JP2019184724A - Imaging device and imaging device control method - Google Patents

Abstract

To provide an imaging device that can determine an appropriate focused position on the basis of imaging signal to be obtained in a plurality of wavelength bands including wavelength bands of a visible light area and a non-visible light area.SOLUTION: An imaging device 200 is configured to: acquire imaging signals of a plurality of wavelength bands including wavelength bands of a visible light area and a non-visible light area; calculate a focus evaluation value for each wavelength band on the basis of the imaging signal; determine whether focusing can be performed in a wavelength band corresponding to the focus evaluation value on the basis of the focus evaluation value; when it is determined that the focusing cannot be performed in the wavelength band of the visible light area, select the wavelength band of the non-visible light area on the basis of a spectral characteristic of the plurality of wavelength bands; and determine a focused position on the basis of a focus evaluation value of the selected wavelength band.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an imaging apparatus and a control method thereof.

  There has been proposed an imaging apparatus (multiband camera) that can acquire a multiband image of a subject by imaging the subject using a plurality of bandpass filters having different wavelength bands. The multiband camera can split light into a specific wavelength band other than the visible light wavelength band, such as R (red), G (green), and B (blue). . Patent Document 1 discloses a focus adjustment method in a multiband camera.

JP 2001-5046 A

  In the focus adjustment method disclosed in Patent Document 1, a visible light region is divided into 16 wavelength bands using a liquid crystal tunable filter, and focus adjustment is performed for each wavelength band. On the other hand, by dividing the optical filter on the front surface of the image sensor into bandpass filters corresponding to each of a plurality of wavelength bands, a multiband camera that captures a plurality of wavelength bands by one imaging is disclosed in Patent Document 1 Different focusing methods are required. In this multi-band camera, it is necessary to select which wavelength band should be used for focus adjustment among imaging signals for each of a plurality of wavelength bands obtained by the band-pass filter. Assume an imaging apparatus having a multiband pass filter including an invisible light region such as an infrared (IR) component region in addition to a visible light region. When this imaging apparatus is applied, it is important to select which of the imaging signals obtained in the wavelength band of the visible light region and the wavelength band of the invisible light region is used for determining the in-focus position. 2. Description of the Related Art Conventionally, there has been proposed an imaging apparatus that selects a wavelength band of an invisible light region to be used for determining a focus position based on a predetermined index when focusing cannot be performed using an imaging signal obtained in the wavelength band of the visible light region. There wasn't. An object of the present invention is to provide an imaging apparatus capable of determining an appropriate in-focus position based on imaging signals obtained in a plurality of wavelength bands including wavelength bands of a visible light region and an invisible light region.

  The imaging apparatus according to an embodiment of the present invention includes an acquisition unit that acquires an imaging signal of a plurality of wavelength bands including a wavelength band of a visible light region and a wavelength band of an invisible light region, and the wavelength based on the imaging signal. A calculation unit that calculates a focus evaluation value for each band; a determination unit that determines whether focusing can be performed in a wavelength band corresponding to the focus evaluation value based on the focus evaluation value; and a wavelength band in the visible light region. When it is determined that focusing cannot be performed, based on spectral characteristics of the plurality of wavelength bands, selection means for selecting a wavelength band of the invisible light region, and based on a focus evaluation value of the selected wavelength band, Determining means for determining the in-focus position.

  According to the imaging apparatus of the present invention, it is possible to determine an appropriate in-focus position based on imaging signals obtained in a plurality of wavelength bands including the wavelength bands of the visible light region and the invisible light region.

It is a figure which shows the structural example of an imaging device. It is a figure which shows the structural example of an optical filter. It is a figure which shows an example of a to-be-photographed object. It is a figure which shows an example of the relationship between a focus lens position and AF evaluation value. It is a figure explaining the example of the selection process of the wavelength band used for the determination of a focus position. It is a figure explaining the selection process of the wavelength band in S108 of FIG. It is a figure explaining an example of the selection process of the wavelength area | region of IR component area | region.

