JP2008118377A - Imaging apparatus and driving method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make each of image data high in quality, the image data being generated through general photography such as daylight photography and through astronomical photography, respectively. <P>SOLUTION: An imaging apparatus has: a photoelectric conversion portion 1141 where pixels each having a photoelectric conversion element converting external incident light into an electric signal are arrayed in two dimensions; a color filter 1143 which is disposed above the photoelectric conversion portion 1141 so as to correspond to each pixel and makes the incident light incident on the photoelectric conversion portion 1141 while placing wavelength limit to the incident light, the color filter 1143 including at least a first red filter (R1) having sensitivity in the visible light range and a second red filter (R2) having sensitivity in both of the visible light range and near infrared range; and a processing means for determining a red signal based on a first output signal of a pixel corresponding to the first red filter (R1) and a second output signal of a pixel corresponding to the second red filter (R2), according to photographic conditions. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an imaging apparatus including a color filter that allows incident light to be incident on a photoelectric conversion unit while limiting the wavelength of the incident light, and a driving method thereof.

  In recent years, in an imaging apparatus such as a digital camera or a video camera, a CCD or a CMOS type image sensor (hereinafter, this CMOS type image sensor is referred to as a “CMOS sensor”) is generally used as an imaging element.

  Among the imaging devices described above, those using a CMOS sensor accumulate light carriers generated by a photodiode (hereinafter, this photodiode is referred to as “PD”) in the gate electrode (floating diffusion = FD) of the MOS transistor. . Then, according to the drive timing from the scanning circuit, the potential change is amplified and output to the output unit. In recent years, MOS-type fixed imaging devices realized by the CMOS process, including the CMOS sensor and its peripheral circuit portion, have attracted particular attention in recent years.

  In general, the image sensor has a color filter disposed on the upper surface of a PD constituting a pixel in order to capture a color image. For example, as a primary color filter, the output of the image sensor has a structure (so-called Bayer arrangement structure) in which any one of red (R), green (G), and blue (B) color filters is associated with each pixel. The signals are color-separated and output as each color signal. Then, the color signal is processed as a gamma conversion and a luminance signal / color difference signal to generate a color image.

  Also, in order to transmit only the visible light region so that the image is normally equivalent to the state seen by humans, an infrared absorption filter or red filter for removing light on the long wavelength side is provided on the upper surface of the color filter. In general, an outer cut filter or the like is provided.

Japanese Patent Laid-Open No. 2005-6066 JP 2003-259380 A

  By the way, in recent years, as an intended use of an imaging apparatus, not only general photography (daylight photography etc.) but also development to astronomical photography is required. The main point required in the astronomical photography is that there is a transmittance in the near-infrared region that is cut in general photography, particularly in the vicinity of the Hα emission line (wavelength 656.3 nm) in order to depict a red nebula and the like. is there.

  Here, FIG. 7 shows an example of the spectral characteristics of a filter used in a conventional astronomical imaging device, and FIG. 8 shows an example of the spectral characteristics of a filter used in a conventional imaging device for general photography (daylight photography, etc.). . FIGS. 7 and 8 show red (R), green (G), and blue (B) color filters, and an infrared cut filter (or infrared absorption filter) for removing the long-wavelength radiation described above. ) Shows the spectral characteristics (sensitivity characteristics) at each wavelength. Further, as can be seen from FIG. 8, in the imaging device for general photography (daylight photography etc.), the red transmission makes the transmission region correspond to the visible light by making the light around the wavelength of 650 nm to 680 nm non-transmission. ing.

FIG. 9 shows an example of comparison of transmission characteristics in the near-infrared region between the filter used for the general imaging (daylight imaging) imaging device of FIG. 8 and the filter used for the astronomical imaging imaging device of FIG.
As can be seen from FIG. 9, the filter used in the astronomical imaging device shown in FIG. 7 has a wavelength of 650 nm to 680 nm in red transmission compared to the filter used in the imaging device for general imaging (daylight imaging etc.) shown in FIG. The light transmittance in the vicinity is set high.

