WO2012008070A1

WO2012008070A1 - Image capturing device and signal processing method

Info

Publication number: WO2012008070A1
Application number: PCT/JP2011/001374
Authority: WO
Inventors: 田中　圭介; 一夫藤原; 信三香山
Original assignee: パナソニック株式会社
Priority date: 2010-07-15
Filing date: 2011-03-09
Publication date: 2012-01-19
Also published as: JP2012023620A

Abstract

Disclosed is an image capturing device (100) provided with a plurality of unit pixels (110) two-dimensionally arranged on an image capturing surface, and a signal processing unit (201), wherein each of the plurality of unit pixels (110) comprises a plurality of light receiving elements (111), and a color filter (112) comprising a plurality of areas so that each of the areas transmits light having a wavelength different from each other; and the signal processing unit (201) comprises a white balance adjustment circuit (234) for adjusting a white balance of a pixel signal, a reference data storage unit (242) for storing correction reference data which indicates properties of each area of the color filter, a coordinate acquisition circuit (244) for acquiring two-dimensional coordinates indicating a position of the light receiving element (111) in the image capturing surface, a correction amount calculation circuit (241) for determining a hue correction amount on the basis of the correction reference data and the two-dimensional coordinates, and a hue correction circuit (235) for correcting the hue of the pixel signal after the pixel signal is subjected to the white balance adjustment, using the correction amount determined by the correction amount calculation circuit (241).

Description

Imaging apparatus and signal processing method

The present invention relates to an imaging apparatus and a signal processing method, and more particularly, to an imaging apparatus and a signal processing method that include a color filter having a plurality of regions that transmit light of different wavelengths for each region and perform color correction.

In recent years, not only compact digital still cameras (DSC: Digital Still Camera) but also single-lens reflex DSCs that require advanced color reproduction, the transition of imaging media from silver-salt films to imaging devices is rapidly progressing.

In addition to thinning of the color filter due to the reduction in the height of the pixels of the image sensor and the miniaturization due to the increase in the number of pixels, the pixel array is becoming larger in size for single lens reflex DSCs and the like. However, when an absorptive color filter such as an organic pigment filter is used for the image pickup element, color unevenness occurs and it is a problem that high-definition color reproducibility cannot be achieved. Even in a multilayer interference filter such as a photonic filter (PCF), unevenness in the filter film thickness causes color unevenness, which is a problem for realizing high-definition color reproducibility. In particular, in a digital camera such as a single-lens reflex DSC, an imaging apparatus and an image processing method that output an image with high-definition color reproducibility are strongly desired.

Therefore, Patent Document 1 discloses a conventional technique for performing color shading correction as an approach to realizing high-definition color reproducibility.

JP 2005-278004 A

However, the above-described conventional technology has a problem that high-definition color reproducibility cannot be realized.

Specifically, in the related art disclosed in Patent Document 1, as a general method of calculating the correction amount, a method of obtaining a luminance ratio mainly from adjacent pixels having different colors is disclosed. However, this method is effective only for color correction by color mixture of adjacent pixels with obliquely incident light.

In other words, the conventional technology can correct color shading mainly due to color mixing of adjacent pixels that changes depending on the illumination conditions and imaging conditions such as lenses, but it does not vary in workmanship such as color filters distributed as fixed values in the wafer surface. It is not possible to correct color unevenness due to.

In the above conventional technology, not only the thinning of the color filter due to the reduction in the pixel height and the miniaturization due to the increase in the pixel size, but also the variation in workmanship of the color filter due to the enlargement of the pixel array such as for a single lens reflex DSC. Due to the uneven color, high-definition color reproducibility cannot be realized.

Therefore, the present invention has been made in view of the above problems, and an object thereof is to provide an imaging apparatus and a signal processing method that can realize high-definition color reproducibility.

In order to solve the above-described problem, an imaging device according to one embodiment of the present invention includes a plurality of pixels arranged two-dimensionally in an imaging surface and a signal that processes a pixel signal output from each of the plurality of pixels. Each of the plurality of pixels includes a plurality of light receiving elements, and a color filter formed on the plurality of light receiving elements and including a plurality of regions that transmit light of different wavelengths for each region, The signal processing unit includes a WB adjustment unit that adjusts a white balance of the pixel signal, a reference data storage unit that stores correction reference data indicating characteristics for each region of the color filter in units of one or a plurality of pixels, and , A coordinate acquisition unit that acquires a two-dimensional coordinate indicating the position of the light receiving element in the imaging surface, correction reference data stored in the reference data storage unit, and a secondary acquired by the coordinate acquisition unit A correction amount calculation unit that determines a hue correction amount based on the coordinates, and a hue correction unit that corrects the hue of the pixel signal after the white balance is adjusted with the correction amount determined by the correction amount calculation unit And have.

As a result, the hue correction amount is determined using correction reference data indicating the characteristics of each color filter region, so that even if color unevenness occurs due to, for example, manufacturing variations in the color filter, an appropriate hue is determined. Can be corrected. Therefore, high-definition color reproducibility can be realized.

The plurality of regions include a red region that transmits red light, a green region that transmits green light, and a blue region that transmits blue light, and the color filter includes a high refractive index material having a first refractive index. N layers (where n is a natural number of 3 or more) and n-1 layers made of a low refractive index material having a second refractive index lower than the first refractive index are alternately stacked. Two of the n-layer films made of the high-refractive index material, and one of the n-1 layers made of the low-refractive index material. Is a layer common to the red region, the green region, and the blue region, and the red region is included in the common layer among n-1 layers composed of the low refractive index material. The film thickness of one layer other than the one layer film may be different from the film thickness of the other layers.

Thus, by adjusting the film thickness, a color filter having an arbitrary transmission wavelength characteristic region can be realized, so that high-definition color reproducibility can be realized.

The plurality of regions may further include a region that transmits only near-infrared light.

This makes it possible to achieve high-definition color reproducibility even under nighttime infrared illumination, since near infrared light is used.

Further, the correction amount is represented by a function expression having the two-dimensional coordinates and the wavelength of light transmitted through the color filter as variables, and the reference data storage unit uses the function expression as the correction reference data. You may remember.

As a result, by storing a functional expression having the two-dimensional coordinates and the wavelength of light as variables, it is not necessary to store correction reference data for each position. Fine color reproducibility can be realized.

