Imaging device, control method, and control program

Abstract

Provided are an imaging device, a control method, and a control program with which hue shift during a change in transmittance can be suppressed.　The present invention comprises: an electronic ND filter (3) capable of controlling the transmittance of light incident through an imaging lens (2); and a processor (6). The processor (6) performs, on first image data obtained b first imaging, first color correction processing using a first color correction value corresponding to a first transmittance which is the transmittance of the electronic ND filter (3) in the first imaging. Next, the processor calculates a first white balance correction value on the basis of the first image data subjected to the first color correction processing. The processor then performs, on second image data obtained by a second imaging performed after the first imaging, second color correction processing using the first white balance correction value and a second color correction value corresponding to a second transmittance which is the transmittance of the electronic ND filter (3) in the second imaging.

Description

Imaging device, control method, and control program

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

[0002] Patent Document 1 describes an imaging device that includes a lens system, a liquid crystal ND filter, an imaging element, and a WB (white balance) correction circuit, the liquid crystal ND filter being constructed using a guest-host (GH) type liquid crystal and capable of adjusting light transmittance (density), but changing the light transmittance (density) can change the spectral characteristics, and the WB correction circuit has, as adjustment modes, an auto WB mode that automatically adjusts WB in accordance with changes in the color temperature of the light source, and a mode that adjusts WB without following changes in the color temperature of the light source.

[0003] Patent Document 2 describes an imaging device that is configured to allow a lens barrel to be attached, and has a liquid crystal dimming element, an image sensor, a camera signal processing unit, and a camera control unit, in which the liquid crystal dimming element uses a guest-host liquid crystal cell, and the camera control unit outputs a liquid crystal dimming correction coefficient for correcting shading caused by the liquid crystal dimming element and a lens barrel correction coefficient for correcting shading caused by the lens system of the lens barrel, and in which the camera signal processing unit multiplies the captured image signal by the liquid crystal dimming correction coefficient and the lens barrel correction coefficient in order to correct the effects of each shading.

[0004] Patent document 3 describes a camera device that includes a lens, an optical filter, an image sensor, a control circuit, a display unit, and a sensor, in which a variable ND filter is used as the optical filter, the sensor is for detecting environmental information at the location where the optical filter is placed, and includes a brightness detection sensor, a temperature detection sensor, and a spectral characteristic detection sensor that measures the amount of light for each wavelength that passes through the optical filter, and the control circuit controls the optical filter by outputting to the optical filter waveform information of the driving voltage stored in a table according to the brightness, temperature, and spectral characteristics detected by each sensor, thereby preventing the observed color from differing from the intended color.

[0005] Patent Document 4 describes an imaging device that includes a first imaging element, a second imaging element, a lens group, a beam splitter, and a variable light transmittance element, and the variable light transmittance element (organic EC element, liquid crystal element) can cause "density deviation," in which the overall density deviates from a set value, or "density unevenness," in which a density distribution occurs within the transmission surface.In order to eliminate exposure errors caused by density deviations and density unevenness, the imaging light beam is split into two by a beam splitter, and the exposure error in the imaging light beam that passes through the variable light transmittance element is corrected based on the imaging light beam that does not pass through.

[0006] Patent Document 5 describes an imaging device that is equipped with an ND filter that is insertable into and removable from the optical path and has a commercially available film-type spectral transmittance, and in order to eliminate color shifts caused by the spectral transmittance of the ND filter, acquires "color data A" of the white balance (WB) when the ND filter is not in the optical path and "color data B" of the WB when the ND filter is in the optical path, calculates and stores "color correction data" as "color data B" - "color data A", and adds them when the ND filter is used.

[0007] Japanese Patent Publication No. 2013-150167 Japanese Patent Publication No. 2017-054030 Japanese Patent Publication No. 2021-026100 Japanese Patent Publication No. 2019-128379 Japanese Patent Publication No. 2003-158743

[0008] One embodiment of the technique of the present disclosure provides an imaging device, a control method, and a control program that are capable of suppressing color shifts during changes in transmittance.

[0009] (1) An imaging device including a light control device capable of controlling the transmittance of light incident through an imaging lens, and a processor, wherein the processor performs a first color correction process on first image data obtained by first imaging using a first color correction value corresponding to a first transmittance, which is the transmittance of the light control device in the first imaging, calculates a first white balance correction value based on the image data that has been subjected to the first color correction process, and performs a second color correction process on second image data obtained by second imaging performed after the first imaging using a second color correction value corresponding to a second transmittance, which is the transmittance of the light control device in the second imaging, and the first white balance correction value.

[0010] (2) The imaging device according to (1), wherein the processor updates color correction values, including the first color correction value and the second color correction value, used in color correction processes including the first color correction process and the second color correction process, in a time shorter than the time required to calculate white balance correction values, including the first white balance correction value.

[0011] (3) The imaging device according to (1) or (2), wherein the processor calculates the first white balance correction value based on a color temperature of the image data that has undergone the first color correction process.

[0012] (4) The imaging device according to any one of (1) to (3), wherein the processor derives the first color correction value corresponding to the first transmittance and the second color correction value corresponding to the second transmittance based on correspondence information between the transmittance of the light control device and a color correction value.

[0013] (5) The imaging device according to (4), wherein the correspondence information is correspondence information between a combination of a parameter relating to the angle of light incident on the dimming device and the transmittance of the dimming device, and a color correction value, and the processor derives the first color correction value corresponding to the parameter and the first transmittance based on the correspondence information, and derives the second color correction value corresponding to the parameter and the second transmittance.

[0014] (6) The imaging device according to (4) or (5), wherein the light control device includes a liquid crystal cell, and the color correction value in the correspondence information is a correction value according to an alignment direction of the liquid crystal cell.

[0015] (7) The imaging device according to any one of (1) to (6), wherein the processor executes imaging at an exposure value corresponding to the transmittance of the light control device.

[0016] (8) The imaging device according to (7), wherein the processor executes imaging at an exposure value obtained by correcting a reference exposure value in accordance with a color correction value corresponding to a first color among color correction values ​​corresponding to the transmittance of the light control device.

[0017] (9) The imaging device according to (7) or (8), wherein the processor controls the exposure value according to the transmittance of the light control device.

[0018] (10) The imaging device according to any one of (7) to (9), wherein the color correction values ​​including the first color correction value and the second color correction value are 1 or more values.

[0019] (11) The imaging device according to any one of (1) to (10), wherein the processor changes color correction values ​​including the first color correction value and the second color correction value based on a temperature of the light control device.

[0020] (12) The imaging device according to any one of (1) to (11), wherein the processor changes a control voltage of the dimmer based on a temperature of the dimmer.

