Image processing apparatus, imaging device, lens device, image processing method and program

Abstract

To provide an image processing apparatus that can suppress a change of luminance of a periphery of an imaged image and appropriately correct a hue of the imaged image.SOLUTION: An image processing apparatus (205) comprises: acquisition means (205a) that acquires image data, the image data being the image data corresponding to an optical image passing through an optical filter (2011) which disperses light passing through an optical system into a first color component (B), a second color component (G) and a third color component (R); and correction means (205b) that corrects color shading of the image data using color shading information depending on characteristics of an optical system (101), the color shading information being information associated with a value (B / G) of a ratio of the first color component to the second color component and a value (R / G) of a ratio of the third color component to the second color component.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] In an image captured through an optical system, color shading can occur significantly due to differences in transmittance caused by differences in lens thickness between the center and periphery of the lenses that make up the optical system, or differences in film thickness between the center and periphery of the lens caused by manufacturing errors in the anti-reflection film on the lens surface. Here, color shading (color unevenness) refers to the phenomenon in which the color of an image captured by an imaging device of a uniform luminance surface differs between the center and periphery of the image.

[0003] Patent Document 1 discloses a method of storing correction terms for correcting the luminance shading and color shading of a captured image according to the shooting conditions, and correcting the luminance shading and color shading using the correction terms when the captured image is acquired. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2012-244239 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the method disclosed in Patent Document 1, not only color shading but also luminance shading is corrected, so that the luminance of the periphery of the captured image is affected.

[0006] SUMMARY OF THE PRESENT DISCLOSURE An object of the present invention is to provide an image processing device capable of suppressing changes in luminance around a captured image and appropriately correcting the color tone of the captured image. [Means for solving the problem]

[0007] An image processing device as one aspect of the present invention has an acquisition means for acquiring image data and a correction means for correcting color shading of the image data using color shading information according to characteristics of an optical system, wherein the image data is image data corresponding to an optical image that has passed through an optical filter that disperses light that has passed through the optical system into a first color component, a second color component, and a third color component, and the color shading information is information relating to a value of the ratio of the first color component to the second color component and a value of the ratio of the third color component to the second color component.

[0008] Other objects and features of the present invention are illustrated in the following examples. Effect of the Invention

[0009] According to the present invention, it is possible to provide an image processing device capable of suppressing changes in luminance around a captured image and appropriately correcting the color tone of the captured image. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 is a configuration diagram of an imaging system in each embodiment. [Diagram 2] 5 is a flowchart showing a color shading correction method in each embodiment. [Diagram 3] 11A to 11C are diagrams showing color shading information in each embodiment. [Figure 4] FIG. 4 is an explanatory diagram of an image circle in each embodiment. [Diagram 5] FIG. 4 is an explanatory diagram of a model of an anti-reflection film of a lens in each embodiment. [Figure 6] FIG. 13 is an explanatory diagram of image information in the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same components are designated by the same reference numerals, and duplicated descriptions will be omitted.

[0012] [First embodiment] (Configuration of imaging system) First, an imaging system 10 according to a first embodiment of the present invention will be described with reference to Fig. 1. Fig. 1 is a configuration diagram of the imaging system 10. The imaging system 10 has a camera (imaging device) 200 and an interchangeable lens (lens device) 100 that is detachable from the camera 200. However, the present embodiment is not limited to this, and can also be applied to an imaging system in which the imaging device and the lens device are integrally configured.

[0013] The interchangeable lens 100 has an optical system (image capturing optical system) 101, a lens microcomputer 102, a lens memory (storage means) 103, an optical system control unit 104, and an operation unit 105. The camera 200 has an image capturing unit 201 (image capturing means), a camera microcomputer 202, a camera memory (storage means) 203, a signal processing unit 204, an image processing unit (image processing device) 205, a recording unit 206, and a display unit 207. The lens microcomputer 102 and the camera microcomputer 202 may be configured as control devices separate from the interchangeable lens 100 and the camera 200, respectively. Note that in FIG. 1, parts that are not directly related to this embodiment are omitted.