A signal processing method according to an aspect of the present invention is a signal processing method for processing a pixel signal output for each pixel from a solid-state imaging device in which a plurality of pixels are two-dimensionally arranged in an imaging surface. Each of the plurality of pixels includes a plurality of light receiving elements and a color filter formed on the plurality of light receiving elements and including a plurality of regions that transmit light of different wavelengths for each region, and the signal processing method Includes a WB adjustment step for adjusting the white balance of the pixel signal, and a hue correction step for correcting the hue of the pixel signal after the white balance is adjusted. In the hue correction step, a region of the color filter A hue correction amount is determined based on correction reference data indicating the characteristics of each pixel in units of one or a plurality of pixels and two-dimensional coordinates indicating the position of the light receiving element in the imaging surface. The determined correction amount for correcting the hue of the pixel signal.

In the hue correction step, the correction amount may be determined independently for each transmission characteristic of the color filter region to correct the hue of the pixel signal.

This makes it possible to achieve high-definition color reproducibility because the hue is corrected independently for each color.

In the hue correction step, the correction amount may be determined so as to change monotonously as the two-dimensional coordinate increases.

This makes it possible to prevent the hue correction amount from changing abruptly between adjacent pixels, and to realize high-definition color reproducibility.

Further, the correction amount is represented by a function equation having the two-dimensional coordinates and the wavelength of light transmitted through the color filter as variables, and the correction amount is determined using the function equation in the hue correction step. May be.

This makes it possible to reduce the amount of memory required for image processing by expressing the hue correction amount with a functional expression having two-dimensional coordinates and wavelength as variables. Therefore, image processing can be performed with low power, and high-definition color reproducibility can be realized.

Further, the correction reference data may be a wafer in-plane distribution of transmittance of the color filter film formation monitor wafer created when forming the color filter.

As described above, using the color filter film formation monitor created at the time of forming the color filter, the transmittance distribution on the entire surface of the wafer of the color filter film formation monitor or the transmittance distribution of a part of the wafer is used as the correction reference data. As a result, using this correction reference data, a correction amount is calculated for each light receiving element arranged two-dimensionally, and hue correction is performed so that there is no color unevenness in the imaging surface, thereby realizing high-definition color reproducibility. can do.

Further, the correction reference data may be an in-wafer distribution of the film thickness of all or part of the color filters of the color filter film formation monitor wafer created when forming the color filter.

Thus, using the color filter film formation monitor created at the time of color filter formation, there is a correlation with the transmittance of the color filter film formation monitor, and the color filter film thickness distribution over the wafer or the wafer that can be measured easily and inexpensively A part of the distribution is used as correction reference data. As a result, using this correction reference data, a correction amount is calculated for each light receiving element, and hue correction is performed so that there is no color unevenness in the imaging surface, thereby realizing high-definition color reproducibility at low cost. Can do.

The signal processing method may further include a reference data calculation step of calculating the correction reference data using a pixel signal generated when reference light is incident on the solid-state imaging device.

Thus, the hue correction amount can be determined using the variation of the pixel signal obtained by entering the reference light for each light receiving element, so that high-definition color reproducibility can be realized.

Further, the reference light may be white light.

Thus, by using a white light source as the reference light, it is possible to simultaneously and easily calculate the hue correction amount for each light receiving element in a light receiving element in which a color filter having a region having a different transmission color is formed. . Therefore, high-definition color reproducibility can be realized.

Further, the reference light may include infrared light.

Thus, by using a light source including infrared light as reference light, a light receiving element formed with a color filter having a region having a different transmission color can be simultaneously and easily used at night, etc. The amount of correction can be calculated. Therefore, high-definition color reproducibility can be realized.

The reference light may be light having a transmission center wavelength in the transmission characteristics of the color filter region.

Thereby, for example, by irradiating the light receiving element corresponding to the red region that transmits red as the reference light, and determining the correction amount of the hue using the correction reference data generated from the image signal at this time, An appropriate correction amount can be determined for each color. Therefore, high-definition color reproducibility can be realized.

According to the imaging apparatus and signal processing method of the present invention, high-definition color reproducibility can be realized.

FIG. 1 is a diagram illustrating an example of a configuration of an imaging apparatus according to Embodiment 1 of the present invention. FIG. 2 is a flowchart showing an example of a signal processing method executed by the imaging apparatus according to Embodiment 1 of the present invention. FIG. 3 is a diagram illustrating an example of the configuration of the imaging apparatus according to Embodiment 2 of the present invention. FIG. 4 is a diagram illustrating an example of a cross-sectional configuration of the color filter provided in the solid-state imaging device of the imaging apparatus according to Embodiment 2 of the present invention.

Hereinafter, embodiments of an imaging apparatus according to the present invention will be described with reference to the drawings, taking a digital still camera as an example. In addition, although this invention is demonstrated using the following embodiment and attached drawing, this is for the purpose of illustration and this invention is not intended to be limited to these.

(Embodiment 1)
The imaging apparatus according to Embodiment 1 of the present invention includes a plurality of pixels arranged two-dimensionally in an imaging surface, and a signal processing unit that processes pixel signals output from each of the plurality of pixels. Each of the plurality of pixels includes a plurality of light receiving elements and a color filter formed on the plurality of light receiving elements and including a plurality of regions that transmit light of different wavelengths for each region. The signal processing unit according to Embodiment 1 of the present invention determines a reference data storage unit that stores correction reference data indicating characteristics of each color filter region in units of one or a plurality of pixels, and a hue correction amount. A correction amount calculation unit; and a hue correction unit that corrects the hue of the pixel signal with the determined correction amount. The correction amount calculation unit determines a hue correction amount based on the two-dimensional coordinates indicating the position of the light receiving element in the imaging surface and the correction reference data stored in the reference data storage unit. .

First, the configuration and signal processing method of the imaging apparatus (camera) according to Embodiment 1 of the present invention will be described. FIG. 1 is a block diagram illustrating an example of a functional configuration of the imaging apparatus 100 according to Embodiment 1 of the present invention.

As shown in FIG. 1, the imaging apparatus 100 according to Embodiment 1 of the present invention includes a solid-state imaging device 101 and a signal processing unit 201. Further, in the signal processing method according to the first embodiment of the present invention, the imaging having the unit pixel 110 having one unit of four pixels in which Bayer array of red (R), green (Gr, Gb), and blue (B) is arranged. In the apparatus 100, an image signal composed of a color signal and a luminance signal is processed.

The solid-state image sensor 101 is a MOS (Metal Oxide Semiconductor) type image sensor that photoelectrically converts incident light to generate an electrical signal. The solid-state imaging device 101 includes a plurality of unit pixels 110, a vertical shift register 121, a horizontal shift register 122, a noise removal circuit 123, and an output amplifier 124. In FIG. 1, only one of the plurality of unit pixels 110 is shown.

