JP5409158B2 - Image pickup apparatus including single-plate color two-dimensional image pickup device - Google Patents

Description

  The present invention relates to a single-plate color two-dimensional imaging device and an imaging apparatus including the same, and more particularly to an imaging device having a color correction function and an imaging device suitable for the imaging device.

  As a conventional technique, there is Patent Document 1 as an apparatus for measuring the spectral characteristics of a light source. Further, there is Patent Document 2 as an apparatus for measuring reflection spectral characteristics of a subject. Further, as a technique for performing color correction from the measured spectrum of illumination light and the spectral reflectance of a color patch, there is Patent Document 3 and the like.

JP 62-185128 A JP 2008-139062 A JP 2008-244613 A

  However, in the measurement apparatuses such as Patent Document 1 and Patent Document 2, a sensor used for measurement is prepared exclusively. For example, when the sensor is used at the same time as an image pickup device that acquires an image, there is a problem of separately installing the measurement device and the image pickup device. was there. Further, in a color correction apparatus such as Patent Document 3, illumination light is measured using a spectroradiometer or measurement means such as Patent Document 1 and Patent Document 2, and when used simultaneously with an image pickup device that acquires an image, the measurement apparatus. And the problem of installing the image sensor separately.

  An object of the present invention is to provide an image pickup apparatus capable of simplifying the measurement necessary for color correction and simultaneously improving the accuracy of color correction by performing image acquisition and color correction measurements with a single image pickup apparatus, and a method suitable for the same. It is to realize an image sensor.

  In order to achieve the above object, according to the present invention, a part of a single-plate color two-dimensional imaging device is set as a monochrome pixel area (monochrome imaging area), and spectral characteristics are measured by performing appropriate optical filter processing on the monochrome pixel area. Alternatively, it is possible to extract spectral characteristic features of an illumination light source or obtain RGB values equivalent to those of a three-plate color imaging device. A lens defocus circuit is also provided, and the focus position of the lens is moved to MOD (shortest shooting distance, closest distance) or infinity during measurement. Furthermore, the operations of the lens defocus circuit, the spectral characteristic measurement circuit, and the lens light quantity measurement circuit are performed in conjunction with the start of white balance adjustment or the start of color correction adjustment.

  According to the present invention, there is an effect that an appropriate color correction can be easily realized with high accuracy in accordance with the condition of a light source irradiating a subject in a single-plate color imaging apparatus. In particular, by providing a monochrome pixel area on the same image sensor as the effective pixel area (color sensor) that performs image output, for example, the same image sensor characteristics, the same element temperature, and the same black reference signal can be obtained. A more stable signal can be obtained. Furthermore, since the same optical system is used, calibration and measurement can be performed relatively easily even with a camera that exchanges lenses. With the lens defocus circuit, the incident light to the monochrome pixel region or the like is diffused as much as possible, and the influence of unevenness in brightness on the surface of the achromatic color chart of the subject is suppressed, so that the spectral characteristics can be measured more accurately. Further, in conjunction with the white balance adjustment switch, there is an effect that appropriate color correction processing can be automatically performed at the time of white balance adjustment.

First embodiment of the present invention Configuration example of effective area and OB area of conventional solid-state imaging device Configuration of an image sensor in an embodiment of the present invention Configuration in which a continuous interference filter is mounted in the monochrome sensor area of FIG. Configuration with multiple bandpass filters in the monochrome sensor area of Fig. 3 Second embodiment of the present invention A configuration in which a plurality of bandpass filters for extracting light source characteristics are mounted in the monochrome sensor region of FIG. Third embodiment of the present invention A configuration in which a bandpass filter having the same spectral characteristics as a color separation optical prism used in a broadcast camera is mounted in the monochrome sensor region of FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In all the drawings, components having the same function are denoted by the same reference numerals, and repeated description thereof is omitted.

  A first embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 shows an image pickup apparatus (single plate color camera) according to a first embodiment of the present invention. In FIG. 1, 100 is a lens, and 101 is an image sensor (single plate color two-dimensional image sensor). Reference numerals 102, 103, and 104 denote an effective area (color sensor), a first OB area, and a second OB area (no light shielding) of the image sensor 101, respectively. Details of these will be described later. Reference numeral 105 denotes a pedestal adjustment circuit, 106 denotes a lens peripheral light amount correction circuit, 107 denotes a ROM circuit, 108 denotes an effective / OB area separation circuit, 109 denotes a color separation circuit, 110 denotes a white balance adjustment circuit, 111 denotes a color correction circuit, and 112 denotes a spectral signal A characteristic measurement circuit, 113 is a color correction coefficient calculation circuit, 114 is a ROM circuit, 115 is a white balance adjustment start switch, 116 is a color correction adjustment start switch, 117 is a lens peripheral light amount measurement circuit, 118 is an electronic shutter control circuit, and 119 is A sensor driving circuit 120 is a lens defocusing circuit.

