Spectral sensitivity measuring device and spectral sensitivity measuring method

Abstract

Provided is a spectral sensitivity measurement device with which it is possible to accurately measure the spectral sensitivity of an imaging device.　The spectral sensitivity measurement device according to the present technology comprises: a chart generation system for generating a chart at a position facing an imaging device, the chart including at least one chart section that has at least one color region; and a processing system for calculating the spectral sensitivity of the imaging device on the basis of a captured image, produced by the imaging device, of the chart generated at the position facing the imaging device. According to this spectral sensitivity measurement device, it is possible to provide a spectral sensitivity measurement device capable of accurately measuring the spectral sensitivity of an imaging device.

Description

[Technical Field]

[0001] The present technology relates to a spectral sensitivity measuring device and a spectral sensitivity measuring method, and more particularly to a spectral sensitivity measuring device and a spectral sensitivity measuring method for measuring the spectral sensitivity of an imaging device. [Background technology]

[0002] In recent years, there has been an increasing demand for imaging devices that include solid-state imaging elements (image sensors), which are the core components of digital cameras. For example, imaging devices that include complementary metal oxide semiconductor (CMOS) image sensors are being considered for use as spectrometers.

[0003] When an imaging device including an image sensor is used as a spectrometer, it is necessary to measure the spectral sensitivity of the imaging device. Conventionally, a common method for measuring the spectral sensitivity of an imaging device is to irradiate the imaging device including the image sensor with light from a light source of a single wavelength. However, this spectral sensitivity measurement method has a problem in that it takes a long time to measure the spectral sensitivity because the imaging device including the image sensor is irradiated with light of a single wavelength while changing the wavelength. To solve this problem, a spectral sensitivity measurement method is known in which a group of charts including multiple local areas (charts) arranged two-dimensionally are collectively imaged by the imaging device including the image sensor, and the spectral sensitivity of the imaging device is measured (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-5053 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the method of Patent Document 1 leaves room for improvement in terms of measuring the spectral sensitivity of the imaging device with high accuracy.

[0006] Therefore, a main object of the present technology is to provide a spectral response measuring device that can measure the spectral response of an imaging device with high accuracy in a short time. [Means for solving the problem]

[0007] The present technology includes a chart generating system that generates a chart including at least one chart portion having at least one color region at a position facing an imaging device; a processing system that calculates the spectral sensitivity of the imaging device based on an image of the chart generated at a position facing the imaging device, captured by the imaging device; The present invention provides a spectral sensitivity measuring device for an imaging device, comprising: The chart generation system may sequentially generate each of the plurality of charts at a position facing the imaging device. The chart generating system may include a light source and an optical filter group including a plurality of optical filters selectively disposed between the light source and the imaging device. The chart generation system may further include a movement mechanism that moves the optical filter group relative to a system including the imaging device and the light source so that each of the plurality of optical filters is sequentially positioned between the imaging device and the light source. The movement mechanism may move the optical filters in a direction substantially perpendicular to a direction in which the imaging device and the light source are arranged. The moving mechanism may include a rotating member on which the plurality of optical filters are arranged in a circumferential direction and which is rotatable around an axis that is approximately parallel to the arrangement direction of the imaging device and the light source, and a driving unit that rotates the rotating member around the axis. The chart generating system may include a diffuser disposed between the imaging device and each of the plurality of optical filters. The chart generating system may include a wavelength-tunable light source that can tune the emission wavelength. The chart generating system may have an optical filter group including a plurality of optical filters selectively disposed between the imaging device and the wavelength-tunable light source. The chart generation system may further include a moving mechanism that moves the optical filter group and a system including the imaging device and the wavelength-tunable light source so that each of the plurality of optical filters is sequentially positioned between the imaging device and the wavelength-tunable light source. The movement mechanism may include a movement mechanism that moves the plurality of optical filters in a direction substantially perpendicular to a direction in which the imaging device and the wavelength-tunable light source are arranged. The tunable light source may face the imaging device. The chart generating system may include an optical waveguide member having an incident end connected to the tunable light source and an exit end facing the imaging device. The chart generating system may include a plurality of optical waveguide members corresponding to the plurality of imaging devices, and each of the plurality of optical waveguide members may have an incident end connected to the wavelength-tunable light source and an exit end facing the corresponding imaging device. The chart generation system may include a light source group including a plurality of light sources with different emission wavelengths, and a movement mechanism that moves the light source group and the imaging device relative to each other so that each of the plurality of light sources faces the imaging device in sequence. The chart generation system may include a light source group including a plurality of light sources with different emission wavelengths, and a movement mechanism that moves the light source group and the imaging device group including the plurality of imaging devices relatively so that each of the plurality of light sources faces each of the plurality of imaging devices in sequence. The spectral response measurement device may further include a control unit that controls, depending on the luminance of the color region, an imaging time during which the imaging device images the chart and / or a time during which the imaging device faces the chart. The spectral response measurement device may further include a control unit that controls, depending on the luminance of the color region, an imaging time during which the imaging device images the chart and / or a time during which the imaging device faces the chart. The processing system may calculate a theoretical value yth of a pixel value of the captured image from the following equation (1), calculate a correction coefficient C from the following equation (2), and calculate a spectral sensitivity x from the following equation (3) using a corrected pixel value yc obtained by multiplying an actual measurement value of a pixel value of a captured image of the chart that is different from the image captured by the imaging device by the correction coefficient C. y th =Ax a (1) (where x a is the spectral sensitivity of the imaging device with known spectral sensitivity, and A is the spectral characteristics of the chart) C=y th / y a (2) (However, y a is the pixel value of an image captured by an imaging device with known spectral sensitivity) y c =Ax (3) (where A is the spectral characteristic of the chart) 19. The spectral sensitivity measurement device according to claim 18, wherein the spectral sensitivity is x calculated by the following equations (4) and (5), and the processing system is capable of setting the value of λ in the following equation (4) according to a wavelength to be calculated when calculating the spectral sensitivity by the following equations (4) and (5): JPEG0007823065000001.jpg15166s(b)=Cb...(5) (where λ is the regularization parameter, F is the differential matrix consisting of a first-order differential equation, A is the spectral characteristics of the chart, and b is the pixel value of the captured image) The spectral sensitivity is x calculated by the following formula (6), and when calculating the spectral sensitivity by the following formula (6), the processing system may be capable of setting the value of λ in the following formula (6) according to the wavelength to be calculated. JPEG0007823065000002.jpg14166 (where λ is the regularization parameter, F is the differential matrix consisting of a first-order differential equation, A is the spectral characteristics of the chart, b is the pixel value of the captured image, and s is the pixel value after light intensity correction) The processing system may set the value of λ in the above equation (6) depending on the magnitude relationship between the wavelength to be calculated and at least one threshold value Th. The processing system may calculate the spectral sensitivity by using λ1 as λ in equation (6) above when the wavelength to be calculated is less than the threshold value Th, and may calculate the spectral sensitivity by using λ2, which is different from λ1, as λ in equation (6) above when the wavelength to be calculated is equal to or greater than the threshold value Th. The at least one threshold value is a plurality of threshold values, and the processing system calculates a wavelength that is the smallest threshold value Th among the plurality of threshold values ​​Th. min If the wavelength is less than the maximum threshold value Th, the spectral sensitivity is calculated using λ1 as λ in the above equation (6), and the calculated wavelength is the maximum threshold value Th among the plurality of threshold values ​​Th. max In the above cases, the spectral sensitivity is calculated using λ2, which is different from λ1, as λ in the above equation (6), and the calculated wavelength is the minimum threshold value Th min Above the maximum threshold Th max If it is less than λ1, the spectral sensitivity may be calculated by using λ3, which is different from λ1, as λ in the above equation (6). The processing system may include a pixel value acquisition unit that acquires pixel values ​​of the captured image, and a spectral sensitivity calculation unit that calculates the spectral sensitivity based on the spectral characteristics of the chart and the pixel values ​​acquired by the pixel value acquisition unit. The at least one color region may be a plurality of color regions. The chart generating system may include a light emitting element array facing the imaging device. The present technology includes a step of generating a chart including at least one chart portion having at least one color region at a position facing an imaging device; capturing an image of the chart generated at a position facing the imaging device with the imaging device; acquiring pixel values ​​of the image of the chart captured in the imaging step; calculating the spectral sensitivity of the imaging device based on the spectral characteristics of the chart and the pixel values ​​acquired in the acquiring step; A method for measuring spectral sensitivity is also provided, which includes: In the generating step, each of the plurality of charts may be generated sequentially at a position facing the imaging device. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram schematically showing a configuration of a spectral response measuring device according to a first embodiment of the present technology. [Figure 2] FIG. 2 is a block diagram showing the functions of a processing system of the spectral response measuring device of FIG. [Figure 3] 2 is a flowchart for explaining the operation of the spectral response measurement apparatus of FIG. [Figure 4] 4A and 4B are diagrams for explaining advantage 1 of the spectral response measurement device of FIG. [Figure 5] 5A and 5B are diagrams for explaining advantage 2 of the spectral response measurement device of FIG. [Figure 6] 6A and 6B are diagrams for explaining advantage 3 of the spectral response measurement device of FIG. [Figure 7] 7A and 7B are diagrams for explaining advantage 4 of the spectral response measurement device of FIG. [Figure 8] FIG. 10 is a diagram schematically illustrating a configuration of a spectral response measuring device according to Example 1 of a second embodiment of the present technology. [Figure 9] FIG. 10 is a diagram schematically illustrating a configuration of a spectral response measuring device according to Example 2 of the second embodiment of the present technology. [Figure 10] FIG. 10 is a diagram schematically illustrating a configuration of a spectral response measuring device according to Example 1 of a third embodiment of the present technology. [Figure 11] FIG. 10 is a diagram schematically illustrating a configuration of a spectral response measuring device according to Example 2 of the third embodiment of the present technology. [Figure 12] FIG. 10 is a diagram schematically illustrating a configuration of a spectral response measuring device according to Example 1 of a fourth embodiment of the present technology. [Figure 13] FIG. 10 is a diagram schematically illustrating a configuration of a spectral response measuring device according to Example 2 of the fourth embodiment of the present technology. [Figure 14] 10 is a diagram schematically showing a configuration and an operation sequence of a spectral response measuring device according to a fifth embodiment of the present technology. FIG. [Figure 15] FIG. 13 is a block diagram showing the functions of a processing system of a spectral response measuring device according to a sixth embodiment of the present technology. [Figure 16] 10 is a flowchart illustrating a correction coefficient acquisition process. [Figure 17] 13 is a flowchart for explaining the operation of the spectral response measuring device according to the sixth embodiment of the present technology. [Figure 18] 18A to 18C are diagrams for explaining effect 1 of the spectral response measurement device according to the sixth embodiment of the present technology. [Figure 19] 19A and 19B are diagrams for explaining effect 2 of the spectral response measurement device according to the sixth embodiment of the present technology. [Figure 20] FIG. 13 is a block diagram showing the functions of a processing system of a spectral response measuring device according to a seventh embodiment of the present technology. [Figure 21] FIG. 19 is a block diagram showing the functions of a processing system of a spectral response measuring device according to an eighth embodiment of the present technology. [Figure 22] 22A to 22C are diagrams for explaining the effect of the spectral response measurement device according to the eighth embodiment of the present technology. [Figure 23] FIG. 1 is a diagram schematically illustrating the configuration of a spectral sensitivity measuring device of a comparative example. [Figure 24] FIG. [Figure 25] 10A and 10B are diagrams for explaining a defect caused by the spectral response measuring device of the comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0009] Preferred embodiments of the present technology will be described in detail below with reference to the accompanying drawings. Note that in this specification and the drawings, components having substantially the same functional configurations are denoted by the same reference numerals, and redundant description will be omitted. The embodiments described below illustrate typical embodiments of the present technology, and the scope of the present technology should not be interpreted as being narrow. Even when the present specification describes that the spectral sensitivity measurement device and the spectral sensitivity measurement method according to the present technology achieve multiple effects, it is sufficient that the spectral sensitivity measurement device and the spectral sensitivity measurement method according to the present technology achieve at least one effect. The effects described in this specification are merely examples and are not limiting, and other effects may also be achieved.

