019] Preferably, the processor performs a subject detection process and receives an input of the subject detection area as the correction target area.

[0020] Preferably, the processor detects a luminance area including a portion having a luminance equal to or greater than a second threshold value in the captured image, and receives input of the luminance area as the area to be corrected.

[0021] Preferably, the first lens position, the second lens position, and the third lens position are obtained based on a focal length obtained by a contrast autofocus method for the area to be corrected.

[0022] Preferably, the first color is green, the second color is red, and the third color is blue.

[0023] Another aspect of the present invention is an imaging method for an imaging device that includes an imaging optical system, an imaging element that acquires a captured image, a memory that stores chromatic aberration correction information for correcting axial chromatic aberration of the imaging optical system, the chromatic aberration correction information corresponding to the image height in the sagittal and tangential directions in the captured image, a drive device that moves the imaging optical system in the optical axis direction, and a processor, in which the processor performs the steps of acquiring an area to be corrected, reading out the corresponding chromatic aberration correction information from the memory based on the image height of the correction area, and determining an imaging position corresponding to the wavelength band of the imaging element based on the chromatic aberration correction information.

[0024] Another aspect of the present invention is an imaging method for an imaging device that includes an imaging optical system, an imaging element that acquires a captured image, a drive device that moves the imaging optical system in the optical axis direction, and a processor, in which the processor performs the steps of acquiring an area to be corrected, scanning the lens group with the drive device to acquire contrast information in the sagittal direction and tangential direction of the wavelength band in the area to be corrected, and determining an imaging position corresponding to the wavelength band of the imaging element based on the contrast information.

[0025] Another aspect of the present invention is a program that causes an imaging device that includes an imaging optical system, an imaging element that acquires a captured image, a memory that stores chromatic aberration correction information for correcting axial chromatic aberration of the imaging optical system according to the image height in the sagittal and tangential directions in the captured image, a drive device that moves the imaging optical system in the optical axis direction, and a processor to execute an imaging method, and causes the processor to execute the steps of acquiring an area to be corrected, reading out the corresponding chromatic aberration correction information from the memory based on the image height of the correction area, and determining an imaging position according to the wavelength band of the imaging element based on the chromatic aberration correction information.

[0026] Another aspect of the present invention is a program that causes an imaging device that includes an imaging optical system, an imaging element that acquires a captured image, a drive device that moves the imaging optical system in the optical axis direction, and a processor to execute an imaging method, and causes the processor to execute the following steps: acquiring an area to be corrected; scanning the lens group with the drive device to acquire contrast information in the sagittal direction and tangential direction of the wavelength band in the area to be corrected; and determining an imaging position corresponding to the wavelength band of the imaging element based on the contrast information. [Brief explanation of the drawings]

[0027] [Figure 1] FIG. 1 is a block diagram showing the internal configuration of an imaging device. [Figure 2]FIG. 2 is a block diagram showing the main functions realized by the processor. [Figure 3] FIG. 3 is a diagram illustrating the sagittal and tangential directions of the correction target area. [Figure 4] FIG. 4 is a diagram illustrating the image height, the sagittal image plane, and the axial chromatic aberration at the tangential image plane. [Figure 5] FIG. 5 is a diagram illustrating an example of chromatic aberration correction information. [Figure 6] FIG. 6 is a diagram for explaining the movement of the lens group and the acquisition of images in each wavelength band. [Figure 7] FIG. 7 is a diagram illustrating the generation of a complete composite image from a multi-color mosaic image. [Figure 8] FIG. 8 is a flowchart showing an imaging method using the imaging device. [Figure 9] FIG. 9 is a functional block diagram showing functions realized by the processor. [Figure 10] FIG. 10 is a diagram for explaining acquisition of contrast information. [Figure 11] FIG. 11 is a flowchart showing an imaging method using the imaging device. [Figure 12] FIG. 12 is a diagram illustrating a specific example 1 of the correction target area. [Figure 13] FIG. 13 is a diagram illustrating a second specific example of the correction target area. [Figure 14] FIG. 14 is a diagram illustrating a specific example 3 of the correction target area. [Figure 15] FIG. 15 is a diagram illustrating a fourth specific example of the correction target area. [Figure 16] FIG. 16 is a diagram illustrating a specific example 5 of the correction target area. DETAILED DESCRIPTION OF THE INVENTION

[0028] Preferred embodiments of an imaging device, an imaging method, and a program according to the present invention will be described below with reference to the accompanying drawings.

[0029] First Embodiment FIG. 1 is a block diagram showing the internal configuration of an imaging device according to the present invention.

[0030] The imaging device 10 records captured images on a memory card 54, and the operation of the entire device is generally controlled by a processor (CPU: Central Processing Unit) 40.

[0031] The imaging device 10 is provided with an operation unit 38 including a shutter button, a power / mode switch, a mode dial, a cross operation button, etc. Signals (commands) from this operation unit 38 are input to a processor 40. The processor 40 controls each circuit of the imaging device 10 based on the input signals, and performs drive control of the shutter 14, drive control of the image sensor 16, lens drive control by the lens drive device (drive device) 20, aperture drive control, imaging operation control, image processing control, image data recording / playback control, and display control of the image monitor 30.

[0032] The imaging optical system 12 is configured, for example, by an interchangeable lens device. The imaging optical system 12 is exchanged as appropriate depending on the application and user preference, and is attached to a camera body (not shown) of the imaging device 10. The imaging optical system 12 and the camera body are electrically connected, and are capable of communicating with each other. The imaging optical system 12 is equipped with a lens-side memory 8. The lens-side memory 8 stores parameters related to the lens group 18 of the imaging optical system 12. The lens-side memory 8 also stores chromatic aberration correction information, which will be described later.