FIG. 1 is a diagram illustrating a configuration example of an imaging apparatus according to the present embodiment.
The following embodiment is an example of the present invention and does not limit the configuration or the like. If it is a configuration to which the present invention is applicable, the following configuration is not necessary.

  An imaging apparatus 200 illustrated in FIG. 1 includes a system control unit 201 through an optical filter selector 212. The system control unit 201 includes a CPU (Central Processing Unit) and the like, and controls the entire system based on a program installed in the storage unit 208. CPU is an abbreviation for Central Processing Unit. The system control unit 201 includes an exposure control unit and a distance measurement control unit, and performs operations related to AE (automatic exposure) processing in addition to AF (automatic focus adjustment) processing. The system control unit 201 performs predetermined arithmetic processing using the image data acquired from the imaging element 205 and the imaging processing unit 206 by the exposure control unit and the distance measurement control unit. The system control unit 201 controls the imaging lens 202 by transmitting a driving signal to the lens driving unit 203 through the lens control unit 204 based on the obtained calculation result.

  The imaging lens 202 has a plurality of lens groups such as a zoom lens, a focus lens, and an image blur correction lens. The imaging lens 202 also has mechanisms such as a diaphragm and a shutter that are related to light amount adjustment. The lens driving unit 203 includes various motors for driving each lens group included in the imaging lens 202 and a mechanism related to light amount adjustment. Examples of the motor included in the lens driving unit 203 include a DC motor and a stepping motor. The lens driving unit 203 causes the imaging lens 202 to perform a desired operation by operating a motor based on a drive control signal from the lens control unit 204. The lens driving unit 203 has sensors such as optical detection, magnetic detection, and tilt detection for detecting the operation of the imaging lens 202 and the lens driving unit 203. The acquisition information of each sensor is transmitted to the lens control unit 204.

  The lens control unit 204 has a driver IC (Integrated Circuit) and controls the imaging lens 202. The lens control unit 204 detects states such as the position of the imaging lens 202 and the speed of each motor of the lens driving unit 203 from information such as detection signals from the respective sensors included in the lens driving unit 203. The lens control unit 204 transmits an appropriate drive signal from the driver IC to each motor based on the detection result. For example, the lens control unit 204 calculates the position and speed of the zoom lens from a signal detected by an encoder such as an optical detection sensor. The lens control unit 204 sends an appropriate drive signal to the lens control unit 203 so that the zoom lens has a predetermined target speed based on the obtained speed of the zoom lens.

  The imaging element 205 has a CCD, a CMOS, or the like. CCD is an abbreviation for Charge Coupled Device. CMOS is an abbreviation for Complementary Metal Oxide. The light beam collected by the imaging lens 202 passes through the optical filter 210 and is then received by the imaging device 205. The optical filter 210 splits light into a plurality of wavelength regions including a wavelength band of a visible light region (RGB component region) and a wavelength region of an invisible light region by a plurality of narrow bandpass filters. The image sensor 205 photoelectrically converts the light dispersed by the optical filter 210 and outputs an image signal. In the present embodiment, an IR (infrared) component region is applied as an example of the invisible light region. The configuration of the optical filter 210 will be described later with reference to FIG.

  The imaging processing unit 206 includes a CDS circuit, an amplifier circuit, an A / D conversion unit, and the like. The CDS circuit removes output noise of the image sensor 205 by a correlated double sampling method. The amplifier circuit performs signal amplification (gain control) on the imaging signal from which noise has been removed by the CDS circuit. The A / D converter converts an imaging signal that is an analog signal into a digital signal.

  The image processing unit 207 performs predetermined various image correction processes on the imaging signal acquired from the imaging processing unit 206. For example, the image processing unit 207 performs white balance processing of the imaging signal. After performing necessary image processing, the image processing unit 207 performs a desired format conversion using the imaging signal as video data.

  The recording unit 208 includes a recording medium such as a high-speed built-in memory (such as RAM), a large-capacity hard disk drive, and various memory cards. RAM is an abbreviation for Random Access Memory. The recording unit 208 is used as a temporary recording medium for recording various data such as video data, time information, and setting information from the image processing unit 207 and image processing. The recording unit 208 further stores various programs executed by the system control unit 201. The program used in this embodiment is also held in the recording unit 208. The video output unit 209 includes various output terminals to a video output system such as a liquid crystal monitor, such as a BNC connector and a driver. BNC is an abbreviation for Bayonet Neil Concelman.