[0010] The explanation will be given in the following order: 1. Introduction 2. Spectral response measuring device according to the first embodiment of the present technology 3. Spectral response measuring device according to a modified example of the first embodiment of the present technology 4. Spectral response measuring device according to Example 1 of the second embodiment of the present technology 5. Spectral response measuring device according to Example 2 of the second embodiment of the present technology 6. Spectral response measuring device according to Example 1 of the third embodiment of the present technology 7. Spectral response measuring device according to Example 2 of the third embodiment of the present technology 8. Spectral response measuring device according to Example 1 of the fourth embodiment of the present technology 9. Spectral response measuring device according to Example 2 of the fourth embodiment of the present technology 10. Spectral response measuring device according to the fifth embodiment of the present technology 11. Spectral response measuring device according to the sixth embodiment of the present technology 12. Spectral response measuring device according to the seventh embodiment of the present technology 13. Spectral response measuring device according to eighth embodiment of the present technology 14. Modifications of this technology

[0011] <1. Introduction>

[0012] A conventional device (spectral sensitivity measuring device) is known that measures the spectral sensitivity of an image pickup device based on an image captured by the image pickup device, which includes an image sensor of a subject, such as a natural object, an artificial object, or a chart for reproducing colors.

[0013] 23, for example, an imaging device 1500 including an image sensor captures an image of a group of charts 2500 illuminated with light from a light source 3500 all at once, and calculates the spectral sensitivity of the imaging device 1500 based on the captured image. This group of charts 2500 is configured by arranging a plurality of charts ch (e.g., Macbeth charts) having color regions in a two-dimensional manner.

[0014] FIG. 24 is a diagram showing a chart group 4000, which has a larger number of charts and a larger number of color regions per chart than the chart group 2500, as viewed from the front.

[0015] The chart group as a whole becomes large when there are a large number of charts and a large number of color regions per chart, as in chart group 4000. When measuring the spectral sensitivity of an imaging device including an image sensor using chart group 4000 in the spectral sensitivity measuring device of the comparative example, an overlapping region between adjacent charts occurs within the shooting angle of view of the imaging device, and therefore measures such as moving the chart group or the imaging device must be taken when measuring the spectral sensitivity at a measurement point within the overlapping region.

[0016] FIG. 25 is a diagram showing an image 5000 captured by the image sensor of the chart group 4000.

[0017] When the spectral sensitivity of an imaging device including an image sensor and a lens (which may be an on-chip lens) is measured using the chart group 4000 in the spectral sensitivity measuring device of the comparative example, the corner portions 5000a (corresponding to the corner portions of the chart group 4000) of the captured image 5000 are deformed due to distortion of the lens, and in particular, the corner portions 5000a1 of the corner portions 5000a are significantly deformed (see FIGS. 24 and 25). For this reason, in the spectral response measurement device of the comparative example, it is difficult to obtain pixel values ​​unless the charts located at the corners of the chart group are shaped to correspond to the distortion or are photographed using a photographing method that corresponds to the distortion (see FIG. 25).

[0018] In any case, the spectral response measuring device of the comparative example has room for improvement in terms of accurately measuring the spectral response of an imaging device including an image sensor.

[0019] Therefore, the inventors have developed a spectral sensitivity measuring device and a spectral sensitivity measuring method according to the present technology, which are capable of accurately measuring the spectral sensitivity of an imaging device including an image sensor. Hereinafter, a spectral response measuring device according to the present technology will be described using several embodiments as examples.

[0020] <2. Spectral response measuring device according to the first embodiment of the present technology> A spectral response measuring device 10 according to a first embodiment of the present technology will be described below with reference to the drawings.

[0021] FIG. 1 is a diagram (perspective view) that schematically shows the configuration of a spectral response measuring device 10 according to a first embodiment of the present technology. The spectral response measuring device 10 according to the first embodiment is a device used as, for example, a spectroscope, for measuring the spectral response of an imaging device IS including an image sensor and a lens. That is, the measurement target of the spectral response measuring device 10 is the spectral response of the imaging device IS including an image sensor and a lens.

[0022] Here, the imaging device IS including the image sensor as a spectroscope can be used, for example, in the agricultural field to recognize specific agricultural products. In addition, the imaging device IS including an image sensor as a spectrometer can be used, for example, in the field of smart construction, to remove unnecessary materials by performing highly accurate 3D segmentation using the wavelength information acquired by the imaging device IS, or to investigate the geology and hardness of the ground before mining. Furthermore, the imaging device IS including an image sensor as a spectrometer can also be used to observe food quality in the retail sector, for example. In addition, the imaging device IS including the image sensor as a spectrometer is expected to be used in the medical and beauty fields, for example.

[0023] Examples of the image sensor of the imaging device IS include a CCD image sensor and a CMOS image sensor. The image sensor of the imaging device IS includes, for example, a plurality of pixels arranged two-dimensionally, and performs photoelectric conversion on the light received by each pixel, outputting an electrical signal corresponding to the amount of light. Each pixel has a light-receiving element such as a photodiode. The signal value of the electrical signal is also called a pixel value. The image sensor of the imaging device IS is controlled by, for example, a control unit 180 (see FIG. 2). For example, the image sensor of the imaging device IS receives light from a subject (for example, a chart) for each pixel via a lens.

[0024] <Configuration of Spectral Sensitivity Measurement Device> The configuration of the spectral response measuring device 10 according to the first embodiment will be described below with reference to FIGS. The spectral response measuring device 10 includes, for example, a chart generating system 100 and a processing system 1000, as shown in FIG.

[0025] (Chart generation system) The chart generation system 100 generates a chart ch including at least one chart portion (e.g., a Macbeth chart) having at least one color region (e.g., a plurality of color regions) at a position facing (specifically, directly facing) an imaging device IS including an image sensor.

[0026] Here, the chart ch is an object to be imaged by the imaging device IS. In this technology, three modes are assumed for generating the chart ch. The first mode is when the chart ch is generated using a transmissive screen (e.g., an optical filter, a transmissive LCD panel, etc.) and a backlight source. The second mode is when the chart ch is generated by light from a light source. The third mode is when the chart ch is generated by a reflective screen (e.g., a reflective LCD panel, etc.) and a light source.

[0027] As an example, the chart generation system 100 sequentially generates a plurality of (e.g., eight) charts ch at positions facing the imaging device IS. Here, the color combination and arrangement of the color areas of each of the plurality of charts ch are the same, but the color combination and / or arrangement may differ between at least two charts ch.

[0028] The chart generating system 100 includes, for example, a light source 110, and generates a chart ch between the image capturing device IS and the light source 110.

[0029] As an example, the chart generating system 100 includes, in addition to the light source 110, an optical filter group 120G including a plurality of (e.g., eight) optical filters 120 (e.g., first to eighth optical filters 120-1 to 120-8) selectively arranged between the light source 110 and the image capturing device IS. The chart generating system 100 further includes a control unit 180. The control unit 180 may be included in the processing system 1000.

[0030] For example, the light source 110 and the imaging device IS are arranged one above the other. Here, for example, the light source 110 is arranged directly below the imaging device IS. The light source 110 emits light, for example, upward. The light source 110 is installed on a support member 115. Note that the light source 110 and the support member 115 may be configured as a single object.

[0031] The imaging device IS is supported by a support structure 150, for example. The support structure 150 has, for example, a support column 150c and first and second arms 150a and 150b each supported in a cantilevered manner by the support column 150c. The first and second arms 150a and 150b are arranged one above the other (with the first arm 150a being above the second arm 150b). The imaging device IS is detachably held at the tip of the first arm 150a. The imaging device IS is held by the first arm 150a with the imaging surface facing downward, for example.

[0032] The light source 110 is controlled by a control unit 180 (see FIG. 2). The light source 110 may be, for example, a light emitting diode (LED), an organic light emitting diode (OLED), a laser, a halogen lamp, a xenon lamp, or a fluorescent lamp.

[0033] Each optical filter 120 is, for example, a monochromatic filter that transmits light in a corresponding wavelength range from the light source 110. Note that each optical filter 120 may have a plurality of transmission sections that correspond to a plurality of color regions and are arranged one-dimensionally or two-dimensionally. In this case, each transmission section transmits light in a wavelength range of the corresponding color region from the light source 110.

[0034] As an example, the chart generation system 100 further includes a moving mechanism 130 that moves the optical filter group 120G and the system including the imaging device IS and the light source 110 relative to each other so that each of the multiple optical filters 120 is sequentially positioned between the imaging device IS and the light source 110.

[0035] As an example, the movement mechanism 130 moves the optical filters 120 in a direction (eg, horizontal direction) substantially perpendicular to the arrangement direction (eg, vertical direction) of the image capture device IS and the light source 110.

[0036] The moving mechanism 130 includes, for example, a turret 130a as a rotating member on which a plurality of (e.g., eight) optical filters 120 are arranged in the circumferential direction, and a motor 130c as a drive unit that rotates the turret 130a. The motor 130c is controlled by, for example, the control unit 180 (see FIG. 2).

[0037] The turret 130a is made of, for example, a substantially disk-shaped member, and has a plurality of (for example, eight) through-holes formed at substantially equal intervals along the circumferential direction on its outer periphery. An optical filter 120 is disposed in each through-hole.

[0038] For example, the turret 130a is rotatable around an axis that is substantially parallel to the arrangement direction (for example, the vertical direction) of the imaging device IS and the light source 110. The motor 130c rotates the turret 130a around this axis.

[0039] More specifically, a rotary shaft 130b that rotates in conjunction with the rotation of a rotor (movable element) of a motor 130c is attached to the center of the turret 130a. The rotary shaft 130b extends, for example, in the vertical direction, and the turret 130a is kept in a substantially horizontal position.

[0040] The chart generating system 100 includes, for example, a diffuser plate 140 disposed between the imaging device IS and each of the plurality of optical filters 120. For example, the diffuser plate 140 is a transmissive diffuser plate, and is held at the tip of the second arm 150b of the support structure 150. The diffuser plate 140 can diffuse the light emitted from the light source 110 and transmitted through the optical filter 120, allowing the optical filter 120 to be made smaller.

[0041] In the chart generation system 100 configured as described above, by rotating the turret 130a, each of the multiple optical filters 120 can be sequentially positioned between the image capture device IS and the light source 110. When each optical filter 120 is positioned between the image capture device IS and the light source 110, the light source 110 can be turned on to irradiate the optical filter 120 with light from the light source 110, and a chart ch corresponding to the optical filter 120 can be generated at a position facing the image capture device IS (for example, the position of the diffuser 140). Note that the multiple optical filters 120 may be moved while the light source 110 is turned on, so that the light from the light source 110 can be sequentially irradiated onto each optical filter 120. In this way, the chart generation system 100 can sequentially generate each of the multiple charts ch at a position facing the image capture device IS. Then, the imaging device IS can capture images of the charts ch that are sequentially generated at positions facing the imaging device IS.

[0042] (Processing system) The processing system 1000 calculates the spectral sensitivity of the image capturing device IS based on an image captured by the image capturing device IS of the chart ch generated at a position facing the image capturing device IS.