[0033] The imaging optical system 12 includes a lens group 18, which is moved on the optical axis toward the object side or the image sensor 16 side via a lens driving device 20 under the control of a processor 40. Note that in this example, a configuration in which the lens group 18 is moved to change the distance between the lens group 18 and the image sensor 16 is described, but application of the present invention is not limited to this. For example, the distance between the lens group 18 and the image sensor 16 may be changed by moving the image sensor 16.

[0034] The light beam passing through the imaging optical system 12 forms an image on the image sensor 16, which is a CMOS (Complementary Metal-Oxide Semiconductor) color image sensor. However, due to the influence of optical axial chromatic aberration, the position at which the image is formed shifts back and forth along the optical axis depending on the wavelength band of the light constituting the light beam. Note that this wavelength band relates to the spectral characteristics of the image sensor 16. The image sensor 16 is not limited to a CMOS type, and may be another type of image sensor, such as a CCD (Charge Coupled Device) type, an organic image sensor, or an image sensor having a three-layer stacked sensor structure with one color per layer.

[0035] The lens driving device (driving device) 20 of the imaging optical system 12 is controlled by the processor 40. The lens driving device 20 moves the lens group 18 of the imaging optical system 12 toward the object side and the image sensor 16 side in the optical axis (L) direction. Therefore, the processor 40 can move the imaging position (or image plane position) of the light beam of each wavelength band by moving the lens group 18 with the lens driving device 20.

[0036] The image sensor 16 has a large number of light receiving elements (e.g., photodiodes) arranged two-dimensionally, and the subject image formed on the light receiving surface of each light receiving element is converted (photoelectrically converted) into a signal voltage (or charge) of an amount corresponding to the amount of incident light, and then converted into a digital signal via an A / D (Analog / Digital) converter within the image sensor 16 and output.

[0037] Image signals (image data) read from the image sensor 16 when capturing a moving image or a still image are temporarily stored in a memory (SDRAM (Synchronous Dynamic Random Access Memory)) 48 via an image input controller 22.

[0038] Furthermore, a flash memory 47 stores a camera control program and various parameters and tables used for image processing and the like.

[0039] The shutter 14 is controlled by the processor 40. When a shutter button, which is part of the operation unit 38, is pressed, the processor 40 controls the opening and closing of the shutter 14, thereby performing exposure for a time period corresponding to a preset shutter speed.

[0040] The image processing unit 24 reads unprocessed image data that is acquired via the image input controller 22 when capturing moving images or still images and that is temporarily stored in the memory 48. The image processing unit 24 performs offset processing, pixel interpolation processing, white balance correction, gain control processing including sensitivity correction, gamma correction processing, demosaic processing (synchronization processing), luminance and color difference signal generation processing, contour enhancement processing, color correction, etc. The image data that has been processed by the image processing unit 24 and that has been processed as a live view image is input to a VRAM (Video RAM Random Access Memory) 50.

[0041] The image data read from the VRAM 50 is encoded by the video encoder 28 and output to the image monitor 30 provided on the rear surface of the camera. As a result, a live view image showing the subject image is displayed on the image monitor 30.

[0042] The image data processed by the image processing unit 24 as a still image or a moving image for recording is stored again in the memory 48.

[0043] When recording a still image or a moving image, the compression / decompression processing unit 26 performs compression processing on the luminance data (Y) and color difference data (Cb), (Cr) that have been processed by the image processing unit 24 and stored in the memory 48. The compressed image data is recorded on a memory card 54 via a media controller 52.

[0044] In addition, in playback mode, the compression / decompression processing unit 26 performs decompression processing on compressed image data obtained from the memory card 54 via the media controller 52. The media controller 52 records and reads compressed image data onto the memory card 54.

[0045] FIG. 2 is a block diagram showing the main functions implemented by the processor 40.

[0046] The processor 40 realizes the functions of a correction target area acquisition unit 40A, a contrast information acquisition unit 40B, a chromatic aberration correction information readout unit 40C, an imaging position determination unit 40D, a drive device control unit 40E, and an image acquisition unit 40F.

[0047] The correction target area acquisition unit 40A acquires the correction target area. The correction target area acquisition unit 40A can acquire the correction target area in various ways. For example, the correction target area acquisition unit 40A can acquire, as the correction target area, an AF (Auto Focus) area selected by the user, an area with high contrast of the subject, an area where a person's face is detected, an area where the subject is recognized, or an area with high brightness in the captured image (or live view image). The correction target area acquisition unit 40A may acquire the correction target area through input in response to user operation of the operation unit 38, or may acquire the correction target area by the correction target area acquisition unit 40A performing a predetermined detection process. Specific examples of the correction target area will be described later.

[0048] The contrast information acquisition unit 40B acquires an area contrast ratio, which is the ratio between the contrast in the sagittal direction and the contrast in the tangential direction of the correction target area. First, the contrast information acquisition unit 40B acquires the contrast in the sagittal direction of the correction target area and the contrast in the tangential direction of the correction target area using a known technique. Then, the contrast information acquisition unit 40B acquires the area contrast ratio, which is the ratio between the contrast in the sagittal direction of the acquired correction target area and the contrast in the tangential direction of the correction target area.

[0049] FIG. 3 is a diagram illustrating the sagittal and tangential directions of the correction target area.

[0050] FIG. 3 shows a photographed image 100, and the sagittal direction (denoted by symbol S) and the tangential direction (denoted by symbol T) of the photographed image 100. The photographed image 100 also shows a correction target area 102. The correction target area 102 also has a sagittal direction (denoted by symbol S) and a tangential direction (denoted by symbol T) based on the sagittal and tangential directions in the photographed image 100. The contrast information acquisition unit 40B acquires the contrast in the sagittal direction by acquiring the difference in luminance between the brightest and darkest points in the correction target area 102 in the sagittal direction. The contrast information acquisition unit 40B also acquires the contrast in the tangential direction by acquiring the difference in luminance between the brightest and darkest points in the correction target area 102 in the tangential direction. The contrast information acquisition unit 40B then acquires an area contrast ratio, which is the ratio between the contrast in the sagittal direction and the contrast in the tangential direction.