[0014] The optical system 101 has a variable magnification optical system 1011, an aperture (aperture stop) 1012, and a focus optical system 1013. The optical system 101 forms an image of a subject on an image sensor 2012 of an image capturing unit 201 by using light rays from a subject at a focused position. The variable magnification optical system 1011 is an optical system for changing the focal length. The aperture 1012 adjusts the amount of light taken in from the subject. The focus optical system 1013 is an optical system for focusing on the subject.

[0015] The lens microcomputer 102 is a communication means for communicating with a camera microcomputer 202 that controls the camera 200. The lens microcomputer 102 reads necessary information from the lens memory 103 in response to a command received from the camera microcomputer 202, and also transmits data requested by the camera microcomputer 202 to the camera microcomputer 202.

[0016] In response to a command from the lens microcomputer 102, the optical system control unit 104 drives the aperture blades of the aperture 1012 and also drives the focus optical system 1013 to perform focusing.

[0017] The lens memory 103 stores color shading information of the optical system 101. As described later, the color shading information of this embodiment is information on the ratio value (B / G) of the first color component (B) to the second color component (G) and the ratio value (R / G) of the third color component (R) to the second color component (G). The color shading information is stored in association with the state (imaging condition) of the optical system 101, such as the focal length of the optical system 101, the in-focus object distance, and the aperture diameter (aperture value, F value), for each position in the image data, such as the image height. That is, the color shading information differs depending on the state of the optical system 101, such as the focal length of the optical system 101, the in-focus object distance, and the aperture diameter.

[0018] By using such color shading information, color shading occurring in a captured image according to the characteristics of the optical system 101 can be well corrected. Here, color shading refers to a color difference in an image when a uniform luminance surface is captured, in particular, a difference in color tone between the central part and the peripheral part of the image. The characteristics of the optical system 101 are, for example, the transmittance of a lens constituting the optical system 101, or characteristics related to an anti-reflection film provided on the lens. Note that instead of the lens memory 103, the camera memory 203 may store the color shading information of the optical system 101. Also, both the lens memory 103 and the camera memory 203 may store the color shading information of the optical system 101.

[0019] The operation unit 105 is provided to allow a user to manually operate the optical system 101. For example, the user can change the focal length by manually operating the position of the variable magnification optical system 1011 of the optical system 101, and can change the focusing position by manually adjusting the position of the focus optical system.

[0020] The imaging unit 201 has a color filter (optical filter) 2011 and an imaging element 2012. The color filter 2011 has a filter that transmits blue light to separate the subject image into a first color component (B), a filter that transmits green light to separate the subject image into a second color component (G), and a filter that transmits red light to separate the subject image into a third color component (R). For example, a Bayer array is used as an arrangement pattern of the colors. The subject image separated into three color components by the color filter 2011 is formed on the imaging element 2012. The imaging element 2012 is a photoelectric conversion element such as a CCD (Charge Coupled Device) image sensor or a CMOS (Complementary Metal Oxide Semiconductor) image sensor. The imaging element 2012 photoelectrically converts the subject image (optical image) formed by the optical system 101 and outputs an analog signal.

[0021] The camera microcomputer 202 controls each unit of the camera 200, and also communicates with the lens microcomputer 102 to control the interchangeable lens 100. The camera microcomputer 202 also corrects color shading of an image. Here, a method of correcting color shading of an image by the camera microcomputer 202 will be described with reference to Fig. 2. Fig. 2 is a flowchart showing the color shading correction method.

[0022] First, in step S1, the camera microcomputer 202 acquires the state of the optical system 101 (information such as focal length, focused object distance (focused object distance), and aperture diameter) from the lens microcomputer 102 and the optical system control unit 104. Next, in step S2, the camera microcomputer 202 acquires color shading information (information according to the characteristics of the optical system 101) due to the characteristics of the optical system 101 in the state of the optical system 101 acquired in step S1 from the lens memory 103. Next, in step S3, the camera microcomputer 202 generates a correction value based on the color shading information acquired in step S2. Next, in step S4, the camera microcomputer 202 corrects the color shading due to the characteristics of the optical system 101.

[0023] The camera memory 203 stores various information necessary for the operations of the camera microcomputer 202 and the lens microcomputer 102. The signal processing unit 204 converts the analog signal output from the imaging unit 201 into a digital signal and outputs it to the image processing unit 205.