  However, in the astronomical imaging apparatus shown in FIG. 7, when the Hα emission line having a wavelength of 656.3 nm is transmitted, the transmission on the long wavelength side (red light) is large during imaging in a general daylight environment. There is a problem that the image becomes too red and becomes reddish.

  Therefore, at present, it is very difficult to set a wavelength that allows both astronomical photography and general photography for the transmission wavelength of the color filter.

  Although it is different from the above-mentioned problem, as a proposal for avoiding the problem due to the transmission wavelength, there is a proposal to switch one of the Bayer color filters to an infrared transmission filter and switch to a red filter for the purpose of combining day and night. (See Patent Document 1). In addition, for the purpose of correcting white balance by a light source, a filter that has a red or green filter with different spectrum and has been proposed to obtain a color difference signal and use it as a white balance color signal (see Patent Document 2).

However, as shown in Patent Document 1, if one of the color filters is completely converted to an infrared transmission filter, there is a problem that it becomes difficult to use during general photographing.
In addition, as shown in Patent Document 2, the proposal using the same color filters with different spectra is only for the purpose of white balance, and is insufficient as a workaround for the problem in the infrared region.

  The present invention has been made in view of the above-described problems, and realizes that each image data generated in both general photography such as daylight photography and astronomical photography has high quality. An object is to provide an imaging device and a driving method thereof.

  An imaging apparatus according to the present invention includes a photoelectric conversion unit in which pixels having photoelectric conversion elements that convert incident light incident from the outside into an electric signal are two-dimensionally arranged, and each pixel above the photoelectric conversion unit. A color filter that is provided correspondingly and that is incident on the photoelectric conversion unit by limiting the wavelength of the incident light; and the color filter includes at least a first red filter having sensitivity in a visible light region; A second red filter having sensitivity up to the near-infrared region together with the visible light region, and a first output signal of the pixel corresponding to the first red filter and the And processing means for performing processing for determining a red signal based on the second output signal of the pixel corresponding to the second red filter.

  According to another aspect of the present invention, there is provided a driving method for an image pickup apparatus in which a pixel having a photoelectric conversion element that converts incident light incident from the outside into an electric signal is two-dimensionally arranged, and the photoelectric conversion unit is disposed above the photoelectric conversion unit. A driving method of an image pickup apparatus provided corresponding to each pixel and provided with a color filter that imposes a wavelength limit on the incident light and enters the photoelectric conversion unit, wherein the color filter includes at least: A first red filter having sensitivity in the visible light region and a second red filter having sensitivity to the near-infrared region together with the visible light region are included, and the first red filter is included depending on photographing conditions. Processing for determining a red signal is performed based on the first output signal of the pixel corresponding to the filter and the second output signal of the pixel corresponding to the second red filter.

According to the present invention, it is possible to improve the quality of each image data generated in both general photography such as daylight photography and astrophotography.
Further, since the red signal is determined based on the output signal of each pixel corresponding to the first red filter and the second red filter, an infrared cut filter (or an infrared absorption filter) that has been conventionally provided. Etc. can be reduced. This also makes it possible to obtain cost advantages.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a block diagram showing a schematic configuration of an electronic camera (imaging device) 100 according to an embodiment of the present invention.
In FIG. 1, reference numeral 110 denotes a known photographing lens for forming an optical image 101 of a subject on an image sensor 114. A lens control unit 111 controls the photographing lens 110 based on the control by the system control circuit unit 150.

  A shutter 112 controls the exposure amount of the image sensor 114. A shutter control unit 140 controls the shutter 112 based on control by the system control circuit unit 150.

  Reference numeral 115 denotes a low-pass filter (hereinafter referred to as “LPF”) for cutting an extra wavelength of light that has passed through the photographing lens 110 (an unnecessary wavelength that affects color reproduction). It is disposed between the lens 110 and the image sensor 114. Reference numeral 114 denotes an image sensor that captures an optical image (incident light) 101 of a subject incident through the photographing lens 110, the shutter 112, and the LPF 115 as an image signal. In the present embodiment, a CMOS sensor is used as the image sensor 114.