  The image pickup device is configured by a single-plate color two-dimensional image pickup device that can obtain a color signal with one image pickup device by performing on-chip color filter processing on the surface of the effective area 102. Usually, on the light receiving surface of the image sensor, an effective pixel region (effective region) for obtaining a two-dimensional image signal and forming a video signal, and an optical black pixel region (hereinafter referred to as an OB region) for obtaining a black reference signal are obtained. Called). FIG. 2 shows such a conventional image sensor (solid-state image sensor). Reference numeral 201 denotes a conventional image sensor, 202 denotes an effective pixel area (effective area), 203 denotes a first OB area, 204 denotes a second OB area, and 205 denotes a light shielding film (such as an aluminum film).

  Here, the present embodiment will be described by taking as an example a configuration in which two OB regions are provided on both sides of an effective pixel region (effective region). FIG. 3 shows the configuration of the image sensor 101 in the embodiment of the present invention. Reference numeral 305 denotes a light shielding film (aluminum film or the like), and the others are as described with reference to FIG. According to the embodiment of the present invention, one of the two OB regions (the first OB region 103) is subjected to a light shielding process by a light shielding film (aluminum film or the like) 305, as in a normal imaging device. . On the other hand, the other OB area (second OB area 104) is not provided with a light-shielding film which is normally performed, and is not subjected to on-chip color filter processing, and as a result, used as a monochrome sensor. Is a monochrome pixel area (monochrome imaging area) (hereinafter, this area may be referred to as the monochrome sensor area 104 or the monochrome area 104).

  Here, the OB area has been described as having two locations on the left and right of the effective area 102, but the OB area may be located on the top and bottom of the effective area 102, or on the left, right, and top and bottom, and the OB area is shielded from light. Other combinations may be used for selecting the OB region that is not shielded from light. Further, the measurement accuracy may be improved by measuring spectral characteristics in a plurality of regions and averaging the measurement results. As described above, one of the features of the embodiment of the present invention is that a monochrome sensor region is provided on the same image sensor as the color sensor that outputs an image. Thereby, for example, the same image sensor characteristics, the same element temperature, and the same black reference signal are obtained, and a more stable signal can be obtained also in the monochrome sensor region 104. Furthermore, since the same optical system is used, calibration and measurement can be performed relatively easily even with a camera that exchanges lenses.

  The image sensor 101 is driven by a sensor drive circuit 119, and all pixel signals in the effective area 102, the first OB area 103, and the second OB area 104 on the light receiving surface are read out of the image sensor. The pixel signal including the effective area 102 and the second OB area 104 is converted into a black signal of the pixel signal based on the signal level of the first OB area 103 in the pedestal adjustment circuit 105 (also referred to as a black level adjustment circuit or a clamp circuit). Clamps the level and obtains stable characteristics against temperature changes. The signal output from the pedestal adjustment circuit 105 passes through the lens peripheral light amount correction circuit 106, the video signal from the effective area 102 is separated in the effective / OB area separation circuit 108, and sent to the color separation circuit 109. In the color separation circuit 109, the pixel signal obtained by the single-plate color two-dimensional imaging device 101 is separated into color signals such as R, G, and B, and sent to the white balance adjustment circuit 110 and the color correction circuit 111.

  On the other hand, the output signal (second OB region signal) from the monochrome sensor region 104 separated by the valid / OB region separation circuit 108 is sent to the spectral characteristic measurement circuit 112. The spectral characteristic measurement circuit 112 generates the spectral characteristic of the light source in the photographed image from the signal intensity obtained from the monochrome sensor region 104 by a method described later. The color correction coefficient calculation circuit 113 calculates an appropriate color correction coefficient based on the information obtained by the spectral characteristic measurement circuit 112. The color correction coefficient calculation circuit 113 also determines an appropriate light source condition based on information from the spectral characteristic measurement circuit 112, reads the appropriate color correction coefficient from the ROM circuit 114 that has been stored in advance, and uses it as a color correction coefficient. It may be used. Information obtained in this way from the color correction coefficient calculation circuit 113 is sent to the color correction circuit 111. The color correction circuit 111 performs an appropriate color correction process on the image signal from the color separation circuit 109 based on information from the color correction coefficient calculation circuit 113. As a result, the color correction circuit 111 outputs a color image signal after color correction.

  On the other hand, the signal from the color separation circuit 109 is also sent to the lens peripheral light amount measurement circuit 117. The lens peripheral light amount measurement circuit 117 is a circuit that measures the peripheral light amount of the lens, and measures the amount when the peripheral light amount decreases with respect to the central portion of the lens. At this time, the accumulation time of the sensor may be adjusted by sending a control signal to the electronic shutter control circuit 118 as necessary so that an exposure image suitable for measuring the amount of light around the lens can be obtained. The position of the lens peripheral light amount measurement circuit 117 may be, for example, before the color separation circuit 109 or after the white balance adjustment circuit 110 if appropriate for measurement.