[0043] 2 is a block diagram showing the functions of the processing system 1000. The processing system 1000 includes a pixel value acquisition unit 1000a that acquires pixel values ​​of an image of a chart ch captured by the imaging device IS, and a spectral sensitivity calculation unit 1000b that calculates the spectral sensitivity of the imaging device IS based on the spectral characteristics of the chart ch and the pixel values ​​acquired by the pixel value acquisition unit 1000a. The processing system 1000 further includes a spectral characteristics storage unit 1000c that stores the spectral characteristics of the chart ch. The processing system 1000 is realized by hardware including, for example, a CPU, a chipset, and the like.

[0044] <<Operation of the spectral response measuring device>> The operation of the spectral sensitivity measurement device 10 according to the first embodiment (an example of the spectral sensitivity measurement method according to the present technology) will be described with reference to the flowchart of FIG. 3. In advance, an imaging device IS as a measurement target is mounted on the tip of the first arm 150a of the support structure 150 and is located directly above the light source 110 (see FIG. 1).

[0045] In the first step S1, the control unit 180 sets 1 to n.

[0046] In the next step S2, the control unit 180 generates the n-th chart. Specifically, the control unit 180 controls the motor 130c to position the n-th optical filter 120-n between the imaging device IS and the light source 110, and lights the light source 110. Thereby, the n-th chart is generated at a position facing the imaging device IS. Note that the optical filter 120-n may be moved while the light source 110 is lit, so that the light from the light source 110 irradiates the optical filter 120-n. The control unit 180 may stop the turret 130a when the n-th optical filter 120-n is positioned between the imaging device IS and the light source 110, or may continue to rotate the turret 130a at a low speed.

[0047] In the next step S3, the imaging device IS images the n-th chart. Specifically, the control unit 180 transmits an imaging trigger signal to the imaging device IS when executing step S2. When the imaging device IS receives the imaging trigger signal, it images the n-th chart and outputs the data of the imaged image (the photoelectrically converted signal for each pixel) to the pixel value acquisition unit 1000a.

[0048] In the next step S4, the pixel value acquisition unit 1000a acquires the pixel values (signal values and luminance values of each pixel) of the imaged image of the n-th chart.

[0049] In the next step S5, the control unit 180 determines whether n is less than N (for example, 8). If the determination in step S5 is affirmative, the process proceeds to step S6; if it is negative, the process proceeds to step S7.

[0050] In step S6, the control unit 180 increments n. After step S6 is executed, the process returns to step S2, whereby the series of processes from steps S2 to S5 is carried out again.

[0051] In step S7, the spectral sensitivity calculation unit 1000b calculates the spectral sensitivity of the image capture device IS.

[0052] Specifically, the spectral sensitivity calculation unit 1000b uses the following formula (F1) to measure the spectral sensitivity x of the imaging device IS when capturing an image of each chart ch, based on the acquired pixel value b of that chart ch and the spectral characteristic A of that chart ch.

[0053]

number

[0054] Here, the pixel value b is an actually measured value and is therefore also called an observed pixel value. The spectral characteristic A is a known value that can be calculated from the spectral intensity of the light source 110 and the spectral transmittance of each optical filter 120. The spectral characteristic A is stored in the spectral characteristic storage unit 1000c for each optical filter 120.

[0055] The spectral sensitivity x can be calculated by the least squares method if there are a sufficient number of equations. However, if the number of equations is less than the number of unknowns, the problem becomes ill-posed, with no solution or multiple solutions. In this case, the spectral sensitivity x cannot be calculated by the least squares method, but it can be calculated by, for example, Tikhonov regularization, Wiener estimation, or quadratic programming.

[0056] Generally, the more equations there are, the more stable the solution. Therefore, it is desirable to increase the number of equations. Increasing the number of equations can be achieved by increasing the number of color regions in the chart portion of each chart to be photographed.

[0057] Furthermore, for example, when the representative value and variance of the spectral sensitivity x are known, an approximate solution of the spectral sensitivity x can be obtained by a non-parametric estimation method that does not depend on the distribution, as in the following equation (F2).

[0058]

number

[0059] Note that x0 is the representative value of the spectral sensitivity, and Σ -1 is the covariance matrix of the spectral sensitivities.

[0060] After the spectral sensitivity of one image capture device IS is measured in the above manner, it is possible to measure the spectral sensitivity of another image capture device IS according to the flow shown in Fig. 3. In other words, the image capture device IS to be measured can be replaced and then measured.

[0061] <Effects of spectral sensitivity measurement equipment> The effects of the spectral response measurement device 10 according to the first embodiment and the spectral response measurement method using the spectral response measurement device 10 will be described below.

[0062] The spectral sensitivity measuring device 10 according to the first embodiment includes a chart generating system 100 that generates a chart ch including at least one chart portion having at least one color region at a position facing the imaging device IS, and a processing system 1000 that calculates the spectral sensitivity of the imaging device IS based on an image captured by the imaging device IS of the chart ch generated at a position facing the imaging device IS. The spectral response measuring device 10 can provide a spectral response measuring device that can measure the spectral response of the imaging device IS with high accuracy.

[0063] This makes it possible to accurately determine whether the imaging device IS is non-defective or not when the imaging device IS is used as a spectroscope, for example. Furthermore, the spectral response measuring apparatus 10 is particularly effective in that it can accurately measure the spectral response of an imaging device such as the imaging device IS, whose image sensor is susceptible to changes in spectral response due to the influence of the oblique incidence characteristics of the lens.

[0064] In the spectral sensitivity measurement device of the comparative example shown in Fig. 23, as shown in the left diagram of Fig. 4A, due to the influence of the lens distortion described above, part of the chart group is missing at the corner of the image ii of the chart group captured by the imaging device, and it is therefore not possible to place the measurement point mp at that corner (see the right diagram of Fig. 4A). As a result, it is not possible to measure the spectral sensitivity at that corner.

[0065] On the other hand, with the spectral response measurement device 10 according to the first embodiment, as shown in the left diagram of Fig. 4B, the entire surface of the chart can be imaged substantially uniformly (substantially flat), so that no part of the chart is lost at the corner of the captured image ii due to the influence of lens distortion, and measurement points mp can be placed at these corners (see the right diagram of Fig. 4B). Thus, with the spectral response measurement device 10 according to the first embodiment, the spectral response can be measured even at the corner of the captured image ii, and there is no need to design a chart that takes lens distortion into account.

[0066] Furthermore, in the spectral sensitivity measuring device of the comparative example shown in FIG. 23, as shown in FIG. 5A, the positions of corresponding pixels (e.g., p1, p2) differ between the captured images of each chart in the captured image ii of the chart group, and therefore the spectral sensitivity is calculated in a state that includes noise in the spatial direction, resulting in a decrease in measurement accuracy.

[0067] On the other hand, in the spectral response measurement device 10 according to the first embodiment, as shown in FIG. 5B, the positions (e.g., p) of corresponding pixels are the same between the captured images ii (e.g., ii1, ii2, ii3) of the chart, and therefore the spectral response can be calculated without including spatial noise, thereby improving the measurement accuracy.

[0068] The chart generation system 100 sequentially generates each of the multiple charts ch at a position facing the image capture device IS. This allows each chart ch to be captured by the image capture device IS while facing directly toward the image capture device IS, making it possible to accurately measure the spectral sensitivity of the image capture device IS without requiring a long time.

[0069] The chart generation system 100 has a light source 110 and an optical filter group 120G including a plurality of optical filters 120 selectively arranged between the light source 110 and the image capture device IS. This makes it possible to generate each of a plurality of charts ch at a position facing the image capture device IS with a small number of parts.

[0070] The chart generating system 100 further includes a moving mechanism 130 that relatively moves the optical filter group 120G and the system including the image capturing device IS and the light source 110 so that each of the plurality of optical filters 120 is sequentially positioned between the image capturing device IS and the light source 110. This allows each of the plurality of optical filters 120 to be sequentially positioned between the image capturing device IS and the light source 110 with a relatively simple configuration.

[0071] The movement mechanism 130 moves the plurality of optical filters 120 in a direction substantially perpendicular to the arrangement direction of the image capture device IS and the light source 110. This allows the plurality of optical filters 120 to move between the image capture device IS and the light source 110 even when the distance between the image capture device IS and the light source 110 is small (even when the dimension of the device in the height direction is short).

[0072] The moving mechanism 130 has a turret 130a as a rotating member on which the plurality of optical filters 120 are arranged in the circumferential direction and which is rotatable around an axis substantially parallel to the arrangement direction of the image capture device IS and the light source 110, and a motor 130c as a drive unit that rotates the turret 130a around the axis. This allows the plurality of optical filters 120 to rotate around the turret 130a, and enables the spectral sensitivity of the image capture device IS to be measured efficiently and accurately.

[0073] The chart generating system 100 includes a diffuser 140 disposed between the imaging device IS and each of the plurality of optical filters 120. This allows the optical filters 120 and the turret 130a to be made smaller, thereby enabling the device to be made smaller.

[0074] The processing system 1000 includes a pixel value acquisition unit 1000a that acquires pixel values ​​of an image of the chart ch captured by the imaging device IS, and a spectral sensitivity calculation unit 1000b that calculates the spectral sensitivity of the imaging device IS based on the spectral characteristic A of the chart ch and the pixel values ​​acquired by the pixel value acquisition unit 1000a. This makes it possible to stably and accurately measure the spectral sensitivity of the imaging device IS.

[0075] A spectral sensitivity measurement method using the spectral sensitivity measurement device 10 according to the first embodiment includes the steps of generating a chart ch including at least one chart portion having at least one color region at a position facing the imaging device IS, capturing an image of the chart ch generated at a position facing the imaging device IS using the imaging device IS, acquiring pixel values ​​of the image of the chart ch captured in the capturing step, and calculating the spectral sensitivity of the image sensor based on the spectral characteristic A of the chart ch and the pixel values ​​acquired in the capturing step. According to this spectral sensitivity measurement method, the spectral sensitivity of the image capture device IS can be measured with high accuracy.

[0076] In the generating step, the plurality of charts ch are generated sequentially at positions facing the image capture device IS, thereby enabling the spectral sensitivity of the image capture device IS to be measured efficiently and accurately.

[0077] <3. Spectral sensitivity measurement device according to a modified example of the first embodiment of the present technology> A spectral sensitivity measurement device according to a modified example of the first embodiment of the present technology will be described below with reference to the drawings. Fig. 7A is a graph showing the light intensity luminance value for each color region (each wavelength) of a chart ch corresponding to each optical filter when multiple (e.g., eight) optical filters are moved at a constant speed and images are captured by an imaging device IS at the same imaging time in the spectral sensitivity measurement device 10 according to the first embodiment. 7A, it can be seen that the luminance values ​​are particularly low on the long wavelength side (for example, 700 nm or longer) of some chart channels. This is because the amount of light on the long wavelength side of those chart channels is low. In this case, the pixel values ​​on the long wavelength side of the captured image are also low, which makes them susceptible to the influence of noise, and there is a risk that the measurement accuracy of the spectral sensitivity will decrease.

[0078] Therefore, in the spectral sensitivity measuring device according to the modified example of the first embodiment, it is preferable that the control unit 180 controls at least one of the imaging time during which the imaging device IS images the chart ch and / or the time during which the imaging device IS faces the chart ch and / or the emission intensity and emission time of the light source 110 (for example, the pulse amplitude and pulse width of the pulse signal for driving the light source 110) in accordance with the light amount for each wavelength of the multiple (e.g., four) optical filters 120.

[0079] Specifically, when generating a chart ch using an optical filter 120 with low transmittance on the long wavelength side, the control unit 180 makes the imaging time of the imaging device IS longer and / or makes the time that the imaging device IS and the chart ch face each other longer and / or makes the light emission intensity of the light source 110 stronger and / or makes the light emission time longer than when generating a chart ch using an optical filter 120 other than the optical filter 120. This allows the luminance value on the long wavelength side of the part of the chart ch to be increased, as shown in FIG. 7B, for example, and makes it possible to obtain sufficient pixel values ​​across the entire wavelength band, thereby improving the measurement accuracy of the spectral sensitivity.