Each of the plurality of unit pixels 110 includes a plurality of light receiving elements 111 and a color filter 112. The unit pixel 110 according to the first embodiment of the present invention is a pixel in which four sub-pixels in which red (R), green (Gr, Gb), and blue (B) are arranged in a Bayer array are used as one unit. That is, as shown in FIG. 1, the unit pixel 110 includes four light receiving elements 111.

The plurality of light receiving elements 111 generate electric signals by photoelectrically converting incident light transmitted through the color filter 112. The generated electrical signal is output to the signal processing unit 201 according to control by the vertical shift register 121 and the horizontal shift register 122.

The color filter 112 is a filter that selectively transmits visible light (R, G, B) for each region. Specifically, the color filter 112 includes a red region 113,

green regions

114 and 115, and a blue region 116. For example, the color filter 112 is an absorptive organic pigment filter that includes different organic pigments for each transmitted color.

The red region 113 is a region that mainly transmits red color (650 nm) in the color filter 112. The

green regions

114 and 115 are regions that mainly transmit green color (550 nm) in the color filter 112. The blue region 116 is a region that mainly transmits blue (450 nm) in the color filter 112.

The vertical shift register 121 selects the plurality of light receiving elements 111 for each row, and the horizontal shift register 122 selects the selected row signal. The noise removal circuit 123 removes noise from the electrical signal output from the light receiving element 111. The output amplifier 124 amplifies the electrical signal selected by the vertical shift register 121 and the horizontal shift register 122 and outputs the amplified signal to the signal processing unit 201.

With the above configuration, the solid-state imaging device 101 outputs an electrical signal as a sub-pixel signal for each light receiving element 111. The subpixel signal is an electrical signal of a color component corresponding to each light receiving element 111.

The signal processing unit 201 generates a luminance signal and a color signal of the unit pixel 110 by processing the pixel signal output from the solid-state imaging device 101. The pixel signal is a signal output from each of the plurality of unit pixels 110, and specifically includes red (R), green (G), and blue (B) sub-pixel signals.

The signal processing unit 201 is a DSP (Digital Signal Processor) or the like that performs image signal processing on the image signal received from the solid-state imaging device 101. The image signal means a group of a plurality of pixel signals.

As shown in FIG. 1, the signal processing unit 201 includes a defect correction circuit 211, an OB calculation circuit 212, a luminance calculation circuit 221, a low-pass filter circuit 231, a color shading correction circuit 232, and a luminance shading correction circuit 233. , White balance adjustment circuit 234, hue correction circuit 235, color gain adjustment circuit 236, γ correction circuit 237, addition circuit 238, correction amount calculation circuit 241, reference data storage unit 242, and reference data input circuit 243 and a coordinate acquisition circuit 244 for two-dimensional coordinates in the imaging plane of the light receiving element. The processed pixel signal is stored in a memory (not shown) or the like. Each processing unit acquires a processed pixel signal or the like from the memory as necessary, and performs each process using the acquired processed pixel signal.

The scratch correction circuit 211 performs pixel defect correction. That is, the defect correction circuit 211 generates and outputs a pixel signal of a defective pixel by performing an operation using a pixel signal of an adjacent pixel in the input image signal.

The OB calculation circuit 212 performs offset removal such as dark current included in the pixel signal. For example, the OB calculation circuit 212 performs offset removal for each sub-pixel signal. The sub-pixel signal processed by the OB calculation circuit 212 is output to the luminance calculation circuit 221 and the low-pass filter circuit 231.

The luminance calculation circuit 221 generates a luminance signal of the unit pixel using a plurality of sub-pixel signals included in the unit pixel. Specifically, the luminance calculation circuit 221 generates a luminance signal by adding the sub-pixel signals. That is, the luminance signal Y is calculated as the sum of the red subpixel signal R, the first green subpixel signal Gb, the second green subpixel signal Gr, and the blue subpixel signal B (Y = R + Gb + Gr + B). .

The low-pass filter circuit 231 removes a noise component included in the sub-pixel signal. The sub-pixel signal from which the noise component has been removed is output to the color shading correction circuit 232.

The color shading correction circuit 232 and the luminance shading correction circuit 233 respectively perform color shading correction and luminance shading correction using output signals from adjacent pixels. Color shading and luminance shading occur, for example, as a mixture of oblique incident light to adjacent pixels, which varies depending on the shooting conditions. The pixel signal whose shading is corrected is output to the white balance adjustment circuit 234.

The white balance adjustment circuit 234 adjusts the white balance (WB) of the pixel signal. That is, color correction is performed between the three primary colors of the sub-pixel signal indicating each color included in the pixel signal. The pixel signal after the white balance is adjusted is output to the hue correction circuit 235.

The hue correction circuit 235 uses the correction amount determined by the correction amount calculation circuit 241 to correct the hue of the pixel signal after the white balance is adjusted. The corrected pixel signal is output to the color gain adjustment circuit 236.

The color gain adjustment circuit 236 adjusts the color gain of the input pixel signal. The pixel signal whose color gain has been adjusted is output to the γ correction circuit 237.

The γ correction circuit 237 performs γ correction on the input pixel signal. The corrected pixel signal is output to the addition circuit 238.

The addition circuit 238 adds the pixel signal output from the γ correction circuit 237 and the luminance signal output from the luminance calculation circuit 221 to generate a pixel signal after signal processing. The pixel signal after the signal processing is output as an image signal to a display device or the like.

The correction amount calculation circuit 241 calculates the hue correction amount for each light receiving element 111 using the hue correction reference data stored in the reference data storage unit 242 and the two-dimensional coordinates indicating the position of the light receiving element in the imaging surface. Calculate and determine. For example, the correction amount calculation circuit 241 determines the hue correction amount so as to change monotonously in accordance with an increase in the two-dimensional coordinates of the light receiving element acquired by the coordinate acquisition circuit 244. In this way, since the hue correction amount is monotonously increased in accordance with the increase in the two-dimensional coordinates, the hue correction amount does not have to be changed suddenly between adjacent pixels, so that high-definition color reproducibility can be achieved. Can be realized. The determined hue correction amount is output to the hue correction circuit 235.

For example, the correction amount calculation circuit 241 uses, as variables for hue correction reference data, a function expression representing a hue correction amount, using the two-dimensional coordinates of the light receiving element 111 and the wavelength of light transmitted through the color filter 112 as variables. Then, the hue correction amount is calculated. That is, the correction amount calculation circuit 241 uses the two-dimensional coordinates (x, y) of the light receiving element acquired by the coordinate acquisition circuit 244 and the wavelength λ of the light incident on the light receiving element to calculate the hue correction amount. Calculate.