[0024] The image processing unit 205 performs color shading correction processing on the digital signal under the control of the camera microcomputer 202, and generates image information (image data). The image data corresponds to an optical image that has passed through a color filter 2011 that separates light that has passed through the optical system 101 into a first color component (B), a second color component (G), and a third color component (R). The image information generated by the image processing unit 205 is output to a recording unit 206, or is displayed on a display unit 207. In this embodiment, the image processing unit 205 has an acquisition unit 205a and a correction unit 205b. The acquisition unit 205a acquires image information of an image captured by the imaging unit 201. The correction unit 205b corrects color shading of the image data acquired by the acquisition unit 205a using color shading information according to the characteristics of the optical system 101.

[0025] (Color shading information and color shading correction due to the characteristics of the optical system 101) Fig. 3 is a diagram showing color shading information. In Fig. 3, the horizontal axis indicates image height h, and the vertical axis indicates color shading information. The color shading information is acquired (calculated) for each image height (distance from the center of the captured image) obtained by dividing the ratio B / G of the first color component (B) to the second color component (G) and the ratio R / G of the third color component (R) to the second color component (G) by an arbitrary number.

[0026] In this embodiment, in order to correct the color components with respect to the center of the captured image (the center position in the image data), a value obtained by dividing the color shading information of each image height by the color shading information of the center of the captured image is stored in advance in the lens memory 103. That is, the color shading information is a value based on the center position in the image data (a value divided by the ratio value of the center position). Then, color shading correction is performed using the color shading information. Here, the color shading correction is multiplying the first color component (B) by the inverse of B / G and multiplying the third color component (R) by the inverse of R / G for each image height. The correction ratio may be adjusted by multiplying the inverse of B / G or the inverse of R / G by a coefficient. In addition, for the B / G or R / G between image heights divided by an arbitrary number, the B / G or R / G of the closest image height may be used, or the B / G or R / G obtained by an arbitrary interpolation method may be used.

[0027] (Deriving color shading information based on characteristics of optical system 101) In this embodiment, color shading information due to the characteristics of the optical system 101 can be calculated by a numerical simulation. In the numerical simulation, the color shading information is calculated using a value (numerical simulation value) of the spectral transmittance Tl of the optical system 101 calculated for each image height, the spectral distribution S of the light source assumed when imaging, and the spectral transmittance of the color filter 2011.

[0028] First, a method for calculating the spectral transmittance of the optical system 101 will be described. Fig. 4 is an explanatory diagram of an image circle formed on the image sensor 2012 by the optical system 101. The optical system 101 is a rotationally symmetric optical system, and when considering a polar coordinate system with the center O of the image circle as the origin, it is sufficient to calculate the spectral transmittance for each image height in any radial direction (for example, θ=0).

[0029] 5 is an explanatory diagram of a model used in a numerical simulation of an anti-reflection film on a lens surface included in the optical system 101. This model assumes that the deposition source of the anti-reflection film is located sufficiently far away from the center of curvature of the lens, and the anti-reflection film is attached to the lens in a direction parallel to the optical axis. Therefore, the film thickness d in the direction parallel to the optical axis is the same (constant) at the center and periphery of the lens. In this embodiment, the spectral transmittance of the optical system 101 is calculated for each image height using the model of the anti-reflection film shown in FIG. 5.

[0030] Next, a typical shooting environment is assumed as the light source when capturing an image, and a spectral distribution S of daylight white with a color temperature of, for example, about 5000K is used.

[0031] Finally, the spectral transmittance of each color component is used as the spectral transmittance of the color filter 2011. The color filter 2011 has a filter (first filter) that transmits blue light for dispersing light into a first color component, a filter (second filter) that transmits green light for dispersing light into a second color component, and a filter (third filter) that transmits red light for dispersing light into a third color component. That is, the spectral transmittance Tb of the first filter, the spectral transmittance Tg of the second filter, and the spectral transmittance Tr of the third filter are used. The peak wavelength of the spectral transmittance Tb is within the range of 400 nm to 500 nm, the peak wavelength of the spectral transmittance Tg is within the range of 500 nm to 570 nm, and the peak wavelength of the spectral transmittance Tr is within the range of 570 nm to 700 nm.