[0080] <4. Spectral response measuring device according to Example 1 of the second embodiment of the present technology> A spectral response measurement device according to Example 1 of the second embodiment of the present technology will be described below with reference to Fig. 8. Fig. 8 is a diagram (perspective view) that schematically shows the configuration of a spectral response measurement device 20-1 according to Example 1 of the second embodiment.

[0081] The spectral response measurement apparatus 20-1 has a configuration generally similar to that of the spectral response measurement apparatus 10 according to the first embodiment, except that the chart generation system 200-1 has a tunable wavelength light source 210 instead of the light source 110, and does not have the optical filter group 120G or the movement mechanism 130. The tunable wavelength light source 210 is a light source whose emission wavelength is tunable.

[0082] In the spectral response measurement device 20-1, the tunable light source 210 faces the image capture device IS. Here, as an example, the image capture device IS is detachably held at the tip of an arm 250a of a support structure 250 including a support column 250b and an arm 250a so as to face the tunable light source 210. Note that a diffusion plate 140 that diffuses light from the tunable light source 210 may be disposed between the tunable light source 210 and the image capture device IS.

[0083] The variable wavelength light source 210 emits light of any wavelength (e.g., R, G, B light) to generate a chart ch at a position facing the imaging device IS. The variable wavelength light source 210 may be, for example, a light emitting diode, a semiconductor laser, or the like.

[0084] In the spectral response measuring device 20-1, the control unit 180 sequentially generates each of the multiple charts ch at a position facing the imaging device IS by changing the emission wavelength of the wavelength-variable light source 210. The control unit 180 causes the imaging device IS to capture each of the charts ch generated at a position facing the imaging device IS. The spectral response measuring device 20-1 can provide a spectral response measuring device that can accurately measure the spectral response of the image pickup device IS with a simple configuration.

[0085] <5. Spectral response measuring device according to Example 2 of the second embodiment of the present technology> A spectral response measurement device according to Example 2 of the second embodiment of the present technology will be described below with reference to Fig. 9. Fig. 9 is a diagram (perspective view) that schematically shows the configuration of a spectral response measurement device 20-2 according to Example 2 of the second embodiment.

[0086] The spectral sensitivity measurement device 20-2 has a configuration generally similar to that of the spectral sensitivity measurement device 20-1 of Example 1, except that the chart generation system 200-2 has an optical filter group 220G including a plurality (e.g., three) optical filters 220 (e.g., first to third optical filters 220-1 to 220-3) selectively arranged between the imaging device IS and the wavelength-tunable light source 210.

[0087] The first optical filter 220-1 is, for example, a high-pass filter, the second optical filter 220-2 is, for example, a band-pass filter, and the third optical filter 220-3 is, for example, a low-pass filter.

[0088] As an example, the chart generation system 200-2 further includes a moving mechanism 230 that moves the optical filter group 220G and the system including the imaging device IS and the wavelength-tunable light source 210 relatively so that each of the multiple optical filters 220 is sequentially positioned between the imaging device IS and the wavelength-tunable light source 210.

[0089] As an example, the movement mechanism 230 moves the plurality of optical filters 220 in a direction substantially perpendicular to the arrangement direction of the image capture device IS and the wavelength-tunable light source 210 (for example, the vertical direction).

[0090] The optical filters 220 are, for example, arranged one-dimensionally in a horizontal plane. The movement mechanism 230 moves the optical filter group 220G in a single axial direction along the direction in which the optical filters 220 are arranged.

[0091] The movement mechanism 230 includes, for example, a holding member 230a that holds the plurality of optical filters 220, a movable support member 230b that supports the holding member 230a at a height position between the image capture device IS and the wavelength-tunable light source 210, and a linear motor 230c that moves the movable support member 230b in the uniaxial direction. The linear motor 230c is controlled by the control unit 180.

[0092] The control unit 180 controls the linear motor 230c to position one of the multiple optical filters 220 between the image capture device IS and the tunable light source 210, turns on the tunable light source 210, and generates a chart ch corresponding to the optical filter 220 at a position facing the image capture device IS (more specifically, a chart ch generated by light with a wavelength in the pass band of the optical filter 220), and causes the image capture device IS to capture the chart. The control unit 180 performs this series of operations for each optical filter 220, thereby obtaining a captured image of the chart ch corresponding to each optical filter 220 and outputting it to the processing system 1000. The processing system 1000 calculates the spectral sensitivity of the image capture device IS based on the captured image.

[0093] The spectral response measurement apparatus 20-2 has the same effects as the spectral response measurement apparatus 20-1 according to the first embodiment, and can generate a chart ch using light in a narrower wavelength band, thereby enabling measurement of spectral response specialized for a narrower wavelength band.

[0094] <6. Spectral response measuring device according to Example 1 of the third embodiment of the present technology> A spectral response measurement device according to Example 1 of the third embodiment of the present technology will be described below with reference to Fig. 10. Fig. 10 is a diagram (perspective view) that schematically shows the configuration of a spectral response measurement device 30-1 according to Example 1 of the third embodiment.

[0095] 10, the spectral sensitivity measurement device 30-1 has a configuration generally similar to that of the spectral sensitivity measurement device 20-1 according to Example 1 of the second embodiment, except that the chart generation system 300-1 has an optical fiber cable 360 ​​as an optical waveguide member, the input end of which is connected to the tunable light source 210 and the output end of which faces the image capture device IS. The operation of the spectral sensitivity measurement device 30-1 is also generally similar to that of the spectral sensitivity measurement device 20-1. The output end of the optical fiber cable 360 ​​is supported, for example, by a movable support stand at a position facing the corresponding image capture device IS.

[0096] The spectral sensitivity measuring device 30-1 can improve the compactness and operability and mobility of the part of the chart generating system 300-1 that faces the imaging device IS, making it easy to use, for example, when measuring the spectral sensitivity of multiple imaging devices IS consecutively.

[0097] <7. Spectral response measuring device according to Example 2 of the third embodiment of the present technology> A spectral response measurement device according to Example 2 of the third embodiment of the present technology will be described below with reference to Fig. 11. Fig. 11 is a diagram (perspective view) that schematically shows the configuration of a spectral response measurement device 30-2 according to Example 2 of the third embodiment.

[0098] 11 , the spectral sensitivity measurement device 30-2 has a chart generation system 300-2 that includes a plurality (e.g., two) of optical fiber cables 360 (e.g., optical fiber cables 360-1 and 360-2) serving as optical waveguide members corresponding to a plurality (e.g., two) of image capture devices IS (e.g., image capture devices IS-1 and IS-2). Each of the optical fiber cables 360 has an input end connected to a tunable light source 210 and an output end facing the corresponding image capture device IS. The spectral sensitivity measurement device 30-2 operates in a similar manner to the spectral sensitivity measurement device 30-1. The output end of each optical fiber cable 360 ​​is supported by a movable support stand, for example, at a position facing the corresponding image capture device IS.

[0099] The spectral response measurement device 30-2 achieves the same effects as the spectral response measurement device 30-1 according to the first embodiment, and because multiple (e.g., two) optical fiber cables 360 are branch-connected to one tunable wavelength light source 210, the spectral response of multiple image capture devices IS can be measured in parallel with a small number of components. Therefore, the spectral response measurement device 30-2 is effective in that it can measure the spectral response of multiple image capture devices IS in a short time, for example. Note that three or more optical fiber cables 360 may be branch-connected to one tunable wavelength light source 210.

[0100] 8. Spectral response measuring device according to example 1 of the fourth embodiment of the present technology A spectral response measurement device according to Example 1 of the fourth embodiment of the present technology will be described below with reference to Fig. 12. Fig. 12 is a diagram (perspective view) that schematically shows the configuration of a spectral response measurement device 40-1 according to Example 1 of the fourth embodiment.

[0101] In the spectral response measuring device 40-1, the chart generating system 400-1 includes a light source group 410G including a plurality of (e.g., eight) light sources 410 (e.g., eight light sources 410-1 to 410-8) with different emission wavelengths, and a moving mechanism 430-1 that moves the light source group 410G and the imaging device IS relative to each other so that each of the plurality of light sources 410 faces the imaging device IS in sequence.

[0102] In more detail, the chart generating system 400-1 includes a light source group 410G including a plurality (e.g., eight) of light sources 410 (e.g., eight light sources 410-1 to 410-8) with different emission wavelengths, and a moving mechanism 430-1 that moves the light source group 410G and the image sensor group ISG including the plurality of imaging devices IS relatively so that each of the plurality of light sources 410 faces each of the plurality (e.g., eight) imaging devices IS (e.g., eight imaging devices IS-1 to IS-8) in sequence.

[0103] As an example, the movement mechanism 430-1 moves the image sensor group ISG relative to the light source group 410G.

[0104] The plurality of light sources 410 (for example, eight light sources 410-1 to 410-8) are held by a light source holding member so as to be arranged at approximately equal intervals on a circumference, for example.

[0105] The multiple imaging devices IS (e.g., eight imaging devices IS-1 to IS-8) are detachably held by a sensor holding member so as to be arranged at approximately equal intervals (approximately equal angular intervals) on a circumference of a circle of the same radius that is coaxial with the circle on which the multiple light sources 410 are arranged. The sensor holding member is rotatable around an axis that passes through the centers of the two circles. The sensor holding member is rotated around the axis by, for example, a motor. The motor is controlled by a control unit.

[0106] The control unit controls the motor so that the plurality of light sources 410 and the plurality of image capture devices IS face each other in a one-to-one relationship. More specifically, the control unit first generates a chart ch for each of eight pairs of opposing light sources 410 and image capture devices IS, and causes the corresponding image capture device IS to capture the chart ch. Next, the control unit controls the motor to rotate the sensor holding member by a predetermined angle (e.g., 45°), and generates a chart ch for each of another eight pairs of opposing light sources 410 and image capture devices IS, and causes the corresponding image capture device IS to capture the chart ch. The control unit repeats this operation until images of the chart ch have been captured for all combinations of light sources 410 and image capture devices IS.

[0107] According to the spectral response measuring device 40-1, by rotating the image sensor group ISG to change the combination of a plurality of pairs (e.g., eight pairs) of opposing light sources 410 and image capturing devices IS, each image capturing device IS can be made to sequentially face each of the plurality of light sources 410 to capture an image of the chart ch, thereby making it possible to measure the spectral response of a plurality of (e.g., eight) image capturing devices IS in parallel. In other words, the spectral response of a plurality of image capturing devices IS can be measured in a short time.

[0108] 9. Spectral response measuring device according to Example 2 of the fourth embodiment of the present technology A spectral response measurement device according to Example 2 of the fourth embodiment of the present technology will be described below with reference to Fig. 13. Fig. 13 is a diagram (perspective view) that schematically shows the configuration of a spectral response measurement device 40-2 according to Example 2 of the fourth embodiment.

[0109] The spectral response measurement device 40-2 has a configuration generally similar to that of the spectral response measurement device 40-1 according to the first embodiment, except that a movement mechanism 430-2 of a chart generation system 400-2 moves the light source group 410G relative to the image sensor group ISG.

[0110] That is, in the spectral response measuring device 40-2, a light source holding member, instead of a sensor holding member, is rotated by, for example, a motor.

[0111] The spectral response measurement device 40-2 performs the same operations as the spectral response measurement device 40-1 according to the first embodiment (but operates on the opposite target), and provides the same effects.