  The lens peripheral light amount correction circuit 106 generates a function (for example, a two-dimensional parabolic shading correction function) for correcting the reduction amount of the lens peripheral light amount characteristic obtained as a result of the measurement by the lens peripheral light amount measurement circuit 117. Then, the pixel signal obtained by the image sensor 101 is corrected. Further, for example, lens information such as lens correction data output from the lens and lens identification signal (lens ID signal), an external lens selection signal by an artificial means, and the like are obtained by measurement or the like in advance in the ROM circuit 107. Correction processing may be performed using an appropriate stored correction value. The lens peripheral light amount correction circuit 106 not only enables image correction of a captured image in which the peripheral light amount is reduced by the lens with respect to the captured effective region image, but also the monochrome sensor region 104 of the image sensor 101. It is also possible to correct the amount of light corresponding to and correct the signal output from the monochrome sensor region 104 correctly.

  The lens defocus circuit 120 is linked to the white balance adjustment start switch 115 or the color correction adjustment start switch 116, and moves the focus position of the lens 100 to MOD (shortest shooting distance, closest distance) or infinity when the color correction adjustment starts. To do. As a result, the incident light to the monochrome sensor region 104 or the like is diffused as much as possible, and the influence of uneven brightness on the surface of the achromatic color chart of the subject is suppressed, so that the spectral characteristic measurement can be performed more accurately.

  Next, the principle of measuring spectral characteristics using the monochrome sensor region 104 will be described. A technique for measuring spectral characteristics using a monochrome line sensor is common (for example, Patent Document 1 and Patent Document 2), and will be briefly described with reference to FIG. A continuous interference filter 401 is mounted on the pixels of the monochrome sensor region 104 of the image sensor to measure spectral characteristics as shown in FIG. The continuous interference filter 401 is generally an interference spectroscopic filter generated on a wedge-shaped glass plate. The interference interference filter generated on the glass plate is made wedge-shaped so that one of the rectangular monochrome sensor regions 104 is formed. The interference film thickness is continuously changed from one terminal to the other terminal (from one side to the opposite side). By doing so, a spectral filter in which the transmission wavelength continuously changes depending on the distance from the terminal is formed by one interference filter. Therefore, the spectral intensity distribution of incident light can be calculated from the pixel position of the monochrome sensor region 104 and the pixel signal output thereof.

  FIG. 5 shows an example in which a plurality of band-pass filters 501 whose transmission wavelength bands are appropriately changed are mounted instead of the continuous interference filter of FIG. Examples of the bandpass filter 501 include an interference filter, a glass color filter, and a gelatin filter. Further, for example, a film may be formed on the pixel in the imaging element manufacturing process, and the color filter may be formed on-chip using a means such as staining. By changing the transmission wavelength band of the bandpass filter according to the distance from the monochrome sensor terminal, the spectral intensity distribution of the incident light can be calculated from the pixel position of the monochrome sensor and the output signal intensity, as in FIG. It becomes possible.

Next, the principle of performing color correction processing from the spectral distribution of the light source irradiated to the photographic subject will be described. A technique for performing color correction based on the measured spectrum of illumination light and the spectral reflectance of a color patch (for example, Patent Document 3) is based on the concept of color engineering and is generally described here. The subject of the camera is illuminated by a light source such as illumination or the sun, and the reflected light is incident on the image sensor through the lens of the camera. At this time, the illumination has a spectral intensity distribution P (λ) determined by the light source and having an intensity corresponding to the wavelength λ of light (hereinafter, P (λ) may be referred to as a spectral characteristic of the light source). The subject also has a spectral reflectance ρ (λ). The product of both is incident on the television camera as reflected light Cs (λ) from the subject. The television camera captures the reflected light with a color sensor in which pixels of the image sensor corresponding to, for example, R, G, and B have spectral sensitivities S _R (λ), S _G (λ), and S _B (λ), respectively. The output corresponding to the integrated value is output as the R, G, B color channel output signals. This can be expressed by the following equation (1).

このとき、被写体の分光反射率ρ（λ）を標準白色板などを用いてなるべく平坦にする、もしくは可能であれば既知のデータで校正することにより、被写体からの反射光Ｃｓ（λ）は、光源の分光分布Ｐ（λ）をできるだけ反映した特性とすることができる。すなわち、Ｃｓ（λ）のスペクトルを測定することにより、撮影環境の光源の分光特性を推定することが可能となる。また、ＲＧＢセンサの分光撮像特性をあらかじめ測定しておけば、そのセンサ出力ＲＧＢ値を計算で求めることが可能となる。従って、例えばマクベスチャートなど反射分光特性ρ（λ）が既知のデータを用いると、光源の分光特性を測定するだけで、各照明条件におけるカメラで撮影した例えばマクベスチャートの再現色を計算で作成することができる。以下、本実施例や他の実施例において、マクベスチャートを用いた例について説明するが、他のカラーチャートを用いてもよいことはいうまでもない。

At this time, the reflected light Cs (λ) from the subject is obtained by flattening the spectral reflectance ρ (λ) of the subject as much as possible using a standard white plate or by calibrating with known data if possible. The characteristic can reflect the spectral distribution P (λ) of the light source as much as possible. That is, by measuring the spectrum of Cs (λ), it is possible to estimate the spectral characteristics of the light source in the shooting environment. If the spectral imaging characteristics of the RGB sensor are measured in advance, the sensor output RGB value can be obtained by calculation. Therefore, when data having a known reflection spectral characteristic ρ (λ), such as a Macbeth chart, is used, a reproduction color of, for example, a Macbeth chart photographed with a camera under each illumination condition is created by calculation only by measuring the spectral characteristic of the light source be able to. Hereinafter, examples of using Macbeth charts will be described in this example and other examples, but it goes without saying that other color charts may be used.