[0051] The chromatic aberration correction information reading unit 40C (see FIG. 2) reads out chromatic aberration correction information stored in the lens-side memory 8. The chromatic aberration correction information is information for correcting axial chromatic aberration of the imaging optical system 12. Here, the axial chromatic aberration varies depending on the image height of the captured image. Furthermore, since the characteristics of a lens (or lens group) differ between the sagittal image plane and the tangential image plane, correction of different axial chromatic aberrations is required even for the same image height. Therefore, the chromatic aberration correction information stored in the lens-side memory 8 includes information for correcting axial chromatic aberration depending on the sagittal image plane, the tangential image plane, and the image height of the captured image. Note that, since the chromatic aberration correction information differs depending on each imaging optical system 12, it is preferable to prepare the chromatic aberration correction information for each imaging optical system 12.

[0052] The chromatic aberration correction information reading unit 40C reads out the corresponding chromatic aberration correction information from the memory based on the image height of the correction target area, where the image height of the correction target area is, for example, the image height corresponding to the center of the correction target area.

[0053] 4 is a diagram illustrating axial chromatic aberration at image height, sagittal image plane, and tangential image plane. In the following example, an image of light having three wavelength bands will be described, but application of the present invention is not limited to this. For example, the present invention can also be applied to light having two wavelength bands.

[0054] In Figure 4, the horizontal axis represents the position of the image plane, and the vertical axis represents the image height. The position of the image of light in the green wavelength band (first color wavelength band) on the sagittal image plane is indicated by G(S), and the position of the image of light in the tangential image plane is indicated by G(T). The position of the sagittal image plane of the image of light in the red wavelength band (second color wavelength band) is indicated by R(S), and the position of the tangential image plane is indicated by R(T). The position of the sagittal image plane of the image of light in the blue wavelength band (third color wavelength band) is indicated by B(S), and the position of the tangential image plane is indicated by B(T).

[0055] As shown in Fig. 4, on the optical axis L where the image height is 0, the image of light in the green wavelength band (denoted by symbol G) is at the center, and the image plane positions of the image of light in the red wavelength band (denoted by symbol R) and the image of light in the blue wavelength band (denoted by symbol B) are different. Furthermore, as the image height increases, the images are formed at different positions on the sagittal image plane and the tangential image plane. The chromatic aberration correction information described below includes information about the image height, the sagittal image plane, and the position of the image plane of light in the wavelength band of each color on the tangential image plane.

[0056] FIG. 5 is a diagram illustrating an example of chromatic aberration correction information stored in the lens-side memory 8. As shown in FIG.

[0057] The chromatic aberration correction information is divided into 0 to 10 steps depending on the position of the zoom lens, 0 to 10 steps depending on the size of the diaphragm opening, 0 to 10 steps depending on the focal length, and 0 to 10 steps depending on the image height, and the positions of the sagittal image plane and the tangential image plane are shown for an image of light in the green wavelength band, an image of light in the red wavelength band, and an image of light in the blue wavelength band.

[0058] For example, the image plane position of the sagittal image plane with zoom 10, aperture 10, focal length 10, and image height 0 is α0(R) for an image of light in the red wavelength band, α0(G) for an image of light in the green wavelength band, and α0(B) for an image of light in the blue wavelength band. Also, the image plane position of the tangential image plane with zoom 10, aperture 10, and focal length 10 is β0(R) for an image of light in the red wavelength band, β0(G) for an image of light in the green wavelength band, and β0(B) for an image of light in the blue wavelength band. Here, when the image height is 0, the sagittal image plane and the tangential image plane are equal, so with α0(G) and β0(G) as references, α0(R) = β0(R), α0(G) = β0(G), and α0(B) = β0(B). 5 shows the image plane positions of image heights 0 to 10 at a zoom 10, an aperture 10, and a focal length 10, and other information in the chromatic aberration correction information is omitted.

[0059] The imaging position determination unit 40D (see FIG. 2) determines the imaging position based on the chromatic aberration correction information read by the chromatic aberration correction information readout unit 40C. Specifically, the imaging position determination unit 40D determines the imaging position based on the area contrast ratio and the readout chromatic aberration correction information. For example, the chromatic aberration correction information readout unit 40C reads out an image plane position according to the image height, and the imaging position determination unit 40D determines the imaging position by taking a weighted average of the sagittal image plane position and the tangential image plane position based on the area contrast ratio. In this way, the imaging position determination unit 40D determines the imaging position (first lens position) of the image of light in the green wavelength band, the imaging position (second lens position) of the image of light in the red wavelength band, and the imaging position (third lens position) of the image of light in the blue wavelength band. At the imaging position for the image of light in the green wavelength band, an image (first captured image) for the G pixel (green pixel) is acquired, at the imaging position for the image of light in the red wavelength band, an image (second captured image) for the R pixel (red pixel) is acquired, and at the imaging position for the image of light in the blue wavelength band, an image (third captured image) for the B pixel (blue pixel) is acquired.

[0060] A specific example of the determination of the imaging position performed by the imaging position determination unit 40D will be described below.

[0061] (Example 1) In this example, the contrast information acquisition unit 40B acquires the area contrast ratio of the correction target area as 2:3 (sagittal direction:tangential direction). Furthermore, the chromatic aberration correction information readout unit 40C reads out the image plane positions (α10(R), α10(G), α10(B), β10(R), β10(G), β10(B)) (see FIG. 5) of the sagittal image plane and tangential image plane at image height 10 from the chromatic aberration correction information. In such a case, the imaging position X1 for acquiring an image for G pixels, the imaging position X2 for acquiring an image for R pixels, and the imaging position X3 for acquiring an image for B pixels are determined based on the following equations 1 to 3.