[0021] (13) A control method for an imaging device including a light control device capable of controlling the transmittance of light incident through an imaging lens, and a processor, wherein the processor performs a first color correction process on first image data obtained by first imaging using a first color correction value corresponding to a first transmittance, which is the transmittance of the light control device in the first imaging, calculates a first white balance correction value based on the image data subjected to the first color correction process, and performs a second color correction process on second image data obtained by second imaging performed after the first imaging using a second color correction value corresponding to a second transmittance, which is the transmittance of the light control device in the second imaging, and the first white balance correction value.

[0022] (14) A control program for an imaging device including a light control device capable of controlling the transmittance of light incident through an imaging lens and a processor, the control program causing the processor to execute the following processes: perform a first color correction process on first image data obtained by first imaging using a first color correction value corresponding to a first transmittance which is the transmittance of the light control device in the first imaging; calculate a first white balance correction value based on the image data subjected to the first color correction process; and perform a second color correction process on second image data obtained by second imaging performed after the first imaging using a second color correction value corresponding to a second transmittance which is the transmittance of the light control device in the second imaging and the first white balance correction value.

[0023] According to the present invention, it is possible to provide an imaging device, a control method, and a control program that are capable of suppressing color shifts during changes in transmittance.

[0024] 7 is a diagram showing the configuration of an imaging device 1 of the present embodiment. FIG. 8 is a cross-sectional view showing the configuration of an electronic ND filter 3. FIG. 9 is a functional block diagram of a processing unit constituted by a processor 6. FIG. 10 is a diagram showing a first example of a correspondence table of correspondence information. FIG. 11 is a diagram showing a time chart of color correction processing according to changes in transmittance. FIG. 12 is a diagram showing a second example of a correspondence table of correspondence information. FIG. 13 is a diagram showing an example of correction of exposure values ​​according to conventional color correction values. FIG. 14 is a diagram showing another correction example that eliminates the lack of R output in a saturated image that occurs in the correction example of FIG. 7. FIG. 15 is a diagram showing an example of correction of exposure values ​​according to color correction values ​​of the present invention. FIG. 16 is a cross-sectional view showing a two-layer electronic ND filter. FIG. 17 is a diagram showing the alignment direction of the liquid crystal layer of the electronic ND filter 3A when viewed from the direction of light incidence.

[0025] Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings.

[0026] <Image Capture Device> Fig. 1 is a diagram showing the configuration of an image capture device 1 according to this embodiment. As shown in Fig. 1, the image capture device 1 includes an imaging lens 2, an electronic ND filter 3, an ND filter driver 4, an image sensor 5, and a processor 6. The image capture device 1 is, for example, a digital still camera or a digital video camera capable of capturing moving images.

[0027] The imaging lens 2 is a lens that forms an image of incident light on the imaging element 5. The imaging lens 2 is provided with, for example, an aperture that can mechanically adjust the amount of incident light. In this example, a single imaging lens 2 is shown, but multiple imaging lenses may be provided.

[0028] The electronic ND (Neutral Density) filter 3 is an example of the "light control device" of the present invention. The electronic ND filter 3 can electrically control the transmittance of light incident through the imaging lens 2. The higher the filter density of the electronic ND filter 3, the lower the transmittance. The electronic ND filter 3 is a guest-host type electronic variable ND filter constructed using, for example, a guest-host (GH) type liquid crystal containing a dye (dichroic dye). Since the dichroic dye has different light absorption levels depending on the axial direction, when a voltage is applied to the liquid crystal, the liquid crystal molecules change their alignment in response to the voltage, following the movement of the liquid crystal and creating a transmissive state and an absorbing (light-blocking) state. The electronic ND filter 3 is a filter that adjusts only the amount of light without affecting color.

[0029] The ND filter driving unit 4 drives the electronic ND filter 3. The ND filter driving unit 4 drives the electronic ND filter 3 between the transmitting state and the light blocking state based on a control signal from the processor 6.

[0030] The image sensor 5 is configured by, for example, a CCD (Charge Coupled Device) element or a CMOS (Complementary Metal Oxide Semiconductor) element. The image sensor 5 captures an image of a target subject at a predetermined frame rate. The "predetermined frame rate" refers to, for example, several tens to several hundreds of frames per second. The image sensor 5 also converts incident light into an electrical signal by photoelectric conversion, converts the converted electrical signal into a digital signal, and outputs the converted digital signal to the processor 6 as imaging data.

[0031] The processor 6 converts the image data output from the image sensor 5 into full-color image data by performing demosaic processing on the image data. The processor 6 also performs image processing such as color correction, white balance adjustment, sharpening, and noise reduction on the converted image data, and outputs the processed image data.

[0032] The processor 6 performs color correction processing on image data obtained by capturing an image using a color correction value corresponding to the transmittance of the electronic ND filter 3 during that capturing. The processor 6 also calculates a white balance correction value based on the image data that has been color corrected. The processor 6 then uses the calculated white balance correction value to perform color correction processing on image data obtained by subsequent capturing. The processor 6 stores the corrected image data in, for example, a nonvolatile memory provided in the imaging device 1. The processor 6 also displays the corrected image data on a display device such as a liquid crystal display provided in the imaging device 1 (for example, a live view display).

[0033] In this example, the electronic ND filter 3 is arranged after the imaging lens 2, but the present invention is not limited to this. For example, the electronic ND filter 3 may be arranged before the imaging lens 2.

[0034] <Electronic ND Filter> Fig. 2 is a cross-sectional view showing the configuration of the electronic ND filter 3. As shown in Fig. 2, the electronic ND filter 3 includes transparent substrates 31a and 31b, transparent electrodes 32a and 32b, alignment films 33a and 33b, and sealing members 34a and 34b. The direction indicated by arrow A in Fig. 2 is the direction in which light incident on the electronic ND filter 3 travels.

[0035] A transparent substrate 31 a, a transparent electrode 32 a, and an alignment film 33 a are stacked in this order on the light incident side. A transparent substrate 31 b, a transparent electrode 32 b, and an alignment film 33 b are stacked in this order on the light exit side. A liquid crystal layer 35 containing liquid crystal molecules and a dye (dichroic dye) is provided between the alignment films 33 a and 33 b.

[0036] The transparent substrates 31a and 31b support the transparent electrodes 32a and 32b and the alignment films 33a and 33b, and also seal the liquid crystal layer 35. The transparent substrates 31a and 31b are made of, for example, glass substrates.

[0037] The transparent electrodes 32a and 32b are electrodes for applying a control voltage to the liquid crystal layer 35. The transparent electrodes 32a and 32b are made of, for example, indium tin oxide.

[0038] The alignment films 33a and 33b are films that align the liquid crystal molecules in a specific direction in the liquid crystal layer 35. The alignment films 33a and 33b are made of a polymer material such as polyimide.

