Storage medium, lens device, image pickup device and processing device

Abstract

A storage medium, a lens device, an image pickup device, and a processing device are disclosed. A storage medium is provided, which stores correction data for obtaining a correction amount, the correction amount being used to correct image data obtained from an image formed by the lens device with respect to a light amount distribution in the image, wherein the correction data includes coefficients of an nth-order polynomial with respect to an image height h (where n is a non-negative integer), the coefficients corresponding to a state of the lens device. The coefficients satisfy a first conditional expression: ‑0.15≤dD′(h)‑dDlens(h)≤1.98, wherein dDlens(h) represents an amount of change in the amount of light at the image height h per increase in the image height h, dh, and dD′(h) represents an amount of change in the reciprocal of the value of the nth-order polynomial at the image height h per increase in the image height h.

Description

[0001] This application is a divisional application of the Chinese invention patent application with application number 201911258256.1, application date December 10, 2019, and titled “Lens device, image pickup device and processing device”. Technical Field

[0002] The present invention relates to a storage medium, a lens device, an image pickup device, a processing device, a camera device, a method of manufacturing a lens device, and a method of manufacturing a processing device. Background Art

[0003] In most broadcast cameras (television cameras), movie cameras, photo cameras, video cameras, and similar cameras, the amount of light in the peripheral portion of the image plane is smaller than the amount of light in the central portion of the image plane. The ratio of the amount of light in the peripheral portion to the amount of light in the central portion (relative illumination) changes as the optical system is operated by operations such as zooming, focusing, or an aperture stop.

[0004] The change in the ratio is caused by one or both of the change in the amount of light in the central part and the change in the amount of light in the peripheral part. The main reason is that when the optical system is operated in the above manner, for example, a part of the on-axis light beam and the off-axis light beam cannot pass through the lens, aperture stop, other optical components or structural components. This is improved by increasing the effective diameter of the lens or similar component so as to cover all paths of the on-axis light beam and the off-axis light beam that change as the optical system is operated. However, the increased effective diameter is not conducive to reducing the size and weight of the lens device. In addition, the increased effective diameter increases spherical aberration, field curvature and other types of aberrations, and their correction is difficult. Therefore, a method of correcting the light drop by image processing rather than optically correcting the light drop is known. With respect to the light distribution in the image formed by the lens device, the correction of the image data obtained by picking up the image by the camera device is hereinafter referred to as "light (distribution) correction" or "light (distribution) compensation".

[0005] In Japanese Patent Application Publication No. 2008-96907, a lens apparatus having information (correction data) on correction of lateral chromatic aberration and reduction in peripheral light amount is disclosed, the lens apparatus being configured to send information to a camera apparatus based on a command from the camera apparatus. In Japanese Patent Application Publication No. H11-164194, a method is disclosed that includes using a second-order, third-order, or fourth-order expression of image height as a correction expression in order to speed up processing of correcting edge darkening characteristics.

[0006] When the correction amount at each image height is expressed by an nth-order polynomial, which is a relatively low-order expression, there is an advantage that the amount of data can be reduced, but when the correction amount in the case where the change in the amount of light depending on the image height is drastic is approximated, it may be disadvantageous in terms of the error shown. For example, in the case where the correction amount is approximated by a fourth-order polynomial, when the correction amount fluctuates with the change in image height, the corrected image data shows annular unevenness, which may make people feel strange. Summary of the invention

[0007] An aspect of the embodiment provides, for example, a storage medium storing correction data useful in light amount compensation of image data acquired by image pickup.

[0008] According to at least one embodiment of the present invention, there is provided a storage medium storing correction data for obtaining a correction amount for correcting image data obtained from an image formed by a lens device with respect to a light amount distribution in the image, wherein the correction data includes coefficients of an n-order polynomial of an image height h (where n is a non-negative integer), the coefficients corresponding to a state of the lens device. The coefficients satisfy a first conditional expression:

[0009] -0.15≤dD′(h)-dDlens(h)≤1.98,

[0010] Wherein dDlens(h) represents the change amount of the light amount at the image height h per increase amount dh of the image height h, and dD′(h) represents the change amount of the reciprocal of the value of the nth-order polynomial at the image height h per increase amount dh.

[0011] Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a diagram showing a configuration example of an image pickup apparatus according to a first embodiment of the present invention.

[0013] Figure 2 is a graph showing an exemplary relationship between focal length (logarithmic scale) and F-number.

[0014] Figure 3 is a diagram showing an exemplary processing flow in the first embodiment.

[0015] Figure 4 is a diagram showing an exemplary optical system of a lens apparatus.

[0016] Figure 5A is a graph showing exemplary light amount distribution before and after correction.

[0017] Figure 5B is a graph showing exemplary light amount distribution before and after correction.

[0018] Figure 5C is a graph showing exemplary light amount distribution before and after correction.

[0019] Figure 5D is a graph showing exemplary light amount distribution before and after correction.

[0020] Figure 6 is a diagram showing a configuration example of an image pickup apparatus according to a second embodiment of the present invention.

[0021] Figure 7 is a diagram showing an exemplary flow of processing in the second embodiment.

[0022] Figure 8 is a diagram showing a configuration example of an image pickup apparatus according to a third embodiment of the present invention.

[0023] Fig. 9 is a diagram showing an exemplary processing flow in the third embodiment.

[0024] Fig.10 : is a diagram showing an exemplary flow of a manufacturing method according to a fourth embodiment of the present invention.

[0025] Fig.11 is a diagram showing an exemplary flow of a manufacturing method according to a fifth embodiment of the present invention.

[0026] Fig. 12A is a graph showing the problem to be solved.

[0027] Fig. 12B is a graph showing the problem to be solved.

[0028] Fig. 12C is a graph showing the problem to be solved.

[0029] Fig.13 It is a graph showing the ratio of the light amount at each image height to the light amount when the image height is 0. DETAILED DESCRIPTION

[0030] Now, embodiments of the present invention are described with reference to the accompanying drawings. In all drawings for illustrating the embodiments, similar components and the like are denoted by similar reference numerals in principle (unless otherwise specified), and repeated descriptions thereof are omitted.

[0031] [First embodiment]

[0032] Figure 1is a diagram showing a configuration example of an image pickup device according to a first embodiment of the present invention. The image pickup device is configured so that a lens device 100 is detachably mounted to a camera device 200. A focusing lens unit 101 is configured to move for focusing. The focusing lens unit may have a function of so-called inner focusing or floating focusing in which a subunit of the focusing lens unit moves for focusing. A zoom lens unit 102 is configured to move for zooming. The zoom lens unit may include three or more lens subunits configured to move for zooming. An aperture stop 103 has an aperture that can be changed according to zooming or an operation performed by a user. The aperture stop may be operated continuously.

[0033] The detector 110 (hereinafter also referred to as a "focus state detector") is configured to detect the state (e.g., position) of the focus lens unit 101. When the focus lens unit 101 includes a plurality of lens sub-units, the detector 110 may detect the state of only any one of the lens sub-units, or may detect the state of each lens sub-unit. The detector 111 (hereinafter also referred to as a "zoom state detector") is configured to detect the state (e.g., position) of the zoom lens unit 102. Typically, the zoom lens unit 102 is composed of two or more lens sub-units, but the detector 111 may detect the state of only any one of the lens sub-units, or may detect the state of each lens sub-unit. The detector 112 (hereinafter also referred to as an "aperture state detector") is configured to detect the state (e.g., aperture or effective F number) of the aperture stop 103. A collimator lens unit and a detector (hereinafter also referred to as an "insertion / removal status detector") may be added, wherein the collimator lens unit is inserted into the optical path to change the focal length range of the zoom lens unit, and the detector is configured to detect the insertion / removal status of the collimator lens unit.

[0034] Furthermore, an image stabilization lens unit for correcting image stability (for image stability) and a detector configured to detect a state (e.g., position) of the image stabilization lens unit (hereinafter also referred to as an "image stabilization state detector") may be added. Light amount correction taking into account asymmetry of relative illumination may be performed based on a relationship between an amount of change of the image stabilization lens unit relative to the optical axis and an amount of change of the optical axis on the image plane. In any case, the state of the lens device 100 is identified based on each state detected by each detector.

[0035] The processor 120 is configured to perform various processes in the lens apparatus. The communication device 130 is configured to send correction data for light amount correction to the camera apparatus 200. The memory 140 stores the correction data and may be formed, for example, by a nonvolatile memory. For each state of the lens apparatus identified by a state such as a focus state, a zoom state, and an aperture state, the memory 140 stores the correction data as coefficients of terms of each order of an n-order expression (n is a non-negative integer) with respect to image height. Details of the correction data will be described later. The processor 120, the communication device 130, and the memory 140 may be formed by a single or multiple logic devices or a combination of a logic device and a memory.