  The AF processing unit 211 performs focus adjustment processing according to the control of the system control unit 201. The AF processing unit 211 calculates a focus evaluation value (hereinafter referred to as “AF evaluation value”) used to specify the in-focus position. Many methods for calculating the AF evaluation value have been proposed in a large number of documents and prior proposals, and therefore, detailed description is omitted here and only the description related to the present invention is given. The AF processing unit 211 extracts a part of a predetermined screen area of the imaging signal obtained from the imaging processing unit 206, and extracts a required high frequency component from a part of the screen of the imaging signal extracted through the band pass filter. . The AF processing unit 211 calculates an AF evaluation value by performing processing such as integration on the extracted high frequency component. The calculated AF evaluation value is a numerical value that serves as an index of contrast in the distance measurement area (focus detection area). The higher the AF evaluation value, the higher the contrast and the closer to the focused state. The lower the AF evaluation value, the lower the contrast and the farther from the focused state.

  For example, the system control unit 201 calculates the AF evaluation value while moving the focus lens in the direction in which the AF evaluation value increases, and detects the position (focus position) of the focus lens where the AF evaluation value is highest. If the peak position of the AF evaluation value cannot be acquired, the system control unit 201 determines that focusing cannot be performed in the currently designated ranging area. The system control unit 201 determines that focusing is possible when the peak position of the AF evaluation value can be acquired. The system control unit 201 acquires an AF evaluation value while finely moving the focus lens in the front-rear direction in the vicinity of the peak position of the AF evaluation value when detecting the detailed in-focus position. The position where the AF evaluation value is the maximum value is set as the in-focus position.

  The optical filter selector 212 selects a wavelength band to be used for determining the in-focus position from a plurality of wavelength bands obtained by a plurality of narrow bandpass filters. The optical filter selector 212 will be described later. The imaging apparatus 200 further includes an operation unit for operating the system. The operation unit includes operation members as required, such as various operation switches and levers of the apparatus main body, and a touch panel incorporated in the display member. With these operation members, the user performs an arbitrary camera operation. Further, the imaging apparatus 200 includes a power control unit having a power detection circuit, a DC-DC converter, an eddy current detection circuit, a battery remaining amount detection circuit, and the like. The power supply control unit supplies power obtained from the power supply unit to each processing unit.

FIG. 2 is a diagram illustrating a configuration example of an optical filter applied in the present embodiment.
The optical filter 201 includes a multiband pass filter 300 disposed in front of the image sensor 205 shown in FIG. The R (red) component region 301 corresponds to the R component region in the Bayer array. The G (green) component region 302 corresponds to the first G component region of the two G component regions in the Bayer array. The B (blue) component region 303 corresponds to the B component region in the Bayer array. The IR (infrared) component region 304 is an example of an invisible light region. The IR (infrared) component region 304 corresponds to a second G component region of the two G component regions in the Bayer array.

  In the multiband pass filter 300, each of the R component region 301, the G component region 302, and the B component region 303 that are visible light regions (RGB component regions) is divided into a plurality of (four in the example of FIG. 2) wavelength bands. It is divided into characteristics. For example, in the R component region 301, four narrow bandpass filters corresponding to the wavelength band of the R component are arranged instead of a normal wide bandpass filter. In the example shown in FIG. 2, in the R component region 301, four narrow bandpass filters that disperse the wavelength band of the R component into four wavelength bands of 640 nm, 670 nm, 700 nm, and 730 nm, respectively, are arranged. This makes it possible to detect detailed spectral characteristics as compared with a conventional wide bandpass filter. Similarly, in the G component region 302 and the B component region 303, four narrow bandpass filters corresponding to the four wavelength bands are arranged. As a result, imaging signals in a plurality of wavelength bands corresponding to the R component region 301, the G component region 302, and the B component region 303 can be obtained.