[0112] <10. Spectral response measuring device according to the fifth embodiment of the present technology> A spectral response measurement device according to a fifth embodiment of the present technology will be described below with reference to Fig. 14. Fig. 14 is a diagram (perspective view) that schematically shows the configuration and operation sequence of a spectral response measurement device 50 according to the fifth embodiment.

[0113] 14, the spectral response measurement device 50 has a configuration generally similar to that of the spectral response measurement device 40-1 according to Example 1 of the fourth embodiment, except that each of a plurality of (e.g., 10) image capture devices IS (e.g., image capture devices IS1 to IS10) is sequentially loaded into a first position (also referred to as a load position LP) that faces the first (first) light source 410 of the light source group 410G, and sequentially unloaded from an eighth position (also referred to as an unload position ULP) that faces the last (eighth) light source 410. The positions at which the image capture device IS faces the second to seventh light sources 410 are referred to as the second to seventh positions, respectively. Each image sensor is attached to a sensor holding member at the load position LP and detached from the sensor holding member at the unload position ULP.

[0114] A description will be given of the operation sequence of the spectral response measuring apparatus 50. Here, the spectral response of a plurality of (for example, 10) image pickup devices IS (for example, image pickup devices IS1 to IS10) is measured continuously.

[0115] (First sequence) The imaging device IS1 is carried into the first position (loading position LP), and the chart ch is generated and imaged at the first position. The imaging devices IS2 to IS10 are in a standby state.

[0116] (Second sequence) The imaging device IS1 is moved to the second position, the imaging device IS2 is carried into the first position, and the chart ch is generated and imaged at each position. The imaging devices IS3 to IS10 are in a standby state.

[0117] (Third sequence) The imaging devices IS1 and IS2 are moved to the third and second positions, respectively, and the imaging device IS3 is carried into the first position, and the chart ch is generated and imaged at each position. The imaging devices IS4 to IS10 are in a standby state.

[0118] (Fourth sequence) The image capturing devices IS1, IS2, and IS3 are moved to the fourth, third, and second positions, respectively, and the image capturing device IS4 is moved to the first position. The image capturing devices IS5 to IS10 are in a standby state.

[0119] (Fifth sequence) The image capturing devices IS1, IS2, IS3, and IS4 are moved to the fifth, fourth, third, and second positions, respectively, and the image capturing device IS5 is moved to the first position. The chart ch is generated and captured at each position. The image capturing devices IS6 to IS10 are in a standby state.

[0120] (Sixth sequence) The image capturing devices IS1, IS2, IS3, IS4, and IS5 are moved to the sixth, fifth, fourth, third, and second positions, respectively, and the image capturing device IS6 is moved to the first position. The image capturing devices IS7 to IS10 are in a standby state.

[0121] (Seventh sequence) The image capturing devices IS1, IS2, IS3, IS4, IS5, and IS6 are moved to the seventh, sixth, fifth, fourth, third, and second positions, respectively, and the image capturing device IS7 is moved to the first position, and the chart ch is generated and captured at each position. The image capturing devices IS8 to IS10 are in a standby state.

[0122] (Eighth sequence) Imagers IS1, IS2, IS3, IS4, IS5, IS6, and IS7 are moved to positions eight, seven, sixth, fifth, fourth, third, and second, respectively, and imager IS8 is moved to position one, where chart ch is generated and imaged at each position. Then, the spectral sensitivity of imager IS1 is calculated based on the captured images acquired at positions one through eight, and imager IS1 is removed. Imagers IS9 and IS10 are in a standby state.

[0123] (Ninth sequence) Image capture devices IS2, IS3, IS4, IS5, IS6, IS7, and IS8 are moved to positions 8, 7, 6, 5, 4, 3, and 2, respectively, and image capture device IS9 is moved to position 1, where chart ch is generated and captured at each position. The spectral sensitivity of image capture device IS2 is then calculated based on the captured images acquired at positions 1 through 8, and image capture device IS2 is then removed. Image capture device IS10 is in a standby state.

[0124] (Tenth sequence) Image capture devices IS3, IS4, IS5, IS6, IS7, IS8, and IS9 are moved to positions 8, 7, 6, 5, 4, 3, and 2, respectively, and image capture device IS10 is moved to position 1. A chart ch is generated and captured at each position. The spectral sensitivity of image capture device IS3 is then calculated based on the captured images acquired at positions 1 to 8, and image capture device IS3 is then removed.

[0125] (Eleventh sequence) Image capture devices IS4, IS5, IS6, IS7, IS8, IS9, and IS10 are moved to positions 8, 7, 6, 5, 4, 3, and 2, respectively, and chart ch is generated and captured at each position. After that, the spectral sensitivity of image capture device IS4 is calculated based on the captured images acquired at positions 1 to 8, and image capture device IS4 is removed.

[0126] The first to eleventh sequences have been described above, but the subsequent sequences are performed in the same manner, so the description will be omitted.

[0127] According to the spectral response measuring device 50, the chart ch is generated and captured in parallel by sequentially facing each of the plurality of image capturing devices IS and each of the plurality of light sources 410, and therefore, the spectral response measuring device 50 is effective in that it can efficiently measure the spectral response of a large number of image capturing devices IS in succession.

[0128] <11. Spectral response measuring device according to the sixth embodiment of the present technology> Hereinafter, a spectral response measuring device according to a sixth embodiment of the present technology will be described with reference to the drawings.

[0129] However, spectral sensitivity measurement devices have a problem in that brightness changes within the chart due to uneven brightness of the light source and lens shading. To address this problem, a method has been proposed in which white areas (spectral reflectance of which is constant regardless of wavelength) are included discretely within the chart, and shading correction is performed using these white areas (see, for example, Patent Document 1). However, the shading correction requires, for example, providing a white area in an optical filter or the like for generating a chart, and also requires highly accurate shading correction calculations so that the amount of light is uniform across the chart surface.

[0130] Therefore, in order to address such problems, the inventors developed a spectral response measuring device according to a sixth embodiment.

[0131] <Configuration of Spectral Sensitivity Measurement Device> The spectral sensitivity measurement device according to the sixth embodiment has a configuration similar to that of the spectral sensitivity measurement device 10 according to the first embodiment, except for a partial difference in the configuration of the processing system 1000. Note that, except for a partial difference in the configuration of the processing system 1000, the spectral sensitivity measurement device according to the sixth embodiment may have the same configuration as any of the spectral sensitivity measurement devices according to the modified example of the first embodiment, the spectral sensitivity measurement devices 20-1 and 20-2 according to Examples 1 and 2 of the second embodiment, the spectral sensitivity measurement devices 30-1 and 30-2 according to Examples 1 and 2 of the third embodiment, the spectral sensitivity measurement devices 40-1 and 40-2 according to Examples 1 and 2 of the fourth embodiment, the spectral sensitivity measurement device 50 according to the fifth embodiment, and the spectral sensitivity measurement device described in Patent Document 1.

[0132] FIG. 15 is a block diagram showing the functions of a processing system 1000 of a spectral response measuring apparatus according to the sixth embodiment. 15, for example, in the spectral sensitivity measurement device according to the sixth embodiment, a spectral sensitivity calculation unit 1000b of a processing system 1000 has a correction coefficient calculation unit 1000b1 and a pixel value correction unit 1000b2. Note that the processing system 1000 may have a pixel value correction unit and a correction coefficient calculation unit separate from the spectral sensitivity calculation unit.

[0133] The processing system 1000 (specifically, the spectral sensitivity calculation unit 1000b) calculates the theoretical pixel value y th Then, a correction coefficient C is calculated from the following equation (F4). Then, the spectral sensitivity x is calculated from the following equation (F5) using a corrected pixel value yc obtained by multiplying the actual measured pixel value y of an image of the chart ch that is different from the image captured by the imaging device IS by the correction coefficient C. y th =Ax a (F3) (where x a is the spectral sensitivity of an image sensor with known spectral sensitivity, and A is the spectral characteristics of the chart) C=y th / y a (F4) (However, y a is the pixel value of an image captured by an image sensor with known spectral sensitivity) y c =Ax (F5) (where A is the spectral characteristics of the chart)

[0134] <Correction coefficient acquisition process> The correction coefficient acquisition process performed by the spectral response measurement device of the sixth embodiment will be described below with reference to the flowchart of Fig. 16. The correction coefficient calculation process is performed using an image capture device ISa whose spectral response is known. In the spectral response measurement device of the sixth embodiment, a processing system 1000 measures the spectral response X of the image capture device ISa. a The spectral sensitivity memory 1000d stores the known spectral sensitivity. The imaging device ISa is previously attached to the tip of the first arm 150a of the support structure 150 and positioned directly above the light source 110 (see FIG. 1).

[0135] In the first step T1, the correction coefficient calculation unit 1000b1 calculates the theoretical pixel value y th Specifically, the correction coefficient calculation unit 1000b1 calculates the spectral characteristic A of the chart ch stored in the spectral characteristic storage unit 1000c and the spectral sensitivity x of the image capture device ISa stored in the spectral sensitivity storage unit 1000d. a Substituting this into the above formula (F3), the theoretical pixel value y th is calculated and stored in the built-in memory.

[0136] In the next step T2, the control unit 180 sets n to 1.

[0137] In the next step T3, the control unit 180 generates the nth chart. Specifically, the control unit 180 controls the motor 130c to position the nth optical filter 120-n between the image capture device ISa and the light source 110, and turns on the light source 110. As a result, the nth chart is generated at a position facing the image capture device ISa.

[0138] In the next step T4, the imaging device ISa images the n-th chart. Specifically, when the control unit 180 executes step T3, it transmits an imaging trigger signal to the imaging device ISa. When the imaging device ISa receives the imaging trigger signal, it images the n-th chart and outputs the data of the captured image (the photoelectrically converted signal for each pixel) to the pixel value acquisition unit 1000a.

[0139] In the next step T5, the pixel value acquisition unit 1000a acquires the pixel value y a (the signal value and luminance value of each pixel) of the captured image of the n-th chart by the imaging device ISa and outputs it to the correction coefficient calculation unit 1000b1. The correction coefficient calculation unit 1000b1 stores the input pixel value y a in the built-in memory.

[0140] In the next step T6, the control unit 180 determines whether n < N (for example, less than 8). If the determination in step T6 is affirmative, the process proceeds to step T7; if it is negative, the process proceeds to step T8.

[0141] In step T7, the control unit 180 increments n. When step T7 is executed, the process returns to step T3. As a result, the series of processes in steps T3 to T6 is performed again.

[0142] In step T8, the correction coefficient calculation unit 1000b1 calculates the correction coefficient C. Specifically, the theoretical pixel value y th calculated in step T1 and the pixel value y a of each chart ch acquired in step T5 are substituted into the above formula (F4) to obtain the correction coefficient C for each chart ch.

[0143] <<Operation of the Spectral Sensitivity Measuring Device>> Hereinafter, the operation of the spectral sensitivity measuring device according to the sixth embodiment (an example of the spectral sensitivity measuring method according to the present technology) will be described with reference to the flowchart of FIG. 17. In advance, the imaging device IS as the measurement object is mounted at the tip of the first arm 150a of the support structure 150 and is located directly above the light source 110 (see FIG. 1).

[0144] In the initial step S11, the control unit 180 sets 1 to n.

[0145] In the next step S12, the control unit 180 generates the nth chart. Specifically, the control unit 180 controls the motor 130c to position the nth optical filter 120 - n between the imaging device IS and the light source 110, and lights up the light source 110. Thereby, the nth chart is generated at the position facing the imaging device IS. The control unit 180 may stop the turret 130a when the nth optical filter 120 is positioned between the imaging device IS and the light source 110, or may continue to rotate the turret 130a at a low speed.