[0032] Using the above values ​​and the following equations (1) and (2), color shading information for each image height can be calculated.

[0033] B(h) / G(h)=∫(Tl(h)·S·Tb)dλ / ∫(Tl(h)·S·Tg)dλ ··· (1) R(h) / G(h)=∫(Tl(h)·S·Tr)dλ / ∫(Tl(h)·S·Tg)dλ ··· (2) In equations (1) and (2), λ is the wavelength, the integral interval is from 400 nm to 700 nm, and h is the image height.

[0034] In this embodiment, furthermore, in order to correct the color components for the center (h=0) of the captured image, values ​​obtained by the following formula (3) obtained by dividing formula (1) by B(0) / G(0) and the following formula (4) obtained by dividing formula (2) by R(0) / G(0) are used. The values ​​obtained by formulas (3) and (4) are each stored in the lens memory 103 as color shading information.

[0035] [B(h) / G(h)] / [B(0) / G(0)] ··· (3) [R(h) / G(h)] / [R(0) / G(0)] ··· (4) Moreover, the color shading information obtained by formulas (3) and (4) changes depending on the state of the optical system 101 (focal length, focused object distance, aperture diameter, etc.). In this embodiment, the lens memory 103 divides the state of the optical system 101 into an arbitrary number and stores a plurality of color shading information that differs depending on the state of the optical system 101. This makes it possible to satisfactorily correct color shading even when the magnification of the optical system 101 is changed, the focused object distance is changed, or the aperture diameter is changed. When the state of the optical system 101 is divided into an arbitrary number, the color shading information between the states can use values ​​obtained by an arbitrary interpolation method, or the color shading information of the closest state may be used. The number of divisions of the state of the optical system 101 may be one without dividing the state of the optical system 101 in order to reduce the storage capacity of the lens memory 103.

[0036] The color shading information calculated as above can be used to perform color shading correction. Specifically, the first color component is multiplied by the inverse of the value obtained by equation (3), and the third color component is multiplied by the inverse of the value obtained by equation (4).

[0037] In this embodiment, the optical system 101 has been described as a rotationally symmetric optical system, but this embodiment can also be applied to a rotationally asymmetric optical system that is not rotationally symmetric. In a rotationally asymmetric optical system, when a polar coordinate system is defined with the center of a captured image as the origin, color shading information in the circumferential direction can be added to color shading information in the radial direction.

[0038] In this embodiment, the light source used when capturing an image has a spectral distribution of neutral white at about 5000 K, but is not limited to this. For example, the spectral distribution of the light source may be changed to any other desired one depending on the environment when capturing an image.

[0039] In this embodiment, since the interchangeable lens 100 is interchangeable with respect to the camera 200, appropriate color shading information can be used for each interchangeable lens. This makes it possible to satisfactorily correct color shading even when different interchangeable lenses are attached to the camera 200 and used.

[0040] [Second embodiment] Next, a second embodiment of the present invention will be described. In this embodiment, color shading information according to the characteristics of the optical system 101 is obtained using the spectral transmittance measurement value of the optical system 101, and is stored in advance in the lens memory 103. That is, in this embodiment, the color shading information is calculated using the measurement value of the spectral transmittance of the optical system 101, the spectral transmittance of the color filter 2011, and the spectral distribution of the light source assumed at the time of imaging. Note that the configuration of the imaging system, the color shading information, and the color shading correction process of this embodiment are the same as those of the first embodiment, and therefore detailed descriptions thereof will be omitted.

[0041] In the first embodiment, the optical system 101 is a rotationally symmetric optical system, and the optical characteristics in the circumferential direction at any image height are the same. Therefore, when calculating the spectral transmittance by numerical simulation, it is sufficient to calculate the spectral transmittance for each image height in any radial direction from the optical axis. However, an actual optical system is a rotationally asymmetric optical system due to decentering caused by manufacturing errors. Therefore, even at the same image height, the optical characteristics in the circumferential direction are different. In addition, although the model of the anti-reflection coating shown in FIG. 5 is a rotationally symmetric system, the anti-reflection coating of an actual lens is rotationally asymmetric due to manufacturing errors. In this embodiment, color shading is corrected using color shading information that also takes such manufacturing errors into account.