  A feature of the multiband pass filter 300 applied in the present embodiment is that it has an IR component region 304 and can obtain an imaging signal in a wavelength band of the IR component region. In addition, a plurality of (four in the example of FIG. 2) narrow bandpass filters are arranged in the IR component region 304, and a plurality of wavelength bands of the IR component region 304 are obtained by the narrow bandpass filter. Normally, in the Bayer array, in consideration of the sensitivity characteristics of human eyes, one R component region and one B component region are provided, and the remaining two are configured by a G component region. In the multiband pass filter 300, one of the two G component regions is assigned to the IR component region 304. Further, four narrow bandpass filters are arranged for the IR component region 304 as in the other regions. As described above, the multiband pass filter 300 divides the pixel into 4 × 4 wavelength bands, arranges the R, G, and B bands in a Bayer array type, and assigns one of the G bands to the IR to generate an RGB component. A multiband configuration is formed from the region to the IR component region. Therefore, the imaging apparatus 200 can acquire imaging signals in a plurality of wavelength bands including the wavelength band of the RGB component area and the wavelength band of the IR component area by imaging through the optical filter 200, which is conventionally difficult to capture. It is possible to image a subject.

FIG. 3 is a diagram illustrating an example of a subject.
For example, a subject obtained by putting water 602 and oil 601 in a white plate 600 is used. When the subject shown in FIG. 3 is picked up by an image pickup device using a conventional color filter, both water and oil are transparent liquids. Therefore, it is difficult to distinguish between water and oil in a white dish. The liquid is imaged. Further, even if the imaging device attempts to perform the AF operation at the time of imaging, the image in the distance measurement area is almost white, the contrast is low, and the peak position of the AF evaluation value cannot be obtained. Cannot focus.

  However, since the imaging apparatus 200 of the present embodiment includes a multiband pass filter that can capture an image up to the IR component region, the reflected light of the water 602 is cut in the IR component region. Therefore, when imaging is performed through a band-pass filter in the IR component region, only water 602 is captured as black, and water 602 and oil 601 can be separated and captured. In the IR component region, since the water 602 is black, the contrast of the image is increased, and the peak position of the AF evaluation value can be acquired. According to the imaging apparatus 200, when the peak position of the AF evaluation value cannot be acquired in the RGB component area, the peak position of the AF evaluation value can be acquired using the IR component area. Even a subject that cannot be focused can be focused.

  When a multiband pass filter composed of a plurality of narrow bandpass filters is used, it is necessary to select which wavelength band to focus on. In the case of a filter having both wavelength bands of the RGB component region and the IR component region, such as the multiband pass filter 300, first, a wavelength band for obtaining an evaluation value for determining the focus position in any region. It becomes a problem whether to give priority as. Even when focusing is not possible in the RGB component area, since there are multiple wavelength bands in the IR component area, what index is used to select the wavelength band for determining the in-focus position It becomes a problem.

FIG. 4 is a diagram illustrating an example of the relationship between the focus lens position and the AF evaluation value when an image is captured by the imaging apparatus of the present embodiment.
Hereinafter, a case where a subject in which a plurality of transparent liquids are placed in a uniform color container as described with reference to FIG. 3 is imaged will be described as an example. In this example, AF evaluation values can be acquired in four wavelength bands. For example, the system control unit 201 of the imaging apparatus 200 acquires the AF evaluation value in each wavelength band of 550 nm which is an RGB component region and 900 nm, 1000 nm and 1100 nm which are IR component regions.

  When the subject shown in FIG. 3 is imaged, the contrast of the imaged subject differs depending on the spectral reflectance of the subject and the spectral transmittance of the optical filter 210. When the system control unit 201 captures an image with a narrow bandpass filter of 550 nm that is an RGB component region, the image is almost white, so the contrast is low and the peak position of the AF evaluation value cannot be acquired. Therefore, the system control unit 201 acquires AF evaluation values in 900 nm, 1000 nm, and 1100 nm that are IR component regions. By using a narrow bandpass filter corresponding to the IR component area according to the spectral reflectance of the subject, even if the peak position of the AF evaluation value cannot be obtained in the RGB component area, the AF evaluation value in the IR component area The peak position can be acquired.