[0146] In the next step S13, the imaging device IS images the nth chart. Specifically, the control unit 180 transmits an imaging trigger signal to the imaging device IS when executing step S12. The imaging device IS images the nth chart when receiving the imaging trigger signal, and outputs the data of the imaged image (the photoelectrically converted signal for each pixel) to the pixel value acquisition unit 1000a.

[0147] In the next step S14, the pixel value acquisition unit 1000a acquires the measured value of the pixel value (measured pixel value y) of the imaged image of the nth chart.

[0148] In the next step S15, the pixel value correction unit 1000b2 corrects the acquired pixel value. Specifically, the pixel value correction unit 1000b2 multiplies the measured pixel value y of the imaged image of the nth chart by the correction coefficient C to calculate the corrected pixel value y c to calculate.

[0149] In the next step S16, the control unit 180 determines whether n is less than N (for example, 8). If the determination in step S16 is affirmative, it proceeds to step S17; if negative, it proceeds to step S18.

[0150] In step S17, the control unit 180 increments n. After step S17 is executed, the process returns to step S12, whereby the series of processes from step S12 to S16 is carried out again.

[0151] In step S18, the spectral sensitivity calculation unit 1000b calculates the spectral sensitivity of the image capture device IS. Specifically, the spectral sensitivity calculation unit 1000b calculates the corrected pixel value y c and the spectral characteristic A of the chart ch, the spectral sensitivity x of the image pickup device IS is measured. When step S18 is executed, the flow ends.

[0152] After the spectral response of one image capture device IS is measured in the above manner, it is possible to measure the spectral response of another image capture device IS according to the flow shown in FIG.

[0153] <Effects of spectral sensitivity measurement equipment> FIG. 18A is a graph showing the spectral sensitivity of the image sensor IS at a measurement position (a position within a pixel being imaged) acquired with high accuracy using another image sensor as a reference value (in this example, the spectral sensitivity waveforms of three pixels). FIG. 18B is a graph showing the spectral sensitivity of the image sensor IS calculated using pixel values ​​after shading correction. FIG. 18C is a graph showing the spectral sensitivity of the image sensor IS calculated using the corrected pixel value y c 18A to 18C are graphs showing the spectral sensitivity of the image pickup device IS calculated using the following equation: Note that the horizontal axis in FIGS. 18A to 18C is in nm. 18A and 18B, the spectral sensitivity of the image sensor IS calculated using pixel values ​​after shading correction shows a relatively large deviation from the reference value, and the reproducibility is not high. In Fig. 18B, the error RMSE (Root Mean Squared Error), which is an index indicating the degree of reproducibility, from Fig. 18A is relatively large, and it can be seen that the numerical reproducibility is also not high. As can be seen from a comparison between FIG. 18A and FIG. 18C, the corrected pixel value y cThe spectral sensitivity of the imager IS calculated using the above formula has a relatively small deviation from the reference value and is highly reproducible. In Fig. 18C, it can be seen that the RMSE is relatively small and the numerical reproducibility is also high. Although the sensitivity of lenses and image sensors varies depending on the position within the image plane being photographed, it is desirable to eliminate the effects of shading when calculating spectral sensitivity (especially when the color regions within the chart are different). Furthermore, although chart spectra use average values, in reality, there are variations within the photographing plane due to nonuniformity within the photographing plane of the light source, nonuniformity within the photographing plane of the filter, and even nonuniformity within the photographing plane of the chart generation system. The spectral sensitivity measuring device of the sixth embodiment can correct these variations, allowing for more accurate measurement of the spectral sensitivity of the image pickup device IS. That is, according to the spectral response measuring device of the sixth embodiment, pixel values ​​of the captured image of the chart ch can be obtained with higher precision, and therefore the spectral response of the imaging device IS can be measured with higher precision.

[0154] This method is also effective when measuring spectral sensitivity using a single chart, as described in JP 2020-5053 A. When capturing a single image, it is necessary to ensure that the pixel values ​​in the white area used for shading correction do not saturate. However, with this method, which can calculate correction coefficients for each individual color area, saturation of the pixel values ​​in the white area used for shading correction does not affect the pixel values ​​in each individual color area. This allows for increased exposure time or light intensity. This reduces the impact of noise during pixel acquisition, enabling more accurate measurements. Therefore, the spectral response measurement device of the sixth embodiment can improve the signal-to-noise ratio.

[0155] <12. Spectral response measuring device according to the seventh embodiment of the present technology> Hereinafter, a spectral response measuring device according to a seventh embodiment of the present technology will be described with reference to the drawings.

[0156] The spectral sensitivity measurement device according to the seventh embodiment has a configuration similar to that of the spectral sensitivity measurement device 10 according to the first embodiment, except for a partial difference in the configuration of the processing system 1000. Note that, except for a partial difference in the configuration of the processing system 1000, the spectral sensitivity measurement device according to the seventh embodiment may have the same configuration as any of the spectral sensitivity measurement devices according to the modified example of the first embodiment, the spectral sensitivity measurement devices 20-1 and 20-2 according to Examples 1 and 2 of the second embodiment, the spectral sensitivity measurement devices 30-1 and 30-2 according to Examples 1 and 2 of the third embodiment, the spectral sensitivity measurement devices 40-1 and 40-2 according to Examples 1 and 2 of the fourth embodiment, the spectral sensitivity measurement device 50 according to the fifth embodiment, and the spectral sensitivity measurement device described in Patent Document 1.

[0157] Incidentally, when calculating the spectral sensitivity x of the image capture device IS using the above-mentioned Tikhonov regularization, the following formula (F6) can be used.

number

[0158] In the above formula (F6), the regularization parameter λ is the contribution rate of the condition that minimizes the brightness difference between adjacent wavelengths. The larger the value, the more the smoothness of the spectrum between adjacent wavelengths is emphasized, and fine waveforms tend to disappear. The smaller the value, the more fine waveforms can be retained, but the more sensitive it becomes to noise, and the more the waveform tends to become distorted. The inventors have noticed that, conventionally, the same value of λ is used for each wavelength to be calculated, and therefore, depending on the wavelength to be calculated, the spectral sensitivity cannot be measured with high accuracy.

[0159] Therefore, the inventors have developed a spectral response measurement device according to a seventh embodiment, which is capable of measuring spectral response with high accuracy regardless of the wavelength to be calculated.

[0160] Specifically, in the spectral response measurement apparatus according to the seventh embodiment, λ is made variable depending on the wavelength to be calculated, and the spectral response is measured using an appropriate λ according to the wavelength. More specifically, when calculating the spectral sensitivity x using the above formula (F6), the processing system 1000 (more specifically, the spectral sensitivity calculation unit 1000b) of the spectral sensitivity measurement device according to the seventh embodiment can set the value of λ in the above formula (F6) according to the wavelength to be calculated.

[0161] FIG. 20 is a block diagram showing the functions of a processing system 1000 of a spectral response measuring apparatus according to the seventh embodiment. 20, the spectral sensitivity measurement device according to the seventh embodiment has, as an example, a spectral sensitivity calculation unit 1000b of a processing system 1000 that includes a pixel value correction unit 1000b5 and an arithmetic unit 1000b3. Note that the processing system 1000 may also include the pixel value correction unit 1000b5 and the arithmetic unit 1000b3 in addition to the spectral sensitivity calculation unit.

[0162] The processing system 1000 (specifically, the spectral sensitivity calculation unit 1000b) sets the value of λ in the above equation (F6) according to the magnitude relationship between the wavelength to be calculated and at least one threshold value Th, for example.

[0163] The spectral sensitivity calculation unit 1000b of the processing system 1000 calculates the spectral sensitivity x by using λ1 as λ in the above equation (F6) when the wavelength to be calculated is less than the threshold value Th, and calculates the spectral sensitivity x by using λ2, which is different from λ1, as λ in the above equation (F6) when the wavelength to be calculated is equal to or greater than the threshold value Th.

[0164] More specifically, as an example, pixel value correction unit 1000b5 performs the shading correction described above on pixel values ​​for each color region from pixel value acquisition unit 1000a. Pixel value correction unit 1000b5 outputs the pixel value s after shading correction to calculation unit 1000b3. Calculation unit 1000b3 calculates spectral sensitivity x using the pixel value s after shading correction input from pixel value correction unit 1000b5 and the above equation (F6). Calculation unit 1000b3 calculates spectral sensitivity x using the above equation (F6) by setting λ to λ1 (e.g., 1) when the wavelength to be calculated is less than threshold value Th (e.g., 700 nm), and by setting λ to λ2 (e.g., 10) when the wavelength to be calculated is equal to or greater than threshold value Th (e.g., 700 nm).

[0165] According to the spectral sensitivity measurement device of the seventh embodiment, when calculating the spectral sensitivity by using the pixel values ​​for each color region of the chart with the above formula (F6), the regularization parameter λ in the above formula (F6) can be changed according to the wavelength to be calculated. Therefore, the spectral sensitivity can be calculated using λ appropriate for the wavelength, and therefore the spectral sensitivity can be measured with higher accuracy.

[0166] <13. Spectral response measuring device according to the eighth embodiment of the present technology> Hereinafter, a spectral response measuring device according to an eighth embodiment of the present technology will be described with reference to the drawings.

[0167] 21 , the spectral sensitivity measurement device according to the eighth embodiment has the same configuration as the spectral sensitivity measurement device 10 according to the first embodiment, except for a partial difference in the configuration of the processing system 1000. Note that, except for a partial difference in the configuration of the processing system 1000, the spectral sensitivity measurement device according to the eighth embodiment may have the same configuration as any of the spectral sensitivity measurement devices according to the modified example of the first embodiment, the spectral sensitivity measurement devices 20-1 and 20-2 according to Examples 1 and 2 of the second embodiment, the spectral sensitivity measurement devices 30-1 and 30-2 according to Examples 1 and 2 of the third embodiment, the spectral sensitivity measurement devices 40-1 and 40-2 according to Examples 1 and 2 of the fourth embodiment, the spectral sensitivity measurement device 50 according to the fifth embodiment, and the spectral sensitivity measurement device described in Patent Document 1.

[0168] In the processing system 1000 of the spectral sensitivity measurement device according to the eighth embodiment, the spectral sensitivity calculation unit 1000b includes a correction coefficient calculation unit 1000b1, a pixel value correction unit 1000b2, and an arithmetic unit 1000b3. The processing system 1000 of the spectral sensitivity measurement device according to the eighth embodiment also includes a spectral sensitivity storage unit 1000d. The processing system 1000 of the spectral response measurement device according to the eighth embodiment calculates the spectral response using the above formula (F6) and the following formula (F7). When calculating the spectral response using the above formula (F6) and the following formula (F7), the processing system 1000 can change the value of λ in the above formula (F6) depending on the wavelength to be calculated. s(b)=Cb (F7) (where b is the pixel value of the captured image, s(b) is the pixel value after light intensity correction, and C is the correction coefficient)

[0169] Specifically, the spectral sensitivity calculation unit 1000b of the processing system 1000 calculates the spectral sensitivity x by using λ1 as λ in the above equation (F6) when the wavelength to be calculated is less than the threshold value Th, and calculates the spectral sensitivity x by using λ2, which is different from λ1, as λ in the above equation (F6) when the wavelength to be calculated is equal to or greater than the threshold value Th.

[0170] More specifically, the pixel value correction unit 1000b2 calculates a corrected pixel value by multiplying the pixel value for each color region from the pixel value acquisition unit 1000a by the correction coefficient C described above. If the calculated wavelength is less than a threshold Th (e.g., 700 nm), the pixel value correction unit 1000b2 outputs the corrected pixel value corresponding to the wavelength to the calculation unit 1000b3. If the wavelength is equal to or greater than the threshold Th (e.g., 700 nm), the pixel value correction unit 1000b2 outputs the corrected pixel value corresponding to the wavelength to the calculation unit 1000b3. The calculation unit 1000b3 calculates the spectral sensitivity x using the corrected pixel value input from the pixel value acquisition unit 1000a as s(b) and λ=λ1 using the above equations (F6) and (F7). A suitable value for λ1 is, for example, 1. The calculation unit 1000b3 calculates the spectral sensitivity x using the above formulas (F6) and (7) with the corrected pixel value input from the pixel value acquisition unit 1000a as s(b) and λ=λ2. The value of λ2 is preferably, for example, 10.