[0039] The sealing members 34a and 34b are members that seal the liquid crystal molecules and dye molecules from leaking from the edges of the liquid crystal layer 35. The sealing members 34a and 34b are made of adhesive such as epoxy or acrylic.

[0040] In this example, a single liquid crystal cell having such a configuration is shown, but the present invention is not limited to this. For example, a plurality of liquid crystal cells may be stacked with different light distribution directions of the alignment films.

[0041] <Functional Block> Fig. 3 is a functional block diagram of a processing unit configured by the processor 6. As shown in Fig. 3, the processing unit of the processor 6 includes a first color correction processing unit 61, a first gain derivation unit 62, a correspondence information storage unit 63, a second gain derivation unit 64, and a second color correction processing unit 65.

[0042] The first color correction processing unit 61 performs first color correction processing on the first image data obtained by the first image capture in the imaging device 1 using a first color correction value corresponding to a first transmittance, which is the transmittance of the electronic ND filter 3 in the first image capture. The "first image data" is image data of a frame used for calculating auto white balance (AWB). The first image data is, for example, image data of multiple frames (for example, discrete frames set every three or four frames). The "first color correction processing" is processing of multiplying by a WB gain.

[0043] The "first transmittance" is, for example, the transmittance of ND3.9. The "first color correction value" is, for example, a white balance (WB) gain corresponding to ND3.9. That is, the first color correction value is, for example, a WB gain that corrects color unevenness that occurs at ND3.9. The first gain derivation unit 62 derives a first WB gain corresponding to the first transmittance based on the "correspondence information" stored in the correspondence information storage unit 63. The first gain derivation unit 62 outputs the derived first WB gain to the first color correction processing unit 61 as the first color correction value corresponding to the first transmittance.

[0044] The correspondence information storage unit 63 stores correspondence information between the transmittance of the electronic ND filter 3 and the color correction value corresponding to that transmittance. The "correspondence information" refers to, for example, a correspondence table stored in the correspondence information storage unit 63. The correspondence information is created in advance by determining color unevenness for each transmittance (filter density) through experiments and simulations. The electronic ND filter 3 includes a liquid crystal cell, and the color correction value in the correspondence information is a correction value corresponding to the alignment direction of the liquid crystal cell. The correction value is a value created by conducting experiments and simulations on an actual device including the liquid crystal cell. Note that when multiple liquid crystal cells (e.g., two) are stacked, the correction value is a value corresponding to the combined direction of the alignment directions of the two liquid crystal cells.

[0045] The information in the correspondence table may be correspondence information between a combination of a parameter related to the angle of light incident on the electronic ND filter 3 and the transmittance of the electronic ND filter 3, and a color correction value corresponding to the transmittance. In this case, the first gain derivation unit 62 derives a first WB gain corresponding to the parameter and the first transmittance based on the "correspondence information" stored in the correspondence information storage unit 63. The "parameter related to the angle of light incident on the electronic ND filter 3" is a parameter that affects the angle of light incident on the electronic ND filter 3. The parameters include, for example, the model number of the imaging lens 2, the position of the zoom lens included in the imaging lens 2, the aperture state (F-number), the position of the focus lens included in the imaging lens (focus position), etc.

[0046] The second gain derivation unit 64 calculates a first white balance correction value based on image data that has been subjected to the first color correction processing by the first color correction processing unit 61. The "image data that has been subjected to the first color correction processing" is image data that is free of color unevenness caused by the electronic ND filter 3, just like image data captured without ND. The "first white balance correction value" is a WB gain calculated from the color temperature of image data equivalent to image data captured without ND. The first white balance correction value is a WB gain calculated based on the color temperature of the light source using the AWB function. The second gain derivation unit 64 derives the second gain through AWB calculation based on image data in which color unevenness caused by ND has been corrected. The second gain derivation unit 64 calculates the first white balance correction value based on the color temperature of the image data that has been subjected to the first color correction processing. The "color temperature" includes, for example, the light source color estimated from the image data.

[0047] The second color correction processing unit 65 performs second color correction processing on second image data obtained by a second image capture performed after the first image capture, using a second color correction value corresponding to a second transmittance, which is the transmittance of the electronic ND filter 3 in the second image capture, and the calculated first white balance correction value. The "second image data" is image data of a frame subsequent to the frame of the first image data, and is image data of a frame to which a WB gain calculated by AWB based on the first image data is applied. The "second color correction processing" refers to a process of multiplying by a WB gain.

[0048] The "second transmittance" is, for example, the transmittance of ND4.2. The "second color correction value" is, for example, the WB gain corresponding to ND4.2. That is, the second color correction value is a WB gain that corrects color unevenness that occurs with ND4.2. The second gain derivation unit 64 derives the second WB gain corresponding to the second transmittance based on the "correspondence information" stored in the correspondence information storage unit 63. The second gain derivation unit 64 outputs the derived second WB gain to the second color correction processing unit 65 as the second color correction value corresponding to the second transmittance. Note that when the information in the correspondence table is correspondence information between combinations of parameters related to the angle of incident light and the transmittance of the electronic ND filter 3, and color correction values ​​corresponding to those transmittances, the second gain derivation unit 64 derives the second WB gain corresponding to the parameters and the second transmittance.

[0049] The first gain derivation unit 62 updates the color correction values, including the first color correction values ​​and the second color correction values, used in the color correction processes, including the first color correction process and the second color correction process, in a time shorter than the time it takes for the second gain derivation unit 64 to calculate the white balance correction values, including the first white balance correction values. The "time it takes to calculate the white balance correction values, including the first white balance correction values," is, for example, the time of about three frames. "Updating in a short time" means updating, for example, at a one-frame cycle.

[0050] The processor 6 also causes imaging to be performed at an exposure value corresponding to the transmittance of the electronic ND filter 3. The "exposure value corresponding to the transmittance" refers to an exposure value that is darker than a reference exposure value (e.g., an exposure value set by the user) by the G gain of the WB gain corresponding to the transmittance (filter density) (a representative value (e.g., the maximum value) of the G gain for each pixel (R, G, B pixel) on the entire screen). The exposure value correction amount is calculated, for example, from the G WB gain corresponding to the transmittance. Alternatively, the exposure value may be directly associated with the transmittance (a correspondence table may be created) and the exposure value correction value may be calculated from the transmittance.

[0051] The processor 6 also captures an image at an exposure value obtained by correcting the reference exposure value in accordance with a color correction value corresponding to a first color among the color correction values ​​corresponding to the transmittance of the electronic ND filter 3. The "first color" refers to green (G) among red (R), green (G), and blue (B). The "color correction value corresponding to the first color" refers to a gain (up-gain) of the G gain among the RGB gains that is greater than 1.