  When the subject shown in FIG. 3 is imaged, an imaging signal in the wavelength band of 900 nm, 1000 nm, and 1100 nm, which is on the longer wavelength side, is gradually obtained, and the reflected light of the subject is gradually cut. Thereby, the contrast becomes high in the IR component region, and the peak position of the AF evaluation value can be acquired, so that the in-focus position can be determined. However, looking at the AF evaluation values shown in FIG. 4, for example, the AF evaluation values of 1000 nm and 1100 nm are substantially the same value. This is because when the reflected light of the subject is cut in a long wavelength band of a certain level or more, the contrast of the captured subject is not changed. In this case, it is necessary to select which of the wavelength bands of 1000 nm and 1100 nm is used to perform the focusing operation.

  When there are a plurality of wavelength bands that can be focused as AF evaluation values, the imaging apparatus 200 according to the present embodiment selects a wavelength band to be used for determining a focus position based on the spectral characteristics of the wavelength band. Specifically, the imaging apparatus 200 uses the spectral intensity as an index, and selects a wavelength band to be used for determining the focal point based on the spectral intensity. An FA camera using an IR component area often evaluates a subject difference. As a method for evaluating the difference between subjects, a method for evaluating based on the value of spectrum intensity is generally used.

  Spectral intensity is an index that focuses on energy per area, wavelength, and time. For example, in the case of a fresh food or the like, when the surface portion changes over time, the reflectance of the light of the object changes in a specific wavelength band. Therefore, when the spectrum intensity is acquired, a difference appears in the energy of the spot of interest. In order to detect a specific wavelength band, the imaging apparatus 200 detects a wavelength band in which the difference in spectral intensity in the region of interest is the largest while changing the wavelength band. The contrast in an image or video is generally focused on the difference in brightness, but the spectral intensity is an index focused on the energy of the reflected light from the object, so it is possible to detect changes that do not easily occur in the contrast. It becomes. Taking advantage of this feature, when there are a plurality of focusable wavelength bands in the IR component region, the imaging apparatus 200 sets a wavelength band in which a greater change can be detected based on the value of the spectral intensity. For example, the optical filter selector 212 included in the imaging apparatus 200 uses the wavelength band corresponding to the spectral intensity having the largest difference from the spectral intensity of the RGB component region wavelength band to determine the in-focus position. Choose as. Accordingly, it is possible to set a wavelength band in which the change can be most captured from both visible light and invisible light areas in the image area of interest at the time of focusing.

FIG. 5 is a flowchart for explaining an example of wavelength band selection processing used for determining the in-focus position, which is executed by the imaging apparatus according to the present embodiment.
FIG. 5 illustrates an example of an operation for performing processing for selecting the wavelength band of the IR component area as the wavelength band used for determining the in-focus position when focusing cannot be performed in the RGB component area. The operation described below is merely an example in the present invention, and the present invention is not limited to the operation described below.

  In step S <b> 101, the system control unit 201 sets a distance measurement area in the imaging screen in accordance with a user operation. Subsequently, in S102, the system control unit 201 controls the lens control unit 204, and the lens driving unit 203 drives the focus lens from the closest end to the infinite end. In step S <b> 103, the AF processing unit 211 executes the following processing according to the control of the system control unit 201. The AF processing unit 211 extracts the imaging signal of the distance measurement area set in S101 from the imaging signal output by the imaging processing unit 206. Since the optical filter 210 includes the multiband pass filter 300, the AF processing unit 211 acquires imaging signals in a plurality of wavelength bands including the wavelength band of the RGB component region and the wavelength band of the IR component region. The AF processing unit 211 calculates an AF evaluation value for each wavelength band based on the acquired imaging signal. When simultaneous acquisition of AF evaluation values is difficult due to signal processing performance of the AF processing unit 211, the system control unit 201, etc., the AF evaluation values may be acquired in multiple steps. Further, the AF processing unit 211 may acquire an AF evaluation value of only the wavelength band of the RGB component region in S103, and separately acquire an AF evaluation value of the wavelength band of the IR component region before the processing of S106.