[0042] Considering a polar coordinate system with the center O of the image circle shown in Fig. 3 as the origin, in this embodiment, the spectral transmittance is measured in the radial direction and the circumferential direction. It is preferable to measure the spectral transmittance in eight radial directions (image heights) every θ = 45 degrees in the circumferential direction, and set the average value of these eight measurement results as the spectral transmittance of the optical system 101. In this case, the color shading information is a value obtained by averaging information in multiple radial directions from the center position in the image data (a common value is obtained for the same image height). The color shading information is calculated from this spectral transmittance in the same manner as in the first embodiment, and stored in the lens memory 103.

[0043] By using the color shading information obtained as described above, color shading can be well corrected even if the optical system 101 is decentered due to a manufacturing error. In this embodiment, when measuring the spectral transmittance in the radial direction and the circumferential direction, the number of divisions in the circumferential direction is set to eight, but this is not limited to this and any number of divisions may be used. In this embodiment, the color shading information is calculated using an average value of the spectral transmittance in a plurality of radial directions, but this is not limited to this and color shading information that differs depending on the radial direction may be used without averaging the spectral transmittance.

[0044] [Third embodiment] Next, a third embodiment of the present invention will be described. In this embodiment, color shading information due to the characteristics of the optical system 101 is obtained in advance from image information (image data) obtained using the camera 200, and stored in the lens memory 103. That is, in this embodiment, the color shading information is calculated using image data obtained by imaging. Note that the configuration of the imaging system, the color shading information, and the color shading correction process of this embodiment are the same as those of the first embodiment, so detailed descriptions thereof will be omitted.

[0045] In this embodiment, it is necessary to measure the spectral transmittance at many positions within the image circle, and therefore the measurement takes time. In this embodiment, in order to obtain color shading information of the optical system 101 more simply, image information obtained by the camera 200 is used.

[0046] A method of calculating color shading information of the optical system 101 using the camera 200 will be described. First, the camera 200 captures an image of a uniform luminance surface having a neutral white light source with a color temperature of about 5000K. At this time, image information is acquired without performing color shading correction processing in the image processing unit 205. By not performing color shading correction processing, image information to which the color shading information of the optical system 101 has been added is obtained.

[0047] Incidentally, in the camera 200, color shading occurs when the position of the color filter 2011 is misaligned with respect to the pixels (light receiving elements) that constitute the image sensor 2012 due to manufacturing errors, or when light rays from the optical system 101 are incident obliquely, causing different color components to mix with adjacent pixels. If the camera 200 further includes an infrared cut filter, the reflection characteristics change when light rays are incident obliquely, causing color shading.

[0048] In this way, the image information includes not only color shading information generated due to the characteristics of the optical system 101, but also color shading information generated due to the characteristics of the camera 200. For this reason, in order to obtain the color shading information of the optical system 101 from the image information, it is necessary to remove the color shading information due to the characteristics of the camera 200.

[0049] In order to remove color shading due to the characteristics of camera 200 from image information, color shading information that occurs due to the characteristics of camera 200 when a light beam equivalent to that of optical system 101 is incident is examined in advance. By removing the color shading information that occurs in camera 200 thus examined in advance from image information, it is possible to obtain color shading information of optical system 101 using camera 200.

[0050] By using the color shading information of the optical system 101 in the entire image information shown in FIG. 6 obtained by the above method, the color shading in the entire image information can be well corrected. In this embodiment, it is preferable to reduce the amount of information stored in the lens memory 103. For this reason, the color shading information in eight directions from the center O of the image information shown in FIG. 6, including the image points H1 and H2 in the horizontal direction, the image points V1 and V2 in the vertical direction, and the image points D1, D2, D3, and D4 in the diagonal direction, may be averaged and stored, and the color shading correction value in the circumferential direction may be the same. In this embodiment, the camera 200 photographed a uniform light source of daylight white with a color temperature of about 5000K, but this is merely an assumption of a light source in a general shooting environment, and is not limited to this. For example, the light source may be changed to any light source according to the environment when shooting.