Here, the internal configuration of the image sensor 114 will be described.
FIG. 2 is a schematic diagram for explaining the internal configuration of the image sensor 114.
As shown in FIG. 2A, the image sensor 114 has a pixel having a PD, which is a photoelectric conversion element that converts an optical image (incident light) 101 of an object incident from the outside into an electric signal, arranged in a two-dimensional matrix. A photoelectric conversion unit 1141 made of a semiconductor is provided. The image sensor 114 is configured by a microlens (ML) 1142 for transmitting and condensing light for each pixel on the upper surface of the photoelectric conversion unit 1141 and a Bayer array above the ML 1142, and has a spectral transmittance. Are provided with different color filters (CF) 1143. That is, the CF 1143 is provided above the photoelectric conversion unit 1141 so as to correspond to each pixel, and allows the incident light to be incident on the photoelectric conversion unit 1141 by limiting the wavelength.

  Here, as shown in FIG. 2B, the CF 1143 has a first red filter (R1) and a second red filter (R2) corresponding to each pixel arranged in a two-dimensional matrix. Any one of the green filter (G) and the blue filter (B) is provided.

  As shown in FIG. 2A, an infrared cut filter IR_Cut (or an infrared absorption filter) for cutting infrared light is usually provided as a part of the LPF 115. Does not use the filter.

  Returning to FIG. 1, reference numeral 116 denotes an A / D converter that converts an analog signal output from the image sensor 114 into a digital signal. A timing generation circuit unit (TG) 118 supplies a clock signal and a control signal to the image sensor 114, the A / D converter 116, and the D / A converter 126. The memory control circuit unit 122 and the system control circuit unit 150 are provided. Controlled by.

  An image processing circuit unit 120 performs predetermined pixel interpolation processing and color conversion processing on the image data (digital signal) from the A / D converter 116 or the image data from the memory control circuit unit 122. Furthermore, the image processing circuit unit 120 performs predetermined arithmetic processing using image data captured as necessary.

  A memory control circuit unit 122 controls the A / D converter 116, the timing generation circuit unit (TG) 118, the image processing circuit unit 120, the image display memory 124, the D / A converter 126, and the memory 130. To do.

  Here, the image data from the A / D converter 116 is transferred to the image display memory 124 or the memory 130 via the image processing circuit unit 120 and the memory control circuit unit 122 or directly via the memory control circuit unit 122. Written.

  Reference numeral 124 denotes an image display memory. A D / A converter 126 converts a digital signal into an analog signal. An image display unit 128 includes, for example, a TFT LCD. A memory 130 stores captured still image data and moving image data, and has a sufficient storage capacity to store a predetermined number of still image data and moving image data for a predetermined time.

  A distance measurement control unit 142 performs AF (autofocus) processing under the control of the system control circuit unit 150. Reference numeral 144 denotes a thermometer for measuring the ambient temperature in the shooting environment of the electronic camera 100. A photometric control unit 146 performs AE (automatic exposure) processing under the control of the system control circuit unit 150. The photometry control unit 146 also has a flash photographing function in cooperation with the flash unit 148. Reference numeral 148 denotes a flash unit used for photographing in the dark, and also has a function of projecting AF auxiliary light.

  Reference numeral 150 denotes a system control circuit unit that controls the entire electronic camera 100 in an integrated manner, and includes a well-known CPU and the like. Reference numeral 152 denotes a memory that is a storage unit that stores constants, variables, programs, and the like for operation of the system control circuit unit 150. Preset shading correction data and the like are stored in the memory 152. . Reference numeral 154 denotes a display unit that displays an operation state, a message, and the like according to execution of a program in the system control circuit unit 150. Reference numeral 156 denotes a non-volatile memory which is a storage means such as an electrically erasable / recordable EEPROM in which a program described later is stored.

  An operation unit 160 includes a known main switch (start switch), a shutter switch, a mode setting dial, and the like for inputting various operation instructions in the system control circuit unit 150.