  In general, when shooting with a broadcast camera, in order to adjust the white balance of the camera according to the shooting environment, an achromatic reflection subject such as a gray or white standard reflection chart is shot before shooting, and the RGB signal intensity at that time To adjust the RGB amplifier gain settings.

  Therefore, first, an achromatic standard reflection chart is photographed by the imaging apparatus of the present embodiment. The signal output from the monochrome sensor area 104 is input to the spectral characteristic measurement circuit 112 via the pedestal adjustment circuit 105, the lens peripheral light amount correction circuit 106, and the effective / OB area separation circuit 108. The spectral characteristic measurement circuit 112 obtains the spectral characteristic P (λ) of the light source from the pixel position of the monochrome sensor region 104 and the pixel signal output, and outputs the obtained spectral characteristic P (λ) of the light source. The spectral characteristic P (λ) of the light source output from the spectral characteristic measurement circuit 112 is input to the color correction coefficient calculation circuit 113.

In the color correction coefficient calculation circuit 113, the spectral characteristic P (λ) of the light source obtained by the spectral characteristic measurement circuit 112, the known Macbeth chart reflection spectral characteristic ρ (λ), and the single plate color of this embodiment measured in advance. The color spectral sensitivity characteristics S _R1 (λ), S _G1 (λ), and S _B1 (λ) of a single-plate color camera using the two-dimensional image sensor 101 are integrated and photographed with the single-plate color camera of this embodiment. An RGB value corresponding to the Macbeth chart image is generated by calculation (see Equation 1). Further, the spectral characteristic P (λ) of the light source obtained by the spectral characteristic measuring circuit 112, the known Macbeth chart reflection spectral characteristic ρ (λ), and the color spectral sensitivity of a general three-plate color camera for broadcasting measured in advance. The characteristics S _R2 (λ), S _G2 (λ), and S _B2 (λ) are integrated to generate an RGB value corresponding to a Macbeth chart image photographed by a three-plate color camera (see Formula 1). Data used for this calculation (Macbeth chart reflection spectral characteristic ρ (λ), color spectral sensitivity characteristics S _R1 (λ), S _G1 (λ), S _B1 (λ) of the single-plate color camera of this embodiment, The color spectral sensitivity characteristics S _R2 (λ), S _G2 (λ), and S _B2 (λ) of a general broadcasting three-plate color camera can be stored in the ROM circuit 114.

  For example, color correction can be performed using RGB values corresponding to two types of Macbeth chart images obtained by this calculation. That is, the RGB values obtained by correcting the RGB values of each of the 24 colors of the Macbeth chart of the single-plate color camera of the present embodiment obtained by the above calculation with the color correction coefficient are the general three-plate type for broadcasting obtained by the above calculation. A color correction coefficient is calculated so as to approach each RGB value of the color camera. For example, when performing color correction with a linear matrix, the RGB values of each of the 24 colors of the Macbeth chart of the single-plate color camera of the present embodiment are closest to the respective RGB values of a general 3-plate color camera for broadcasting. The correction coefficient of the linear matrix is obtained by the least square method.

  In the linear matrix correction, adjustment is performed by changing the RGB mixing ratio with the following primary conversion matrix of RGB three primary colors.

ここで、Ｒ_１，Ｇ_１，Ｂ_１は本実施例の単板式カラーカメラで撮影したマクベスチャートの画像に相当するＲＧＢ値、Ｒ_２，Ｇ_２，Ｂ_２は３板式カラーカメラで撮影したマクベスチャートの画像に相当するＲＧＢ値である。

Here, R ₁ , G ₁ , B ₁ are RGB values corresponding to the image of the Macbeth chart photographed with the single-plate color camera of this embodiment, and R ₂ , G ₂ , B ₂ are Macbeth photographed with the three-plate color camera. RGB values corresponding to the chart image.

  The correction matrix LM is

で算出する。実際には最小二乗法により最も近い行列を求める。具体的には例えば、いくつかの色票（例えばマクベスチャートの２４色）を選定し、補正処理後のＲＧＢ値をＲ_２’，Ｇ_２’，Ｂ_２’とすると、補正ターゲット（Ｒ_２，Ｇ_２，Ｂ_２）との差の二乗平均を、

Calculate with Actually, the nearest matrix is obtained by the least square method. Specifically, for example, when several color charts (for example, 24 colors of Macbeth chart) are selected and the RGB values after correction processing are R ₂ ′, G ₂ ′, B ₂ ′, correction targets (R ₂ , G ₂ , B ₂ )

とし、全ての色に対してその値が最も小さくなるようなＬＭを求める。このとき、任意の色票を選んだり、特定の色（例えば肌色）を重視して加重平均を行ってもよい。

And LM is obtained such that the value is the smallest for all colors. At this time, an arbitrary color chart may be selected, or weighted averaging may be performed with emphasis on a specific color (for example, skin color).

