JP2010193378A - Adjustment device and adjustment method; and imaging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adjustment device and an adjustment method for accurately adjusting dispersion of a spectral sensitivity characteristic of an imaging element that may occur on a product basis; and an imaging device adjusted by the adjusting device. <P>SOLUTION: The adjustment device includes a light source part, a spectral part, a holding part, a memory, an obtaining part and a calculation part. The light source part emits a visible light ray. The spectral part spectrally disperses the visible light ray. The holding part holds this imaging device including an imaging element. The memory records data of a spectral sensitivity characteristic used as a reference of the adjustment. The obtaining part obtains image data of RGB by subjecting the visible light ray spectrally dispersed by the spectral part to photoelectric conversion by the imaging element. The calculation part respectively calculates, based on the image data obtained by the obtaining part, differences between respective RGB values obtained by multiplying the RGB values calculated on a predetermined wavelength basis by a predetermined coefficient, and respective corresponding RGB values on the basis of wavelength of the spectral sensitivity characteristic used as the reference to obtain a coefficient minimizing the average value of the sum of the differences. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an adjustment device and adjustment method for adjusting spectral sensitivity characteristics of an image sensor, and an imaging device.

  2. Description of the Related Art Conventionally, there has been disclosed an adjustment method for adjusting variation in spectral sensitivity characteristics of an image sensor that may occur for each product in an electronic camera that is one of imaging apparatuses (see, for example, Patent Document 1).

  However, in the adjustment method disclosed in Patent Document 1, consideration is given to fine adjustment for each wavelength (frequency) with respect to image data of R (red), G (green), and B (blue) primary color signals. There is room for improvement.

  SUMMARY OF THE INVENTION In view of the above circumstances, the present invention provides an adjustment device and an adjustment method for accurately adjusting variations in spectral sensitivity characteristics of image pickup devices that can occur for each product, and an image pickup device adjusted by the adjustment device. Objective.

  An adjustment device according to a first aspect includes a light source unit, a spectroscopic unit, a holding unit, a memory, an acquisition unit, and a calculation unit. The light source unit emits visible light. The spectroscopic unit performs spectral spectroscopy on visible light. The holding unit holds an imaging apparatus having an imaging element whose spectral sensitivity characteristics are to be adjusted. The memory records spectral sensitivity characteristic data which is a reference for adjustment. The obtaining unit obtains image data including a combination of R (red), G (green), and B (blue) color components by photoelectrically converting visible light spectrally separated by the spectroscopic unit using an image sensor. The calculation unit, based on the image data acquired by the acquisition unit, each RGB value obtained by multiplying the RGB value calculated for each predetermined wavelength by a predetermined coefficient, and each wavelength of the spectral sensitivity characteristic serving as a reference for adjustment The difference with each RGB value corresponding to is calculated, and the coefficient that minimizes the average value of the sum of the differences is obtained.

  The adjustment device according to the second invention includes a light source unit, a filter, a holding unit, a memory, an acquisition unit, and a calculation unit. The light source unit emits visible light. The filters have different pass wavelength bands in visible light. The holding unit holds an imaging apparatus having an imaging element whose spectral sensitivity characteristics are to be adjusted. The memory records spectral sensitivity characteristic data which is a reference for adjustment. The acquisition unit acquires image data including a combination of R (red), G (green), and B (blue) color components by photoelectrically converting visible light that has passed through the filter with an imaging device. The calculation unit, based on the image data acquired by the acquisition unit, each RGB value obtained by multiplying the RGB value calculated for each predetermined wavelength by a predetermined coefficient, and each wavelength of the spectral sensitivity characteristic serving as a reference for adjustment The difference with each RGB value corresponding to is calculated, and the coefficient that minimizes the average value of the sum of the differences is obtained.

  In a third aspect based on the first aspect, the coefficient is preferably a determinant of N rows and N columns.