[0036] In the camera apparatus 200, the processor 210 is configured to perform various processes in the camera apparatus. The communication device 220 is configured to communicate to / from the lens apparatus. The memory 230 stores correction data sent from the lens apparatus 100. The image pickup element 240 is arranged on the image plane of the lens apparatus and is configured to convert an image (optical signal) formed by the lens apparatus into an electrical signal, and may be formed of, for example, a CCD or CMOS device.

[0037] In the first embodiment, for example, for each state of the lens apparatus, a correction amount (≥1) based on the assumption that the light amount at the optical axis position (position where the image height is 0) in the reference state is set to the reference amount (1) is expressed by an n-th order expression (approximate expression) with respect to the image height. That is, the correction amount D is expressed by the following polynomial with respect to the image height "h":

[0038]

[0039] Wherein, D, "h", Z, O, P and "i" represent the correction amount, image height, zoom state, focus state, aperture state and insertion / removal state of the beam expander lens unit, respectively, and A j(Z，O，P，i) Represents the coefficient of the j-th order term with respect to the image height "h". The term "reference state" herein refers to a state of the lens device identified by, for example, a specific zoom state, a specific focus state, a specific aperture state, and a specific insertion / removal state. Specifically, for example, the term "reference state" refers to states such as a wide-angle end, focusing at infinity, an aperture stop open, and an insertion / removal state of a beam expander lens unit. The reference state can be set for each aperture state or each insertion / removal state of the beam expander lens unit. The amount of correction data can be reduced by expressing the correction amount with respect to the image height and setting the coefficient as the correction data.

[0040] When the correction amount D is expressed by a third-order expression with respect to the image height "h", the correction amount D is expressed as:

[0041] D=A3h 3 +A2h2 +A1h+A0

[0042] Wherein A3, A2, A1 and A0 represent the coefficients of the third, second, first and 0th order terms, respectively. The memory 140 stores the third, second, first and 0th order coefficients A3, A2, A1 and A0 as correction data. As described above, for each state of the lens device, the coefficients A3, A2, A1 and A0 are stored. In this case, the state can be identified by a finite number of states of the zoom lens unit, the focusing lens unit and the aperture stop, and a finite number of states of the beam expander lens unit. When the current state of the lens device is different from the finite number of states stored in the memory 140, correction data (correction amount) is generated by interpolation processing. The interpolation processing may be, for example, a linear interpolation processing. In addition, the linear interpolation may be a nearest neighbor interpolation processing that generates correction data in a state that is closest to the current state of the lens device among the states of the lens device stored in the memory 140. In this way, the interpolation processing may be performed by an interpolation method different from linear interpolation.

[0043] It is more preferable that the correction amount D is expressed by a fourth-order expression with respect to the image height. In this case, the correction amount D is expressed by the following expression.

[0044] D=A4h 4 +A3h 3 +A2h 2 +A1h+A0…(1)

[0045] The memory 140 stores coefficients A4, A3, A2, A1, and A0, which are coefficients of fourth-order to 0th-order terms, as correction data. As described above, for each state of the lens device, coefficients A4, A3, A2, A1, and A0 are stored. In this case, the state can be identified by, for example, a limited number of states of each of the zoom lens unit, the focus lens unit, and the aperture stop, and a limited number of states of the expander lens unit. The fourth-order polynomial is more advantageous than the third-order polynomial in terms of approximation of the light quantity distribution including a sharp change in the light quantity due to a change in the image height in the peripheral portion of the image. At the same time, the fifth-order or higher-order polynomial is less advantageous than the fourth-order polynomial in terms of the time period required to obtain the correction amount, and is therefore less advantageous in terms of real-time processing of moving image data.

[0046] Now, correction data according to the first embodiment is described.

[0047] Fluctuations in the correction amount as a problem to be solved may appear as a light quantity distribution in the corrected image data, in which the relative illuminance (the ratio of the light quantity with respect to the center of the image) excessively increases or decreases as the image height changes, or the excessive increase or decrease in the relative illuminance is repeated. Therefore, all that is needed is to generate correction data to reduce the fluctuations in the correction amount.

[0048] FIG. 12A to FIG. 12C is a graph showing the problem to be solved. In Fig. 12A it, the light quantity distribution (before correction) and the light quantity distribution (after correction) are shown, which exhibit a sharp change in the light quantity (relative illuminance) depending on the image height. In Fig. 12B it, the slope dDlens(h) of the light quantity (relative illuminance) before correction is shown. The slope dDlens(h) represents the amount of change in the light quantity at the image height "h" with respect to the value "dh". In this case, the value "dh" represents a predetermined increase in the image height "h". In Fig. 12B it, the slope dD′(h) of the reciprocal of the n-th order expression is also shown, which represents the correction amount showing fluctuations. The correction amount dD′(h) represents the amount of change in the reciprocal of the n-th order expression at the image height "h" with respect to "dh". In Fig. 12A it, the light quantity distribution after correction increases at the image height where dD′(h) in Fig. 12B exceeds dDlens(h) (dD′(h) < 0 and dD′(h) < dDlens(h)). This is because the product of the relative illuminance before correction and the value of the n-th order expression is the relative illuminance after correction. In Fig. 12C it, the difference between dD′(h) and dDlens(h) is shown. The slope dDlens(h) of the relative illuminance of the lens device is expressed as "Dlens(h + dh) - Dlens(h)" by using the relative illuminance Dlens(h) of the lens device. In addition, the slope dD′(h) of the reciprocal of the n-th order expression D(h) is expressed as "1 / D(h + dh) - 1 / D(h)".

[0049] The coefficients of the n-th order expression are the coefficients of the n-th order expression that satisfy the following conditional expression (also referred to as the "first conditional expression").

[0050] -0.15 ≤ dD′(h) - dDlens(h) ≤ 1.98…(2)

[0051] By satisfying the conditional expression (2), it is possible to prevent the relative illuminance after correction from excessively increasing as the image height increases, and thus it is possible to reduce the fluctuations in the relative illuminance after correction.

[0052] When the value of conditional expression (2) is below its lower limit, the corrected relative illuminance increases excessively with the increase in image height, which may make the observer of the image feel strange. Meanwhile, when the value of conditional expression (2) exceeds its upper limit, the corrected relative illuminance is under-corrected.

[0053] Generally, a reduction in the amount of peripheral light in a lens device occurs due to, for example, vignetting, the fourth law of cosines, or distortion. In particular, the relative illumination decreases sharply from the intermediate image height largely due to vignetting. In particular, when the lens device is in a wide-angle state, in many cases, off-axis light at a large image height (high image height) is blocked by the optical components or mechanical components of the first lens unit and the second lens unit, and the relative illumination decreases sharply near the maximum image height (highest image height). In addition, in a lens device with a large magnification, in order to reduce the size of the lens device, the change in the F number is small from the wide-angle end to a specific intermediate zoom state, while the F number increases from a specific zoom state to the telephoto end (a phenomenon called "F drop" occurs). In the case of such a lens device, from the vicinity of the zoom state (focal length) where the F drop starts to the zoom state on the telephoto end side, for example, the off-axis light traveling to the image height side higher than the intermediate image height is blocked due to the limitation of the outer diameter of the first lens unit. This causes the relative illumination to decrease sharply on the higher image height side.

[0054] exist Fig.13 An example of the above reduction is shown in FIG. Fig.13 Graph showing the ratio of the amount of light at each image height to the amount of light at the center of the image (image height is 0) in each aperture state of F2.0, F2.8, and F4.0. As the aperture decreases, the amount of light drop in the peripheral portion (at a high image height) becomes smaller. The amount of light in the peripheral portion depends not only on the aperture state but also on zoom and focus operations.

[0055] In the lens apparatus according to the first embodiment, the open F number at the wide angle end, the open F number at the telephoto end, the focal length at the wide angle end, and the focal length at the telephoto end are represented by Fw, Ft, "fw", and "ft", respectively. In addition, the open F number at the focal length "fd" represented by "fd = Fw / Ft × ft" is represented by Fd. By the above definition, the lens apparatus satisfies the following conditional expression.

[0056] 1.10 <Ft / Fd<4.00…(3)

[0057] -0.01<(Fd-Fw) / Log(fd / fw)<1.20…(4)

[0058] Conditional expression (3) defines the range of the ratio of the open F number at the telephoto end to the open F number at the focal length "fd". A lens device having a configuration in which the ratio of conditional expression (3) is below its lower limit has a central light amount that varies too little compared to the peripheral light amount. Therefore, the change in relative illumination is too small, and the correction effect in the first embodiment is too small. When the light amount at the telephoto end is corrected to about the light amount at the wide-angle end, a lens device having a configuration in which the ratio of conditional expression (3) exceeds its upper limit overemphasizes noise.