[0052] The processor 6 also controls the exposure value according to the transmittance of the electronic ND filter 3. For example, when the reference exposure value is 0 and the exposure value is reduced to −1 according to the transmittance (filter density), the processor 6 halves the amount of light according to the filter density.

[0053] The color correction values, including the first color correction value and the second color correction value, corresponding to the transmittance of the electronic ND filter 3 are values ​​equal to or greater than 1. That is, the color correction values ​​(RGB gains) of the correspondence information do not include gains less than 1 (non-down gains). However, gains such as 0.99 that have almost no effect on the color of the image may be included.

[0054] The processor 6 also changes color correction values, including first and second color correction values ​​corresponding to the transmittance of the electronic ND filter 3, based on the temperature of the electronic ND filter 3. Spectral characteristics change according to temperature characteristics. For this reason, parameters of color correction values ​​according to the temperature of the electronic ND filter 3 are prepared. The processor 6 also changes the control voltage applied to the electronic ND filter 3 based on the temperature of the electronic ND filter 3. The higher the temperature, the less anisotropy of the liquid crystal molecules there is, and the density of the electronic ND filter 3 changes. For this reason, the voltage applied is changed according to the temperature of the electronic ND filter 3.

[0055] <First Example of Correspondence Table> Fig. 4 is a diagram showing a first example of a correspondence table of correspondence information. As shown in Fig. 4, the correspondence table 71 stores correspondence information between the ND value (transmittance) of the electronic ND filter 3 and color correction values. For example, the color correction value corresponding to an ND value of 3.9 stores a WB gain for each pixel (R, G, B) for correcting color unevenness that occurs when the ND value is 3.9. Furthermore, the color correction value corresponding to an ND value of 4.3 stores a WB gain for each pixel for correcting color unevenness that occurs when the ND value is 4.3.

[0056] <Time Chart of Color Correction Processing> FIG. 5 is a diagram showing a time chart of color correction processing according to changes in transmittance.

[0057] The processor 6 reads one frame of the captured image (VD) from the nonvolatile memory (time t1 to t2). At this stage, the target value of the transmittance (filter density) is assumed to be ND3.9. The image read between times t1 and t2 is an image captured with a filter density value between ND3.8 and ND3.83.

[0058] The processor 6 performs exposure calculations for the read image (time t2 to t3). In this example, the processor 6 performs exposure calculations using AE (Automatic Exposure) control, and controls the transmittance (ND) of the electronic ND filter 3 based on the results of this calculation. However, instead of using AE control, the user may specify an ND value through a user operation, for example, to control the transmittance (ND).

[0059] Based on the results of the exposure calculation, the processor 6 sets the target ND value to ND 4.3 in order to adjust the exposure through ND control. The processor 6 increases the control voltage applied to the electronic ND filter 3 in a stepwise manner for each frame. For example, for the image read out this time, the processor 6 applies a control voltage to the electronic ND filter 3 that will result in ND 3.9, and for the image to be read out next, the processor 6 applies a control voltage that will result in ND 4.0.

[0060] In actuality, the processor 6 gradually changes the ND value, for example, during the period in which a control voltage is applied to achieve ND 3.9, the ND value is gradually changed to ND 3.82, ND 3.85, ND 3.875, ND 3.90, etc. In other words, ND 3.9 is the target value for the image of that frame, and a control voltage is applied to the electronic ND filter 3 to achieve the gradually changing ND value, and finally (at time t3) a control voltage is applied to achieve ND 3.9.

[0061] The processor 6 performs color correction processing (ND3.8 correction) on the image of the frame read out this time (between times t1 and t2). The ND3.8 correction is a color correction process that multiplies the transmittance by a color correction value (WB gain corresponding to ND3.8) that corresponds to the transmittance when a control voltage that results in ND3.8 is applied to the electronic ND filter 3. The transmittance at the density of the electronic ND filter 3 and the corresponding color correction value are stored as correspondence information in a correspondence table in the correspondence information storage unit 63. Therefore, the processor 6 simply reads the color correction value that corresponds to the transmittance from the correspondence table and performs the ND3.9 correction process.

[0062] The processor 6 displays the image that has been subjected to ND3.8 correction on the display device, for example, in live view.

[0063] The processor 6 reads the next frame of the captured image (VD) from the nonvolatile memory (time t3 to t4). The image read here is the frame image captured when a control voltage that results in ND 3.90 is applied, at least at the initial point of reading.

[0064] The processor 6 applies a control voltage to the electronic ND filter 3 so that the ND value of the read image finally becomes 4.0 (at time t6). Although not shown in the figure, in reality, the ND value is gradually changed, for example, from ND 3.92 to ND 3.95, ND 3.975, and ND 4.00, just like in the case of ND 3.9.

[0065] The processor 6 performs color correction processing (ND3.9 correction) on the frame images read out between times t3 and t4. ND3.9 correction is a color correction process that multiplies the transmittance by a color correction value (WB gain corresponding to ND3.9) corresponding to the transmittance when a control voltage that results in ND3.9 is applied to the electronic ND filter 3. The ND3.9 frame images read out between times t3 and t4 are an example of the "first image data" of the present invention. The transmittance at the density of the electronic ND filter 3 and the corresponding color correction value are stored as correspondence information in a correspondence table.

[0066] The processor 6 displays the image that has been subjected to ND3.9 correction on the display device, for example, in live view.

[0067] The processor 6 also starts AWB calculation (ND3.9) (time t5) based on the color temperature of the image of the frame that has undergone color correction processing ("ND3.9 correction") for the WB gain corresponding to ND3.9. "AWB calculation (ND3.9)" refers to calculating the WB gain (white balance correction value) using the AWB function. As shown in the figure, the AWB calculation (ND3.9) requires a time equivalent to about three frames across the controls for ND4.0, ND4.1, and ND4.2.

[0068] The processor 6 reads the next frame of the captured image (VD) from the nonvolatile memory (times t6 to t7). The image read here is the frame image captured when a control voltage that results in ND 4.00 is applied, at least at the initial point of reading.

[0069] As in the above, the processor 6 applies a control voltage to the image read out so that the final ND value (at time t8) becomes ND 4.1, and the ND value is gradually changed, for example, to ND 4.02, ND 4.05, ND 4.075, and ND 4.10.

[0070] Processor 6 performs color correction processing (ND4.0 correction) on the frame images read out between times t6 and t7. ND4.0 correction is a color correction process that multiplies the image by a color correction value (WB gain corresponding to ND4.0) corresponding to the transmittance when a control voltage that results in ND4.0 is applied.

[0071] The processor 6 displays the image that has been subjected to ND4.0 correction on the display device, for example, in live view.