  In a fourth aspect based on the first aspect, the coefficient is preferably a correction value calculated from a nonlinear gamma function.

  In a fifth aspect based on the first or second aspect, the arithmetic unit combines the determinant of N rows and N columns with a correction value calculated from a nonlinear gamma function, thereby calculating an average value of each difference. Minimize.

  An adjustment method according to a sixth aspect includes an imaging step, an acquisition step, and a calculation step. The imaging step irradiates an imaging apparatus having an imaging element whose spectral sensitivity characteristics are to be adjusted with visible light that is spectrally dispersed, and performs photoelectric conversion by the imaging element. In the acquisition step, image data including a combination of R (red), G (green), and B (blue) color components generated by photoelectric conversion is acquired. The calculation step includes each RGB value obtained by multiplying the RGB value calculated for each predetermined wavelength by a predetermined coefficient based on the image data acquired in the acquisition step, and each wavelength of the spectral sensitivity characteristic serving as a reference for adjustment. The difference with each RGB value corresponding to is calculated, and the coefficient that minimizes the average value of the sum of the differences is obtained.

  An adjustment method according to a seventh aspect includes an imaging step, an acquisition step, and a calculation step. The imaging step irradiates an imaging device having an imaging device whose spectral sensitivity characteristics are to be adjusted with visible light selectively passed by filters having different pass wavelength bands, and performs photoelectric conversion by the imaging device. In the acquisition step, image data including a combination of R (red), G (green), and B (blue) color components generated by photoelectric conversion is acquired. The calculation step includes each RGB value obtained by multiplying the RGB value calculated for each predetermined wavelength by a predetermined coefficient based on the image data acquired in the acquisition step, and each wavelength of the spectral sensitivity characteristic serving as a reference for adjustment. The difference with each RGB value corresponding to is calculated, and the coefficient that minimizes the average value of the sum of the differences is obtained.

  An imaging device according to an eighth invention includes an imaging element and a coefficient recording unit. The image sensor generates image data by photoelectric conversion. The coefficient recording unit records the coefficient calculated by the adjustment device according to any one of claims 1 to 5.

  According to the present invention, it is possible to accurately adjust the variation in spectral sensitivity characteristics of the image sensor that may occur for each product.

The block diagram which shows the structure of the adjustment apparatus 1 of this embodiment. The block diagram which shows the structure of the electronic camera 100 The block diagram which shows the structure of the computer 200 The figure explaining the visible light irradiated to the light-receiving surface of the image pick-up element 103 The figure explaining the image data recorded for every wavelength Schematic diagram illustrating spectral sensitivity characteristics that serve as a reference for adjustment Flow chart showing an example of the operation of the adjusting device Diagram showing an example of analog waveform image data The figure explaining the flow until the coefficient in the first embodiment is calculated The figure explaining the flow until the coefficient in 2nd Embodiment is calculated

(Description of the first embodiment)
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram illustrating a configuration of the adjusting device 1 according to the present embodiment. As shown in FIG. 1, the adjustment device 1 includes a dark room 10 and a computer (PC) 200. The dark room 10 is used to block light from the outside. Further, the dark room 10 includes a light source chamber 4, a spectroscopic chamber 5, and an electronic camera chamber 6. A slit 7 is provided between the light source chamber 4 and the spectroscopic chamber 5. A slit 7 is provided between the spectroscopic chamber 5 and the electronic camera chamber 6. The light source 2 is disposed in the light source chamber 4. The prism 3 is disposed in the spectroscopic chamber 5. A stage 9 is disposed in the electronic camera room 6 and holds the electronic camera 100. Further, the stage 9 moves up and down and left and right in response to an instruction from the computer 200. Thereby, the electronic camera 100 is arrange | positioned in the desired position.

  The light source 2 is a light source that emits light similar to sunlight (color temperature 5500K as an example).

  The prism 3 continuously spectrally separates visible light emitted from the light source 2. The relationship between the spectrally dispersed visible light and the image sensor will be described later. In the present embodiment, 380 nm to 780 nm is adopted as an example of visible light.