[0062] X1=(α10(G)×2+β10(G)×3) / 5...(Formula 1) X2=(α10(R)×2+β10(R)×3) / 5...(Formula 2) X3=(α10(B)×2+β10(B)×3) / 5...(Formula 3) Here, the imaging position refers to the relative positional relationship between the position of the lens group 18 and the imaging element 16, and in this embodiment, the imaging position is changed by moving the lens group 18.

[0063] (Example 2) In this example, the imaging position X1 for capturing an image for a G pixel is determined by AF control, MF (Manual Focus) control, or the like. In this case, the imaging position X1 for capturing an image for a G pixel is set to 0, and the imaging position X2 for capturing an image for an R pixel and the imaging position X3 for capturing an image for a B pixel are determined by calculating the differences between α10(G) and β10(G) and based on the following formulas 1a to 3a. Note that the area contrast ratio (2:3 (sagittal direction:tangential direction)) of the correction target area and the image plane positions of the sagittal image plane and tangential image plane at image height 10 read out by the chromatic aberration correction information readout unit 40C are the same as in the above specific example 1.

[0064] X1=0...(Equation 1a) X2=((α10(R)-α10(G))×2+(β10(R)-β10(G))×3) / 5...(Formula 2a) X3=((α10(B)-α10(G))×2+(β10(B)-β10(G))×3) / 5...(Formula 3a) The drive device control unit 40E (see FIG. 2) moves the lens group 18 to the imaging position determined by the imaging position determination unit 40D via the lens drive device 20. The drive device control unit 40E moves the lens group 18, for example, to an imaging position for capturing an image for G pixels, an imaging position for capturing an image for R pixels, and an imaging position for capturing an image for B pixels, in that order.

[0065] The image acquisition unit 40F causes the image sensor 16 to acquire a captured image after the drive device control unit 40E has moved the lens group 18 to the imaging position. For example, the image acquisition unit 40F causes the image sensor 16 to acquire a captured image for a G pixel after the lens group 18 has completed moving to the imaging position for an image for a G pixel. Alternatively, for example, the image acquisition unit 40F causes the image sensor 16 to acquire a captured image for an R pixel after the lens group 18 has completed moving to the imaging position for an image for an R pixel. Alternatively, for example, the image acquisition unit 40F causes the image sensor 16 to acquire a captured image for a B pixel after the lens group 18 has completed moving to the imaging position for an image for a B pixel.

[0066] FIG. 6 is a diagram for explaining the movement of the lens group 18 and the acquisition of images in each wavelength band.

[0067] 6A is a diagram illustrating the acquisition of a captured image for a G pixel. The drive device control unit 40E moves the lens group 18 to a position where an image of light in the green wavelength band is captured (a position where an image for a G pixel is captured). Thereafter, the image acquisition unit 40F acquires a captured image 110 for a G pixel.

[0068] 6(B) is a diagram illustrating the acquisition of a captured image for R pixels. The drive device control unit 40E moves the lens group 18 to a position for capturing an image of light in the red wavelength band (a position for capturing an image for R pixels). Thereafter, the image acquisition unit 40F acquires a captured image 112 for R pixels.

[0069] 6(C) is a diagram illustrating the acquisition of a captured image for a B pixel. The drive device control unit 40E moves the lens group 18 to an image capturing position of light in the blue wavelength band (an image capturing position for a B pixel image). Thereafter, the image acquisition unit 40F acquires a captured image 114 for a B pixel.

[0070] The image acquisition unit 40F generates one multi-color mosaic image (separately captured image) using the obtained G pixels of the captured image 110 for G pixels, the R pixels of the captured image 112 for R pixels, and the B pixels of the captured image 114 for B pixels. Then, the image acquisition unit 40F causes the image processing unit 24 to perform demosaic processing on the multi-color mosaic image, thereby acquiring a completed composite image.

[0071] FIG. 7 is a diagram illustrating the generation of a complete composite image from a multi-color mosaic image.

[0072] The multi-color mosaic image 116 is composed of G pixels (indicated as "1" in the figure) of the captured image 110 for G pixels, R pixels (indicated as "2" in the figure) of the captured image 112 for R pixels, and B pixels (indicated as "3" in the figure) of the captured image 114 for B pixels. In this example, the color filters arranged on the image sensor 16 are arranged in a Bayer pattern. The image acquisition unit 40F then demosaices the multi-color mosaic image using the image processing unit 24 to acquire a completed composite image 118. The completed composite image 118 obtained in this manner is an image in which axial chromatic aberration has been corrected in accordance with the contrast ratio of the area to be corrected.

[0073] 8 is a flowchart showing an imaging method using the imaging device 10. Note that in this imaging method, each step is performed by the processor 40 executing a program stored in the flash memory 47.

[0074] First, the correction target area acquisition unit 40A acquires a correction target area (step S100). For example, the correction target area acquisition unit 40A acquires an area where the face of a subject is captured and detected by face detection processing performed by the imaging device 10 as the correction target area. In this example, the focus is automatically adjusted to the detected face in the correction target area (autofocusing is performed). Next, the contrast information acquisition unit 40B calculates the contrast in the sagittal direction and the contrast in the tangential direction in the correction target area (step S101). Thereafter, the contrast information acquisition unit 40B acquires an area contrast ratio, which is the ratio between the contrast in the sagittal direction and the contrast in the tangential direction (step S102).