As described above, the amount of memory required for image processing can be reduced by expressing the hue correction amount by a functional expression having two-dimensional coordinates and wavelength as variables. Therefore, image processing can be performed with low power, and high-definition color reproducibility can be realized.

The reference data storage unit 242 is a memory for storing hue correction reference data. For example, the reference data storage unit 242 stores, as hue correction reference data, a functional expression having two-dimensional coordinates in the imaging surface and the wavelength of light transmitted through the color filter as variables. In this way, by storing a functional expression having two-dimensional coordinates and the wavelength of light as variables, it becomes unnecessary to store correction reference data for each position, so that the amount of memory can be reduced, High-definition color reproducibility can be realized.

The reference data input circuit 243 stores the hue correction reference data used for calculating the hue correction amount in the reference data storage unit 242. For example, the reference data input circuit 243 stores the in-wafer distribution of the transmittance of the color filter film formation monitor wafer created at the time of forming the color filter in the reference data storage unit 242 as hue correction reference data.

Using the color filter film formation monitor created at the time of color filter formation, measure the entire surface distribution of the color filter film formation monitor or the transmittance distribution from a part of the wafer, and use the measured transmittance distribution as the correction reference data. The data input circuit 243 is stored in the reference data storage unit 242. As a result, using this correction reference data, a correction amount is calculated for each light receiving element arranged two-dimensionally, and hue correction is performed so that there is no color unevenness in the imaging surface, thereby realizing high-definition color reproducibility. can do.

As described above, the imaging apparatus 100 according to Embodiment 1 of the present invention uses the correction reference data and the two-dimensional coordinates indicating the position of the pixel in the imaging surface to calculate the correction amount for determining the hue correction amount. A circuit 241 and a hue correction circuit 235 that corrects the hue of the pixel signal with the determined correction amount are provided. The correction reference data indicates the characteristics of each region of the color filter 112 in units of one or a plurality of pixels.

As a result, the hue correction amount is determined using the correction reference data indicating the characteristics of each region of the color filter 112. For example, even when color unevenness due to manufacturing variation of the color filter 112 occurs Correct hue correction. For example, the correction reference data is a transmittance distribution of the color filter film formation monitor wafer. The correction amount calculation circuit 241 calculates a correction amount for each light receiving element that is two-dimensionally arranged in the imaging surface of the imaging apparatus 100 from the correction reference data, and the hue correction circuit 235 prevents color unevenness in the imaging surface. Correct the hue. Thereby, according to the imaging device 100 which concerns on Embodiment 1 of this invention, high-definition color reproducibility is realizable.

Here, an example of a signal processing method executed by the imaging apparatus 100 according to Embodiment 1 of the present invention will be described with reference to FIG. FIG. 2 is a flowchart illustrating an example of a signal processing method executed by the imaging apparatus 100 according to Embodiment 1 of the present invention.

First, the white balance adjustment circuit 234 adjusts the white balance of the input pixel signal (S110). As described above, the pixel signal input to the white balance adjustment circuit 234 is subjected to predetermined processing such as shading correction processing and LPF processing.

Next, the correction amount calculation circuit 241 calculates a hue correction amount using the correction reference data stored in the reference data storage unit 242 and the two-dimensional coordinates acquired by the coordinate acquisition circuit 244 (S120). ).

At this time, the coordinate acquisition circuit 244 acquires two-dimensional coordinates indicating the pixel position of the target pixel that has output the pixel signal that is the target of the hue correction processing. In addition, the correction amount calculation circuit 241 calculates the hue correction amount using, for example, the above-described function formula. Specifically, the correction amount is determined independently for each transmission characteristic of the color filter 112 region. Since hue correction is performed independently for each color, high-definition color reproducibility can be realized.

At this time, the wavelength, which is one of the variables of the functional equation corresponding to the transmission color of the color filter formed on the pixel, is obtained from the in-wafer distribution of the transmittance of the color filter film formation monitor wafer created at the time of forming the color filter. It is done. The wafer in-plane distribution is stored in the reference data storage unit 242 as correction reference data.

Next, the hue correction circuit 235 corrects the hue of the pixel signal of the target pixel using the correction amount calculated by the correction amount calculation circuit 241 (S130).

As described above, according to the signal processing method according to the first embodiment of the present invention, the correction reference data indicating the characteristics of each color filter region and the two-dimensional coordinates indicating the position of the target pixel are used. Even when the characteristics of the color filter are different depending on the position in the imaging surface due to manufacturing variation or the like, an appropriate correction amount can be calculated. Therefore, according to the signal processing method according to Embodiment 1 of the present invention, high-definition color reproducibility can be realized.

Note that the predetermined correction reference data may be an in-wafer distribution of the film thickness of all or a part of the color filter of the color filter film formation monitor wafer created at the time of forming the color filter. Thus, using the color filter film formation monitor created at the time of color filter formation, there is a correlation with the transmittance of the color filter film formation monitor, and the color filter film thickness distribution over the wafer or the wafer that can be measured easily and inexpensively A part of the distribution is used as correction reference data. As a result, using this correction reference data, a correction amount is calculated for each light receiving element, and hue correction is performed so that there is no color unevenness in the imaging surface, thereby realizing high-definition color reproducibility at low cost. Can do.

Further, the predetermined correction reference data may be calculated from an image signal from the light receiving element when white light is incident on the imaging apparatus 100 as reference light. Thus, by using a white light source as the reference light, it is possible to simultaneously and easily calculate the hue correction amount for each light receiving element in a light receiving element in which a color filter having a region having a different transmission color is formed. . Therefore, high-definition color reproducibility can be realized.

At this time, the reference light may include infrared light. By using a light source that includes infrared light as the reference light, it is possible to simultaneously and easily adjust the amount of hue correction within the imaging surface by using a light-receiving element with a color filter with a different transmission color, even at night. It is possible to calculate and correct the hue using the correction amount. Therefore, high-definition color reproduction can be realized.

As described above, the hue correction amount can be determined by using the variation of the pixel signal obtained by entering the reference light for each light receiving element, so that high-definition color reproducibility can be realized. .

Further, the reference light may be light having a transmission center wavelength in the transmission characteristics of the color filter region. For example, the correction reference data is acquired by irradiating the light receiving element corresponding to the red region with red light. Then, by performing the hue correction using the correction amount calculated from the correction reference data, the imaging apparatus 100 can determine an appropriate correction amount for each color, and can realize high-definition color reproducibility.