  Next, the adjustment electronic camera 100 will be described.

  FIG. 2 is a block diagram illustrating a configuration of the electronic camera 100. As shown in FIG. 2, the electronic camera 1 includes a photographing lens 101, a cut filter 102, an image sensor 103, an analog front end (hereinafter referred to as “AFE”) 104, a RAM (Random Access Memory) 105, A ROM (Read Only Memory) 106, an operation unit 107, a CPU (Central Processing Unit) 108, and a communication interface (I / F) 109 are provided.

  Among these, the AFE 104, the RAM 105, the ROM 106, the CPU 108, and the communication interface (I / F) 109 are connected to each other via the bus 110. The operation unit 107 is connected to the CPU 108.

  The taking lens 101 is composed of a plurality of lens groups including a zoom lens and a focus lens. For the sake of simplicity, FIG. 2 shows the photographing lens 101 as a single lens.

  The cut filter 102 cuts the wavelength component on the infrared side and the wavelength component on the ultraviolet side among the wavelength components of incident light. In this cut filter 102, an IR (InfraRed) cut filter for cutting an infrared component is deposited on an optical low-pass filter for cutting a wavelength of an ultraviolet component.

  The image sensor 103 generates image data by photoelectrically converting incident light from the photographing lens 101. As this image sensor 103, a CCD (Charge Coupled Devices) or a CMOS (Complementary Metal-Oxide Semiconductor) image sensor can be appropriately selected and used.

  Note that three types of RGB color filters are arranged in a known Bayer array on the light receiving surface of the image sensor 103 in order to detect incident light in color. Thus, three types of pixels of R pixel, G pixel, and B pixel are arranged on the light receiving surface of the image sensor 103. That is, the image data is composed of three types of signals: R signal (R), G signal (G), and B signal (B). Note that the Bayer array is an example, and the present invention is not limited to this array.

  The AFE 104 is an analog front end circuit that performs signal processing on image data generated by the image sensor 103. The AFE 104 performs image data gain adjustment, A / D conversion, and the like. Image data output from the AFE 104 is recorded in the RAM 105. The RAM 105 also functions as a frame memory.

  The ROM 106 is a non-volatile memory that stores a program for controlling the electronic camera 100 in advance. Note that a coefficient for adjusting variation in spectral sensitivity characteristics of the image sensor 103 is written in the ROM 106 during the adjustment work before factory shipment (details will be described later).

  The operation unit 107 includes, for example, a command dial, a cross-shaped cursor key, a power button, a release button, and the like. Then, the operation unit 107 receives an operation instruction input to the electronic camera 1.

  The CPU 108 is a processor that performs overall control of the electronic camera 100. The CPU 108 also has an image processing function, reads image data recorded in the RAM 105, and performs various image processing (gradation conversion processing, contour enhancement processing, white balance processing, etc.).

  A communication interface (I / F) 109 is a communication interface for realizing transmission / reception of image data and the like with the computer 200 by electrically connecting a communication cable (not shown). The communication interface (I / F) 109 may be a communication interface for realizing a wireless LAN (Local Area Network) that transmits and receives image data and the like wirelessly.

  Next, the computer 200 will be described.

  FIG. 3 is a block diagram illustrating a configuration of the computer 200. As illustrated in FIG. 3, the computer 200 includes a communication interface (I / F) 201, a ROM 202, a RAM 203, a computer CPU 204, a display monitor 205, and a keyboard 206. Here, the display monitor 205 and the keyboard 206 are also included in the computer 200 for convenience of explanation.

  A communication interface (I / F) 201 is a communication interface for realizing transmission and reception of image data and the like with the electronic camera 100 by being electrically connected by a communication cable (not shown). The ROM 202 is a non-volatile memory that stores programs for controlling the computer 200 in advance.