[0075] Thereafter, the chromatic aberration correction information reading unit 40C reads out the image plane positions of the sagittal image plane and the tangential image plane corresponding to the image height from the lens-side memory 8 as chromatic aberration correction information. Then, the imaging position determination unit 40D determines the imaging positions of the captured image for the G pixel, the R pixel, and the B pixel based on the area contrast ratio and the acquired chromatic aberration correction information (positions of the sagittal image plane and the tangential image plane) (step S103). Specifically, the imaging position determination unit 40D weights the image plane positions by the area contrast ratio and determines the weighted average of the image plane positions of the sagittal image plane and the tangential image plane as the imaging position.

[0076] Thereafter, the drive unit control unit 40E moves the lens group 18 of the imaging optical system 12 to each imaging position determined by the imaging position determination unit 40D. First, the drive unit control unit 40E moves the lens group 18 to an imaging position for capturing an image for G pixels (step S104). Then, the image acquisition unit 40F causes the imaging device 10 to perform imaging and capture an image for G pixels (step S105). Then, the drive unit control unit 40E moves the lens group 18 to an imaging position for capturing an image for R pixels (step S106). Then, the image acquisition unit 40F causes the imaging device 10 to perform imaging and capture an image for R pixels (step S107). Then, the drive unit control unit 40E moves the lens group 18 to an imaging position for capturing an image for B pixels (step S108). Then, the image acquisition unit 40F causes the imaging device 10 to perform imaging and capture an image for B pixels (step S109). In this case, the captured image for G pixels, the captured image for R pixels, and the captured image for B pixels are configured as RAW data.

[0077] Thereafter, the image acquisition unit 40F generates one multicolor mosaic image using the G pixels of the captured image for G pixels, the R pixels of the captured image for R pixels, and the B pixels of the captured image for B pixels (step S110). Thereafter, the image acquisition unit 40F causes the image processing unit 24 to perform demosaic processing on the multicolor mosaic image, thereby acquiring the completed composite image 118 (step S111).

[0078] In the above example, the focus is automatically adjusted to the area detected by the face detection process and acquired as the correction target area, but the present invention is not limited to this. The focus can be adjusted automatically or manually in various ways when acquiring the captured image for G pixels, the captured image for R pixels, and the captured image for B pixels.

[0079] As described above, in this embodiment, the imaging positions of the captured images for G pixels, R pixels, and B pixels are determined based on the area contrast ratio, which is the ratio of the sagittal contrast to the tangential contrast of the correction target area. Then, a multi-color mosaic image is generated using the obtained captured images for G pixels, R pixels, and B pixels, and the multi-color mosaic image is demosaic-processed to generate a completed composite image. This allows the present embodiment to obtain a completed composite image in which axial chromatic aberration is appropriately suppressed according to the captured images.

[0080] <Second embodiment> Next, a second embodiment will be described.

[0081] FIG. 9 is a functional block diagram showing the functions realized by the processor 40 of this embodiment.

[0082] The processor 40 of this embodiment realizes the functions of a correction target area acquisition unit 40A, a contrast AF control unit 40G, an imaging position determination unit 40D, a drive device control unit 40E, and an image acquisition unit 40F. Note that the same reference numerals are used to denote parts that have already been described in FIG. 2, and descriptions thereof will be omitted.

[0083] The contrast AF control unit 40G causes the imaging device 10 to perform AF using a contrast autofocus method in the area to be corrected. Then, the contrast AF control unit 40G acquires contrast information in the area to be corrected. Specifically, the contrast AF control unit 40G scans the lens group 18 using the drive device from infinity to a close distance, measures the contrast in the sagittal direction and the contrast in the tangential direction in the area to be corrected, and acquires the contrast information.

[0084] FIG. 10 is a diagram for explaining the acquisition of contrast information performed under the control of the contrast AF control unit 40G.

[0085] In FIG. 10, the vertical axis represents contrast and the horizontal axis represents the position of the lens group 18. FIG. 10 also shows the sagittal contrast and tangential contrast in the correction target area obtained by scanning the lens group 18 from infinity to a close distance. Specifically, the sagittal contrast of the image of light in the green wavelength band is shown by line 122A, and the tangential contrast of the image of light in the green wavelength band is shown by dotted line 122B. The sagittal contrast of the image of light in the red wavelength band is shown by line 120A, and the tangential contrast of the image of light in the red wavelength band is shown by dotted line 120B. The sagittal contrast of the image of light in the blue wavelength band is shown by line 124A, and the tangential contrast of the image of light in the blue wavelength band is shown by dotted line 124B. FIG. 10 also shows the peak positions of the contrast for each color. Specifically, the peak position of the sagittal contrast of the image of light in the green wavelength band (line 122A) is (P1(S), L1(S)), and the peak position of the tangential contrast of the image of light in the green wavelength band (dotted line 122B) is (P1(T), L1(T)). Also, the peak position of the sagittal contrast of the image of light in the red wavelength band (line 120A) is (P2(S), L2(S)), and the peak position of the tangential contrast of the image of light in the red wavelength band (dotted line 120B) is (P2(T), L2(T)). In addition, the peak position of the sagittal contrast (line 124A) of the image of light in the blue wavelength band is indicated by (P3(S), L3(S)), and the peak position of the tangential contrast (dotted line 124B) of the image of light in the blue wavelength band is indicated by (P3(T), L3(T)).

[0086] As shown in FIG. 10, the contrast AF control unit 40G acquires the contrast of each color for each position of the lens group 18 by scanning the lens group 18, and acquires the peak position of the contrast.

[0087] Then, the contrast AF control unit 40G acquires the area contrast ratio, which is the ratio of the contrast in the sagittal direction to the contrast in the tangential direction from the contrast peak position. Specifically, in the case shown in FIG. 10, the area contrast ratio (sagittal direction:tangential direction) of the green wavelength band is L1(S):L1(T), the area contrast ratio (sagittal direction:tangential direction) of the red wavelength band is L2(S):L2(T), and the area contrast ratio (sagittal direction:tangential direction) of the blue wavelength band is L3(S):L3(T). In this way, in this embodiment, the area contrast ratio of the green wavelength band, the area contrast ratio of the red wavelength band, and the area contrast ratio of the blue wavelength band are acquired.