As described above, according to the imaging apparatus 100 according to the first embodiment of the present invention, not only thinning of the color filter by reducing the height of pixels or miniaturization by increasing the number of pixels, but also for a digital single lens reflex camera, etc. It is possible to reduce color unevenness caused by variations in workmanship such as color filters due to the large pixel array. Therefore, according to the imaging device 100 according to Embodiment 1 of the present invention, high-definition color reproducibility can be realized.

(Embodiment 2)
An imaging apparatus according to Embodiment 2 of the present invention includes a color filter including a region that transmits near-infrared light, and processes an image signal including a near-infrared signal. According to the imaging apparatus according to Embodiment 2 of the present invention, since the near-infrared signal is used, for example, even when the visible light signal is weak, such as at night, the color component signal is effectively left. High-definition color reproducibility can be realized.

First, the configuration of the imaging apparatus and the signal processing method according to Embodiment 2 of the present invention will be described. FIG. 3 is a block diagram illustrating an example of a functional configuration of the imaging apparatus 300 according to Embodiment 2 of the present invention.

As shown in FIG. 3, the imaging apparatus 300 according to Embodiment 2 of the present invention includes a solid-state imaging device 310, a signal processing unit 320, an imaging control unit 330, a light source control unit 341, and an IR light source 342. And an objective lens 351 and a diaphragm 352. In addition, the signal processing method according to Embodiment 2 of the present invention includes red (R) + near infrared (IR), green (G) + near infrared (IR), blue (B) + near infrared (IR). ), And an image pickup apparatus 100 having a unit pixel 311 having four units of near infrared (IR) as a unit, an image signal composed of a color signal and a luminance signal is processed.

The solid-state imaging device 310 is a MOS type image sensor that photoelectrically converts incident light to generate a color signal. The solid-state imaging device 310 includes a plurality of unit pixels 311, a vertical shift register 121, a horizontal shift register 122, a noise removal circuit 123, and an output amplifier 124. FIG. 3 shows only one of the plurality of unit pixels 311. In the following, the same components as those in the first embodiment are denoted by the same reference numerals and description thereof may be omitted.

Each of the plurality of unit pixels 311 includes a plurality of light receiving elements 111 and a color filter 312. The color filter 312 includes an R + IR transmission region 313, a G + IR transmission region 314, a B + IR transmission region 315, and an IR transmission region 316. That is, the color filter 312 is a filter that selectively transmits visible light (R, G, B) for each region and transmits infrared light.

Compared to the color filter 112 according to the first embodiment, it differs in that one of the two

green regions

114 and 115 included in the unit pixel 110 is replaced with an IR transmission region 316 that transmits near-infrared light. Yes. The red region 113, the other of the

green regions

114 and 115, and the blue region 116 included in the unit pixel 110 are respectively an R + IR transmission region 313, a G + IR transmission region 314, and a B + IR transmission region 315 that also transmit near infrared light. It is also different in that it is replaced by.

The solid-state imaging device 310 selects each row of the unit pixels 311 arranged two-dimensionally by the vertical shift register 121, selects the row signal by the horizontal shift register 122, and outputs a color signal (pixel signal) for each unit pixel 311. Output from the output amplifier 124. That is, the solid-state imaging device 310 outputs pixel signals including R + IR, G + IR, B + IR, and IR sub-pixel signals to the signal processing unit 320.

Here, the configuration of the color filter 312 will be described. In order to easily realize a pixel configuration having an RGB + IR filter including an IR pixel, a photonic crystal color filter is integrated as a color filter 312 on an image sensor (a plurality of light receiving elements 111). An optical multilayer film obtained by alternately laminating a low refractive index material and a high refractive index material, such as a photonic crystal color filter, has a forbidden band that does not transmit light. In Embodiment 2 of the present invention, a transmission band through which light is transmitted is designed so that near-infrared light is transmitted and used as an IR filter.

The R + IR transmissive region 313, the G + IR transmissive region 314, and the B + IR transmissive region 315 of the color filter 312 are formed by alternately laminating a low refractive index material and a high refractive index material at a film thickness of λ / 4 (λ: wavelength). This can be realized by introducing a “defect layer” having a film thickness different from λ / 4 into the optical multilayer film. Due to this defect layer, the optical periodicity is disturbed, and a transmission band can be generated in the forbidden band. By appropriately designing the thickness of the defect layer, a transmission band of a desired wavelength band can be realized. That is, R + IR pixels that transmit red light and near infrared light, G + IR pixels that transmit green light and near infrared light, B + IR pixels that transmit blue light and near infrared light, and only near infrared light transmit. A color filter having IR pixels can be easily designed. Simply adjusting the film thickness of each defect layer in the R + IR transmission region 313, G + IR transmission region 314, and B + IR transmission region 315, red light and near infrared light, green light and near infrared light, blue light and near infrared light. A light transmission band can be formed.

This will be specifically described with reference to FIG. FIG. 4 is a diagram illustrating an example of a cross-sectional configuration of the color filter 312 provided in the solid-state imaging device 310 of the imaging apparatus 300 according to Embodiment 2 of the present invention. As shown in FIG. 4, a color filter 312 is formed on the substrate 401.

A plurality of light receiving elements 111 are formed on the substrate 401, and an R + IR transmission region 313, a G + IR transmission region 314, a B + IR transmission region 315, and an IR transmission region 316 are formed on each of the plurality of light reception elements 111. .

The color filter 312 includes an n-layer film (

first films

402, 404, 406, and 408) made of a high refractive index material having a first refractive index, and a low refractive index having a second refractive index lower than the first refractive index. N-1 layer films (

second films

403, 405, and 407) composed of the following dielectric layers are included. Here, n is a natural number of 3 or more. Further, in the example illustrated in FIG. 4, the color filter 312 includes a planarization film 409 formed on the first film 408.

The

first films

402, 404, 406, and 408 are made of, for example, titanium dioxide (TiO ₂ ). The

second films

403, 405, and 407 are made of, for example, silicon dioxide (SiO ₂ ).

First films

404 and 406, which are two layers of n layers made of a high refractive index material, and one film of n-1 layers made of a low refractive index material The second film 405 is common to the R + IR transmission region 313, the G + IR transmission region 314, the B + IR transmission region 315, and the IR transmission region 316. That is, the

first films

404 and 406 and the second film 405 are included in a layer common to each region of the color filter 312, and when the set wavelength of incident light is λ, ¼ of the set wavelength λ. A film thickness equal to

In addition, among the n−1 layers of the low refractive index material, at least one film other than the second film 405 included in the common layer is different from the film thickness of the other layers. For example, the

second films

403 and 407 correspond to “defect layers” and have a film thickness different from λ / 4. The

second films

403 and 407 are layers used to control light to be transmitted, and transmit red, green, blue, or near-infrared light by changing the film thickness for each region.