  As the shutter switch, for example, two switches (SW1 and SW2) are turned on stepwise by pressing, and AF (autofocus) processing, AE (automatic exposure) processing, AWB (automatic exposure processing) are performed in the first step (SW1 ON). White balance) processing, EF (flash dimming) processing, etc. operate, control the shutter 112 and the like in the second stage (SW2 ON), and the signal read from the image sensor 114 is controlled by the A / D converter 116 and memory control Recording processing for writing image data in the memory 130 via the circuit unit 122, development processing using computations in the image processing circuit unit 120 and the memory control circuit unit 122, reading out the image data from the memory 130, compression, and recording The operation start of a series of processing called recording processing for writing image data on the medium 170 is performed.

  Examples of mode setting dials include various shooting modes (automatic shooting mode, program shooting mode, shutter speed priority shooting mode, aperture priority shooting mode, manual shooting mode, night scene shooting mode, daylight shooting mode, astronomical shooting mode, portrait (Shooting mode etc.)

  In addition to the above, the operation unit 160 includes a single / continuous shooting switch for switching between single shooting / continuous shooting, a still image / moving image shooting mode switching switch, an ISO sensitivity setting switch for setting shooting sensitivity (ISO sensitivity), A power switch for supplying power to various systems is included. In this embodiment, the term “moving image capturing mode” is used. However, the moving image capturing is not limited to moving image recording, and includes moving image capturing for display in which a viewfinder or the like displays an image almost in real time. It is a thing.

  A power supply control unit 182 includes a battery detection circuit, a DC-DC converter, and the like. A power supply unit 186 includes a primary battery such as an alkaline battery or a lithium battery, a secondary battery such as a NiCd battery, a NiMH battery, or a Li battery, or an AC adapter. Reference numeral 170 denotes a removable recording medium such as a memory card or a hard disk.

Next, spectral characteristics (sensitivity characteristics) of CF 1143 will be described.
FIG. 3 is a characteristic diagram illustrating an example of spectral characteristics of the CF 1143 included in the image sensor 114. The spectral characteristics of the CF 1143 shown in FIG. 3 indicate the spectral characteristics of the CF 1143 via the LPF 115.

  As shown in FIG. 3, the sensitivity of the filters arranged in each Bayer array as shown in FIG. 2B is as follows: blue filter (B), green filter (G), first filter from the short wavelength side. Red filter (R1) and second red filter (R2).

  Here, the spectral sensitivities of the first red filter (R1) and the second red filter (R2) are different in the near infrared region (long wavelength side in FIG. 3). Specifically, the sensitivity of the second red filter (R2) is high up to the vicinity of the Hα emission line (wavelength 656.5 nm), whereas the first red filter (R1) has a sensitivity in the vicinity of the Hα emission line. Sensitivity is low. That is, the first red filter (R1) is a filter having sensitivity in the visible light region, and the second red filter (R2) is a filter having sensitivity to the near infrared region together with the visible light region. Therefore, for the light in the near infrared region, the output level of the second red filter (R2) is higher than the output generated in the first red filter (R1).

  When the output signal of the image sensor 114 having the CF 1143 having spectral characteristics as shown in FIG. 3 is color-converted, the image processing circuit unit 120 uses the three primary colors R, G, and B as the output signal of each pixel ( Perform color conversion (by Bayer). When performing this color conversion processing, in the present embodiment, as an output of the red signal R, instead of using R1 and R2 at the same ratio, for example, a celestial body that emphasizes the near-infrared region with the Hα emission line In photographing or the like, “R = R2” (only R2 is used). In this case, R = R1 + R2 may be set to add a red signal in the visible light region.