[0051] [Other embodiments] The present invention can also be realized by a process in which a program for implementing one or more of the functions of the above-described embodiments is supplied to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device read and execute the program. The present invention can also be realized by a circuit (e.g., ASIC) that implements one or more of the functions.

[0052] In each embodiment, color shading is corrected according to the characteristics of the optical system using color shading information that is a ratio value (B / G) of the first color component to the second color component and a ratio value (R / G) of the third color component to the second color component. Therefore, according to each embodiment, it is possible to provide an image processing device, an imaging device, a lens device, an image processing method, and a program that can suppress a change in luminance around a captured image and appropriately correct the color of the captured image.

[0053] The disclosure of each embodiment includes the following configurations and methods. (Configuration 1) An acquisition means for acquiring image data; a correction unit that corrects color shading of the image data by using color shading information according to the characteristics of the optical system; the image data corresponds to an optical image that has passed through an optical filter that separates light that has passed through the optical system into a first color component, a second color component, and a third color component; 13. An image processing apparatus, comprising: an image shading information section that is configured to obtain color shading information relating to a ratio value of the first color component to the second color component, and a ratio value of the third color component to the second color component. (Configuration 2) 2. The image processing device according to configuration 1, further comprising a storage means for storing the color shading information. (Configuration 3) 3. The image processing device according to claim 1, wherein the color shading information differs depending on a focal length of the optical system. (Configuration 4) 4. The image processing device according to any one of configurations 1 to 3, wherein the color shading information differs depending on a focused object distance of the optical system. (Configuration 5) 5. The image processing device according to any one of configurations 1 to 4, wherein the color shading information differs depending on an aperture diameter of the optical system. (Configuration 6) 6. The image processing device according to any one of configurations 1 to 5, wherein the color shading information is a value based on a central position in the image data. (Configuration 7) the optical filter includes a first filter that separates the light into the first color component, a second filter that separates the light into the second color component, and a third filter that separates the light into the third color component; The peak wavelength of the spectral transmittance of the first filter is within a range of 400 nm to 500 nm; The peak wavelength of the spectral transmittance of the second filter is within a range of 500 nm to 570 nm; 7. The image processing device according to any one of configurations 1 to 6, wherein the peak wavelength of the spectral transmittance of the third filter is within a range of 570 nm to 700 nm. (Configuration 8) 8. The image processing device according to any one of configurations 1 to 7, wherein the color shading information is an average value of information in a plurality of radial directions from a central position in the image data. (Configuration 9) 9. The image processing device according to any one of configurations 1 to 8, wherein the color shading information is calculated using a numerical simulation value of the spectral transmittance of the optical system, the spectral transmittance of the optical filter, and the spectral distribution of a light source. (Configuration 10) 9. The image processing device according to any one of configurations 1 to 8, wherein the color shading information is calculated using a measured value of the spectral transmittance of the optical system, the spectral transmittance of the optical filter, and the spectral distribution of a light source. (Configuration 11) 9. The image processing device according to any one of configurations 1 to 8, wherein the color shading information is calculated using the image data. (Configuration 12) An imaging element; 12. An imaging device comprising the image processing device according to any one of configurations 1 to 11. (Configuration 13) An optical system; 12. A lens device comprising the image processing device according to any one of configurations 1 to 11. (Configuration 14) A lens device that is detachable from an imaging device, An optical system; a storage means for storing color shading information corresponding to characteristics of the optical system, for use in correcting color shading of image data acquired by the imaging device; A communication means for communicating with the imaging device, the communication means transmits the color shading information stored in the storage means to the imaging device in response to a request from the imaging device; the image data corresponds to an optical image that has passed through an optical filter that separates light that has passed through the optical system into a first color component, a second color component, and a third color component; A lens device, wherein the color shading information is information regarding a ratio value of the first color component to the second color component, and a ratio value of the third color component to the second color component. (Method 1) acquiring image data; and correcting color shading of the image data using color shading information according to characteristics of an optical system, the image data corresponds to an optical image that has passed through an optical filter that separates light that has passed through the optical system into a first color component, a second color component, and a third color component; An image processing method, characterized in that the color shading information is information regarding a ratio value of the first color component to the second color component, and a ratio value of the third color component to the second color component. (Configuration 15) A program for causing a computer to execute the image processing method according to Method 1.