[0088] The imaging position determination unit 40D determines the imaging positions of the captured image for the G pixel, the captured image for the R pixel, and the captured image for the B pixel by taking a weighted average based on the peak position (position of the lens group 18) of the wavelength band of each color acquired by the contrast AF control unit 40G and the area contrast ratio of the wavelength band of each color.

[0089] The imaging position determination unit 40D can determine, for example, imaging position Y1 of the captured image for G pixels, imaging position Y2 of the captured image for R pixels, and imaging position Y3 of the captured image for B pixels using the following equations (4) to (6).

[0090] Y1=(P1(S)×L1(S)+P1(T)×L1(T)) / (L1(S)+L1(T))...(Formula 4) Y2=(P2(S)×L2(S)+P2(T)×L2(T)) / (L2(S)+L2(T))...(Formula 5) Y3=(P3(S)×L3(S)+P3(T)×L3(T)) / (L3(S)+L3(T))...(Formula 6) 11 is a flowchart showing an imaging method using the imaging device 10 of this embodiment. Note that in this imaging method, each step is performed by the processor 40 executing a program stored in the flash memory 47.

[0091] First, the correction target area acquisition unit 40A acquires a correction target area (step S200). For example, the correction target area acquisition unit 40A acquires an area where the subject's face is captured and detected by face detection processing as the correction target area. Next, the contrast AF control unit 40G causes the driving device to scan the lens group 18, and performs contrast AF in the correction target area (step S201). By performing contrast AF in the correction target area, the contrast AF control unit 40G calculates contrast in the sagittal direction and tangential direction for each position of the lens group 18 (step S202). Thereafter, the correction target area acquisition unit 40A acquires an area contrast ratio, which is the ratio of the contrast in the sagittal direction to the contrast in the tangential direction (step S203).

[0092] Next, the imaging position determination unit 40D determines the imaging position from the weighted average based on the area contrast ratio (step S204). Specifically, the imaging position determination unit 40D determines the imaging position of the captured image for the G pixel, the imaging position of the captured image for the R pixel, and the imaging position of the captured image for the B pixel by taking a weighted average based on the contrast peak position of the wavelength band of each color.

[0093] Thereafter, the drive device control unit 40E moves the lens group 18 of the imaging optical system 12 to each imaging position determined by the imaging position determination unit 40D. First, the drive device control unit 40E moves the lens group 18 to an imaging position for capturing an image for G pixels (step S205). Then, the image acquisition unit 40F executes imaging and captures an image for G pixels (step S206). Then, the drive device control unit 40E moves the lens group 18 to an imaging position for capturing an image for R pixels (step S207). Then, the image acquisition unit 40F executes imaging and captures an image for R pixels (step S208). The drive device control unit 40E moves the lens group 18 to an imaging position for B pixels (step S209). Then, the image acquisition unit 40F executes imaging and captures an image for B pixels (step S210).

[0094] Next, the image acquisition unit 40F generates one multicolor mosaic image using the G pixels of the captured image for G pixels, the R pixels of the captured image for R pixels, and the B pixels of the captured image for B pixels (step S211).The image acquisition unit 40F then performs demosaic processing on the multicolor mosaic image to acquire a composite image (step S212).

[0095] As described above, in this embodiment, the imaging positions of the captured images for G pixels, R pixels, and B pixels are determined based on the area contrast ratio, which is the ratio of the sagittal contrast to the tangential contrast of the correction target area. Then, a multi-color mosaic image is generated using the obtained captured images for G pixels, R pixels, and B pixels, and the multi-color mosaic image is demosaiced to generate a completed composite image. This allows this embodiment to obtain a completed composite image in which axial chromatic aberration is appropriately suppressed depending on the captured images. Furthermore, in this embodiment, even when using an imaging optical system 12 in which the chromatic aberration correction information described in the first embodiment is not stored in the lens-side memory 8, a completed composite image in which axial chromatic aberration is suppressed can be obtained.

[0096] <Example of correction target area> Next, a specific example of the correction target area will be described. The correction target area acquisition unit 40A can acquire the correction target area in various ways. Below, a specific example of acquisition of the correction target area by the correction target area acquisition unit 40A will be described.

[0097] FIG. 12 is a diagram illustrating a specific example 1 of the correction target area.

[0098] In this example, the correction target area acquisition unit 40A accepts input of the correction target area based on an area selection instruction from the user. As shown in FIG. 12, the user selects the AF area 132 on the image monitor 30. For example, the user selects the AF area 132 via the operation unit 38. The correction target area acquisition unit 40A acquires the AF area 132 as the correction target area based on an input signal from the operation unit 38. In this way, by acquiring the area selected by the user as the correction target area, it is possible to correct axial chromatic aberration in accordance with the user's intention.

[0099] FIG. 13 is a diagram illustrating a second specific example of the correction target area.

[0100] In this example, the correction target area acquisition unit 40A receives an input of the contour of the subject as the correction target area. The contour of the subject is an area with high contrast, and in areas with high contrast, axial chromatic aberration appears prominently.

[0101] FIG. 13 shows a subject 130. Processor 40 detects a contour portion 134 in a captured image (live view image) by detecting a contrast area having a contrast equal to or greater than a predetermined first threshold. Correction target area acquisition unit 40A then acquires the detected contour portion 134 as a correction target area. In this manner, by acquiring contour portion 134 (contrast area) as a correction target area, it is possible to acquire an image in which axial chromatic aberration is suppressed at the contour portion of the subject. Note that the first threshold is preferably determined in advance from the perspective of detecting the contour of the subject.