  Next, based on the AF evaluation value calculated in S103, the system control unit 201 determines whether focusing can be performed in the wavelength band corresponding to the AF evaluation value. Specifically, in S104, the system control unit 201 determines whether focusing can be performed from the AF evaluation values in the wavelength bands of the RGB component areas. If the peak position of the AF evaluation value in the wavelength band of the RGB component region can be acquired, the system control unit 201 determines that focusing can be performed from the AF evaluation value of the wavelength band in the RGB component region. When the peak position of the AF evaluation value in the wavelength band of the RGB component region cannot be acquired, the system control unit 201 determines that focusing cannot be performed from the AF evaluation value of the wavelength band in the RGB component region. If the system control unit 201 determines that focusing is possible from the AF evaluation values in the wavelength band of the RGB component region, the process proceeds to S105. In step S105, the system control unit 201 determines an in-focus position based on the AF evaluation value in the wavelength band of the RGB component region.

  If the system control unit 201 determines that focusing cannot be performed from the AF evaluation values in the wavelength band of the RGB component region, the process proceeds to S106. In step S <b> 106, the system control unit 201 determines whether focusing can be performed from the AF evaluation value in the wavelength band of the IR component region. When the peak position of the AF evaluation value in the wavelength band of the IR component region can be acquired, the system control unit 201 determines that focusing can be performed from the AF evaluation value of the wavelength band in the IR component region. If the peak position of the AF evaluation value in the IR component region wavelength band cannot be acquired, the system control unit 201 determines that focusing cannot be performed from the AF evaluation value in the IR component region wavelength band. If the system control unit 201 determines that focusing cannot be performed based on the AF evaluation value in the wavelength band of the IR component region, the peak position of the AF evaluation value is acquired in the wavelength bands of all the narrow bandpass filters of the multiband pass filter 300. It will not be possible. Therefore, in this case, since it cannot focus in the distance measurement area set in the current imaging screen, the process returns to S101.

  If the system control unit 201 determines that focusing can be performed from the AF evaluation value in the wavelength band of the IR component region, the process proceeds to S107. In step S <b> 107, the system control unit 201 determines whether there are a plurality of wavelength bands in the IR component region determined to be in focus. If the wavelength band of the IR component region determined to be in focus is not plural but one, the process proceeds to S105. In step S <b> 105, the system control unit 201 determines the focus position based on the AF evaluation value of the wavelength band of one IR component region determined to be in focus.

  If there are a plurality of wavelength bands in the IR component region determined to be in focus, the process proceeds to S108. In the following description, a plurality of wavelength bands in the IR component area determined to be in focus in S106 are also described as selected wavelength band candidates. In S <b> 108, the system control unit 201 selects a wavelength band to be used for determining the in-focus position among a plurality of wavelength bands in the IR component region determined to be in focus. Then, the process proceeds to S105. In step S105, the system control unit 201 determines an in-focus position based on the AF evaluation value in the wavelength band of the selected IR component region. In step S109, the system control unit 201 controls the lens control unit 204 to move the focus lens to the in-focus position determined in step S105.

  In the above flowchart, the determination of whether or not focusing is possible for the RGB component area (S104) is performed prior to the determination of whether or not focusing is possible for the IR component area (S106). The order of these processes may be reversed. The order of these processes may be arbitrarily selected by the user.

FIG. 6 is a flowchart illustrating the wavelength band selection process in S108 of FIG.
In step S701, the system control unit 201 calculates the spectral intensity of the wavelength band with the highest AF evaluation value among the wavelength bands of the RGB component region acquired in step S103 of FIG. Subsequently, in S702, the system control unit 201 calculates a spectrum intensity for each of a plurality of wavelength bands (selected wavelength band candidates) in the IR component region determined to be in focus in S106 of FIG. A method for calculating the spectral intensity has been introduced in many documents and is already known, and thus the description thereof will be omitted.