[0072] The processor 6 reads the next frame of the captured image (VD) from the nonvolatile memory (times t8 to t9). The image read here is a frame image captured when a control voltage that results in ND 4.10 is applied, at least at the initial point of reading.

[0073] As in the above, the processor 6 applies a control voltage to the image so that the ND value finally becomes 4.2 (at time t10), and the ND value is gradually changed. Also, as in the above, the processor 6 performs color correction (ND4.1 correction) on the image read out between times t8 and t9, and displays the ND4.1 corrected image on the display device.

[0074] Processor 6 reads the next frame of the captured image (VD) from nonvolatile memory (time t10 to t11). The image read here is a frame image captured when a control voltage was applied that resulted in an ND of 4.20, at least at the initial point of reading. Since the ND value has reached the target ND of 4.3, processor 6 performs exposure calculations for the read image (time t11 to t12).

[0075] Based on the results of the exposure calculation, the processor 6 sets the target ND value to ND 4.8. For example, the processor 6 applies a control voltage to the electronic ND filter 3 so that the ND value becomes ND 4.3 for the read image, and then applies a control voltage to the next read image so that the ND value becomes ND 4.4. In practice, the processor 6 applies a control voltage to the read image while gradually changing the ND value, such as ND 4.22, ND 4.25, ND 4.275, and ND 4.30, as in the above case. Finally, the processor 6 applies a control voltage so that the ND value becomes ND 4.3 (at time t13).

[0076] The processor 6 performs color correction processing (ND4.2 correction) on the frame images read out between times t10 and t11. The ND4.2 correction is a color correction process that multiplies the image by a color correction value (WB gain corresponding to ND4.2) corresponding to the transmittance when a control voltage that results in ND4.2 is applied to the electronic ND filter 3. The ND4.2 frame images read out between times t10 and t11 are an example of the "first image data" of the present invention.

[0077] Furthermore, the processor 6 performs color correction processing (AWB correction / 2) on the frame image that has undergone color correction processing (ND4.2 correction). "AWB correction / 2" is a color correction process that multiplies the WB gain (white balance correction value) by WB gain / 2, which is half the gain of the WB gain (white balance correction value) by AWB derived in "AWB calculation (ND3.9)." The ND4.2 frame image read out between times t10 and t11 is an example of the "second image data" of the present invention. The WB gain / 2 is used to avoid a sudden change in color tone that would occur if all the WB gains by AWB were multiplied.

[0078] The processor 6 displays the image that has been subjected to the ND4.2 correction and the AWB / 2 correction on the display device, for example, in a live view.

[0079] The processor 6 also starts AWB calculation (ND4.2) (time t12) based on the color temperature of the image of the frame that has undergone color correction processing ("ND4.2 correction") for the WB gain corresponding to ND4.2. "AWB calculation (ND4.2)" is to calculate the WB gain (white balance correction value) using the AWB function.

[0080] The processor 6 reads the next frame of the captured image (VD) from the nonvolatile memory (times t13 to t14). The image read here is a frame image captured when a control voltage that results in ND 4.30 is applied, at least at the initial point of reading.

[0081] As described above, the processor 6 applies a control voltage to the image read out so that the final ND value (at time t15) is ND 4.4, and the ND value is gradually changed, for example, to ND 4.32, ND 4.35, ND 4.375, and ND 4.40.

[0082] The processor 6 performs color correction processing (ND4.3 correction) on the frame images read out between times t13 and t14. The ND4.3 correction is a color correction process that multiplies the transmittance by a color correction value (WB gain corresponding to ND4.3) corresponding to the transmittance when a control voltage that results in ND4.3 is applied.

[0083] Furthermore, processor 6 performs color correction processing (AWB correction) on the frame image that has undergone color correction processing (ND4.3 correction). "AWB correction" is a color correction process that multiplies the WB gain (white balance correction value) by AWB derived in "AWB calculation (ND3.9)." While AWB correction / 2 was performed on the image that has undergone ND4.2 correction by multiplying it by WB gain / 2, here AWB correction is performed on the image that has undergone ND4.3 correction by multiplying it by a WB gain obtained by adding the remaining WB gain / 2. The ND4.3 frame image read out between times t13 and t14 is an example of the "second image data" of the present invention.

[0084] The processor 6 displays the image that has been subjected to the ND4.3 correction and the AWB correction on the display device, for example, in a live view.

[0085] "WB gain" includes R gain, G gain, and B gain. There are WB gains determined by filter density, etc., and WB gains determined by AWB, and both WB gains are multiplied by each pixel.

[0086] <Second Example of Correspondence Table> Fig. 6 is a diagram showing a second example of a correspondence table of correspondence information. As shown in Fig. 6, the correspondence table 72 stores correspondence information between the model number of the imaging lens 2, the ND value (transmittance) of the electronic ND filter 3, and the color correction value. In this manner, the correspondence table may store information that combines, for example, the "lens model number," which is a parameter related to the angle of light incident on the electronic ND filter 3, with the ND value (transmittance) of the electronic ND filter 3, in association with the color correction value corresponding to the transmittance. Furthermore, the correspondence information in the correspondence table may also be stored for each combination of the position of the zoom lens included in the imaging lens 2, the state of the aperture (F-number), the position of the focus lens included in the imaging lens 2 (focus position), and the ND value. Three or more combinations including the ND value may also be stored.

[0087] As described above, the imaging device 1 of this embodiment performs a first color correction process on the first image data obtained by the first capture using a first color correction value corresponding to the first transmittance of the electronic ND filter 3 in the first capture, calculates a first white balance correction value using the AWB function based on the color temperature of the first image data subjected to the first color correction process, and performs a second color correction process on the second image data obtained by the second capture performed after the first capture using a second color correction value corresponding to the second transmittance of the electronic ND filter 3 in the second capture, and a second color correction process using the first white balance correction value. With this configuration, even if the first white balance correction value calculated based on the first image data (using the AWB function) is used in the second color correction process on the second image data obtained after the first image data (when the calculation of the first white balance correction value is too late for the first color correction process on the first image data), color correction can be performed using a color correction value corresponding to the transmittance separately from the white balance correction value. Therefore, color shifts occurring during changes in transmittance (filter density) can be suppressed in the color correction processes for the second and subsequent image data. This makes it possible to capture images without noticeable color variations.

[0088] Furthermore, according to the imaging device 1, the first color correction value corresponding to the transmittance used in the first color correction process and the second color correction value corresponding to the transmittance used in the second color correction process are derived in a time shorter than the time required to calculate the first white balance correction value. This allows color correction to be performed in response to changes in transmittance, thereby suppressing color shifts during changes in transmittance.