[0059] Conditional expression (4) defines the range of the ratio of the F-number change from the focal length "fw" at the wide-angle end to the focal length "fd". A lens device having a configuration in which the ratio of conditional expression (4) is lower than its lower limit can be realized by excessively increasing the effective diameter of the optical component (e.g., lens), but has disadvantages in reducing the size and weight of the lens device. In addition, the lens device has disadvantages in aberrations such as spherical aberration and field curvature. In a lens device having a configuration in which the ratio of conditional expression (4) exceeds its upper limit, the F-number changes excessively due to zooming, and therefore, unless the amount of correction data is set too large, the interpolation error of the correction data will be too large, resulting in overcorrection or undercorrection of the amount of light.

[0060] In a lens device that satisfies conditional expressions (3) and (4), the change in F number is small within the range of the zoom state from the wide-angle end to the focal length "fd", and the F number becomes significantly larger within the range of the zoom state from the focal length "fd" to the telephoto end. This is the so-called "F drop" phenomenon. In a lens device having a configuration including a broadcast lens device, a sharp change in relative illumination depending on image height is particularly noticeable within the focal length range from near the focal length where the F drop occurs to the telephoto side. In view of this, it is necessary to appropriately generate correction data. Figure 2 , changes in F number due to zooming in a lens apparatus satisfying conditional expressions (3) and (4) are shown. Figure 2 is a graph showing an exemplary relationship between focal length (logarithmic scale) and F-number.

[0061] The light amount correction is not limited to the correction of reducing the difference between the light amount at the center image height and the light amount at the peripheral image height. For example, the light amount correction also includes the following correction: while correcting the light amount at the center image height that varies depending on the zoom state (focal length), reducing the difference between the light amount at the center image height after correction and the light amount at the peripheral image height.

[0062] In the first embodiment, when the maximum image height is represented by Y, it is preferable that the image height “h” satisfying the conditional expression (2) satisfies the following expression.

[0063] 0.10×Y≤h≤0.80×Y…(5)

[0064] Conditional expression (5) defines a range of image heights in which fluctuations in the correction amount are to be reduced. Fluctuations in the correction amount within this range may be noticeable. When the value of conditional expression (5) is lower than its lower limit value or exceeds its upper limit value, by limiting the fluctuations in the correction amount also in the image height range in which fluctuations are not noticeable, fluctuations in the correction amount in the image height range in which fluctuations may be noticeable actually increase.

[0065] In the first embodiment, when the tilt of the relative illumination between two points having an image height of zero (the center of the image) and an image height of "hn" (the peripheral part of the image) is represented by dDlens_0n and the tilt of the relative illumination between two points having an image height of "hn" and a maximum image height Y is represented by dDlens_nY, it is preferred that conditional expression (2) is satisfied in a state of the lens device having "hn" satisfying the following expression (for example, each state of the zoom lens unit, the focusing lens unit, the aperture stop, and the expander lens unit).

[0066] 0.10≤|dDlens_0n-dDlens_nY|…(6)

[0067] Conditional expression (6) defines a range related to the state of the lens device in which the change in relative illumination depending on the image height is sharp, which satisfies conditional expression (2). When the fluctuation of the correction amount is to be reduced even in the state of the lens device in which the value of conditional expression (6) is lower than its lower limit, the restriction related to conditional expression (2) is unnecessarily imposed on the state of the lens device in which the correction effect is originally low.

[0068] In the first embodiment, when the maximum image height is represented by Y, it is preferable that the image height "hn" satisfying the conditional expression (6) satisfies the following expression.

[0069] 0.10×Y≤hn≤0.80×Y…(7)

[0070] Conditional expression (7) defines the range of image heights where the relative illumination changes sharply. When the value of conditional expression (7) is lower than its lower limit or exceeds its upper limit, the fluctuation of the correction amount is also reduced in the image height range where the correction effect is originally low, and therefore, the fluctuation of the image height range where the fluctuation may be significant increases.

[0071] In the first embodiment, when the average value of the product of the relative illumination and the correction amount D at each image height "h" from image height zero to image height "hn" is represented by Ave_0n, and the average value of the product of the relative illumination and the correction amount D at each image height "h" from image height "hn" to maximum image height Y is represented by Ave_nY, it is preferred that the correction data satisfies the following conditional expression.

[0072] Ave_nY / Ave_0n≤0.95…(8)

[0073] Conditional expression (8) defines a ratio between an average value of the corrected relative illumination from image height zero to image height "hn" and an average value of the corrected relative illumination from image height "hn" to maximum image height Y. Conditional expression (8) defines that the latter average value is not overcorrected relative to the former average value. When the ratio of conditional expression (8) exceeds its upper limit value, in a lens device in which the relative illumination changes sharply depending on the image height, the corrected relative illumination fluctuates at an intermediate image height.

[0074] In the first embodiment, when the maximum image height is represented by Y, it is preferable that the image height “hn” satisfying the conditional expression (6) or the conditional expressions (6) and (8) satisfy the following conditional expression.

[0075] 0.70×Y≤hn<1.00×Y…(9)

[0076] Conditional expression (9) defines the range of image heights where the relative illuminance changes dramatically. Within this range, the area within the image is relatively small, so the reduction in relative illuminance after correction is unlikely to be noticeable. When the value of conditional expression (9) is below its lower limit, undercorrection is disadvantageously noticeable.

[0077] In order to reduce the fluctuation of the correction amount, it is only necessary to generate such correction data: the correction data does not have a correction amount in which the relative illumination excessively increases or decreases as the image height changes or a correction amount in which the excessive increase or decrease of the relative illumination occurs repeatedly. When the correction data is represented by an n-order expression, usually, the n-order expression has n-1 or fewer extreme values. Now, when there are multiple extreme values, consider two extreme values ​​where the respective values ​​of the image height are adjacent to each other. In this case, for these two extreme values, when the difference between the two image heights falls within a specific range (not a range that is too small or too large) and the difference (absolute value) between the two extreme values ​​exceeds the allowable value, the correction amount fluctuates excessively.

[0078] For example, when the correction amount is expressed by a fourth-order expression, the number of extreme values ​​is three or less, and the correction amount has an extreme value at an image height "h" that satisfies the following expression.

[0079] dD / dh(h)=4A4h 3 +3A3h 2 +2A2h+A1=0

[0080] When the two image heights where the correction amount takes two adjacent extreme values ​​are represented by h1 and h2, respectively, dD / dh(h1)=0 and dD / dh(h2)=0 are satisfied. Therefore, each of the coefficients A1 and A2 can be represented by using the coefficients A3 and A4 and the image heights h1 and h2. When the above-mentioned allowable value is represented by C, the relationship between the difference between the two extreme values ​​(|D(h2)-D(h1)|) and the allowable value C can be represented by the following expression using the sum of h1 and h2, the difference therebetween, and the coefficients A3 and A4 of the higher-order terms.

[0081] |D(h2)-D(h1)|=|(0.5×(h1-h2) 3 )A3+(0.5×(h1-h2) 3 ×2(h1+h2))A4|≤C

[0082] That is, when there are two extreme values, the difference between the two extreme values ​​exceeds the allowable value C at the image height interval within a specific range that is not too small or too large relative to the maximum image height Y, and the correction amount may make the observer of the image feel strange due to the fluctuation of the correction amount.

[0083] In the first embodiment, it is preferable that the coefficient A4 of the fourth-order term and the coefficient A3 of the third-order term of the fourth-order expression (1) representing the correction amount D satisfy the following conditional expression.

[0084] -0.10 <A3+2Y×A4<0.10…(10)

[0085] When the value of conditional expression (10) is lower than its lower limit or exceeds its upper limit, overcorrection or undercorrection occurs, and thus ring-shaped brightness unevenness appears in the image.

[0086] Generally, except for the maximum image height at which a sharp change in the peripheral light amount depending on the image height is exhibited due to vignetting, the inclination of the relative illumination in the lens device between the image height zero (the center of the image) and the image height "hn" (the peripheral portion of the image) can be considered to be substantially constant. Therefore, when correction data is generated in consideration of the image height range of a specific image height "hn" while allowing a sharp change in the peripheral light amount near the maximum image height where the fluctuation is less noticeable, the coefficient of the higher-order term of the n-th order expression is a relatively small value. When the value of the coefficient of the higher-order term is made relatively small, although the correction effect at the maximum image height and the image height near the maximum image height is low, the fluctuation of the correction amount at the intermediate image height can be reduced. Therefore, in the first embodiment, it is preferable that the following conditional expression is satisfied.