[0102] FIG. 14 is a diagram illustrating a specific example 3 of the correction target area.

[0103] 14, the processor 40 performs face detection processing on a main subject (person) 138, and displays a face detection area 136. The face detection area 136 is detected by the processor 40 in a captured image (live view image) using a known face detection technique. The correction target area acquisition unit 40A then accepts the detected face detection area 136 as the correction target area. In this example, the correction target area acquisition unit 40A accepts input of the face detection area for which face detection processing has been performed as the correction target area. This makes it possible to correct axial chromatic aberration with priority given to the main subject.

[0104] FIG. 15 is a diagram illustrating a fourth specific example of the correction target area.

[0105] In this example, the correction target area acquisition unit 40A receives input of the subject detection area in which the subject detection process has been performed as the correction target area.

[0106] In FIG. 15, subject detection processing of a main subject 142 is performed by the processor 40, and a subject detection area 140 is shown. The subject detection area 140 is detected by the processor 40 in the captured image (live view image) using a known subject detection technique. The correction target area acquisition unit 40A then accepts the detected subject detection area 140 as the correction target area. In this way, by using the subject detection area 140 as the correction target area, axial chromatic aberration in the subject can be suppressed. Note that either a single subject or multiple subjects may be detected. When there are multiple correction target areas, processing is performed by averaging or weighted averaging.

[0107] FIG. 16 is a diagram illustrating a specific example 5 of the correction target area.

[0108] In this example, the correction target area acquisition unit 40A receives an input of a brightness area that includes a portion of the captured image having brightness equal to or greater than the second threshold as the correction target area. Since axial chromatic aberration is most noticeable in contour areas where there is a large difference in brightness, acquiring contour areas with a large difference in brightness as the correction target area more effectively suppresses axial chromatic aberration.

[0109] 16, a subject (tree) is shown with a high-luminance light 146. The processor 40 detects a luminance area 144 having a luminance equal to or greater than a preset second threshold in the captured image (live view image). The correction target area acquisition unit 40A then acquires the detected luminance area 144 as the correction target area. By acquiring the luminance area 144 as the correction target area in this manner, it is possible to acquire a completed composite image in which axial chromatic aberration is suppressed in areas with high luminance.

[0110] In the above embodiment, the hardware structure of the processing units (correction target area acquisition unit 40A, contrast information acquisition unit 40B, chromatic aberration correction information readout unit 40C, imaging position determination unit 40D, drive device control unit 40E, image acquisition unit 40F, and contrast AF control unit 40G) that perform various processes is made up of various processors as shown below. The various processors include a CPU (Central Processing Unit), which is a general-purpose processor that executes software (programs) and functions as various processing units, a programmable logic device (PLD), such as an FPGA (Field Programmable Gate Array), whose circuit configuration can be changed after manufacture, and a dedicated electrical circuit, such as an ASIC (Application Specific Integrated Circuit), which is a processor having a circuit configuration designed specifically for performing specific processes.

[0111] A single processing unit may be configured with one of these various processors, or may be configured with two or more processors of the same or different types (for example, multiple FPGAs, or a combination of a CPU and an FPGA). Also, multiple processing units may be configured with a single processor. Examples of multiple processing units configured with a single processor include, first, a configuration in which one processor is configured with a combination of one or more CPUs and software, as typified by computers such as client and server, and this processor functions as multiple processing units. Second, a configuration in which a processor is used to realize the functions of an entire system including multiple processing units on a single IC (Integrated Circuit) chip, as typified by a system-on-chip (SoC). In this way, the various processing units are configured with one or more of the above-mentioned various processors as a hardware structure.

[0112] Furthermore, the hardware structure of these various processors is, more specifically, an electric circuit made up of a combination of circuit elements such as semiconductor elements.

[0113] The above-described configurations and functions can be realized by any hardware, software, or a combination of both. For example, the present invention can be applied to a program that causes a computer to execute the above-described processing steps (processing procedures), a computer-readable recording medium (non-transitory recording medium) on which such a program is recorded, or a computer on which such a program can be installed.

[0114] Although examples of the present invention have been described above, it goes without saying that the present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the present invention. [Explanation of symbols]

[0115] 8: Lens memory 10: Aperture 12: Imaging optical system 14: Shutter 16: Image sensor 18: Lens group 20: Lens drive device 22: Image input controller 24: Image processing section 26: Compression / expansion processing unit 28: Video Encoder 30: Image monitor 38:Operation unit 40: Processor 47: Flash memory 48: Memory 52: Media Controller 54: Memory card

Claims

1. an imaging device comprising: an imaging optical system; an imaging element for acquiring a captured image; a memory for storing chromatic aberration correction information for correcting axial chromatic aberration of the imaging optical system, the chromatic aberration correction information corresponding to an image height in the captured image in a sagittal direction and a tangential direction in the captured image; a drive device for moving the imaging optical system in an optical axis direction; and a processor; The processor: Obtain the area to be corrected, Calculating a contrast in a sagittal direction and a contrast in a tangential direction of the correction target area, and calculating an area contrast ratio between the contrast in the sagittal direction and the contrast in the tangential direction; reading out the corresponding chromatic aberration correction information from the memory based on the image height of the correction target area; determining an imaging position according to a wavelength band of the imaging element based on the chromatic aberration correction information and the area contrast ratio; Imaging device.

2. The processor: The driving device moves the lens group of the imaging optical system to the imaging position; acquiring the captured image by the imaging element; The imaging device according to claim 1 .

3. the wavelength bands include a first color wavelength band, a second color wavelength band, and a third color wavelength band; The processor: determining, based on the chromatic aberration correction information, a first lens position that is a position of the lens group when imaging the wavelength band of the first color, a second lens position that is a position of the lens group when imaging the wavelength band of the second color, and a third lens position that is a position of the lens group when imaging the wavelength band of the third color, as the imaging positions; causing the image sensor to acquire a first captured image that is the captured image of the wavelength band of the first color at the first lens position, a second captured image that is the captured image of the wavelength band of the second color at the second lens position, and a third captured image that is the captured image of the wavelength band of the third color at the third lens position; The imaging device according to claim 2 .