As described above, in the structure in which the n-layer high refractive index film and the n-1 layer low-refractive index film are stacked, the film thickness of at least one layer of the low-refractive index film is set to the wavelength of light to be transmitted. Depending on the region, the transmission bands of red light and near infrared light, green light and near infrared light, blue light, near infrared light, and only near infrared light are different. Can be formed. In this manner, by adjusting the film thickness, a color filter having an arbitrary transmission wavelength characteristic region can be realized, so that high-definition color reproducibility can be realized.

The signal processing unit 320 is a DSP or the like that performs image signal processing on the image signal received from the solid-state image sensor 310. Compared with the signal processing unit 201 according to the first embodiment, the signal processing unit 320 newly includes a 4 × 4 matrix calculation circuit 321, a color difference calculation circuit 322, a near-infrared signal control circuit 323, and a k calculation circuit. 324.

The imaging control unit 330 includes an exposure time control unit 331 and an aperture control unit 332.

The exposure time control unit 331 controls the exposure time of the solid-state image sensor 310. For example, the exposure time control unit 331 determines the exposure time based on the control from the near-infrared signal control circuit 323, and controls the solid-state image sensor 310 so that the light receiving element 111 is exposed for the determined exposure time. .

The aperture control unit 332 controls the aperture 352. For example, the aperture control unit 332 determines the aperture amount of the aperture 352 based on the control from the near infrared signal control circuit 323, and controls the aperture 352 so as to realize the determined aperture amount.

The light source control unit 341 controls the irradiation amount of near-infrared light emitted from the IR light source 342 to the subject. For example, the light source control unit 341 determines the irradiation amount of near infrared light based on the control from the luminance calculation circuit 221.

The IR light source 342 irradiates the subject with an irradiation amount of near-infrared light determined by the light source control unit 341.

The objective lens 351 forms an image of incident light on the imaging region of the solid-state imaging device 310.

The diaphragm 352 controls the amount of light passing through the objective lens 351.

As shown in FIG. 3, the signal processing unit 320 outputs the luminance signal and the color signal of the pixels of the red (R), green (G), and blue (B) filters from the pixel signal output from the solid-state imaging device 310. Generate.

In order to generate the sub-pixel signals of the red (R), green (G), and blue (B) filter pixels from the pixel signal output from the solid-state imaging device 310, for example, in the case of red (R), Invisible light (IR) is obtained from a red (R) + near infrared (IR) signal that is an output signal of a sub-pixel having an R + IR transmission region 313 that transmits visible light (R) and invisible light (IR). Red (R) is derived by subtracting the near-infrared (IR) signal that is the output signal of the sub-pixel having the IR transmitting region 316 that transmits the light. Then, the derived red (R) may be used as the sub-pixel signal.

Also, if this pixel configuration is used, the red, green, and blue signals can be obtained by subtracting the IR signal component of the IR pixel from the original red, green, and blue signals including near-infrared light components in the daytime. Obtainable. Thus, the imaging apparatus 300 according to Embodiment 2 of the present invention does not require a mechanical IR cut filter even during daytime.

On the other hand, near-infrared light images are obtained at night by using signals from all pixels. Therefore, the resolution of the IR image is higher than that of the RGB image in the daytime because the IR components of R + IR pixels, G + IR pixels, and B + IR pixels are used.

Hereinafter, components included in the signal processing unit 320 will be described. Note that description of the same components as those in Embodiment 1 may be omitted.

The pixel signal output from the solid-state imaging device 310 includes an R + IR subpixel signal, a G + IR subpixel signal, a B + IR subpixel signal, and an IR subpixel signal. That is, each sub-pixel signal is different from the first embodiment in that it includes a near-infrared light component. The defect correction circuit 211, the OB calculation circuit 212, and the low-pass filter circuit 231 process the input pixel signal as in the first embodiment.

The 4 × 4 matrix calculation circuit 321 generates color signals of R, G, and B visible light by subtracting the IR signal subjected to specific gravity from the original signal of each sub-pixel. The specific gravity coefficient at this time is adjusted so that near-infrared light disappears from each sub-pixel signal. That is, the 4 × 4 matrix operation circuit 321 performs 3 × 4 matrix operations on the R + IR subpixel signal, the G + IR subpixel signal, the B + IR subpixel signal, and the IR subpixel signal, thereby generating three RGB signals. Generate and output.

After the difference processing, the color shading correction circuit 232 and the luminance shading correction circuit 233 execute the color shading correction and the luminance shading correction using output signals from adjacent pixels as in the case of the normal three primary colors. Further, the white balance adjustment circuit 234 adjusts the white balance of the pixel signal.

Further, signal processing is performed by the color difference calculation circuit 322, the hue correction circuit 235, and the color gain adjustment circuit 236. At this time, the color difference calculation circuit 322 calculates and outputs a plurality of color difference component signals (RY signal, BY signal) using a plurality of types of color signals (that is, R, G, B). Finally, the color signal output from the γ correction circuit 237 is output as an image signal to the display device or the like together with the luminance signal output from the luminance calculation circuit 221.

The hue correction circuit 235 corrects the color difference component signal output from the color difference calculation circuit 322 with the correction amount determined by the correction amount calculation circuit 241. The correction amount calculation circuit 241 uses the hue correction reference data input from the reference data input circuit 243 and stored in the reference data storage unit 242, and the two-dimensional coordinates of the light receiving element acquired by the coordinate acquisition circuit 244. The correction amount for each light receiving element is calculated.

In the present embodiment, the luminance calculation circuit 221 uses a signal output from a light receiving element equipped with a color filter that passes only near-infrared light (that is, an IR sub-pixel signal) in an operation for generating a luminance signal. To do. The luminance signal Y is calculated by luminance signal = (R + IR subpixel signal) + (G + IR subpixel signal) + (B + IR subpixel signal) + k × IR subpixel signal. That is, Y = (R + IR) + (G + IR) + (B + IR) + kIR.

Where k is an arbitrary variable. Specifically, it is a mixing coefficient indicating the mixing ratio of the IR sub-pixel signal with respect to the ((R + IR) + (G + IR) + (B + IR)) signal, or the mixing indicating the mixing ratio of the IR sub-pixel signal with respect to the luminance signal Y. It is a coefficient. In this case, k is determined within a range of −3 to +1.