  Further, in other shooting (for example, general daylight shooting), since the color reproducibility is better when the redness due to the near infrared sensitivity is suppressed, for example, “R = ( R1-R2) ”(in this case, x and y in FIG. 4 are 1) and so on. In this case, as a matter of course, when performing the difference calculation so that the output sensitivities of R1 and R2 can correspond to wavelength-output, R = (x · R1) − (y · R2) in FIG. The output signals of the pixels corresponding to R1 and R2 may be multiplied by coefficients (x, y). Here, x is a coefficient (first coefficient) multiplied by the output signal (first output signal) of the pixel corresponding to R1, and y is the output signal (second output) of the pixel corresponding to R2. Signal) is a coefficient (second coefficient) to be multiplied. That is, in the image processing circuit unit (processing unit) 120, the output signal (first output signal) of the pixel corresponding to the first red filter (R1) and the second red filter (R1) according to the shooting conditions. The process of determining the red signal R from the output signal (second output signal) of the pixel corresponding to is performed.

  The color conversion process described above may be changed depending on, for example, the setting mode of the electronic camera 100 (for example, the shooting mode set in the memory 152 in FIG. 1). In this case, if the setting mode of the electronic camera 100 is “astrophotography mode”, as described above, for example, R = R2, and if the setting mode is “general shooting mode including daylight shooting” other than the astrophotography mode, For example, a change such as R = (R1-R2) is performed. If the shooting conditions (long-second shooting, photometric value, remote control shooting, etc.) are close to the astronomical shooting conditions, for example, the usage ratio of R2 is automatically increased (ie, the coefficient y is increased). The value of R may be changed.

Next, a method for driving the electronic camera (imaging device) 100 will be described.
FIG. 5 is a flowchart showing a driving method of electronic camera (imaging device) 100 according to the embodiment of the present invention.

  First, in step S101, the system control circuit unit 150 detects a shooting mode set by the operator from, for example, a mode setting dial (shooting mode setting unit) of the operation unit 160. Here, the detected photographing mode is stored and set in the memory 152 as described above.

  Subsequently, in step S102, the system control circuit unit 150 determines whether or not the shooting mode detected in step S101 is the astronomical shooting mode. As a result of the determination, if the astrophotography mode is selected, the process proceeds to step S103, whereas if the photographic mode is a general shooting mode other than the astrophotography mode, the process proceeds to step S104.

  In step S103, the system control circuit unit 150, based on the set astrophotography mode, for example, the electronic camera in the astrophotography mode based on the setting value stored in the internal memory, the setting condition by the operation unit 160, or the like. 100 shooting conditions are set. On the other hand, in step S104, the system control circuit unit 150, based on each shooting mode in the set general shooting mode, for example, according to a setting value stored in its internal memory, a setting condition by the operation unit 160, or the like. The shooting conditions of the electronic camera 100 corresponding to each shooting mode are set.

  After the processing ends in step S103 or S104, in step S105, the system control circuit unit 150 performs shooting based on the shooting conditions set in step S103 or S104.

  Specifically, the system control circuit unit 150 causes the lens control unit 111 to drive the photographing lens 110 and causes the shutter control unit 140 to drive the shutter 112 based on the set photographing conditions. Control. As a result, the optical image (incident light) 101 of the subject enters the imaging element 114 via the photographing lens 110, the shutter 112, and the LPF 115. In the image sensor 114, the photoelectric conversion unit 1141 converts the incident light transmitted through the CF 1143 including the first red filter (R1) and the second red filter (R2) into an electrical signal (image signal) for each pixel. Convert to

  Thereafter, an electrical signal (image signal) captured by the image sensor 114 is analog / digital converted by the A / D converter 116 and output to the image processing circuit unit 120 as image data.

  Subsequently, in step S <b> 106, the image processing circuit unit 120 performs color conversion processing on the image data output from the A / D converter 116 based on control by the system control circuit unit 150. Specifically, for the red signal R, the image processing circuit unit 120 outputs the pixel output signal corresponding to the first red filter (R1) and the second red color according to the set shooting condition (shooting mode). This is determined based on the output signal of the pixel corresponding to the filter (R2). The color conversion processing by the image processing circuit unit 120 will be described in detail below with reference to FIG.

  FIG. 6 is a characteristic diagram showing an example of spectral characteristics of each color filter after color conversion processing is performed by the image processing circuit unit 120 in the electronic camera (imaging device) 100 according to the embodiment of the present invention.