[0087] |A4|≤0.0020…(11)

[0088] |A3|≤0.0150…(12)

[0089] Conditional expressions (11) and (12) define the corresponding coefficients of the higher-order terms of the n-th order expression. In the state of the lens device where the relative illumination depends on the image height and changes sharply, the fluctuation of the correction amount can be reduced (limited within the allowable range) by setting the value of the coefficient within the corresponding range given above. When the values ​​of conditional expressions (11) and (12) exceed their corresponding upper limits, in the state of the lens device where the relative illumination depends on the image height and changes sharply, it is difficult to simultaneously achieve the reduction of the fluctuation of the correction amount and the appropriate correction.

[0090] In the first embodiment, when the maximum image height is represented by Y, it is preferable that the image height “hn” satisfying the conditional expressions (11) and (12) and satisfying the conditional expression (6) satisfies the following conditional expression.

[0091] 0.70×Y≤hn<1.00×Y…(13)

[0092] Conditional expression (13) defines the image height at which the relative illumination changes dramatically. Preferably, the dramatic change is limited to an image height range near the maximum image height. In the case where the correction amount is represented by an n-order expression as a low-order expression, when the relative illumination decreases from an image height relatively close to the center of the image (image height is zero), undercorrection of the relative illumination is noticeable. When the value of conditional expression (13) is lower than its lower limit value, then undercorrection is noticeable, disadvantageously.

[0093] In the first embodiment, when the value of the second-order derivative at each image height "h" of the product of the relative illumination and the correction amount D at each image height "h" from image height zero to image height "hn" is represented by ddAve, and the coefficient of the 0th-order term of the fourth-order expression (1) is represented by A0, it is preferred that the following conditional expression is satisfied at each image height "h".

[0094] |ddAve / A0|≤0.50…(14)

[0095] Conditional expression (14) defines the magnitude of the change in the tilt of the corrected relative illuminance from image height zero to image height "hn". Conditional expression (14) indicates that the magnitude of the change in the tilt of the corrected relative illuminance is gentle. When the value of conditional expression (14) is outside its range, disadvantageously, the change in the tilt of the corrected relative illuminance is not allowed.

[0096] The first embodiment may include a user interface device (adjustment device) that enables setting of a correction coefficient multiplied by an n-order term. Thus, the correction amount can be adjusted according to, for example, the degree of significance of the image noise. For example, in the case of a lens device with a large F drop, the correction amount in the telephoto state can be reduced (the amount of light at all corrected image heights can be uniformly reduced), thereby reducing the noise. This can be achieved by multiplying the same correction coefficient (<1) with all terms of the n-order polynomial including a constant term in this state. In addition, for example, in the case of a lens device with a significantly reduced peripheral light amount, the noise in the peripheral part of the image can be reduced while maintaining the light amount at the center of the image (image height zero). This can be achieved by multiplying the same correction coefficient (<1) with all terms of the n-order polynomial except the constant term. For example, a correction coefficient greater than 1 can be used to improve the light amount correction effect or achieve a visual performance effect.

[0097] In the first embodiment, it is preferable to enable switching whether the communication device of the lens device sends correction data to the communication device of the camera device. This enables selective correction to be performed as needed. In addition, in the first embodiment, it is preferable that the communication device sends correction data on the zoom state and the aperture state among the zoom state, the focus state, and the aperture state to an external device such as the camera device. The change in relative illumination due to a change in the focus state is smaller than the change in relative illumination due to a change in the zoom state or the aperture state. Therefore, the data size required for correction can be reduced by sending only the correction data on the zoom state and the aperture state to the external device.

[0098] In the first embodiment, it is preferable that the aperture stop and the lens unit closer to the image side than the aperture stop do not move for zooming. When the aperture stop and the lens unit closer to the image side than the aperture stop move for zooming, the F number changes due to zooming, and as a result, the amount of light at the center of the image and the amount of light at the peripheral portion of the image change excessively, which may cause overcorrection or undercorrection. In addition, in the first embodiment, it is preferable that the diameter of the aperture stop does not change due to zooming or focusing. In addition, in the first embodiment, the first lens unit closest to the object side is a lens unit configured not to move for zooming, and may include a lens subunit configured to move for focusing. Thus, the change in relative illumination is not sharp relative to the change in the corresponding states of the zoom lens unit, the focus lens unit, and the stop, and therefore, a lens device that is advantageous because the amount of correction data is small or the correction accuracy is high can be provided. In addition, when the focus lens unit also moves for zooming, the focal length also changes in order to change the object distance, and the amount of light at the center of the image and the amount of light at the peripheral portion change excessively, which may cause overcorrection or undercorrection.

[0099] In the first embodiment, when the focal length of the first lens unit of the lens apparatus is denoted by f1, the focal length of the second lens unit of the lens apparatus is denoted by f2, and the focal length of the lens apparatus at the wide angle end is denoted by “fw”, it is preferable that the following conditional expressions are satisfied.

[0100] 2.0 <f1 / fw<35.0…(15)

[0101] -15.0 <f1 / f2<-1.2…(16)

[0102] Conditional expressions (15) and (16) define conditions to be satisfied by a lens device having a wide angle of view and a large magnification which is greatly affected by vignetting. When the ratio of the above conditional expressions is outside the corresponding range, the change in relative illumination due to the change in image height is not considered to be sharp, and therefore a full effect cannot be exerted. When realizing a lens device having a wide angle of view and a large magnification, there are also disadvantages in reducing the size and weight of the first lens unit and reducing the size and weight of the lens device.

[0103] In the first embodiment, in the open state of the aperture stop, it is preferable that the following conditional expression is satisfied:

[0104] 1.21 0(ft) / A 0(fd) <16.0…(17); and

[0105] -0.01<(A 0(fd) -A 0(fw) ) / Log(fd / fw)<0.50…(18),

[0106] Among them, "fw", A 0(fw) , A 0(ft) and A 0(fd) The focal length at the wide angle end, the coefficient A0 at the focal length "fw", the coefficient A0 at the focal length "ft", and the coefficient A0 at the focal length "fd" are respectively represented. In a lens apparatus in which the first lens unit is a lens unit configured not to move for zooming and the first lens unit includes a lens subunit configured to move for focusing, the F-number ray on the telephoto side is defined by the lens diameter of the first lens unit. In this case, the amount of light can be corrected by satisfying the following conditions.

[0107] A 0(fd) 0(ft) …(19)

[0108] A 0(fw) =A 0(fd) …(20)

[0109] Figure 2 ​​: is a diagram of F-number variation of a lens apparatus having the characteristics of conditional expressions (15) and (16) and the characteristics of conditional expressions (3) and (4). In a lens apparatus in which the first lens unit is a lens unit configured not to move for zooming and the F-number ray on the telephoto side is defined by the lens diameter of the first lens unit, as Figure 2 As shown, the F number is set to a fixed value within the range of the zoom state from the wide-angle end to the predetermined focal length. Therefore, the lens device satisfies conditional expressions (19) and (20). However, the image (video) visually recognized by the user is affected by, for example, the characteristics of the camera device including the characteristics of the image pickup element and the processing of the signal sent from the camera device. In addition, when correction is performed based on limited data due to limitations in communication or storage capacity, an interpolation processing error occurs, and therefore conditional expressions (19) and (20) cannot always be satisfied. In such a case, conditional expressions (17) and (18) may be satisfied.

[0110] In the first embodiment, it is preferable to include a beam expander lens unit and a detector configured to detect the insertion / removal state of the beam expander lens unit to switch the correction data based on the insertion / removal state. In a lens device having a beam expander lens unit, the F number changes depending on the insertion / removal state of the beam expander lens unit, and the relative illumination also changes. Therefore, by switching the correction data based on the insertion / removal state using separate correction data in the corresponding state of insertion / removal of the beam expander lens unit, it is possible to perform more accurate correction.

[0111] More preferably, the numerical ranges of conditional expressions (2), (3), (4), (5), (6), (7), (8), (9), (10), (11), (12), (13), (14), (17) and (18) are set as follows.

[0112] -0.10≤dD′(h)-dDlens(h)≤1.50…(2a)

[0113] 1.10 <Ft / Fd<3.80…(3a)

[0114] -0.01<(Fd-Fw) / Log(fd / fw)<1.00…(4a)

[0115] 0.20×Y≤h≤0.70×Y…(5a)

[0116] 0.11≤|dDlens_0n-dDlens_nY|…(6a)

[0117] 0.20×Y≤hn≤0.70×Y…(7a)

[0118] Ave_nY / Ave_0n≤0.90…(8a)

[0119] 0.80×Y≤hn<1.00×Y…(9a)

[0120] -0.05≤A3+10×A4<0.05…(10a)

[0121] |A4|≤0.0010…(11a)

[0122] |A3|≤0.0100…(12a)

[0123] 0.80×Y≤hn<1.00×Y…(13a)

[0124] |ddAve / A0|≤0.45…(14a)

[0125] 1.21 0(ft) / A 0(fd) <14.0…(17a)

[0126] -0.01<(A 0(fd) -A 0(fw) ) / Log(fd / fw)<0.40…(18a)

[0127] Furthermore, it is still more preferred that the numerical ranges of conditional expressions (2), (3), (4), (5), (6), (7), (8), (9), (10), (11), (12), (13), (14), (17) and (18) are set as follows.