[0089] Furthermore, the imaging device 1 derives color correction values ​​used in color correction processing based on correspondence information (correspondence table) between the transmittance of the electronic ND filter 3 and its color correction value, or on correspondence information between the color correction value and a combination of a parameter related to the angle of light incident on the electronic ND filter 3 and the transmittance of the electronic ND filter 3. This makes it possible to perform color correction that follows changes in transmittance, thereby suppressing color shifts that occur during changes in transmittance.

[0090] <Example of Exposure Value Correction According to Color Correction Value> The electronic ND filter 3 may require a correction of 20% or more when taking into account the color tone for each filter density, the color tone of light obliquely incident on the imaging lens 2, color tone dependent data for the filter temperature, etc. As an example, the following describes a case where a 30% color correction is performed on the red (R) pixel and a 20% color correction is performed on the blue (B) pixel for red (R), green (G), and blue (B) pixels.

[0091] 7 is a diagram showing an example of conventional exposure value correction according to color correction values. This correction example is a correction example in which a WB gain (down gain) of less than 1 is multiplied when performing 30% and 20% color correction processing. When performing color correction by multiplying a down gain, the color correction value of 30% for the R pixel and the color correction value of 20% for the B pixel become corresponding information of WB gain (color correction value) according to transmittance (filter density) (R=0.7, G=1.0, B=0.8). This is an example of first color correction processing using a first color correction value corresponding to a first transmittance.

[0092] (1) in Figure 7 shows an example (representative value) of the output values ​​of R pixels, G pixels, and B pixels in the image data output from the image sensor 5 in, for example, the imaging device 1 currently capturing an image, where (R1, G1, B1) = (70, 100, 60).

[0093] When R1, G1, and B1 in (1) are multiplied by the corresponding information of the WB gain (color correction value) (R=0.7, G=1.0, B=0.8), the balance of (R1, G1, B1) = (70, 100, 60) becomes the balance of (R2, G2, B2) = (49, 100, 48) as shown in (2).

[0094] When R2, G2, and B2 in (2) are further multiplied by the WB gain calculated by AWB, the balance of (R2, G2, B2) = (49, 100, 48) becomes the balance of (R3, G3, B3) = (59, 100, 58) as shown in (3). Here, it is assumed that the WB gain calculated by AWB is 1.2 times. The image data of the values ​​shown in (3) is image data that has been white balanced (and has had color unevenness corrected) through correction by AWB.

[0095] Next, when the same color correction process is performed on saturated image data, the results are as shown in (4) to (6) in the lower row of FIG.

[0096] (4) is image data in a saturated pure white state in which the output values ​​of the R, G, and B pixels reach the maximum value, resulting in (R4, G4, B4) = (1024, 1024, 1024).

[0097] When R4, G4, and B4 in (4) are multiplied by the corresponding information of the WB gain (R=0.7, G=1.0, B=0.8), the balance of (R4, G4, B4) = (1024, 1024, 1024) becomes the balance of (R5, G5, B5) = (716, 1024, 819) as shown in (5).

[0098] When R5, G5, and B5 in (5) are further multiplied by the WB gain calculated by AWB (1.2 times the same as above), the balance of (R5, G5, B5) = (716, 1024, 819) becomes the balance of (R6, G6, B6) = (860, 1024, 1024) as shown in (6). The image data of the values ​​shown in (6) has an insufficient R value, and the saturated white becomes greenish white image data.

[0099] In this way, if a down gain (a gain less than 1) is used when creating a WB gain for correcting color unevenness, there is a problem in that saturated portions may be tinted.

[0100] Fig. 8 is a diagram showing another correction example that eliminates the shortage of R output in a saturated image that occurs in the correction example of Fig. 7. In this correction example, when performing 30% color correction on R pixels and 20% color correction on B pixels, instead of multiplying the R and B pixels by a WB gain (down gain) of less than 1, the G pixels are multiplied by a WB gain (up gain) of 1 or more, thereby performing color correction processing so that the R / G and B / G become equivalent to those obtained by multiplying the R and B pixels by the down gain.

[0101] 8(11) shows an example of output values ​​of R pixels, G pixels, and B pixels in image data output from the imaging element 5, (R11, G11, B11)=(70, 100, 60), similar to FIG. 7(1).

[0102] Here, since (R11, G11, B11) = (70, 100, 60), the WB gain of 1 or more to be multiplied for the G pixels is calculated as G11 / R11 = 100 / 70 = 1.428 when G11 is a fixed value. When R11, G11, and B11 in (11) are multiplied by the WB gain correspondence information (R = 1.0, G = 1.428, B = 1.0), the balance of (R11, G11, B11) = (70, 100, 60) becomes the balance of (R12, G12, B12) = (70, 142, 68) as shown in (12). Note that, since G12 has increased by 42.8%, B12 increases by 14% from R / B = 80 / 70 = 1.14, to 60 × 1.14 = 68.

[0103] When R12, G12, and B12 in (12) are further multiplied by the WB gain calculated by AWB (1.2 times the same as above), the balance of (R12, G12, B12) = (70, 142, 68) becomes the balance of (R13, G13, B13) = (84, 142, 82) as shown in (13). The image data of the values ​​shown in (13) has been adjusted for WB, but because the G value that contributes to the brightness of the user's eyes is high, the overall brightness of the image data is bright.

[0104] Next, when the same color correction process is performed on saturated image data, the results are as shown in (14) to (16) in the lower row of FIG.

[0105] (14) is image data in a saturated pure white state in which the output values ​​of the R, G, and B pixels reach the maximum value, resulting in (R14, G14, B14) = (1024, 1024, 1024).

[0106] When R14, G14, and B14 in (14) are multiplied by the corresponding information of the WB gain (R=1.0, G=1.428, B=1.0), the balance of (R14, G14, B14) = (1024, 1024, 1024) becomes the balance of (R15, G15, B15) = (1024, 1024, 1024) as shown in (15).

[0107] When R15, G15, and B15 in (15) are further multiplied by the WB gain calculated by AWB (1.2 times the same as above), the balance of (R15, G15, B15) = (1024, 1024, 1024) becomes the balance of (R16, G16, B16) = (1024, 1024, 1024) as shown in (16). The image data with the values ​​shown in (15) and (16) are saturated in all RGB, so they are image data with no color unevenness.

[0108] To address this issue of color tinge in saturated areas, down gains are not used when creating WB gains for color shading correction. Specifically, down gains are not included when creating correspondence information between filter densities and WB gains. For example, instead of using (R gain, G gain, B gain) = (0.7, 1, 0.7) as a WB gain for reducing the "ratio of R and B luminance to G luminance" by 30%, (R gain, G gain, B gain) = (1, 1.428, 1) is used. This also applies to WB gains that increase the "ratio of R and B luminance to G luminance," in which down gains are not used. This can prevent the problem of color tinge in saturated areas described in FIG. 7 . However, if down gains are not included in the WB gains, the image becomes brighter due to the increased G luminance, as shown in (13) in FIG. 8 above.