  In the example shown in FIG. 6, in both general imaging and astronomical imaging, for the red signal R, each pixel corresponding to the first red filter (R1) and the second red filter (R2) at the time of color conversion processing. The case where the process by the difference calculation of this output signal is performed is shown. Then, for the red signal R, the output of the pixels corresponding to the blue filter (B) and the green filter (G) for the other blue signal B and green signal G, respectively, based on the calculated calculation processing result. Color conversion processing is performed based on the signal.

  Specifically, for the red signal R, in the example shown in FIG. 6, an arithmetic process is performed by R = (x · R1) − (y · R2) excluding the sensitivity in the near-infrared region at the time of general photography, and astronomical photography. Occasionally, arithmetic processing is performed by R = (x · R1) − (z · R2), in which the sensitivity is extended to the near infrared region. Here, x is a coefficient (first coefficient) to be multiplied with the output signal (first output signal) of the pixel corresponding to R1, and y and z (z is a value different from y) corresponds to R2. This is a coefficient (second coefficient) multiplied by the output signal (second output signal) of the pixel to be processed. In other words, the image processing circuit unit 120 changes the ratio (ratio of multiplication coefficients: y / x, z / x) used at the time of calculation for the output signals of the respective pixels corresponding to R1 and R2 according to the photographing conditions, thereby changing the red signal. R is determined, and the sensitivity in the near infrared region is changed. In addition, the image processing circuit unit 120 performs differential processing on the output signal of the pixel corresponding to the first red filter (R1) and the output signal of the pixel corresponding to the second red filter (R2), thereby making incident light. The electric signal in the infrared region is removed.

  Thereafter, after predetermined image processing is performed in the image processing circuit unit 120, the image data processed in the image processing circuit unit 120 is recorded in the image display memory 124 or the memory 130 in step S107.

  Through the processes in steps S101 to S107 described above, image data is recorded in the red signal R generated according to the shooting conditions from the output signals of the pixels corresponding to R1 and R2.

  According to the present embodiment, it is possible to use one imaging device by providing pixels corresponding to red filters (R1, R2) having different sensitivities, and changing the ratio of output signals of each pixel to be used according to shooting conditions. Both shooting and astronomical shooting can be performed. Thereby, the scene which can be image | photographed in an imaging device is expandable.

  In addition, by setting the spectral sensitivity of the red filter (for example, performing the difference processing of R1-R2), members such as an infrared cut filter (or an infrared absorption filter) that have been conventionally provided can be reduced, and the cost can be reduced. It is also possible to acquire special advantages.

  Note that the arithmetic processing for calculating the red signal R is generally performed in the image processing circuit unit 120 as in the present embodiment, and the color conversion operation (from the RAW image) of the image processing circuit unit 120 is performed. This is most effective before color conversion) or during color conversion operation. However, the present invention is not limited to this. For example, there is no problem even if calculation is performed by the A / D converter 116 at the time of RAW imaging.

(Modification of this embodiment)
In the above-described embodiment, as the red signal R, image processing (color conversion processing) is performed with the output signals of the pixels corresponding to the first red filter (R1) and the second red filter (R2) as the same calculation result = output value. A technique that performs However, although this method is simple, it interpolates one pixel data for two pixels, and thus has a drawback that the resolution is slightly lowered.

  Therefore, as a modification of the present embodiment, in R1 and R2, the coefficient applied to each pixel corresponding to each R1 and R2 is changed according to the shooting conditions for the output signal of each pixel. As a result, it is possible to realize color reproduction according to each shooting scene with higher quality without impairing the resolution of each pixel.

  For example, in the astrophotography mode, the output value of the pixel at R1 is compared with the output signal of the pixel at R1 and the difference output signal at (R1-R2), and the difference is larger than a predetermined value (≈near infrared) When the output is large), R2 is also used as the output value at R1. On the other hand, when the difference is smaller than a predetermined value, an output value obtained by multiplying the output signal of the pixel R1 or a coefficient (for example, the ratio of (R1 / R2) in a predetermined area of the output signal of the CMOS sensor). To use the output signal of the pixel R1. Here, the output signal of the pixel of R2 may use its own output as it is.