[0128] -0.05≤dD′(h)-dDlens(h)≤1.00…(2b)

[0129] 1.20 <Ft / Fd<3.50…(3b)

[0130] -0.01<(Fd-Fw) / Log(fd / fw)<0.50…(4b)

[0131] 0.30×Y≤h≤0.60×Y…(5b)

[0132] 0.12≤|dDlens_0n-dDlens_nY|…(6b)

[0133] 0.30×Y≤hn≤0.60×Y…(7b)

[0134] Ave_nY / Ave_0n≤0.85…(8b)

[0135] 0.90×Y≤hn<1.00×Y…(9b) ​

[0136] -0.02≤A3+10×A4<0.02…(10b)

[0137] |A4|≤0.0006…(11b)

[0138] |A3|≤0.0050…(12b)

[0139] 0.90×Y≤hn<1.00×Y…(13b)

[0140] |ddAve / A0|≤0.25…(14b)

[0141] 1.44 0(ft) / A 0(fd) <12.25…(17b)

[0142] -0.01<(A 0(fd) -A 0(fw) ) / Log(fd / fw)<0.20…(18b)

[0143] Figure 3 is a flowchart showing an exemplary flow of processing in the first embodiment. In step S100, processing is started. In step S110, first, the processor 210 of the camera apparatus 200 requests correction data from the processor 120 of the lens apparatus 100 via the communication device 220 of the camera apparatus 200 and the communication device 130 of the lens apparatus 100. In step S120, the processor 120 of the lens apparatus 100 reads the correction data from the memory 140. Then, the processor 120 outputs the correction data to the processor 210 of the camera apparatus 200 via the communication device 130 of the lens apparatus 100 and the communication device 220 of the camera apparatus 200. In step S130, the processor 210 of the camera apparatus 200 writes the received correction data in the memory 230.

[0144] The subsequent processing is for one frame of the image (video). In step S140, the processor 120 of the lens apparatus 100 obtains each state (state of the lens apparatus) from the focus state detector 110, the zoom state detector 111, and the aperture state detector 112. Then, the processor 120 of the lens apparatus 100 outputs the state of the lens apparatus to the processor 210 of the camera apparatus 200 via the communication device 130 of the lens apparatus 100 and the communication device 220 of the camera apparatus 200.

[0145] ​In step S150, the processor 210 of the camera device 200 receives image data (video data) from the image pickup element 240. In step S160, the processor 210 of the camera device 200 reads correction data corresponding to the state of the lens device received in step S140 from the memory 230 of the camera device 200. The correction data stored in the memory 230 of the camera device 200 is discrete data for each state of the focus state, the zoom state, and the aperture state. Therefore, when the processor 210 of the camera device 200 has recognized the state of the lens device, the processor 210 generates correction data corresponding to the recognized state through interpolation processing based on the read correction data. In step S170, the processor 210 of the camera device 200 generates a correction amount based on the generated correction data, and corrects the image data based on the correction amount. After that, the process returns to step S140, and the process continues until a predetermined end condition is met.

[0146] Now, the configuration of the optical system of the lens apparatus according to the first embodiment is described. Figure 4 is a diagram showing an exemplary optical system of a lens apparatus. Figure 4 is a cross-sectional view of the optical system at the wide-angle end in a state where the focus is on infinity. Figure 4 In the embodiment, the first lens unit U1 having a positive refractive power is configured not to move for zooming. A portion of the first lens unit U1 is configured to move toward the object side for focusing from infinity to a close distance. The second lens unit U2 having a negative refractive power is configured to move toward the image side for zooming from a wide angle end (short focal length end) to a telephoto end (long focal length end).

[0147] The third lens unit U3 having a positive refractive power is configured to move in association with the second lens unit U2 to correct (compensate) image plane changes due to magnification. The aperture stop is represented by SP. The fourth lens unit U4 having a positive refractive power is composed of a first lens subunit, a second lens subunit, and a third lens subunit having a positive refractive power, in sequence from the object side. Although the fourth lens unit U4 is configured not to move for zooming, all or part of the fourth lens unit U4 may be configured to move to correct (reduce) image blur due to various reasons. The optical block P includes at least one of a prism, an optical filter or other components. The image plane of the lens device is represented by IP, and when the lens device is connected to a camera device, an image pickup element (photoelectric conversion element) is arranged on the image plane IP.

[0148] Next, the configuration of each lens unit is described. The first lens unit U1 is composed of a negative lens, a positive lens, a positive lens, a positive lens, and a positive lens in sequence from the object side to the image side. The three positive lenses closest to the image side are configured to move from the image side to the object side for focusing. The second lens unit U2 is composed of a negative lens, a cemented lens of a negative lens and a positive lens, and a negative lens in sequence from the object side to the image side. The third lens unit U3 is composed of a positive lens, a positive lens, a cemented lens of a negative lens and a positive lens, and a positive lens in sequence from the object side to the image side. The first lens subunit U41 is composed of a negative lens, a positive lens, and a negative lens from the object side to the image side. The second lens subunit U42 is composed of a cemented lens of a negative lens and a positive lens, and a positive lens from the object side to the image side. The third lens subunit U43 is composed of a positive lens, a cemented lens of a negative lens and a positive lens, a cemented lens of a positive lens and a negative lens, and a positive lens from the object side to the image side.

[0149] A numerical implementation example of the optical system of the lens device 100 is described later. In the numerical implementation example, the order of the surfaces from the object side is represented by "i". The radius of curvature of the i-th surface from the object side is represented by "ri", and the interval between the i-th surface and the (i+1)-th surface from the object side is represented by "di". The refractive index and Abbe number of the optical component (optical medium) between the i-th surface and the (i+1)-th surface are represented by "ndi" and "νdi", respectively. The air equivalent back focal length is represented by BF. The last three surfaces are surfaces in a glass block (e.g., a filter). In the numerical implementation example, an asterisk (*) attached to the surface number indicates that the surface is an aspherical surface.

[0150] The aspherical shape is represented by setting the X-axis in the optical axis direction, setting the H-axis in the direction perpendicular to the optical axis, and defining the traveling direction of light as positive. In addition, the paraxial curvature radius is represented by R, the cone constant is represented by "k", and the aspherical coefficients are represented by A4, A6, A8, ···, A16, A3, A5, A7, ···, and A15 to represent the aspherical shape by the following expression. In addition, "eZ" represents "×10 -Z ”.

[0151]

[0152] In Table 1, numerical examples of correction data (coefficients) are shown, and in Tables 2 to 7, values ​​associated with each conditional expression are shown. FIG. 5A to FIG. 5D are graphs each showing the light amount distribution (relative illuminance) before and after correction. FIG. 5A to FIG. 5D , relative illumination in a state where the second lens sub-unit is inserted into the optical path in the zoom lens of the embodiment of the present invention is shown. Figure 5A , Figure 5B , Figure 5C and Figure 5D, the relative illumination in the following states are shown respectively: open aperture, zoom lens focused at infinity and wide angle end; open aperture, zoom lens focused at infinity and focal length of 348.30mm; open aperture, zoom lens focused at infinity and telephoto end; aperture state of F / 2.088, zoom lens focused at infinity and focal length of 348.30mm. The relative illumination before correction and the relative illumination after correction are shown when the correction amount is approximated by a fourth-order expression. These are the results obtained by correcting the amount of light at the center of the image and correcting the relative illumination, and the amount of light at the center of the image is set to 100%. From FIG. 5A to FIG. 5D It can be understood that, by executing the correction processing described in the first embodiment, the relative illuminance is appropriately corrected after the correction compared to the relative illuminance before the correction.

[0153] exist Figure 5A The wide-angle end status and Figure 5D At the reduced aperture and 348.30mm focal length, the amount of light near the maximum image height is significantly dispersed relative to 100% because the correction amount is prevented from fluctuating against abrupt changes in relative illumination. FIG. 5A to FIG. 5D As illustrated, by correction using correction data according to the first embodiment, relative illumination can be appropriately corrected using a small amount of data. In the numerical embodiment, by correction satisfying conditional expressions (2) to (18), the fluctuation of the amount of light (brightness) from the center of the image to its peripheral portion is small, and thus high uniformity of the amount of light is achieved.