[0109] 9 is a diagram showing an example of exposure value correction according to the color correction value of the present invention. This correction example is similar to the correction example of FIG. 8 in that, when performing color correction of 30% on R pixels and 20% on B pixels, the G pixels are multiplied by a WB gain (up-gain) of 1 or more to achieve color correction processing such that R / G and B / G are equivalent to those obtained by multiplying the R and B pixels by down-gains. In addition, in this correction example, the filter density is increased by the amount of the WB gain to be multiplied by the G pixels in the color correction corresponding to the filter density, thereby darkening the entire image so that the overall brightness does not become bright image data when multiplied by the WB gain calculated by AWB (1.2 times the same as above).

[0110] 9 (21) shows the output values ​​(R21, G21, B21) = (49, 70, 42) of the R, G, and B pixels in image data captured darkly by increasing the filter density by the amount of the WB gain to be multiplied by the G pixel in color correction corresponding to the filter density. "Darkly captured by increasing the filter density by the amount of the WB gain to be multiplied by the G pixel" means capturing an image darker by 1 / 1.428 based on the WB gain correspondence information (R = 1.0, G = 1.428, B = 1.0) in FIG.

[0111] Here, since (R21, G21, B21) = (49, 70, 42), the WB gain of 1 or more to be multiplied for the G pixels is calculated as G21 / R21 = 70 / 49 = 1.428 when G21 is a fixed value. When R21, G21, and B21 in (21) are multiplied by the WB gain correspondence information (R = 1.0, G = 1.428, B = 1.0), the balance of (R21, G21, B21) = (49, 70, 42) becomes the balance of (R22, G22, B22) = (49, 100, 48) as shown in (22). Note that, since G22 has increased by 42.8%, B22 increases by 14% from R / B = 80 / 70 = 1.14, to 42 × 1.14 = 48.

[0112] When R22, G22, and B22 in (22) are further multiplied by the WB gain calculated by AWB (1.2 times the same as above), the balance of (R22, G22, B22) = (49, 100, 48) becomes the balance of (R23, G23, B23) = (59, 100, 58) as shown in (23). The image data of the values ​​shown in (23) is image data that has been white balanced by correction using AWB.

[0113] Next, when the same color correction process is performed on saturated image data, the results are as shown in (24) to (26) in the lower row of FIG.

[0114] (24) is image data in a saturated pure white state in which the output values ​​of the R, G, and B pixels reach the maximum value, resulting in (R24, G24, B24) = (1024, 1024, 1024).

[0115] When R24, G24, and B24 in (24) are multiplied by the corresponding information of the WB gain (R=1.0, G=1.428, B=1.0), the balance of (R24, G24, B24) = (1024, 1024, 1024) becomes the balance of (R25, G25, B25) = (1024, 1024, 1024) as shown in (25).

[0116] When R25, G25, and B25 in (25) are further multiplied by the WB gain calculated by AWB (1.2 times the same as above), the balance of (R25, G25, B25) = (1024, 1024, 1024) becomes the balance of (R26, G26, B26) = (1024, 1024, 1024) as shown in (26). The image data with the values ​​shown in (25) and (26) are saturated for all RGB, so they are image data with no color unevenness.

[0117] In this way, a WB gain that does not use a down gain is used, and when the G gain is greater than 1 (up gain), the exposure is set lower for shooting. Specifically, for a filter density associated with a WB gain that has a G gain greater than 1, the exposure is set lower by the amount of that G gain. This improves the problem of saturated areas being tinted, while suppressing the problem of the image becoming brighter due to increased G brightness.

[0118] Note that when a WB gain greater than 1 is associated with the G gain, control is performed to lower the exposure, but up-gains for R and G are ignored because they have little effect on the apparent brightness. Also, although Figures 7 to 9 show control for a pixel (R, G, B) with a certain representative value on the screen, this control is performed for all pixels on the screen.

[0119] Methods for lowering exposure include adjusting the shutter speed, aperture, ISO sensitivity, and filter density. Adjusting the filter density can reduce the impact on image quality compared to adjusting the shutter speed, aperture, and ISO sensitivity. However, when adjusting the filter density to lower exposure, the WB gain corresponding to the filter density before adjustment may not be the optimal WB gain for correcting color unevenness. Therefore, when creating correspondence information between filter density and WB gain, it is desirable to determine the R, G, and B WB gains for each filter density so that the optimal WB gain for correcting color unevenness is obtained when the filter density is adjusted according to the WB gain.

[0120] <Electronic ND Filter> Figure 10 is a cross-sectional view showing a two-layer electronic ND filter. The electronic ND filter 3A has a configuration in which two electronic ND filters 3 described in Figure 2 are stacked on top of each other. As shown in Figure 10, the electronic ND filter 3A includes transparent substrates 31a, 31b, and 31c, transparent electrodes 32a, 32b, 32c, and 32d, alignment films 33a, 33b, 33c, and 33d, and sealing members 34a, 34b, 34c, and 34d. The direction of arrow A indicates the traveling direction of light incident on the electronic ND filter 3A.

[0121] A liquid crystal layer 35a containing liquid crystal molecules and a dye (dichroic dye) is provided between alignment films 33a and 33b, and a liquid crystal layer 35b containing liquid crystal molecules and a dye (dichroic dye) is provided between alignment films 33c and 33d. When viewed from the direction of incident light, the alignment direction of each liquid crystal molecule in liquid crystal layer 35a differs by 90 degrees from the alignment direction of each liquid crystal molecule in liquid crystal layer 35b. The color correction value in the correspondence information of the electronic ND filter 3A is a value corresponding to the combined direction of the alignment direction of each liquid crystal molecule in liquid crystal layer 35a and the alignment direction of each liquid crystal molecule in liquid crystal layer 35b.

[0122] Fig. 11 is a diagram showing the alignment direction of the liquid crystal layer of the electronic ND filter 3A when viewed from the direction of light incidence. The liquid crystal molecules in the liquid crystal layer 35a are aligned, for example, in the horizontal direction, as indicated by an alignment direction 36a in Fig. 11. In contrast, the liquid crystal molecules in the liquid crystal layer 35b are aligned, for example, in the vertical direction, as indicated by an alignment direction 36b, which is 90 degrees different from the alignment direction 36a in Fig. 11.

[0123] The control method described in the above-described embodiment can be realized by executing a prepared control program on a computer. The control program is recorded on a computer-readable storage medium and executed by being read from the storage medium. The control program may be provided in a form stored on a non-transitory storage medium such as a flash memory, or may be provided via a network such as the Internet. The computer that executes the control program may be included in the imaging device, or may be included in an electronic device such as a smartphone, tablet, or personal computer that can communicate with the imaging device, or may be included in a server device that can communicate with these imaging devices and electronic devices.