  The color correction coefficient calculation circuit 113 outputs the color correction coefficient calculated in this way (linear matrix coefficient when linear matrix correction is performed).

  Using the color correction coefficient obtained by the color correction coefficient calculation circuit 113, color correction processing (in the case of linear matrix correction, linear matrix color correction processing) in the color correction circuit 111 of the single-plate color camera (imaging device) of this embodiment. ), The color reproduction characteristics of the image pickup apparatus (single-plate color camera) of this embodiment can be brought close to the color reproduction characteristics of the three-plate color camera.

  Further, in this embodiment, the spectral characteristic measurement circuit 112, the color correction coefficient calculation circuit 113, the lens peripheral light amount measurement circuit 117, and the lens defocus circuit 120 are interlocked with the white balance adjustment start switch 115 or the color correction adjustment start switch 116. Appropriate color correction processing is performed simultaneously with the white balance adjustment or with the start of the color correction adjustment.

  A second embodiment using the present invention will be described with reference to FIGS.

  FIG. 6 shows an image pickup apparatus (single plate color camera) according to a second embodiment of the present invention. In FIG. 6, reference numeral 601 denotes an image sensor (single plate color two-dimensional image sensor). Reference numerals 602, 603, and 604 denote an effective area (color sensor), a first OB area, and a second OB area (no light shielding) of the image sensor 601, respectively. 612 is a light source feature extraction circuit, 613 is a color correction coefficient selection circuit, and 614 is a ROM circuit. The rest is the same as in the first embodiment.

  FIG. 7 shows the configuration of the image sensor used in the second embodiment. Similar to the first embodiment, a plurality of band pass filters 701 to 706 having different transmission wavelength bands are mounted on the monochrome sensor region 604 formed on the light receiving surface of the sensor. Reference numeral 707 denotes a light shielding film (aluminum film or the like) that covers a portion other than the effective region 602 and the bandpass filters 701 to 706.

  Here, as a light source generally used for camera photographing illumination, the spectral distribution spreads relatively flat from a short wavelength to a long wavelength, and the spectral distribution spreads similarly to sunlight, but the color temperature (black body) Various types of lamps, such as blue lamps, sun rays and sunsets whose radiation temperature is biased to short or long wavelengths, or halogen lamps that emit light due to filament heat, fluorescent lamps that have peaks characteristic of several wavelengths as artificial light sources, etc. A light source is conceivable. Among them, for example, it has been reported that fluorescent lamps can be classified according to several types of peak wavelengths. (Haraguchi Hidehiro, Tominaga Shoji, “Classification of fluorescent lamp illumination using a spectrum camera”, Information Processing Society of Japan Visual Information Study Group, A-11, 2004, etc.). Therefore, by selecting an appropriate transmission wavelength band for extracting the characteristics of the spectral characteristics of the light source as this bandpass filter, the signal output intensity from the monochrome sensor region 604 is a characteristic output corresponding to the spectral distribution of the light source. Thus, light source estimation can be performed. 7 illustrates the monochrome sensor region 604 provided with seven band-pass filters 701 to 706, the number of band-pass filters is the number that can extract the characteristics of the spectral characteristics of the light source. Any number is acceptable. Further, in FIG. 7, bandpass filters are provided in seven portions partitioned by the light shielding film 707. For example, as many bandpass filters as necessary for one rectangular monochrome sensor region as shown in FIG. It may be provided.

  In FIG. 6, the signal output from the pedestal adjustment circuit 105 is sent to the light source feature extraction circuit 612. The light source feature extraction circuit 612 estimates the light source used for illumination based on the signal output intensity from the monochrome sensor region 604. The ROM circuit 614 stores color correction coefficients appropriate for various light sources. The color correction coefficient selection circuit 613 selects an appropriate color correction coefficient from the ROM circuit 614 based on information from the light source feature extraction circuit 612, and the color correction circuit 111 performs color correction processing.

  A third embodiment using the present invention will be described with reference to FIGS.

  FIG. 8 shows an image pickup apparatus (single plate color camera) according to a third embodiment of the present invention. In FIG. 8, reference numeral 801 denotes an image sensor (single plate color two-dimensional image sensor). Reference numerals 802, 803, and 804 denote an effective area (color sensor), a first OB area, and a second OB area (no light shielding) of the image sensor 801, respectively. Reference numeral 809 denotes a color separation circuit, 812 denotes a memory circuit, 813 denotes a color correction coefficient calculation circuit, and 814 denotes a ROM circuit. Unlike the color separation circuit 109 of the first and second embodiments, the color separation circuit 809 not only outputs a signal to the white balance adjustment circuit 110 but also outputs a signal to the memory circuit 812. The signal (a) output from the color separation circuit 809 to the memory circuit 812 is a single-plate RGB output signal (effective area signal), and the signal (b) output from the effective / OB area separation circuit 108 to the memory circuit 812 is This is a three-plate RGB output equivalent signal (OB area signal). The rest is the same as in the first embodiment.