[0171] According to the spectral sensitivity measurement device of the eighth embodiment, the spectral sensitivity is calculated by using the pixel values ​​for each color region of the chart according to the above formulas (F6) and (F7), and the regularization parameter λ in formula (F6) can be changed according to the wavelength to be calculated. Therefore, the spectral sensitivity can be calculated using the accurately corrected pixel values ​​and a λ appropriate for the wavelength, and thus the spectral sensitivity can be measured with even greater precision.

[0172] Fig. 22A is a graph showing, as a reference value, the waveform of spectral sensitivity obtained from a captured image of, for example, a chart ch having three color regions, acquired with high accuracy using another imaging device. The left diagram of Fig. 22B is a graph showing the waveform of spectral sensitivity obtained when λ is set to λ1 for each color region when calculating the spectral sensitivity using equations (F6) and (F7) from the pixel values ​​of the captured image of chart ch acquired by imaging device IS. The right diagram of Fig. 22B is a graph showing the waveform of spectral sensitivity obtained when λ is set to λ2 for each color region when calculating the spectral sensitivity using equations (F6) and (F7) from the pixel values ​​of the captured image of chart ch acquired by imaging device IS. Fig. 22C is a graph showing the waveform of spectral sensitivity acquired by a spectral sensitivity measurement device according to the eighth embodiment. The horizontal axes of Figs. 22A to 22C are in nm. Comparing the left graph of Figure 22A with the left graph of Figure 22B, it can be seen that the waveform shown in the left graph of Figure 22B is distorted by the influence of noise, especially on the long wavelength side (e.g., 700 nm or longer). In the left graph of Figure 22B, the RMSE error from the reference value, which is an index of the high reproducibility, is relatively high, and it can be seen that the numerical reproducibility is not high. Comparing Figure 22A with the right panel of Figure 22B, it can be seen that the waveform shown in the right panel of Figure 22B is too blunt, especially on the short wavelength side (for example, less than 700 nm). In the right panel of Figure 22B, it can be seen that the RMSE is relatively high and the numerical reproducibility is not high.

[0173] Comparing Figures 22A and 22C, it can be seen that the waveform shown in Figure 22C has high waveform reproducibility on both the long wavelength side (e.g., 700 nm or more) and the short wavelength side (e.g., less than 700 nm). Figure 22C shows that the RMSE is relatively low, indicating high numerical reproducibility.

[0174] In the spectral response measurement devices according to the seventh and eighth embodiments, the at least one threshold value Th may be a plurality of threshold values ​​Th. In this case, the processing system 1000 calculates the wavelength at the smallest threshold value Th among the plurality of threshold values ​​Th. min If the wavelength is less than the maximum threshold value Th, the spectral sensitivity is calculated using λ1 as λ in the above formula (F6), and the calculated wavelength is the maximum threshold value Th among the plurality of threshold values ​​Th. max In the above cases, the spectral sensitivity is calculated using λ2, which is different from λ1, as λ in the above formula (F6), and the calculated wavelength is the minimum threshold value Th min Maximum threshold Th max If the wavelength is less than λ1, the spectral sensitivity may be calculated using λ3, which is different from λ1, as λ in the above formula (F6). This allows the spectral sensitivity to be calculated using λ that is more appropriate for the wavelength being calculated, thereby further improving the accuracy of measuring the spectral sensitivity.

[0175] 14. Modifications of the present technology

[0176] It should be noted that the embodiments according to the present technology are not limited to the above-described embodiments, and various modifications are possible within the scope of the gist of the present technology.

[0177] In the spectral response measuring device according to the present technology, the configuration of the chart generating system can be changed as appropriate.

[0178] For example, the chart generating system may have a reflective screen. In this case, light from a light source (such as an LED, OLED, laser, halogen lamp, xenon lamp, or fluorescent lamp) is irradiated onto the reflective screen, and the chart generated by the reflected light is captured by the image capture device IS. In the case of a reflective screen, a prism can be used to output a specific wavelength.

[0179] For example, the chart generating system may include a light emitting element array facing the imaging device. The light emitting element array includes light emitting elements (e.g., LEDs, OLEDs, lasers, etc.) arranged two-dimensionally and is capable of emitting multiple lights of different wavelengths.

[0180] For example, the chart generation system may include a liquid crystal panel facing the imaging device and a light source (e.g., LED, OLED, laser, halogen lamp, xenon lamp, fluorescent lamp, etc.) that irradiates the liquid crystal panel with light. The liquid crystal panel may be of a transmissive type or a reflective type.

[0181] In the spectral response measurement device 10 according to the first embodiment, the movement mechanism 130 is of a rotary type, but is not limited to this and may be of a translational type (linear type) like the movement mechanism 230 of the spectral response measurement device 20-2 according to Example 2 of the second embodiment. Furthermore, the movement mechanism 130 has a configuration for moving the plurality of optical filters 120 relative to a system including the light source 110 and the image capture device IS, but instead of or in addition to this, the movement mechanism 130 may have a configuration for moving the system including the light source 110 and the image capture device IS relative to the plurality of optical filters 120.

[0182] In the spectral response measurement device 20-2 according to Example 2 of the second embodiment, the movement mechanism 230 is of a translation type (linear type), but is not limited to this and may be of a rotation type like the movement mechanism 130 of the spectral response measurement device 10 according to the first embodiment. Furthermore, the movement mechanism 230 has a configuration for moving the plurality of optical filters 220 relative to a system including the light source 210 and the image capture device IS, but instead of or in addition to this, the movement mechanism 230 may have a configuration for moving the system including the light source 210 and the image capture device IS relative to the plurality of optical filters 220.

[0183] When the moving mechanism is of a linear type, in addition to a linear motor, for example, a combination of a rack and pinion and a motor, or a combination of a ball screw and a motor may be used.

[0184] When the moving mechanism is of a rotary type, members having shapes other than a disk shape may be used.

[0185] The number of optical filters can be increased or decreased as appropriate.

[0186] The configurations of the above-described embodiments, examples, and modifications may be combined to the extent that they are not contradictory to one another.

[0187] The present technology can also be configured as follows. (1) a chart generating system that generates a chart including at least one chart portion having at least one color region at a position facing an imaging device; a processing system that calculates the spectral sensitivity of the imaging device based on an image of the chart generated at a position facing the imaging device, captured by the imaging device; A spectral response measuring device comprising: (2) The spectral response measurement device according to (1), wherein the chart generation system has a light source and generates the chart between the imaging device and the light source. (3) The spectral response measurement device according to (1) or (2), wherein the chart generation system sequentially generates each of the plurality of charts at a position facing the imaging device. (4) A spectral sensitivity measuring device according to any one of (1) to (3), wherein the chart generating system has a light source and an optical filter group including a plurality of optical filters selectively arranged between the light source and the imaging device. (5) The spectral sensitivity measuring device described in (4), wherein the chart generating system further includes a moving mechanism that relatively moves the optical filter group and a system including the imaging device and the light source so that each of the plurality of optical filters is sequentially positioned between the imaging device and the light source. (6) The spectral sensitivity measuring device according to (5), wherein the movement mechanism moves the plurality of optical filters in a direction substantially perpendicular to the direction in which the imaging device and the light source are arranged. (7) A spectral sensitivity measuring device according to (5) or (6), wherein the moving mechanism includes a rotating member on which the plurality of optical filters are arranged in a circumferential direction and which is rotatable around an axis substantially parallel to the arrangement direction of the imaging device and the light source, and a driving unit which rotates the rotating member around the axis. (8) The spectral response measurement device according to any one of (4) to (7), wherein the chart generating system includes a diffusion plate disposed between the imaging device and each of the plurality of optical filters. (9) The spectral response measurement device according to any one of (1) to (3), wherein the chart generating system includes a wavelength-tunable light source capable of varying the emission wavelength. (10) The spectral sensitivity measuring device according to (9), wherein the chart generating system has an optical filter group including a plurality of optical filters selectively arranged between the imaging device and the wavelength-tunable light source. (11) The spectral sensitivity measuring device according to claim (10), wherein the chart generating system further includes a moving mechanism that moves the optical filter group relative to a system including the imaging device and the tunable light source so that each of the plurality of optical filters is sequentially positioned between the imaging device and the tunable light source. (12) The spectral response measurement device according to (11), wherein the movement mechanism moves the plurality of optical filters in a direction substantially perpendicular to the direction in which the imaging device and the wavelength-tunable light source are arranged. (13) The spectral response measurement device according to (9), wherein the tunable light source faces the imaging device. (14) The spectral response measurement device according to (9), wherein the chart generating system includes an optical waveguide member having an incident end connected to the tunable light source and an exit end facing the imaging device. (15) The spectral sensitivity measuring device described in (9), wherein the chart generating system includes a plurality of optical waveguide members corresponding to a plurality of the imaging devices, and each of the plurality of optical waveguide members has an incident end connected to the wavelength-tunable light source and an exit end facing the corresponding imaging device. (16) The spectral sensitivity measuring device according to any one of (1) to (3), wherein the chart generating system includes a light source group including a plurality of light sources with different emission wavelengths, and a movement mechanism that moves the light source group and the imaging device relative to each other so that each of the plurality of light sources faces the imaging device in sequence. (17) The spectral sensitivity measuring device described in any one of (1) to (3), wherein the chart generating system includes a light source group including a plurality of light sources with different emission wavelengths, and a movement mechanism that moves the light source group and the imaging device group including the plurality of imaging devices relatively so that each of the plurality of light sources and each of the plurality of imaging devices sequentially face each other. (18) The spectral sensitivity measuring device according to any one of (4) to (8), further comprising a control unit that controls, in accordance with the transmittance for each wavelength of the plurality of optical filters, the imaging time during which the imaging device images the chart, and / or the time during which the imaging device faces the chart, and / or at least one of the emission intensity and emission time of the light source. (19) The spectral sensitivity measuring device according to any one of (1) to (18), wherein the processing system calculates a theoretical value yth of a pixel value of the captured image from the following equation (1), calculates a correction coefficient C from the following equation (2), and calculates a spectral sensitivity x from the following equation (3) using a corrected pixel value yc obtained by multiplying an actual measurement value of a pixel value of a captured image of the chart that is different from the captured image by the imaging device by the correction coefficient C. The spectral sensitivity measuring device according to claim 1. y th =Ax a (1) (where x a is the spectral sensitivity of the imaging device with known spectral sensitivity, and A is the spectral characteristics of the chart) C=y th / y a (2) (However, y a is the pixel value of an image captured by an imaging device with known spectral sensitivity) y c =Ax (3) (where A is the spectral characteristic of the chart) (20) The spectral sensitivity measurement device according to (19), wherein the spectral sensitivity is x calculated by the following equations (4) and (5), and the processing system is capable of setting the value of λ in the following equation (4) according to the wavelength to be calculated when calculating the spectral sensitivity by the following equations (4) and (5). JPEG0007823065000006.jpg15166s(b)=Cb...(5) (where λ is the regularization parameter, F is the differential matrix consisting of a first-order differential equation, A is the spectral characteristics of the chart, and b is the pixel value of the captured image) (21) The spectral sensitivity measurement device according to any one of (1) to (20), wherein the spectral sensitivity is x calculated by the following formula (6), and the processing system is capable of setting the value of λ in the following formula (6) according to the wavelength to be calculated when calculating the spectral sensitivity by the following formula (6). JPEG0007823065000007.jpg14166 (where λ is the regularization parameter, F is the differential matrix consisting of a first-order differential equation, A is the spectral characteristics of the chart, b is the pixel value of the captured image, and s is the pixel value after light intensity correction) (22) The spectral response measurement device according to (20) or (21), wherein the processing system sets the value of λ depending on the magnitude relationship between the wavelength to be calculated and at least one threshold value Th. (23) The spectral sensitivity measuring device according to (22), wherein the processing system calculates the spectral sensitivity using λ1 as the λ when the wavelength to be calculated is less than the threshold Th, and calculates the spectral sensitivity using λ2, which is different from λ1, as the λ when the wavelength to be calculated is equal to or greater than the threshold Th. (24) The at least one threshold Th is a plurality of thresholds Th, and the processing system calculates a wavelength that is the smallest threshold Th among the plurality of thresholds Th. min If the wavelength is less than the maximum threshold value Th, the spectral sensitivity is calculated using λ1 as the λ. max In the above cases, the spectral sensitivity is calculated using λ2, which is different from λ1, as the λ, and the calculated wavelength is equal to or smaller than the minimum threshold value Th min and the maximum threshold value Th maxIf the difference is less than λ1, λ3, which is different from λ1, is used as λ to calculate the spectral sensitivity. (25) The spectral sensitivity measuring device according to any one of (1) to (24), wherein the processing system includes a pixel value acquiring unit that acquires pixel values ​​of the captured image, and a spectral sensitivity calculating unit that calculates the spectral sensitivity based on the spectral characteristics of the chart and the pixel values ​​acquired by the pixel value acquiring unit. (26) The spectral response measurement device according to any one of (1) to (25), wherein the at least one color region is a plurality of color regions. (27) The spectral response measurement device according to any one of (1) to (3), wherein the chart generating system includes a light emitting element array facing the imaging device. (28) The spectral response measurement device according to any one of (1) to (3), wherein the chart generating system includes a liquid crystal panel facing the imaging device and a light source that irradiates the liquid crystal panel with light. (29) generating a chart including at least one chart portion having at least one color region at a position facing an imaging device; capturing an image of the chart generated at a position facing the imaging device with the imaging device; acquiring pixel values ​​of the image of the chart captured in the imaging step; calculating the spectral sensitivity of the imaging device based on the spectral characteristics of the chart and the pixel values ​​acquired in the acquiring step; A method for measuring spectral sensitivity, comprising: (30) The spectral response measurement device according to (29), wherein the chart generation system has a light source and generates the chart between the imaging device and the light source. (31) The spectral sensitivity measuring method according to (29) or (30), wherein in the generating step, each of the plurality of charts is generated sequentially at a position facing the imaging device. [Explanation of symbols]