[0054] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of the gist of the present invention.

[0055] In each embodiment, the image processing unit 205 of the camera 200 corrects color shading due to the characteristics of the optical system 101, but is not limited to this. For example, the interchangeable lens 100 or another external device such as a personal computer may have an image processing unit that corrects color shading due to the characteristics of the optical system 101. [Explanation of symbols]

[0056] 101 Optical system 2011 Color filter (optical filter) 205 Image processing unit (image processing device) 205a Acquisition method 205b Correction means

Claims

1. Means for acquiring image data, It includes a correction means for correcting the color shading of the image data using color shading information corresponding to the characteristics of the optical system, The aforementioned image data is image data corresponding to an optical image obtained by passing through an optical filter that spectrally separates the light that has passed through the optical system into a first color component, a second color component, and a third color component. The color shading information is information relating to the ratio of the first color component to the second color component, and the ratio of the third color component to the second color component. The image processing apparatus is characterized in that the color shading information is calculated using the spectral transmittance for each image height of the optical system.

2. The image processing apparatus according to claim 1, further comprising a storage means for storing the aforementioned color shading information.

3. The image processing apparatus according to claim 1, characterized in that the color shading information differs depending on the focal length of the optical system.

4. The image processing apparatus according to claim 1, characterized in that the color shading information differs depending on the focal distance of the optical system.

5. The image processing apparatus according to claim 1, characterized in that the color shading information differs depending on the aperture diameter of the optical system.

6. The image processing apparatus according to claim 1, characterized in that the color shading information is a value based on the central position in the image data.

7. The optical filter comprises a first filter that spectrally separates the light into the first color component, a second filter that spectrally separates the light into the second color component, and a third filter that spectrally separates the light into the third color component. The peak wavelength of the spectral transmittance of the first filter is in the range of 400 nm to 500 nm. The peak wavelength of the spectral transmittance of the second filter is in the range of 500 nm to 570 nm. The image processing apparatus according to claim 1, characterized in that the peak wavelength of the spectral transmittance of the third filter is in the range of 570 nm to 700 nm.

8. The image processing apparatus according to claim 1, characterized in that the color shading information is an average value obtained by averaging information in multiple radial directions from the central position in the image data.

9. The image processing apparatus according to claim 1, characterized in that the color shading information is calculated using numerical simulation values ​​of the spectral transmittance of the optical system, the spectral transmittance of the optical filter, and the spectral distribution of the light source.

10. The image processing apparatus according to claim 1, characterized in that the color shading information is calculated using the measured spectral transmittance of the optical system, the spectral transmittance of the optical filter, and the spectral distribution of the light source.

11. The image processing apparatus according to claim 1, characterized in that the color shading information is calculated using the image data.

12. Image sensor and An imaging apparatus characterized by having an image processing apparatus according to any one of claims 1 to 11.

13. Optical system and A lens device characterized by having an image processing apparatus according to any one of claims 1 to 11.

14. A lens device that can be attached to and detached from an imaging device, Optical system and A storage means for storing color shading information according to the characteristics of the optical system, for use in correcting the color shading of image data acquired by the imaging device, It has communication means for communicating with the imaging device, The communication means transmits the color shading information stored in the storage means to the imaging device in response to a request from the imaging device. The aforementioned image data is image data corresponding to an optical image obtained by passing through an optical filter that spectrally separates the light that has passed through the optical system into a first color component, a second color component, and a third color component. The color shading information is information relating to the ratio of the first color component to the second color component, and the ratio of the third color component to the second color component. The lens device is characterized in that the color shading information is calculated using the spectral transmittance for each image height of the optical system.

15. Steps to acquire image data, The process includes a step of correcting the color shading of the image data using color shading information corresponding to the characteristics of the optical system. The aforementioned image data is image data corresponding to an optical image obtained by passing through an optical filter that spectrally separates the light that has passed through the optical system into a first color component, a second color component, and a third color component. The color shading information is information relating to the ratio of the first color component to the second color component, and the ratio of the third color component to the second color component. The image processing method is characterized in that the color shading information is calculated using the spectral transmittance for each image height of the optical system.

16. A program characterized by causing a computer to execute the image processing method described in claim 15.

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