[0154] [Second embodiment]

[0155] Figure 6is a diagram showing an example of a configuration of an image pickup device according to a second embodiment of the present invention. The difference from the exemplary configuration of the image pickup device according to the first embodiment is that the image pickup device includes a beam expander lens unit 104, and the beam expander lens unit 104 can be selectively inserted into or removed from the optical path. In addition, another difference is that the image pickup device includes an insertion / removal state detector 113 configured to detect the insertion or removal state of the beam expander lens unit 104. In addition, another difference is that the image pickup device includes an adjustment device 150 configured to adjust the correction amount and a switching device 160 for switching the on / off (ON / OFF) of the transmission of correction data. The adjustment device 150 and the switching device 160 each serve as a user interface device. Similar to the first embodiment, the correction amount is expressed by a third-order expression or a fourth-order expression (expression (1)) with respect to the image height. The adjustment device 150 can set an adjustment coefficient that is multiplied by all coefficients of the third-order expression or the fourth-order expression (expression (1)) to adjust the degree of correction of F drop. Furthermore, the adjustment device 150 may set an adjustment coefficient that is multiplied by coefficients of all terms other than the constant term of the third-order expression or the fourth-order expression (Expression (1)) in order to adjust the degree of correction of the peripheral light amount.

[0156] Furthermore, the second embodiment is different from the first embodiment in that the lens apparatus transmits correction data corresponding to the state of the lens apparatus (each state of the focus lens unit, the zoom lens unit, the aperture stop, and the beam expander lens unit) to the camera apparatus. Furthermore, as a result, the second embodiment is different from the first embodiment in that the camera apparatus 200 does not include a memory configured to store data for obtaining correction data through interpolation processing.

[0157] Figure 7 2 is a diagram showing an exemplary flow of processing in the second embodiment. In step S200, processing is started. In step S210, the state of the switching device 160 is first acquired, and when the state of sending correction data is ON, the processing proceeds to step S220. In addition, when the state of sending correction data is OFF, the processing proceeds to step S215 and ends. The subsequent processing is processing for one frame of an image (video).

[0158] In step S220, the processor 120 of the lens apparatus 100 acquires each state from the focus state detector 110, the zoom state detector 111, the aperture state detector 112, and the insertion / removal state detector 113. In step S230, the processor 120 of the lens apparatus 100 reads the correction data corresponding to each state (state of the lens apparatus) from the memory 140. Then, the processor 120 transmits the correction data to the processor 210 of the camera apparatus 200 via the communication device 130 of the lens apparatus 100 and the communication device 220 of the camera apparatus 200. The correction data stored in the memory 140 is discrete correction data related to each state of the focus lens unit, the zoom lens unit, and the aperture stop. Therefore, when each state of the focus lens unit, the zoom lens unit, and the aperture stop is identified, the processor 120 of the lens apparatus 100 generates the correction data corresponding to the identified state through interpolation processing.

[0159] In step S240 , the processor 120 of the lens apparatus 100 reads the adjustment coefficient from the adjustment device 150 , and transmits the adjustment coefficient to the processor 210 of the camera apparatus 200 via the communication device 130 of the lens apparatus 100 and the communication device 220 of the camera apparatus 200 .

[0160] In step S250, the processor 210 of the camera device 200 acquires image data (video data) from the image pickup element 240. In step S260, the processor 210 of the camera device 200 corrects the image data by a correction amount based on a correction coefficient acquired by multiplying the adjustment coefficient by the correction data. Thereafter, the process returns to step S220, and the process continues until a predetermined end condition is satisfied.

[0161] In the second embodiment, the transmission of the correction data is switched ON / OFF by the switching device 160 of the lens apparatus 100. However, the configuration is not limited thereto. That is, the camera apparatus may include a switching device configured to switch between execution and non-execution of the correction processing by the processor 210 of the camera apparatus 200, thereby achieving a similar effect.

[0162] [Third embodiment]

[0163] Figure 8is a diagram showing an example of a configuration of an image pickup apparatus according to a third embodiment of the present invention. The difference from the exemplary configuration of the first embodiment is that the image pickup apparatus includes one or more beam expander lens units 104 that are selectively inserted into or removed from the optical path and configured to change the focal length range of the lens apparatus implemented by the zoom lens unit in a stepwise manner. In addition, another difference is that the image pickup apparatus includes an insertion / removal state detector 113 configured to detect the insertion or removal state of the beam expander lens unit 104. In addition, another difference is that the lens apparatus 100 does not include the memory 140, and the camera apparatus 200 includes a memory 235 and a switching device 250 configured to switch ON / OFF of the correction process. The switching device 250 may not switch between ON / OFF of the correction process, but may switch ON / OFF of the communication to / from the lens apparatus. In addition, the exemplary configuration of the third embodiment is different from the exemplary configuration of the first embodiment in that the camera apparatus stores the correction data, and in the third embodiment, the lens apparatus 100 and the camera apparatus 200 do not transmit the correction data to each other. As a result, the communication load is reduced, and high-speed processing can be performed.

[0164] Fig. 9 3 is a flowchart showing an exemplary flow of processing in the third embodiment. In step S300, processing is started. Next, in step S310, the processor 210 of the camera apparatus 200 checks the state of the switching device 250, and when the state of the correction processing is ON, the processing proceeds to step S320. In addition, when the state of the correction processing is OFF, the processing proceeds to step S315 and ends.

[0165] In step S320, the processor 210 of the camera apparatus 200 receives each state from the detectors 110, 111, 112, and 113 via the communication device 130 of the lens apparatus 100 and the communication device 220 of the camera apparatus 200. In step S330, the processor 210 of the camera apparatus 200 reads the correction data corresponding to the received state (state of the lens apparatus) from the memory 235. The correction data stored in the memory 235 is discrete data related to each state of the focus lens unit, the zoom lens unit, and the aperture stop. Therefore, when the processor 210 of the camera apparatus 200 has recognized each state of the focus lens unit, the zoom lens unit, the aperture stop, and the insertion / removal, the processor 210 generates the correction data corresponding to the recognized state of the lens apparatus through interpolation processing based on the read correction data. In step S340, the processor 210 of the camera apparatus 200 obtains image data (video data) from the image pickup element 240. In step S350, the processor 210 of the camera performs correction processing on the image data. After that, the process returns to step S320, and the process continues until a predetermined end condition is satisfied.

[0166] As described above, by performing correction of coefficients of each order of the n-th order expression about the image height based on the approximate correction data, the amount of light at each image height can be corrected by a small amount of data. Only the coefficient of the 0th order term (constant term) can be used for the correction process. For example, only the 0th order correction data that depends on the state of the lens device and does not depend on the image height can be used for correction in order to correct the reduction in the amount of light caused by the F drop on the telephoto side. In this case, only the coefficient of the 0th order term is sent from the lens device to the camera device as correction data, or can be stored in the camera device in advance.

[0167] In addition, in the above configuration, the image data is corrected in the camera device having an image processing function, but the configuration is not limited to this. For example, an external device (image processing device) different from the camera device and the lens device can perform correction processing based on the image data from the camera device and the correction data from the lens device.

[0168] [Fourth embodiment]

[0169] Now, a method of generating correction data and a manufacturing method of each type of device are described. In the case where the relative illuminance changes drastically depending on the image height within an image height range greater than a specific image height, in order to reduce the change in the relative illuminance after correction depending on the image height, it is necessary to generate correction data by a method different from the method in the case where the relative illuminance does not change drastically. This generation method is described below. Fig.10: is a diagram showing an exemplary flow of a manufacturing method according to a fourth embodiment of the present invention. The flow is used to reduce the fluctuation of the corrected relative illumination accompanying the image height change by reducing or eliminating the contribution of the peripheral image height in the generation of correction data (production of each type of device) (to allow the fluctuation to fall within the allowable range).

[0170] exist Fig.10 In step SS100, the processing starts. In step SS110, the relative illumination under the state of the lens device (for example, the state of each of the zoom lens unit, the focusing lens unit, the aperture stop, and the beam expander lens unit) is obtained. The relative illumination can be obtained based on the design data or measurement of the lens device. In step SS120, at least one of the image height range or the contribution ratio of each image height to be used to generate correction data is set (a condition for generating correction data). For example, the entire image height range is set as the image height range, and the contribution ratio of each image height is set to 1. In this case, instead of setting the entire image height range, a part of the image height (for example, the maximum image height) may be excluded from the image height range. In addition, instead of setting the contribution ratio of each image height to 1, the contribution ratio of a part of the image height (for example, the maximum image height) may be set to less than 1.