4. An imaging device comprising: an imaging optical system; an imaging element for acquiring a photographed image; a driving device for moving the imaging optical system in an optical axis direction; and a processor, The processor: Obtain the area to be corrected, The lens group is scanned by the driving device to obtain contrast information in the sagittal direction and the tangential direction of the wavelength band in the correction target area; calculating an area contrast ratio between the contrast information in the sagittal direction and the contrast information in the tangential direction; determining an imaging position according to the wavelength band of the imaging element based on the contrast information and the area contrast ratio; Imaging device.

5. The processor: The driving device moves the imaging optical system to the imaging position, The imaging device according to claim 4 , wherein the captured image is acquired by the imaging element.

6. the wavelength bands include a first color wavelength band, a second color wavelength band, and a third color wavelength band; The processor: determining, based on the contrast information, imaging positions including a first lens position that is a position of the lens group when imaging the first color wavelength band, a second lens position that is a position of the lens group when imaging the second color wavelength band, and a third lens position that is a position of the lens group when imaging the third color wavelength band; causing the image sensor to acquire a first captured image that is the captured image of the wavelength band of the first color at the first lens position, a second captured image that is the captured image of the wavelength band of the second color at the second lens position, and a third captured image that is the captured image of the wavelength band of the third color at the third lens position; The imaging device according to claim 5 .

7. The imaging device according to claim 1 , wherein the wavelength band relates to a spectral characteristic of the imaging element.

8. The imaging device according to claim 7 , wherein the processor acquires the captured image for each spectral characteristic and generates a separate captured image from the captured image.

9. The processor: The imaging device according to claim 1 , wherein the imaging position is determined by applying different weights to the sagittal direction and the tangential direction based on the area contrast ratio.

10. The imaging device according to claim 1 , wherein the processor accepts an input of the correction target area based on an area selection instruction from a user.

11. The imaging device according to claim 1 , wherein the processor detects a contrast area including a portion in the captured image having a contrast equal to or greater than a first threshold, and accepts input of the contrast area as the correction target area.

12. The imaging device according to claim 1 , wherein the processor performs face detection processing and receives an input of a face detection area as the correction target area.

13. The imaging device according to claim 1 , wherein the processor performs a subject detection process and receives an input of a subject detection area as the correction target area.

14. The imaging device according to claim 1 , wherein the processor detects a brightness area including a portion in the captured image having a brightness equal to or greater than a second threshold, and accepts input of the brightness area as the correction target area.

15. The imaging device according to claim 3 or 6, wherein the first lens position, the second lens position, and the third lens position are acquired based on a focal length obtained by a contrast autofocus method for the correction target area.

16. 7. The imaging device according to claim 3, wherein the first color is green, the second color is red, and the third color is blue.

17. An imaging method for an imaging device including an imaging optical system, an imaging element that acquires a captured image, a memory that stores chromatic aberration correction information for correcting axial chromatic aberration of the imaging optical system, the chromatic aberration correction information corresponding to an image height in the captured image in a sagittal direction and a tangential direction in the captured image, a drive device that moves the imaging optical system in an optical axis direction, and a processor, the processor: obtaining a correction target area; calculating a contrast in a sagittal direction and a contrast in a tangential direction of the correction target area, and calculating an area contrast ratio between the contrast in the sagittal direction and the contrast in the tangential direction; reading out the corresponding chromatic aberration correction information from the memory based on the image height of the correction target area; determining an imaging position according to a wavelength band of the imaging element based on the chromatic aberration correction information and the area contrast ratio; An imaging method for performing the above.

18. An imaging method for an imaging device including an imaging optical system, an imaging element that acquires a captured image, a driving device that moves the imaging optical system in an optical axis direction, and a processor, comprising: the processor: obtaining a correction target area; a step of scanning the lens group by the driving device to acquire contrast information in the sagittal direction and the tangential direction of the wavelength band in the correction target area; calculating an area contrast ratio between the contrast information in the sagittal direction and the contrast information in the tangential direction; determining an imaging position of the imaging element according to the wavelength band based on the contrast information and the area contrast ratio; An imaging method for performing the above.

19. A program for causing an imaging device to execute an imaging method, the program comprising: an imaging optical system; an imaging element for acquiring a captured image; a memory for storing chromatic aberration correction information for correcting axial chromatic aberration of the imaging optical system, the chromatic aberration correction information corresponding to an image height in the captured image in a sagittal direction and a tangential direction in the captured image; a drive device for moving the imaging optical system in an optical axis direction; and a processor, the processor, obtaining a correction target area; calculating a contrast in a sagittal direction and a contrast in a tangential direction of the correction target area, and calculating an area contrast ratio between the contrast in the sagittal direction and the contrast in the tangential direction; reading out the corresponding chromatic aberration correction information from the memory based on the image height of the correction target area; determining an imaging position according to a wavelength band of the imaging element based on the chromatic aberration correction information and the area contrast ratio; A program that executes the following.

20. A program for causing an imaging device including an imaging optical system, an imaging element for acquiring a captured image, a driving device for moving the imaging optical system in an optical axis direction, and a processor to execute an imaging method, the processor, obtaining a correction target area; a step of scanning the lens group by the driving device to acquire contrast information in the sagittal direction and the tangential direction of the wavelength band in the correction target area; calculating an area contrast ratio between the contrast information in the sagittal direction and the contrast information in the tangential direction; determining an imaging position of the imaging element according to the wavelength band based on the contrast information and the area contrast ratio; A program that executes the following.

Images