  Further, for example, in the general shooting mode such as daylight shooting, the output value of the pixel in R2 is compared with the output signal of the pixel of R2 and the difference output signal of (R1-R2), and the difference is larger than a predetermined value. If it is small (≈when the near-infrared output is small), the output signal of the R2 pixel is used as a substitute for general imaging output. Here, the differential output signal of (R1-R2) is used as the output signal of the pixel of R1.

  As described above, image processing using the pixel output signal can be performed more effectively by changing the calculation method and the pixel use ratio according to the output value.

  The output described in the embodiment of the present invention is not limited to the output of raw image (RAW image) data, but is a pixel output level used for color conversion or the like (used for so-called image processing). If it can be determined as a pixel output level), there is no problem. That is, the value output as RAW image data does not have to be an output that has already been subjected to the arithmetic processing in the present embodiment. For example, the RAW image data includes information such as a shooting mode as supplementary information. From the supplementary information, it is determined what kind of calculation processing is performed when performing image processing such as color conversion, and the output level of each pixel. It is also possible to perform processing.

  Also, in the calculation process, the calculation of the difference / coefficient is not limited to the method described in the present embodiment. For example, the average value of the outputs of R1 and R2 is used, or in a predetermined area. There is no problem even if calculation is performed such as using the ratio of R1 and R2 for the entire image.

  Furthermore, the present invention is not specialized for the spectroscopy described in the present embodiment, and is characterized by deriving two spectra of near infrared and visible light from two different types of spectroscopy. “Use R1 and R2 spectra that are both steep, find the optimum R sensitivity by adding and multiplying two pixels,” and “Infrared cut filter is not omitted. R1 with a steep spectrum and R2 with a wide effective wavelength up to the near infrared are used. In general imaging mode, both R1 and R2 use their own outputs. In astronomical imaging mode, the R signal is based on the output of R2. And the like "are also intended by the present invention.

  In addition, although not mentioned in the present embodiment, regarding the image conversion parameters used for color conversion of image data, there is no problem in individually having each mode (astrophotography mode, general shooting mode, etc.). There is nothing. In this embodiment, a CMOS sensor is used as an image sensor. However, the present invention is not limited to this, and for example, the same effect can be obtained even in an image pickup apparatus using a CCD as an image sensor. It is obtained.

  1 constituting the electronic camera (imaging device) 100 according to the present embodiment described above, and the steps of FIG. 5 showing the driving method of the electronic camera 100 are stored in a RAM or ROM of a computer. It can be realized by running the program. This program and a computer-readable storage medium storing the program are included in the present invention.

  Specifically, the program is recorded in a storage medium such as a CD-ROM, or provided to a computer via various transmission media. As a storage medium for recording the program, a flexible disk, a hard disk, a magnetic tape, a magneto-optical disk, a nonvolatile memory card, and the like can be used in addition to the CD-ROM. On the other hand, as the transmission medium of the program, a communication medium in a computer network (LAN, WAN such as the Internet, wireless communication network, etc.) system for propagating and supplying program information as a carrier wave can be used. Moreover, examples of the communication medium at this time include a wired line such as an optical fiber, a wireless line, and the like.

  Further, by executing the program supplied by the computer, not only the functions of the electronic camera 100 according to the present embodiment are realized, but also the OS (operating system) or other application in which the program is running on the computer. When the functions of the electronic camera 100 according to the present embodiment are realized in cooperation with software, etc., or all or part of the processing of the supplied program is performed by a function expansion board or function expansion unit of the computer. Such a program is also included in the present invention when the functions of the electronic camera 100 according to the present embodiment are realized.