  Next, in S703, the system control unit 201 calculates a difference between the spectral intensity of the wavelength region of the RGB component area calculated in S701 and the spectral intensity of the wavelength region of each IR component area calculated in S702. Subsequently, in S704, the optical filter selector 212 selects the wavelength region of the IR component region based on the difference calculated in S703. That is, the optical filter selector 212 determines the wavelength band of the IR component region used for determining the in-focus position based on the spectral intensities of a plurality of wavelength bands including the wavelength band of the RGB component region and the wavelength band of the IR component region. select.

FIG. 7 is a diagram for explaining an example of the selection process of the wavelength region of the IR component region in S704 of FIG.
The graph shown in FIG. 7 shows an example of the relationship between each of the four wavelength bands described with reference to FIG. 4 and the spectral intensity. In this graph, the horizontal axis indicates the wavelength. The vertical axis represents the spectral intensity. It is assumed that the selection wavelength band candidates, that is, the plurality of wavelength bands of the IR component region that can be focused, are three wavelength bands of 900 nm, 1000 nm, and 1100 nm.

  The spectral intensity 501 is a spectral intensity calculated in the wavelength band of 550 nm, that is, the wavelength band of the RGB component region having the highest AF evaluation value. The spectrum intensity 502 is a spectrum intensity calculated in the wavelength band of 900 nm. The spectrum intensity 503 is a spectrum intensity calculated in the wavelength band of 1000 nm. The spectral intensity 504 is a spectral intensity calculated in the wavelength band of 1100 nm.

Examples of the wavelength band selection method performed by the optical filter selector 212 include the following first selection method and second selection method.
In the first selection method, the optical filter selector 212 calculates a difference between the spectral intensity of the wavelength band of each IR component area included in the selected wavelength band candidate and the spectral intensity of the RGB component area having the highest AF evaluation value. calculate. Then, the optical filter selector 212 selects the wavelength band of the IR component region corresponding to the spectral intensity having the maximum difference. That is, among the selected wavelength band candidates, the wavelength band having the maximum difference in spectral intensity from the RGB component area having the highest AF evaluation value is selected. In the example shown in FIG. 7, the difference between the spectral intensity 504 in the 1100 nm wavelength band and the spectral intensity 501 in the 550 nm wavelength band is the maximum. Therefore, the optical filter selector 212 selects the 1100 nm wavelength band. This is because it is easier to take the difference (discrimination) of the substance from the wavelength band of 550 nm when the wavelength band of 1100 nm is selected as the evaluation result in the spectral intensity.

  In the second selection method, the optical filter selector 212 first determines a wavelength band having the highest AF evaluation value among the wavelength bands of the IR component region included in the selected wavelength band candidate. When there is one wavelength band with the highest AF evaluation value, the one wavelength band is selected as the wavelength band used for determining the in-focus position. Assume that there are a plurality of wavelength bands having the highest AF evaluation value. For example, as shown in FIG. 4, the maximum AF evaluation values in the two wavelength bands of 1000 nm and 1100 nm are substantially the same. In this case, the optical filter selector 212 calculates the difference between the spectral intensity of each of the plurality of wavelength bands with the highest AF evaluation value and the spectral intensity of the RGB component region with the highest AF evaluation value. Then, the optical filter selector 212 selects the wavelength band of the IR component region corresponding to the spectral intensity having the maximum difference. As a result, the wavelength band of 1100 nm is selected as the wavelength band used for determining the in-focus position.

  The system control unit 201 may set the priority of the AF evaluation value and the spectrum intensity in accordance with a user operation. Then, the second selection method is applied when the AF evaluation value has a higher priority than the spectrum intensity, and the first selection method is applied when the spectrum intensity has a higher priority than the AF evaluation value. It may be. The above-described wavelength band selection method is an example, and does not limit the application range of the present invention. Returning to the description of FIG. In step S <b> 705, the system control unit 201 sets the wavelength band selected by the optical filter selector 212 as the wavelength band used for determining the in-focus position.