  FIG. 9 shows the configuration of the image sensor used in the third embodiment. As in the first embodiment, the RGB spectral characteristics in a general broadcasting three-plate color camera using an optical prism with respect to the monochrome sensor region 804 formed on the light receiving surface of the sensor using an interference filter or the like RGB band pass filters 901 to 903 that realize equivalent spectral characteristics are mounted. For example, 901 is an R band pass filter, 902 is a G band pass filter, and 901 is a B band pass filter. In FIG. 9, an RGB bandpass filter is provided in each of the three portions partitioned by the light shielding film 904. For example, the RGB bandpass is provided in different regions of one rectangular monochrome sensor region as shown in FIG. A filter may be provided.

  In the first embodiment, the RGB values corresponding to the Macbeth chart image photographed by the three-plate color camera are calculated by calculation. However, in the third embodiment, an actual Macbeth color chart placed in the photographing environment is used, By shooting up 24 colors on the subject (Macbeth color chart) with the image pickup apparatus of this embodiment, the same RGB signals as those shot with a single-plate color camera and a three-plate color camera can be acquired.

  That is, when any one of the 24 colors of the Macbeth color chart is photographed up with the imaging apparatus of the present embodiment, the imaging element 801 is driven by the sensor drive circuit 119, and the effective area 802 of the light receiving surface, the first All pixel signals in the OB area 803 and the second OB area (monochrome sensor area) 804 are read out to the outside of the image sensor. The pixel signal including the effective area 802 and the second OB area (monochrome sensor area) 804 clamps the black level of the pixel signal with reference to the signal level of the first OB area 803 in the pedestal adjustment circuit 105, Get stable characteristics against changes. The signal output from the pedestal adjustment circuit 105 passes through the lens peripheral light amount correction circuit 106, the video signal from the effective area 802 is separated in the effective / OB area separation circuit 108, and sent to the color separation circuit 809. In the color separation circuit 809, the pixel signal obtained in the effective area 802 of the single-plate color two-dimensional imaging device 801 is separated into R, G, and B color signals, sent to the white balance adjustment circuit 110, and to the memory circuit 812. Is also sent ((a) of FIG. 8). The memory circuit 812 stores the color signal intensities of R, G, and B as single plate R, G, and B values for one color of the Macbeth chart that is being photographed.

  On the other hand, the output signal (second OB area signal) from the monochrome sensor area 804 separated by the valid / OB area separation circuit 108 is sent to the memory circuit 812 ((b) of FIG. 8). The memory circuit 812 calculates the signal intensity from the pixel area in which the R, G, and B bandpass filters of the monochrome sensor area 804 are mounted, respectively, for each color of the Macbeth chart being photographed. Store as a value. The RGB band-pass filters 901 to 903 realize spectral characteristics equivalent to RGB spectral characteristics in a general broadcasting three-plate color camera using an optical prism, and are thus stored in the memory circuit 812. The three-plate RGB value can be said to be an RGB value corresponding to the RGB value when the same color of the Macbeth chart is photographed up by a general broadcasting three-plate color camera.

  When this is performed for all 24 colors of the Macbeth chart, the single-plate RGB values and the three-plate RGB values for each color are stored in the memory circuit 812. From the obtained RGB values of 24 colors, a color correction coefficient calculation circuit 813 obtains a color correction coefficient by the same method as in the first embodiment, and the color correction circuit 111 performs color correction processing.

  In each of the embodiments described above, a computer and a program may be used instead of the circuit.

  As described above, each embodiment of the present invention has been described in detail. However, the single-plate color two-dimensional image pickup device according to the embodiment of the present invention has a monochrome pixel region in which an optical filter is mounted in a portion other than the effective pixel region of the light receiving surface. And a single-plate color two-dimensional image sensor that outputs a signal from the effective pixel region and a signal from the monochrome pixel region, and the image pickup apparatus according to the embodiment of the present invention has the single-plate color two-dimensional image sensor. An image pickup apparatus that determines a color correction coefficient based on a signal from the monochrome pixel area of the image sensor and performs color correction of a signal from the effective pixel area of the single-plate color two-dimensional image sensor based on the color correction coefficient. That's fine.

  The single-plate color two-dimensional imaging element has an optical black pixel region for obtaining a black reference signal formed on a light receiving surface, and the optical black pixel region is provided with a light-shielding film. The shading film is not applied to the pixel area and the monochrome pixel area, and the imaging device receives signals from the optical black pixel area in addition to signals from the effective pixel area and signals from the monochrome pixel area. It may be a single-plate color two-dimensional image sensor that outputs a signal, and clamps the black level of the signal from the effective pixel region and the signal from the monochrome pixel region with reference to the signal from the optical black pixel region. It may be an imaging device.