1 is a block diagram showing a schematic configuration of an electronic camera (imaging device) according to an embodiment of the present invention. It is a schematic diagram for demonstrating the internal structure of an image pick-up element. It is a characteristic view which shows an example of the spectral characteristic of CF which an image sensor has. FIG. 4 is a characteristic diagram showing an example of the spectral characteristic when the output signal from the first red filter (R1) and the output signal from the second red filter (R2) are differentially processed in the spectral characteristic shown in FIG. It is a flowchart which shows the drive method of the electronic camera (imaging device) which concerns on embodiment of this invention. In the electronic camera (imaging device) according to the embodiment of the present invention, it is a characteristic diagram showing an example of spectral characteristics of each color filter after color conversion processing by the image processing circuit unit. It is a characteristic view which shows an example of the spectral characteristic of the filter used for the conventional astronomical imaging device. It is a characteristic view which shows an example of the spectral characteristic of the filter used for the conventional imaging device for general imaging | photography (daylight imaging | photography etc.). FIG. 9 is a characteristic diagram showing an example of comparison of transmission characteristics in the near-infrared region between a filter used in the general imaging (daylight imaging) imaging device of FIG. 8 and a filter used in the astronomical imaging imaging device of FIG.

Explanation of symbols

100 Electronic camera (imaging device)
101 Optical image of subject (incident light)
DESCRIPTION OF SYMBOLS 110 Lens for imaging | photography 111 Lens control part 112 Shutter 114 Image pick-up element 115 Low pass filter (LPF)
116 A / D converter 118 Timing generation circuit (TG)
120 Image processing circuit unit 122 Memory control circuit unit 124 Image display memory 126 D / A converter 128 Image display unit 130 Memory 140 Shutter control unit 142 Distance control unit 144 Thermometer 146 Photometry control unit 148 Flash unit 150 System control circuit unit 152 Memory 154 Display unit 156 Non-volatile memory 160 Operation unit 170 Recording medium 182 Power source control unit 186 Power source unit 1141 Photoelectric conversion unit 1142 Micro lens (ML)
1143 color filter (CF)

Claims (6)

A photoelectric conversion unit in which pixels having photoelectric conversion elements for converting incident light incident from the outside into electric signals are two-dimensionally arranged;
A color filter provided above the photoelectric conversion unit corresponding to each of the pixels and allowing the incident light to enter the photoelectric conversion unit with a wavelength limit;
The color filter includes at least a first red filter having sensitivity in the visible light region and a second red filter having sensitivity to the near infrared region together with the visible light region,
Processing for determining a red signal based on a first output signal of a pixel corresponding to the first red filter and a second output signal of a pixel corresponding to the second red filter in accordance with an imaging condition An imaging device comprising: processing means for performing   The imaging apparatus according to claim 1, wherein the processing unit determines the red color signal by performing a differential process on the first output signal and the second output signal.   The processing means changes a ratio of a first coefficient to be multiplied to the first output signal and a second coefficient to be multiplied to the second output signal in accordance with the photographing condition, so that the red signal The imaging device according to claim 1, wherein the imaging device is determined.   The said processing means removes the said electrical signal in the infrared region of the said incident light by carrying out differential processing of the said 1st output signal and the said 2nd output signal. Imaging device. At least a shooting mode setting means capable of setting a mode related to shooting conditions suitable for astronomical shooting and a mode related to shooting conditions suitable for general shooting;
The processing means changes the processing method for the first output signal and the second output signal based on the mode set by the shooting mode setting means, and determines the red signal. The imaging device according to any one of claims 1 to 4. A pixel having a photoelectric conversion element that converts incident light incident from the outside into an electric signal is arranged in a two-dimensional manner, and is provided above the photoelectric conversion unit corresponding to each pixel. A driving method of an imaging apparatus including a color filter that imposes a wavelength limit on incident light and enters the photoelectric conversion unit,
The color filter includes at least a first red filter having sensitivity in the visible light region and a second red filter having sensitivity to the near infrared region together with the visible light region,
Processing for determining a red signal based on a first output signal of a pixel corresponding to the first red filter and a second output signal of a pixel corresponding to the second red filter in accordance with an imaging condition A method for driving an imaging apparatus, comprising:

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