  What is assumed in the application scene of this invention is described. Normally, the visible light and the invisible light in the IR component region shift the imaging position of the infrared light with respect to the visible light (the focus shift occurs). Therefore, when performing the focus adjustment processing using the AF evaluation value in the wavelength band of the IR component region, the system control unit 201 may correct the focus shift with respect to visible light based on the wavelength of the IR component region.

  Further, the system control unit 201 may perform focus adjustment processing using the wavelength band of the IR component region, and may perform RGB color display as video display. In addition, the system control unit 201 may display in which wavelength band the focusing is performed at the time of focusing. As mentioned above, although it explained in full detail based on suitable embodiment of the present invention, the present invention is not limited to the above-mentioned specific embodiment, and various forms of the range which does not deviate from the gist of this invention are also included in the present invention. .

(Other embodiments)
The present invention supplies a program that realizes one or more functions of the above-described embodiments to a system or apparatus via a network or a storage medium, and one or more processors in a computer of the system or apparatus read and execute the program This process can be realized. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

200 Imaging Device 201 System Control Unit

Claims (8)

An acquisition means for acquiring imaging signals of a plurality of wavelength bands including a wavelength band of a visible light region and a wavelength band of an invisible light region;
Calculation means for calculating a focus evaluation value for each wavelength band based on the imaging signal;
Based on the focus evaluation value, determination means for determining whether focusing can be performed in a wavelength band corresponding to the focus evaluation value;
When it is determined that focusing cannot be performed in the wavelength band of the visible light region, based on the spectral characteristics of the plurality of wavelength bands, selection means for selecting the wavelength band of the invisible light region;
An imaging apparatus comprising: a determining unit that determines a focus position based on a focus evaluation value of the selected wavelength band. Each of the wavelength band of the visible light region and the wavelength band of the invisible light region includes a plurality of wavelength bands,
The selection means is unable to focus in the wavelength band of the visible light region, but when there are a plurality of wavelength bands of the invisible light region that can be focused, each spectral intensity of the plurality of wavelength bands of the invisible region that can be focused And the wavelength band of the invisible light region used for determining the in-focus position among the wavelength bands of the plurality of invisible light regions based on the difference between the spectral intensity of the wavelength band of the visible light region The imaging apparatus according to claim 1, wherein: The selecting means selects a wavelength band having a maximum difference in spectral intensity from the visible light region having the highest focus evaluation value among a plurality of wavelength bands of the invisible light region that can be focused. The imaging apparatus according to claim 3. Setting means for setting the priority of the focus evaluation value and the spectral intensity;
When the spectral intensity has a higher priority than the focus evaluation value, the selection unit has the visible light having the highest focus evaluation value among a plurality of wavelength bands of the invisible light region that can be focused. The imaging apparatus according to claim 3, wherein a wavelength band having a maximum difference in spectral intensity between the regions is selected. The said selection means selects the wavelength band of the said one invisible area | region, when the wavelength band of the said invisible light area | region which can be focused is one, The any one of Claim 1 thru | or 4 characterized by the above-mentioned. The imaging device described. The acquisition means outputs an image pickup signal by photoelectrically converting the dispersed light into an optical filter that separates light into a plurality of wavelength bands including a wavelength band of the visible light region and a wavelength band of an invisible light region. The imaging device according to claim 1, further comprising: an imaging device that performs imaging. The optical filter has a bandpass filter corresponding to each of a plurality of wavelength bands in the R component region, a plurality of wavelength bands in the G component region, a plurality of wavelength bands in the B component region, and a plurality of wavelength regions in the invisible light region. The imaging apparatus according to claim 6. Obtaining an imaging signal of a plurality of wavelength bands including a wavelength band of a visible light region and a wavelength band of an invisible light region;
Calculating a focus evaluation value for each wavelength band based on the imaging signal;
Determining whether or not focusing can be performed in a wavelength band corresponding to the focus evaluation value based on the focus evaluation value;
When it is determined that focusing cannot be performed in the wavelength band of the visible light region, the step of selecting the wavelength band of the invisible light region based on the spectral characteristics of the plurality of wavelength bands;
And a step of determining an in-focus position based on a focus evaluation value of the selected wavelength band.

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