For example, the k calculation circuit 324 calculates k. Specifically, the k calculation circuit 324 calculates the mixing coefficient according to the signal amount of the IR sub-pixel signal.

For example, when k = −3, the luminance calculation circuit 221 can generate the luminance signal Y from which the IR sub-pixel signal is completely removed. This is suitable for imaging in the daytime mode. When k = + 1, the luminance calculation circuit 221 can generate the luminance signal Y including all of the IR subpixel signals. This is suitable for generating a monochrome image. When k is an intermediate value between -3 and +1, a color image is generated, and the degree of colorization is determined according to k. This is suitable for colorizing in the night mode.

The near-infrared signal control circuit 323 controls the imaging control unit 330 according to the component amount of the near-infrared signal (IR subpixel signal) used for the luminance signal calculation, and sets the exposure amount of the solid-state imaging device 310 to a predetermined value. The value can be controlled.

Specifically, in order to adjust the exposure amount of the solid-state image sensor 310 to a predetermined value, the near-infrared signal control circuit 323 controls the exposure time control unit 331 to adjust the exposure time to a predetermined value. To do. Further, in order to adjust the exposure amount of the solid-state imaging device 310 to a predetermined value, the near-infrared signal control circuit 323 controls the aperture control unit 332 and adjusts the aperture 352 of the objective lens 351 to reduce the incident light amount. Adjust to a predetermined value. Further, in order to adjust the exposure amount of the solid-state imaging device 310 to a predetermined value, the near-infrared signal control circuit 323 controls the light source control unit 341 so as to irradiate the subject with predetermined near-infrared light. The irradiation amount of the light source 342 is adjusted.

The near-infrared signal control circuit 323 controls the color gain adjustment circuit 236 according to the output of the white balance adjustment circuit 234 in order to adjust the component amount of the IR subpixel signal applied to the color signal component. Then, adjust the gain. In particular, in order to obtain red color reproducibility such as signs required for in-vehicle cameras and security cameras, the amount of the near-infrared signal component is controlled so as to maximize the gain of the red signal. Further, the signal processing unit 320 gives the maximum gain to the step of generating a color reproduction signal composed of only the visible light component excluding the near-infrared signal component of each light receiving element and the step of generating the red signal component. Control.

Also, the near infrared signal control circuit 323 controls the amount of the near infrared light component applied to the luminance signal according to the intensity of the color reproduction signal.

In the imaging apparatus 300 according to Embodiment 2 of the present invention, the calculation of the hue correction amount and the hue correction processing are the same as the operations performed by the imaging apparatus 100 according to Embodiment 1 (see FIG. 2). . In the imaging device 300 according to Embodiment 2 of the present invention, each sub-pixel signal includes a near infrared component, but the 4 × 4 matrix calculation circuit 321 removes the near infrared component. Since the white balance adjustment circuit 234 and the hue correction circuit 235 perform processing on the signal from which the near-infrared component has been removed, the same processing as in the first embodiment can be performed.

As described above, the imaging apparatus 300 according to Embodiment 2 of the present invention includes the color filter 312 including the region that transmits near-infrared light and the signal processing unit 320, and the signal processing unit 320 includes the near-red light. An image signal including an external signal is processed. Specifically, the signal processing unit 320 removes the near-infrared light component from each of the sub-pixel signals including the near-infrared light component, and the signal from which the near-infrared light component is removed, that is, R, G, For each of the signals of B, a hue correction amount is determined, and the hue is corrected with the determined correction amount.

Thereby, according to the imaging apparatus 300 according to Embodiment 2 of the present invention, high-definition color reproducibility can be realized even in the case of an image signal including a near-infrared component. In addition, since near infrared signals are used, high-definition color reproduction is possible even in the night mode where the visible light signal is weak in image sensors that receive near infrared light at night, such as day and night cameras. Can be realized. As described above, since near infrared light is used, high-definition color reproducibility can be realized even under infrared light illumination such as at night.

Hereinafter, a comparative example of the embodiment of the present invention will be described.

First, in the comparative example of the embodiment of the present invention, color mixture shading due to obliquely incident light is color-corrected, and the correction data is calculated from the luminance ratio of green pixels adjacent to blue pixels or red pixels. Since this method performs color shading correction before white balance, it is possible to completely correct the spectral wavelength shift due to variations in the color filter performance (color unevenness) within the pixel array, which is a fixed value. Therefore, there is a problem that high-definition color reproduction cannot be performed.

Also, a method is conceivable in which the color shading correction amount is lighter than the luminance shading correction amount (about 1/3), and the color shading correction and the luminance shading correction are performed after white balance. In this method, the correction of the color information and the correction of the luminance information are obtained from the same gain information, so that the spectral wavelength shift due to the color filter performance variation (color unevenness) in the pixel array, which is a fixed value, is completely eliminated. Therefore, there is a problem that high-definition color reproduction cannot be performed.

Also, it is conceivable to adjust the saturation of the photographed image to correct the color shading. In this method, since color shading correction is performed before white balance, the spectral wavelength shift that causes color unevenness due to variations in the performance of color filters in the pixel array, which is a fixed value, is completely eliminated. There is a problem that correction cannot be performed and high-definition color reproduction cannot be performed.

As described with reference to the drawings for the comparative example of the above-described embodiment of the present invention, the imaging device and the signal processing method according to the embodiment of the present invention are thin films of color filters by reducing the height of pixels. In addition to miniaturization by increasing the number of pixels and increasing the number of pixels, high-definition color reproducibility is achieved by reducing color unevenness caused by variations in workmanship such as color filters due to large pixel arrays such as for digital SLR cameras. can do.

As mentioned above, although the imaging device and the signal processing method according to the present invention have been described based on the embodiments, the present invention is not limited to these embodiments. Unless it deviates from the meaning of this invention, the form which carried out the various deformation | transformation which those skilled in the art can think to the said embodiment, and the form constructed | assembled combining the component in a different embodiment is also contained in the scope of the present invention. .

For example, the components included in the

signal processing units

201 and 320 illustrated in FIGS. 1 and 3 do not necessarily have to include all of them. For example, the signal processing unit 201 may not include the addition circuit 238, and outputs the luminance signal calculated by the luminance calculation circuit 221 and the color difference signal corrected by the γ correction circuit 237 to an external display device or the like. May be.

In addition, the arrangement of the sub-pixels included in the unit pixel may not be a Bayer arrangement.