[0171] In step SS130, coefficients (correction data) of an n-order expression for approximating the correction amount are generated. By setting, for example, the correction amount or the relative illumination after correction as a target, the coefficients are generated by an optimization method (e.g., the least squares method). As another example, by setting the relative illumination before correction as a target, a polynomial can be generated by an optimization method (e.g., the least squares method), and the coefficients can be generated based on the polynomial. In this case, in order to facilitate the generation of the coefficients, for example, the contribution ratio of each image height or the correction amount (target value) at each image height can be appropriately changed within a small range. Preferably, the order of the n-order expression is 4 or less. It is also preferred that the corrected relative illumination is highly uniform over the entire image height range.

[0172] In the next step SS140, determination of the fluctuation is performed. When the fluctuation caused by the change in the image height of the corrected relative illumination based on the correction data generated in the previous step is within the allowable range, the processing proceeds to step SS150, and the processing ends. When the fluctuation is not within the allowable range, the processing proceeds to step SS145. In this case, the situation where the fluctuation is not within the allowable range can correspond to a situation where, for example, the corrected relative illumination increases and decreases or decreases and increases with the increase of the image height and exceeds the allowable range. The situation can also correspond to a situation where the difference between two consecutive extreme values ​​in the corrected relative illumination exceeds the allowable range. The situation can also correspond to a situation where the conditional expression (2) given above is not satisfied. The situation can also correspond to a situation where a ring-shaped light amount distribution is exhibited in the corrected image (simulation of the image). The situation can also correspond to a situation where a phenomenon corresponding to any of the above-mentioned phenomena occurs in the correction amount based on the nth-order expression.

[0173] In step SS145, at least one of the image height range or the contribution ratio of each image height used to generate the correction data is changed. In this case, the change may be, for example, at least one of excluding the maximum image height at the current time or reducing the contribution ratio of the maximum image height. For example, when both exclusion and reduction are performed, setting the contribution ratio of the maximum image height to zero corresponds to excluding the maximum image height. Thereafter, the process returns to step SS130, and the process proceeds to step SS150, or the process continues until another predetermined end condition is satisfied.

[0174] Through the above process, appropriate correction can be performed for as large an image height as possible according to the pattern of change in relative illumination depending on image height (e.g., how drastic the change is). Such processing is effective because images are generally rectangular, and the maximum image height corresponds to each of the four corners of the rectangle, so changes in relative illumination are less likely to be noticeable at the maximum image height.

[0175] Furthermore, in step SS145, instead of changing at least one of the image height range or the contribution ratio of each image height, the correction amount set as the target may be changed. In this case, the target correction amount may be changed so that its change depending on the image height is smoother. For example, a portion where the target correction amount changes sharply may be replaced with a portion where the target correction amount changes smoothly by, for example, using a known interpolation method. Note that the method for generating correction data is not limited to the exemplary method described above. It is only required that the method for generating correction data is capable of generating correction data that allows, for example, correction to be performed at other image heights so that fluctuations at other image heights fall within an allowable range even when correction at the maximum image height and near the maximum image height is insufficient.

[0176] The correction data generated in the above-described manner is stored in a memory of the lens device, so that a lens device that is advantageous in terms of correction of the light amount of image data acquired by image pickup can be produced. In addition, the correction data generated in the above-described manner is stored in a memory of a processing device (for example, a processing device included in a camera device), so that a processing device (camera device) that is advantageous in terms of correction of the light amount of image data acquired by image pickup can be produced.

[0177] [Fifth embodiment]

[0178] Fig.11 1 is a diagram showing an exemplary flow of a manufacturing method according to a fifth embodiment of the present invention. In the flow described in the fourth embodiment, the conditions for generating correction data are repeatedly changed based on the determination of fluctuations. In contrast, in the fifth embodiment, when the relative illumination before correction changes sharply, correction data is generated under predetermined conditions.

[0179] exist Fig.11 In the fourth embodiment, the details of the processing of step SS200 to step SS220 are the same as the details of the processing of step SS100 to step SS120 in the fourth embodiment. In the next step SS230, it is determined whether the change of the relative illuminance before correction depending on the image height is sharp. When the change is sharp, the processing proceeds to step SS235. Meanwhile, when the change is not sharp, the processing proceeds to step SS240. When the change is sharp, it is difficult for the n-order expression, which is a low-order expression, to accurately approximate the correction amount, and thus fluctuations occur in the relative illuminance after correction that changes with the image height. Therefore, when the change is sharp, it is necessary to make settings different from those in SS220. For example, the determination of whether the change is sharp can be made based on whether the change of the inclination of the relative illuminance related to the image height (for example, the second-order derivative of the relative illuminance related to the image height) falls within the allowed range. The determination can also be made based on whether the conditional expression (6) is satisfied, or whether the conditional expressions (6) and (7) are satisfied. The determination can also be made based on whether a sharp change of the light amount ratio depending on the image height is shown in the image before correction or in its simulation.

[0180] In step SS235, at least one of the image height range or the contribution ratio of each image height used to generate the correction data is changed. In this case, the change can be, for example, at least one of excluding the maximum image height at the current time or reducing the contribution ratio of the maximum image height. For example, when both exclusion and reduction are performed, setting the contribution ratio of the maximum image height to zero corresponds to excluding the maximum image height. For example, the contribution ratio from the image height at the beginning of the sharp change in relative illumination to the maximum image height can be reduced. In addition, for example, the image height range can be limited to a range of image heights from image height zero to an image height lower than the image height at the beginning of the sharp change in relative illumination. In addition, the contribution ratio in the image height range (for example, 80% to 100% of the image height) in which the sharp change in relative illumination is unlikely to be obvious can be uniformly reduced. In short, the change only needs to be such a change that enables the generation of a correction amount that emphasizes the range from the center of the image to the intermediate image height.

[0181] Next, in step SS240, coefficients (correction data) for an n-order expression for approximating the correction amount are generated. By setting, for example, the correction amount or the relative illumination after correction as a target, the coefficients are generated by an optimization method (e.g., the least squares method). As another example, by setting the relative illumination before correction as a target, a polynomial for approximating the relative illumination before correction can be generated, for example, by an optimization method (e.g., the least squares method) or by solving simultaneous equations relative to the amount of light at a specific image height, and an n-order polynomial for the correction amount can be generated based on the polynomial. In this case, in order to facilitate the generation of the coefficients, for example, the contribution ratio of each image height or the correction amount (target value) at each image height can be appropriately changed within a small range. Preferably, the order of the n-order expression is 4 or less. It is also preferred that the corrected relative illumination is highly uniform over the entire image height range. In step SS250, the processing ends.

[0182] Through the above process, appropriate correction can be performed for as large an image height as possible according to the pattern of change in relative illumination depending on image height (e.g., how drastic the change is). Such processing is effective because images are generally rectangular, and the maximum image height corresponds to each of the four corners of the rectangle, so changes in relative illumination are less likely to be noticeable at the maximum image height.

[0183] Furthermore, in step SS235, instead of changing at least one of the image height range or the contribution ratio of each image height, the correction amount set as the target may be changed. In this case, the target correction amount may be changed so that its change depending on the image height is smoother. For example, the portion where the target correction amount changes sharply may be replaced by a portion where the target correction amount changes smoothly, for example, by using a known interpolation method. Note that the method for generating correction data is not limited to the exemplary method described above. It is only required that the method for generating correction data is capable of generating correction data that allows correction to be performed at other image heights so that fluctuations at other image heights fall within an allowable range, even when correction at the maximum image height and near the maximum image height is insufficient, for example. Furthermore, because repeated processing is omitted, the time period required to generate correction data is superior to the process described in the fourth embodiment.

[0184] The correction data generated in the above-described manner is stored in a memory of the lens device, so that a lens device that is advantageous in terms of correction of the light amount of image data acquired by image pickup can be produced. In addition, the correction data generated in the above-described manner is stored in a memory of a processing device (for example, a processing device included in a camera device), so that a processing device (camera device) that is advantageous in terms of correction of the light amount of image data acquired by image pickup can be produced.

[0185] Exemplary embodiments of the present invention are described above, but it should be understood that the present invention is not limited to these embodiments and can be modified and changed in various ways within the scope of the gist thereof.