  Further, the optical filter mounted in the monochrome pixel region of the single-plate color two-dimensional imaging device is a continuous interference filter or a plurality of bandpass filters having different transmission wavelength bands, and the imaging device is an achromatic reflection subject. A spectral characteristic measuring means for measuring a spectral intensity distribution of the light source from a pixel position of the monochrome pixel region when the image is taken and a pixel signal output thereof; a spectral intensity distribution of the light source measured by the spectral characteristic measuring means; The reflection spectral characteristics of the color chart and the color spectral sensitivity characteristics of the imaging apparatus measured in advance are integrated to calculate the first RGB value, and the spectral intensity distribution of the light source measured by the spectral characteristic measuring means, By integrating the reflection spectral characteristics of the known color chart and the color spectral sensitivity characteristics of the three-plate color camera measured in advance, the second RGB The color correction coefficient calculation means for calculating a color correction coefficient using the first RGB value and the second RGB value, and the color correction coefficient calculated by the color correction coefficient calculation means. The image pickup apparatus may include a color correction unit that performs color correction of a signal from the effective pixel region of the plate color two-dimensional image pickup device.

  The optical filter mounted in the monochrome pixel region of the single-plate color two-dimensional image sensor is a plurality of bandpass filters selected in a transmission wavelength band suitable for extracting the characteristics of the spectral characteristics of the light source. A light source feature extraction unit configured to estimate a light source based on a plurality of outputs corresponding to the plurality of bandpass filters from the monochrome pixel region when an achromatic reflection subject is photographed; and the light source Based on the light source estimated by the feature extraction means, the color correction coefficient selecting means for selecting the color correction coefficient from the color correction coefficients stored in the storage means, and the color correction coefficient selected by the color correction coefficient selecting means, The image pickup apparatus may include a color correction unit that performs color correction of a signal from the effective pixel region of the single-plate color two-dimensional image pickup device.

  The optical filter mounted in the monochrome pixel region of the single-plate color two-dimensional image sensor is a filter that realizes spectral characteristics equivalent to RGB spectral characteristics in a three-plate color camera, and the imaging device Means for obtaining a third RGB value obtained from a signal from the effective pixel region and a fourth RGB value obtained from a signal from the monochrome pixel region when a color chart placed in an environment is photographed; The single plate color 2 is obtained by color correction coefficient calculation means for calculating a color correction coefficient using the third RGB value and the fourth RGB value, and by the color correction coefficient calculated by the color correction coefficient calculation means. The image pickup apparatus may include a color correction unit that performs color correction of a signal from the effective pixel region of the two-dimensional image pickup device.

  The imaging apparatus may be an imaging apparatus that calibrates the signal output of the monochrome pixel region by a lens peripheral light amount correction unit.

  The imaging apparatus may be an imaging apparatus having a lens defocusing unit that moves the focus position of the lens to MOD (shortest shooting distance, closest distance) or infinity.

  The lens peripheral light amount measuring means for measuring the peripheral light amount of the lens and the lens defocusing means are interlocked with a white balance adjustment start switch or a color correction adjustment start switch. Based on the measurement result by the lens peripheral light amount measuring means, the lens peripheral light amount correcting means also calibrates the signal output of the monochrome pixel region, and the lens defocusing means sets the lens focus position to MOD (shortest shooting distance, closest distance) or It may be an imaging device that moves to infinity and determines the color correction coefficient.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiment. However, the invention is not limited to the embodiment, and various modifications can be made without departing from the scope of the invention. Of course.

DESCRIPTION OF SYMBOLS 100 ... Lens, 101 ... Image pick-up element (single-plate color two-dimensional image pick-up element), 102 ... Effective pixel area (effective area), 103 ... 1st OB area | region (optical black pixel area), 104 ... 2nd OB area | region ( (No shading) (monochrome pixel area), 105 ... pedestal adjustment circuit, 106 ... lens peripheral light amount correction circuit, 107 ... ROM circuit, 108 ... effective / OB area separation circuit, 109 ... color separation circuit, 110 ... white balance adjustment circuit, DESCRIPTION OF SYMBOLS 111 ... Color correction circuit, 112 ... Spectral characteristic measurement circuit, 113 ... Color correction coefficient calculation circuit, 114 ... ROM circuit, 115 ... White balance adjustment start switch, 116 ... Color correction adjustment start switch, 117 ... Lens peripheral light amount measurement circuit, 118 ... Electronic shutter control circuit, 119 ... Sensor drive circuit, 120 ... Lens defocus circuit, 601 ... Image sensor Single plate color two-dimensional imaging device), 602... Effective pixel region (effective region), 603... First OB region (optical black pixel region), 604... Second OB region (no light shielding) (monochrome pixel region), 612 ... Light source feature extraction circuit, 613 ... Color correction coefficient selection circuit, 614 ... ROM circuit, 801 ... Image sensor (single-plate color two-dimensional image sensor), 802 ... Effective pixel area (effective area), 803 ... First OB Area (optical black pixel area), 804... Second OB area (no light shielding) (monochrome pixel area), 809... Color separation circuit, 812... Memory circuit, 813. a) ... Single-plate RGB output signal (effective area signal), (b) ... 3-plate RGB output equivalent signal (OB area signal)

Claims (4)