Further, all the numbers used above are illustrated for specifically explaining the present invention, and the present invention is not limited to the illustrated numbers. Further, the materials of the constituent elements shown above are all exemplified for specifically explaining the present invention, and the present invention is not limited to the exemplified materials. In addition, the connection relationship between the components is exemplified for specifically explaining the present invention, and the connection relationship for realizing the function of the present invention is not limited to this.

Further, the configuration of the imaging apparatus is for illustration in order to specifically describe the present invention, and the imaging apparatus according to the present invention is not necessarily provided with all of the above configurations. In other words, the imaging apparatus according to the present invention only needs to have a minimum configuration that can realize the effects of the present invention.

Similarly, the above-described signal processing method by the imaging apparatus is for illustration in order to specifically describe the present invention, and the signal processing method by the imaging apparatus according to the present invention does not necessarily include all the above steps. There is no need. In other words, the signal processing method according to the present invention needs to include only the minimum steps that can realize the effects of the present invention. In addition, the order in which the above steps are executed is for illustration in order to specifically describe the present invention, and may be in an order other than the above.

The imaging device and the signal processing method according to the present invention have the effect of being able to realize high-definition color reproducibility, such as a digital single-lens reflex camera, a digital camera, a camera-equipped mobile phone, and a day / night monitoring camera. Can be used.

100, 300

Imaging device

101, 310 Solid-

state image sensor

110, 311 Unit pixel 111

Light receiving element

112, 312 Color filter 113

Red region

114, 115 Green region 116 Blue region 121 Vertical shift register 122 Horizontal shift register 123 Noise removal circuit 124

Output amplifier

201, 320 Signal processing unit 211 Scratch correction circuit 212 OB calculation circuit 221 Luminance calculation circuit 231 Low-pass filter circuit 232 Color shading correction circuit 233 Luminance shading correction circuit 234 White balance adjustment circuit 235 Hue correction circuit 236 Color gain adjustment circuit 237 γ correction circuit 238 Addition circuit 241 Correction amount calculation circuit 242 Reference data storage unit 243 Reference data input circuit 244 Coordinate acquisition circuit 313 R + IR transmission region 314 G + IR transmission region 315 + IR transmission region 316 IR transmission region 321 4 × 4 matrix operation circuit 322 Color difference calculation circuit 323 Near infrared signal control circuit 324 k calculation circuit 330 Imaging control unit 331 Exposure time control unit 332 Aperture control unit 341 Light source control unit 342 IR light source 351 Objective lens 352 Diaphragm 401

Substrate

402, 404, 406, 408

First film

403, 405, 407 Second film 409 Flattening film

Claims

A plurality of pixels arranged two-dimensionally in the imaging plane;
A signal processing unit that processes a pixel signal output from each of the plurality of pixels,
Each of the plurality of pixels is
A plurality of light receiving elements;
A color filter comprising a plurality of regions formed on the plurality of light receiving elements and transmitting light of different wavelengths for each region;
The signal processing unit
A WB adjustment unit for adjusting the white balance of the pixel signal;
A reference data storage unit that stores correction reference data indicating characteristics of each color filter region in units of one or a plurality of pixels;
A coordinate acquisition unit for acquiring a two-dimensional coordinate indicating the position of the light receiving element in the imaging surface;
A correction amount calculation unit that determines a correction amount of hue based on the correction reference data stored in the reference data storage unit and the two-dimensional coordinates acquired by the coordinate acquisition unit;
An image pickup apparatus comprising: a hue correction unit that corrects the hue of the pixel signal after white balance is adjusted with the correction amount determined by the correction amount calculation unit.
The plurality of regions are:
A red region that transmits red light, a green region that transmits green light, and a blue region that transmits blue light,
The color filter is
A film of n (n is a natural number of 3 or more) layer composed of a high refractive index material having a first refractive index and n−1 composed of a low refractive index material having a second refractive index lower than the first refractive index. Including dielectric layers alternately stacked with layers of films,
Two of the n-layer films composed of the high refractive index material and one of the n-1 layer films composed of the low refractive index material are the red region, A layer common to the green region and the blue region,
In the red region,
2. The film thickness of one layer other than the one layer film included in the common layer among the n−1 layers composed of the low refractive index material is different from the film thickness of the other layers. The imaging device described.
The imaging device according to claim 2, wherein the plurality of regions further include a region that transmits only near-infrared light.
The correction amount is represented by a functional expression having the two-dimensional coordinates and the wavelength of light transmitted through the color filter as variables,
The imaging apparatus according to claim 1, wherein the reference data storage unit stores the functional expression as the correction reference data.
A signal processing method for processing a pixel signal output for each pixel from a solid-state imaging device in which a plurality of pixels are two-dimensionally arranged in an imaging surface,
Each of the plurality of pixels is
A plurality of light receiving elements;
A color filter comprising a plurality of regions formed on the plurality of light receiving elements and transmitting light of different wavelengths for each region;
The signal processing method includes:
A WB adjustment step for adjusting the white balance of the pixel signal;
A hue correction step of correcting the hue of the pixel signal after the white balance is adjusted,
In the hue correction step,
A hue correction amount is determined based on correction reference data indicating characteristics of each color filter region in units of one or a plurality of pixels and two-dimensional coordinates indicating the position of the light receiving element in the imaging surface. A signal processing method of correcting the hue of the pixel signal with the determined correction amount.
The signal processing method according to claim 5, wherein in the hue correction step, the correction amount is determined independently for each transmission characteristic of the color filter region, and the hue of the pixel signal is corrected.
The signal processing method according to claim 5, wherein in the hue correction step, the correction amount is determined so as to change monotonously with an increase in the two-dimensional coordinates.
The correction amount is represented by a functional expression having the two-dimensional coordinates and the wavelength of light transmitted through the color filter as variables,
The signal processing method according to claim 5, wherein in the hue correction step, the correction amount is determined using the function formula.
The signal processing method according to claim 5, wherein the correction reference data is a wafer in-plane distribution of transmittance of a color filter film formation monitor wafer created when the color filter is formed.
The signal processing method according to claim 5, wherein the correction reference data is a wafer in-plane distribution of a film thickness of all or a part of a color filter of a color filter film formation monitor wafer created when the color filter is formed.
The signal processing method further includes:
The signal processing method according to claim 5, further comprising a reference data calculation step of calculating the correction reference data using a pixel signal generated when reference light is incident on the solid-state imaging device.
The signal processing method according to claim 11, wherein the reference light is white light.
The signal processing method according to claim 11, wherein the reference light includes infrared light.
The signal processing method according to claim 11, wherein the reference light is light having a transmission center wavelength in transmission characteristics of the color filter region.