[0188] 10, 20-1, 20-2, 30-1, 30-2, 40-1, 40-2, 50: spectral sensitivity measuring device, 100, 200-1, 200-2, 300-1, 300-2, 400-1, 400-2: chart generating system, 110, 410, 410-1 to 410-8: light source, 410G: light source group, 210: wavelength tunable light source, 120, 120-1 to 120-8, 220-1 to 220-3: optical filter, 1 20G: optical filter group, 130c: motor (drive unit), 130, 230, 430-1, 430-2: moving mechanism, 140: diffuser, 180: control unit, 360, 360-1, 360-2: optical fiber cable (optical waveguide member), 1000: processing system, 1000a: pixel value acquisition unit, 1000b: spectral sensitivity calculation unit, IS, IS1 to IS10: imaging devices, ISG: imaging device group, ch: chart.

Claims

1. a chart generating system that generates a chart including at least one chart portion having at least one color region at a position facing the imaging device; a processing system that calculates the spectral sensitivity of the imaging device based on an image of the chart generated at a position facing the imaging device, captured by the imaging device; Equipped with the chart generation system sequentially generates each of the plurality of charts at a position facing the imaging device; The chart generation system includes: a light source group including a plurality of light sources having different emission wavelengths; a movement mechanism that moves the light source group and the imaging device relative to each other so that each of the plurality of light sources and the imaging device sequentially faces each other; A spectral sensitivity measuring device comprising:

2. a chart generating system that generates a chart including at least one chart portion having at least one color region at a position facing the imaging device; a processing system that calculates the spectral sensitivity of the imaging device based on an image of the chart generated at a position facing the imaging device, captured by the imaging device; Equipped with the chart generation system sequentially generates each of the plurality of charts at a position facing the imaging device; The chart generation system includes: a light source group including a plurality of light sources having different emission wavelengths; a movement mechanism that relatively moves the light source group and an imaging device group including the plurality of imaging devices so that each of the plurality of light sources and each of the plurality of imaging devices sequentially faces each other; A spectral sensitivity measuring device comprising:

3. a chart generating system that generates a chart including at least one chart portion having at least one color region at a position facing the imaging device; a processing system that calculates the spectral sensitivity of the imaging device based on an image of the chart generated at a position facing the imaging device, captured by the imaging device; Equipped with The processing system calculates a theoretical value y th of a pixel value of the captured image from the following equation (1), calculates a correction coefficient C from the following equation (2), and calculates a spectral sensitivity x from the following equation (3) using a corrected pixel value yc obtained by multiplying an actual measurement value of a pixel value of an image of the chart that is different from the image captured by the imaging device by the correction coefficient C. y th =Ax a (1) (where x a is the spectral sensitivity of an imaging device with known spectral sensitivity, and A is the spectral characteristic of the chart) C=y th / ya (2) (where ya is the pixel value of an image captured by an imaging device with known spectral sensitivity) yc = Ax (3) (where A is the spectral characteristic of the chart)

4. The spectral sensitivity is x calculated by the following formulas (4) and (5):

4. The spectral sensitivity measuring device according to claim 3, wherein the processing system is capable of setting the value of λ in the following equation (4) according to a wavelength to be calculated when calculating the spectral sensitivity using the following equations (4) and (5): s(b)=Cb...(5) (where λ is a regularization parameter, F is a differential matrix formed by a first-order differential equation, A is the spectral characteristics of the chart, and b is the pixel value of the captured image)

5. a chart generating system that generates a chart including at least one chart portion having at least one color region at a position facing the imaging device; a processing system that calculates the spectral sensitivity of the imaging device based on an image of the chart generated at a position facing the imaging device, captured by the imaging device; Equipped with The spectral sensitivity is x calculated by the following formula (6): When calculating the spectral sensitivity by the following equation (6), the processing system can set the value of λ in the following equation (6) according to a wavelength to be calculated, The processing system sets the value of λ in the above equation (6) depending on the magnitude relationship between the wavelength to be calculated and at least one threshold value Th. (where λ is a regularization parameter, F is a differential matrix formed by a first-order differential equation, A is the spectral characteristics of the chart, b is the pixel value of the captured image, and s is the pixel value after light intensity correction)

6. 6. The spectral sensitivity measuring device according to claim 5, wherein the processing system calculates the spectral sensitivity by using λ1 as λ in equation (6) when the wavelength to be calculated is less than the threshold value Th, and calculates the spectral sensitivity by using λ2, which is different from λ1, as λ in equation (6) when the wavelength to be calculated is equal to or greater than the threshold value Th.

7. the at least one threshold is a plurality of thresholds; The processing system is configured to calculate a wavelength that is smaller than the minimum threshold value Th among the plurality of threshold values ​​Th. ｍｉｎ If the wavelength is less than the maximum threshold value Th, the spectral sensitivity is calculated using λ1 as λ in the above formula (6), and the calculated wavelength is equal to or smaller than the maximum threshold value Th of the plurality of threshold values ​​Th. ｍａｘ In the above cases, the spectral sensitivity is calculated using λ2, which is different from λ1, as λ in the above formula (6), and the calculated wavelength is the minimum threshold value Th ｍｉｎ The maximum threshold value Th ｍａｘ 6. The spectral response measurement device according to claim 5, wherein when λ<λ<λ<λ<λ<1, ...λ<1, λ<λ<λ<λ<1, λ<λ<λ<λ<1, λ

8. 8. The spectral response measurement device according to claim 1, wherein the chart generation system has a light source and generates the chart between the imaging device and the light source.

9. The chart generation system includes: A light source and an optical filter group including a plurality of optical filters selectively disposed between the light source and the imaging device; The spectral response measuring device according to any one of claims 1 to 8, comprising:

10. 10. The spectral sensitivity measuring device according to claim 9, wherein the chart generating system further includes a moving mechanism that relatively moves the optical filter group and a system including the imaging device and the light source so that each of the plurality of optical filters is sequentially positioned between the imaging device and the light source.

11. The spectral response measurement device according to claim 10 , wherein the movement mechanism moves the plurality of optical filters in a direction substantially perpendicular to a direction in which the image capture device and the light source are arranged.

12. The moving mechanism includes: a rotating member on which the plurality of optical filters are arranged in a circumferential direction and which is rotatable around an axis substantially parallel to an arrangement direction of the imaging device and the light source; a drive unit that rotates the rotary member around the axis; 12. The spectral response measuring device according to claim 10, further comprising:

13. 13. The spectral response measurement device according to claim 9, wherein the chart generating system includes a diffusion plate disposed between the imaging device and each of the plurality of optical filters.

14. 9. The spectral response measurement device according to claim 1, wherein the chart generating system includes a wavelength-tunable light source capable of varying an emission wavelength.

15. 15. The spectral response measurement device according to claim 14, wherein the chart generating system has an optical filter group including a plurality of optical filters selectively disposed between the image capturing device and the wavelength-tunable light source.

16. 16. The spectral sensitivity measurement device according to claim 15, wherein the chart generation system further includes a movement mechanism that relatively moves the optical filter group and a system including the image capture device and the tunable light source so that each of the plurality of optical filters is sequentially positioned between the image capture device and the tunable light source.

17. 17. The spectral response measurement device according to claim 16, wherein the movement mechanism moves the plurality of optical filters in a direction substantially perpendicular to the direction in which the image capture device and the wavelength-tunable light source are arranged.

18. The spectral response measurement device according to claim 14 , wherein the tunable light source faces the image capture device.

19. 15. The spectral response measurement device according to claim 14, wherein the chart generating system includes an optical waveguide member having an incident end connected to the tunable light source and an exit end facing the imaging device.

20. the chart generating system includes a plurality of optical waveguide members corresponding to the plurality of imaging devices; 15. The spectral response measurement device according to claim 14, wherein each of the plurality of optical waveguide members has an incident end connected to the wavelength-tunable light source and an exit end facing the corresponding imaging device.

21. 14. The spectral sensitivity measurement device according to claim 9, further comprising a control unit that controls, in accordance with the transmittance for each wavelength of the plurality of optical filters, an image capturing time during which the image capturing device captures the chart, and / or a time during which the image capturing device and the chart face each other, and / or at least one of an emission intensity and an emission time of the light source.

22. The processing system includes: a pixel value acquisition unit that acquires pixel values ​​of the captured image; a spectral sensitivity calculation unit that calculates the spectral sensitivity based on the spectral characteristics of the chart and the pixel values ​​acquired by the pixel value acquisition unit; 22. The spectral response measuring device according to any one of 1 to 21, comprising:

23. 23. The spectral response measurement device according to claim 1, wherein the at least one color region is a plurality of color regions.

24. 9. The spectral response measurement device according to claim 1, wherein the chart generating system includes a light emitting element array facing the imaging device.

25. The chart generation system includes: a liquid crystal panel facing the imaging device; a light source that irradiates the liquid crystal panel with light; The spectral response measuring device according to any one of claims 1 to 8, comprising:

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