In an imaging device including a single-plate color two-dimensional imaging device,
The single-plate color two-dimensional image sensor is
In a portion other than the effective pixel area of the light receiving surface, a monochrome pixel area having an optical filter mounted thereon,
Outputting a signal from the effective pixel region and a signal from the monochrome pixel region ;
An optical black pixel region for obtaining a black reference signal configured on the light receiving surface;
The optical black pixel area is provided with a light shielding film, and the effective pixel area and the monochrome pixel area are not provided with the light shielding film,
In addition to the signal from the effective pixel area and the signal from the monochrome pixel area, the optical black pixel area is output,
The optical filter is a single-plate color two-dimensional imaging device , which is a continuous interference filter or a plurality of bandpass filters having different transmission wavelength bands ,
A color correction coefficient is determined based on a signal from the monochrome pixel region of the single-plate color two-dimensional image sensor, and a color correction of a signal from the effective pixel region of the single-plate color two-dimensional image sensor is performed based on the color correction coefficient. An imaging device for performing
Spectral characteristic measurement means for measuring the spectral intensity distribution of the light source from the pixel position of the monochrome pixel region and the pixel signal output when shooting the achromatic reflection subject;
The spectral intensity distribution of the light source measured by the spectral characteristic measuring means, the reflection spectral characteristic of the known color chart, and the color spectral sensitivity characteristic of the imaging device measured in advance are integrated, and the first RGB value is calculated. The second RGB value is calculated by integrating the spectral intensity distribution of the light source measured by the spectral characteristic measuring means, the reflection spectral characteristic of the known color chart, and the color spectral sensitivity characteristic of the three-plate color camera measured in advance. Color correction coefficient calculating means for calculating a color correction coefficient using the first RGB value and the second RGB value;
Color correction means for performing color correction of a signal from the effective pixel area of the single-plate color two-dimensional imaging device, using the color correction coefficient calculated by the color correction coefficient calculation means;
An imaging apparatus comprising: In an imaging device including a single-plate color two-dimensional imaging device,
The single-plate color two-dimensional image sensor is
In a portion other than the effective pixel area of the light receiving surface, a monochrome pixel area having an optical filter mounted thereon,
Outputting a signal from the effective pixel region and a signal from the monochrome pixel region ;
An optical black pixel region for obtaining a black reference signal configured on the light receiving surface;
The optical black pixel area is provided with a light shielding film, and the effective pixel area and the monochrome pixel area are not provided with the light shielding film,
In addition to the signal from the effective pixel area and the signal from the monochrome pixel area, the optical black pixel area is output,
The optical filter is a single-plate color two-dimensional imaging device that is a plurality of bandpass filters having different transmission wavelength bands .
A color correction coefficient is determined based on a signal from the monochrome pixel region of the single-plate color two-dimensional image sensor, and a color correction of a signal from the effective pixel region of the single-plate color two-dimensional image sensor is performed based on the color correction coefficient. An imaging device for performing
The plurality of band-pass filters having different transmission wavelength bands are a plurality of band-pass filters selected to have an appropriate transmission wavelength band for extracting the characteristics of the spectral characteristics of the light source,
Light source feature extraction means for estimating a light source based on a plurality of outputs corresponding to the plurality of bandpass filters from the monochrome pixel region when an achromatic reflection subject is photographed;
A color correction coefficient selection means for selecting a color correction coefficient from the color correction coefficients stored in the storage means based on the light source estimated by the light source feature extraction means;
Color correction means for performing color correction of a signal from the effective pixel area of the single-plate color two-dimensional imaging device, using the color correction coefficient selected by the color correction coefficient selection means;
An imaging apparatus comprising: In an imaging device including a single-plate color two-dimensional imaging device,
The single-plate color two-dimensional image sensor is
In a portion other than the effective pixel area of the light receiving surface, it has a monochrome pixel area on which an optical filter is mounted,
Outputting a signal from the effective pixel region and a signal from the monochrome pixel region ;
An optical black pixel region for obtaining a black reference signal configured on the light receiving surface;
The optical black pixel area is provided with a light shielding film, and the effective pixel area and the monochrome pixel area are not provided with the light shielding film,
In addition to the signal from the effective pixel area and the signal from the monochrome pixel area, the optical black pixel area is output,
The optical filter is a single-plate color two-dimensional imaging device that is a plurality of bandpass filters having different transmission wavelength bands .
A color correction coefficient is determined based on a signal from the monochrome pixel region of the single-plate color two-dimensional image sensor, and a color correction of a signal from the effective pixel region of the single-plate color two-dimensional image sensor is performed based on the color correction coefficient. An imaging device for performing
The plurality of bandpass filters having different transmission wavelength bands are a plurality of bandpass filters that realize spectral characteristics equivalent to RGB spectral characteristics in a three-plate color camera,
Means for obtaining a third RGB value obtained from a signal from the effective pixel region and a fourth RGB value obtained from a signal from the monochrome pixel region when a color chart placed in a photographing environment is photographed When,
Color correction coefficient calculating means for calculating a color correction coefficient using the third RGB value and the fourth RGB value;
Color correction means for performing color correction of a signal from the effective pixel area of the single-plate color two-dimensional imaging device, using the color correction coefficient calculated by the color correction coefficient calculation means;
An imaging apparatus comprising: In the imaging device according to any one of claims 1 to 3 ,
Before SL based on the signal from the optical black pixel region, an imaging apparatus characterized by clamping the black level of the signal and the signal from the monochrome pixel area from the effective pixel region.

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