[0186] (Numerical Example)

[0187] Unit: mm

[0188] Area data

[0189]

[0190]

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[0192] Aspheric surface data

[0193] Page 11

[0194] K=-2.61129e+006 A4=1.14924e-006 A6=-4.20242e-010 A8=7.06050e-012A10=1.71748e-014 A12=-3.95143e-018 A14=-2.50492e-020 A16=2.74832e-023 A3=-7.41007e-007 A5=-2.86209e-008 A7=4.68402e-011 A9=-6.67517e-013 A11=-2.87644e-016 A13=1.44174e-018 A15=-1.26241e-021

[0195] Page 19

[0196] K=-8.09196e+003 A4=2.70610e-007 A6=1.07566e-009 A8=-3.82716e-014 A10=-1.89869e-016 A12=1.74435e-020 A14=-2.31461e-023 A16=5.87253e-027 A3=-1.02923e-007 A5=-2.58308e-008 A7=-1.15844e-011 A9=3.14187e-015 A11=2.64931e-018 A13=8.56747e-022 A15=-2.81713e-025

[0197] Page 25

[0198] K=6.92275e+001 A4=-4.53959e-007 A6=-6.59771e-011 A8=-3.55842e-013 A10=-1.48669e-016 A12=8.98957e-020 A14=6.50522e-022 A16=1.24233e-026 A3=7.06566e-007 A5=-1.77804e-008 A7=3.13155e-011 A9=8.81552e-016 A11=-1.46851e-017 A13=1.62371e-021 A15=-1.37737e-023

[0199] Various data

[0200]

[0201]

[0202]

[0203] Zoom lens unit data

[0204]

[0205]

[0206] Single lens data

[0207]

[0208]

[0209]

[0210]

[0211]

[0212]

[0213]

[0214]

[0215]

[0216] <Other embodiments>

[0217] The (one or more) embodiments of the present invention may also be implemented by a computer of a system or device that reads out and executes computer executable instructions (e.g., one or more programs) recorded on a storage medium (which may also be more completely referred to as a "non-transitory computer-readable storage medium") to perform the functions of one or more of the above (one or more) embodiments and / or includes one or more circuits (e.g., application-specific integrated circuits (ASICs)) for performing the functions of one or more of the above (one or more) embodiments, and by, for example, reading out and executing computer executable instructions from a storage medium to perform the functions of one or more of the above (one or more) embodiments and / or controlling one or more circuits to perform the functions of one or more of the above (one or more) embodiments and by a method executed by a computer of a system or device. The computer may include one or more processors (e.g., a central processing unit (CPU), a microprocessing unit (MPU)), and may include a network of separate computers or separate processors to read out and execute computer executable instructions. The computer executable instructions may be provided to the computer, for example, from a network or a storage medium. The storage medium may include, for example, one or more of a hard disk, a random access memory (RAM), a read-only memory (ROM), a memory of a distributed computing system, an optical disk (such as a compact disk (CD), a digital versatile disk (DVD), or a Blu-ray Disc (BD)TM), a flash memory device, a memory card, etc.

[0218] Other embodiments

[0219] The embodiments of the present invention may also be implemented by providing software (program) for performing the functions of the above-described embodiments to a system or device via a network or various storage media, and a computer or a central processing unit (CPU) or a microprocessing unit (MPU) of the system or device reads and executes the program.

[0220] While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments.The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

Claims

1. A lens device, characterized in that: Configured to form an image, the lens device includes a memory and a communication device. The memory stores correction data for obtaining a correction amount, which is used to correct image data obtained from the image with respect to the light amount distribution in the image formed by the lens device. The communication device is configured to send the correction data to an external device. Wherein, The lens device satisfies the inequality 1.10 < Ft / Fd < 4.00; and -0.01 < (Fd - Fw) / Log(fd / fw) < 1.20, where Fw represents the minimum F-number at the wide-angle end, Ft represents the minimum F-number at the telephoto end, fw represents the focal length at the wide-angle end, ft represents the focal length at the telephoto end, and Fd represents the minimum F-number at the focal length fd represented by the following expression: fd = Fw / Ft × ft, The correction data includes the coefficients of an nth-order polynomial with respect to the image height h, where n is a non-negative integer, and the coefficients correspond to the state of the lens device. The correction data satisfies: -0.15 ≤ dD′(h) - dDlens(h) ≤ 1.98, where dDlens(h) represents the slope of the light amount at the image height h, and dD′(h) represents the slope of the reciprocal of the value of the nth-order polynomial at the image height h, and where the correction data satisfies in the state of the lens device: Ave_nY / Ave_0n ≤ 0.95, and where, Ave_0n represents the average value of the product of the relative illuminance of the image at each image height from image height zero to the first image height hn and the correction amount represented by the nth-order polynomial, and Ave_nY represents the average value of the product of the relative illuminance of the image at each image height from the first image height hn to the maximum image height Y and the correction amount represented by the nth-order polynomial. where the first image height hn satisfies: 0.70×Y ≤ hn < 1.00×Y.

2. The lens device according to claim 1, wherein: The correction data is the correction data in the state of the lens device that satisfies the following inequality: 0.10 ≤ |dDlens_0n - dDlens_nY|, where, dDlens_0n represents the slope of the relative illuminance of the image between image height zero and the second image height hn, and dDlens_nY represents the slope of the relative illuminance of the image between the second image height hn and the maximum image height Y.

3. The lens device according to claim 2, wherein: The second image height hn satisfies the following inequality: 0.10×Y ≤ hn ≤ 0.80×Y.

4. The lens device according to claim 2, wherein: The second image height hn satisfies the following inequality: 0.70×Y ≤ hn < 1.00×Y.

5. The lens device according to claim 1, wherein: The coefficients include the coefficient A0, coefficient A1, coefficient A2, coefficient A3, and coefficient A4 of a fourth-order polynomial as the nth-order polynomial, and the nth-order polynomial is represented by the following expression: D=A4×h 4 +A3×h 3 +A2×h 2 +A1×h+A0, where, D represents the correction amount.

6. The lens device according to claim 5, wherein: The coefficients A3 and A4 satisfy the following inequality: -0.10 < A3 + 10×A4 < 0.

10.

7. The lens device according to claim 5, wherein: The coefficients A3 and A4 satisfy the following inequality: |A4| ≤ 0.0020; and |A3|≤0.0150。 8. The lens device according to claim 1, wherein: The following inequality is satisfied: |ddAve / A0| ≤ 0.50, Wherein, ddAve represents the value of the second-order derivative at image height h of the product of the relative illumination of the image at each image height h from image height zero to the second image height hn and the correction amount represented by the nth-order polynomial, and A0 represents the coefficient of the 0th-order term of the nth-order polynomial.

9. The lens device according to claim 1, in, The lens device includes a focusing lens unit, an aperture stop, and a lens unit arranged on the image side of the aperture stop, and Among them, the focus lens unit, the aperture stop, and the lens unit arranged on the image side of the aperture stop are configured not to move for zooming.

10. The lens device according to claim 1, in, The lens arrangement includes an aperture stop, and The lens device satisfies the following inequality when the aperture stop is at its maximum aperture: 1.21 0(ft) / A 0(fd) <16.00; and​ -0.01<(A 0(fd) -A 0(fw) ) / Log(fd / fw)<0.50 Among them, A 0(fw) represents the coefficient A0 of the 0th order term of the nth order polynomial at the focal length fw, A 0(ft) represents the coefficient A0 at the focal length ft, and A 0(fd) Represents the coefficient A0 at focal length fd.

11. The lens device according to claim 1, wherein: The lens assembly includes: a beam expander lens unit configured to be inserted into and removed from the optical path; and A detector is configured to detect the insertion or removal status of the beam expander lens unit.

12. The lens device according to claim 1, further comprising: A user interface device is provided for adjusting coefficients of terms of the nth order polynomial.

13. An image pickup device, characterized in that: include: The lens device according to any one of claims 1 to 12, and The image pickup element is configured to pick up an image formed by the lens device.

14. A processing device, characterized in that: is configured to correct image data derived from an image formed by the lens arrangement with respect to a light amount distribution in the image, wherein The processing device is configured to correct the image data using the correction data sent from the lens device according to any one of claims 1 to 12.

15. A camera device, characterized in that: It comprises a processing device configured to correct image data according to claim 14, and an image pickup element configured to pick up an image formed by the lens device to obtain image data.

16. A method for manufacturing a lens device, characterized in that: The method includes: generating correction data to be stored in a memory included in the lens apparatus according to any one of claims 1 to 12; and The generated correction data is stored in a memory included in the lens apparatus.

17. The method according to claim 16, wherein: The generation includes: changing one of a weight and a value of a correction target regarding each image height based on a change caused by the image height in one of a relative illuminance before correction using correction data and a relative illuminance after correction, and generating correction data based on one of the changed weight and the changed value.

18. A method for manufacturing a processing device, characterized in that The method includes: generating correction data to be stored in a memory included in the lens apparatus according to any one of claims 1 to 12; and The generated correction data is stored in a memory included in a processing device configured to correct image data acquired from an image formed by the lens device with respect to light amount distribution in the image.

19. The method for manufacturing a processing device according to claim 18, wherein: The generation includes: changing one of a weight and a value of a correction target regarding each image height based on a change caused by the image height in one of a relative illuminance before correction using correction data and a relative illuminance after correction, and generating correction data based on one of the changed weight and the changed value.

Images