[0124] In this embodiment, each process is executed by a computer. The computer may execute these processes by a processor, a program, or a combination thereof. The computer may be a general-purpose computer, a computer for specific applications, a system such as a workstation, or other hardware element capable of executing a program.

[0125] The processor may be configured with one or more pieces of hardware, and the type of hardware is not limited. For example, the processor may be configured with hardware such as a programmable logic device such as a central processing unit (CPU), a micro processing unit (MPU), a field programmable gate array (FPGA), a dedicated circuit for executing specific processing such as an application specific integrated circuit (ASIC), a graphics processing unit (GPU), or a neural processing unit (NPU). The processor also has various units or means for executing various processes in this embodiment. The type of hardware may also be a combination of different types of hardware. When multiple pieces of hardware are configured to execute one or more processes of a certain processor, the multiple pieces of hardware may be located in devices physically separated from each other, or may be located in the same device. Furthermore, in any embodiment, the order of each process performed by the processor is not limited to the order described above and may be changed as appropriate. The hardware is configured by an electric circuit (circuitry) or the like that combines circuit elements such as semiconductor elements.

[0126] Furthermore, the present embodiment may be implemented by hardware, software, firmware, microcode, or a combination thereof. Software, firmware, and microcode may be configured by a program. A program may also be, for example, a group of program modules, each function of which may be implemented by a processor configured to perform the respective function. The program may be program code or multiple code segments stored in one or more non-transitory computer-readable media (e.g., storage media or other storages). The program may be stored in multiple non-transitory computer-readable media that reside in physically separate devices. Program code or a code segment may represent a procedure, a function, a subprogram, a routine, a subroutine, a module, a software package, a class, or any combination of instructions, data structures, or program statements. Program code or a code segment may be connected to another code segment or a hardware circuit by sending or receiving information, data, arguments, parameters, or memory contents.

[0127] Although various embodiments have been described above, it goes without saying that the present invention is not limited to such examples. It is clear that a person skilled in the art can conceive of various modifications or alterations within the scope of the claims, and it is understood that these also naturally fall within the technical scope of the present invention. Furthermore, the components of the above embodiments may be combined in any manner as long as they do not deviate from the spirit of the invention.

[0128] This application is based on a Japanese patent application (Patent Application No. 2024-124237) filed on July 31, 2024, the contents of which are incorporated herein by reference.

[0129] REFERENCE SIGNS LIST 1 imaging device 2 imaging lens 3, 3A electronic ND filter 4 ND filter driver 5 imaging element 6 processor 31a, 31b, 31c transparent substrate 32a, 32b, 32c, 32d transparent electrode 33a, 33b, 33c, 33d alignment film 34a, 34b, 34c, 34d sealing member 35, 35a, 35b liquid crystal layer 36a, 36b alignment direction 61 first color correction processor 62 first gain derivation unit 63 correspondence information storage unit 64 second gain derivation unit 65 second color correction processor 71, 72 correspondence table t1 to t15 time

Claims

1. An imaging device comprising a light control device capable of controlling the transmittance of light incident through an imaging lens, and a processor, wherein the processor performs a first color correction process on first image data obtained by a first imaging using a first color correction value corresponding to a first transmittance, which is the transmittance of the light control device in the first imaging, calculates a first white balance correction value based on the image data that has been subjected to the first color correction process, and performs a second color correction process on second image data obtained by a second imaging performed after the first imaging using a second color correction value corresponding to a second transmittance, which is the transmittance of the light control device in the second imaging, and the first white balance correction value.

2. An imaging device according to claim 1, wherein the processor updates color correction values, including the first color correction value and the second color correction value, used in color correction processing including the first color correction processing and the second color correction processing, in a time shorter than the time required to calculate white balance correction values, including the first white balance correction value.

3. An imaging device according to claim 1, wherein the processor calculates the first white balance correction value based on the color temperature of the image data that has undergone the first color correction processing.

4. An imaging device according to claim 1, wherein the processor derives the first color correction value corresponding to the first transmittance and the second color correction value corresponding to the second transmittance based on correspondence information between the transmittance of the light control device and color correction values.

5. An imaging device according to claim 4, wherein the correspondence information is correspondence information between a combination of a parameter relating to the angle of light incident on the dimming device and the transmittance of the dimming device, and a color correction value, and the processor derives the first color correction value corresponding to the parameter and the first transmittance based on the correspondence information, and derives the second color correction value corresponding to the parameter and the second transmittance.

6. An imaging device according to claim 4, wherein the light control device includes a liquid crystal cell, and the color correction value in the correspondence information is a correction value according to an alignment direction of the liquid crystal cell.

7. An imaging device according to claim 1, wherein the processor causes imaging to be performed at an exposure value corresponding to the transmittance of the light control device.

8. An imaging device according to claim 7, wherein the processor executes imaging at an exposure value obtained by correcting a reference exposure value in accordance with a color correction value corresponding to a first color among color correction values ​​corresponding to the transmittance of the light control device.

9. An imaging device according to claim 7, wherein the processor controls the exposure value according to the transmittance of the light control device.

10. An imaging device according to claim 7, wherein the color correction values ​​including the first color correction value and the second color correction value are one or more values.

11. The imaging device according to claim 1, wherein the processor varies color correction values ​​including the first color correction value and the second color correction value based on the temperature of the light control device.

12. An imaging device according to any one of claims 1 to 11, wherein the processor changes the control voltage of the dimmer based on the temperature of the dimmer.

13. A control method for an imaging device comprising a light control device capable of controlling the transmittance of light incident through an imaging lens, and a processor, wherein the processor performs a first color correction process on first image data obtained by a first imaging using a first color correction value corresponding to a first transmittance, which is the transmittance of the light control device in the first imaging, calculates a first white balance correction value based on the image data after the first color correction process, and performs a second color correction process on second image data obtained by a second imaging performed after the first imaging using a second color correction value corresponding to a second transmittance, which is the transmittance of the light control device in the second imaging, and the first white balance correction value.

14. A control program for an imaging device equipped with a light control device capable of controlling the transmittance of light incident through an imaging lens and a processor, the control program causing the processor to execute the following processes: perform a first color correction process on first image data obtained by a first imaging using a first color correction value corresponding to a first transmittance, which is the transmittance of the light control device in the first imaging; calculate a first white balance correction value based on the image data after the first color correction process; and perform a second color correction process on second image data obtained by a second imaging performed after the first imaging using a second color correction value corresponding to a second transmittance, which is the transmittance of the light control device in the second imaging, and the first white balance correction value.

Images