  A RAM 203 is a memory that records image data acquired by the electronic camera 100. A RAM 203 is a memory used for arithmetic processing of the computer CPU 204.

  The computer CPU 204 is a processor that performs overall control of the computer 200. In addition, a program for performing the adjustment method of the present embodiment is incorporated in the computer CPU 204. Thereby, the computer CPU 204 also functions as the imaging control unit 204a, the acquisition unit 204b, and the calculation unit 204c.

  The shooting control unit 204a causes the electronic camera 1 to perform still image shooting. That is, the imaging control unit 204 a issues an instruction to start imaging to the CPU 108 of the electronic camera 100 via the communication interface (I / F) 201. As a result, the CPU 108 of the electronic camera 100 receives a shooting start instruction from the shooting control unit 204a, and then sends a drive signal to the image sensor 103 via a timing generator (not shown) to take a still image. Let it be done. The image data obtained by taking the still image is recorded in the RAM 105 of the electronic camera 100.

  Here, image data obtained by taking a still image after receiving an instruction to start shooting from the shooting control unit 204a will be described. As an example, the image data obtained by taking a still image is data indicating the light intensity of visible light subjected to spectrum spectroscopy by a combination of RGB color components.

  FIG. 4 is a diagram for explaining visible light irradiated on the light receiving surface of the image sensor 103. As shown in FIG. 4A, the visible light emitted from the light source 2 is spectrally separated by the prism 3. At this time, the visible light (electromagnetic wave) passing through the prism is spectrally dispersed because the refractive index differs depending on the wavelength (frequency). In this case, the blue wavelength (380 nm) has a higher refractive index than the red wavelength (780 nm). By utilizing the properties of this prism, image data obtained by spectral spectroscopy can be acquired by one imaging, and the measurement time can be shortened. Therefore, in the adjustment device 1, the adjustment electronic camera 100 is arranged so that the spectrally dispersed wavelength (for example, 380 nm to 780 nm) can be received by the light receiving surface of the image sensor 103. In this case, when the stage 9 moves the electronic camera 100, the image sensor 103 is arranged at an optimal position.

  As shown in FIG. 4B, in the adjustment device 1, a filter 20 may be disposed between the light source 2 and the image sensor 103. The filter 20 has a pass wavelength band that allows a specific wavelength component to pass through in visible light. For example, image data can be acquired for each specific wavelength by using a plurality of filters 20 having different pass wavelength bands.

  The acquisition unit 204 b acquires image data (RGB image data) recorded in the RAM 105 of the electronic camera 100 via the communication interface (I / F) 201 and records it in the RAM 203.

  The calculation unit 204c calculates an RGB value for each predetermined wavelength based on the image data acquired by the acquisition unit 204b. In the present embodiment, for each wavelength (frequency), a plurality of specific wavelengths (frequencies) may be selected, or a plurality of wavelength bands (frequency bands) may be used. In the following example, description will be continued for each wavelength band. Therefore, it may be called a wavelength band.

  FIG. 5 is a diagram for explaining the image data recorded for each wavelength.

  FIG. 5A is a front view of the image sensor 103 and corresponds to an image diagram of a captured image. In this case, as shown in FIG. 4 (a), the visible light spectrally split by the prism 3 is incident as a spectral line in the vertical line direction of the image sensor 103 as shown in FIG. 5 (a). It becomes. Then, a continuous spectral line is formed in the horizontal line direction. For convenience of explanation, the left end is 380 nm and the right end is 780 nm when the image sensor 103 is viewed from the front.

  Here, each RGB value (each R value, G value, B value) of the image data of the spectral line corresponding to a certain wavelength band is represented by the RGB of the Bayer array in the vertical line direction as shown in FIG. The value is extracted and taken as an average value. For example, each RGB value takes a value from 0 to 255 as the dynamic range when 8-bit data is used. In this example, since the RGB values of two rows of Bayer arrays are extracted, the number of G is twice as large as the number of R and B, and accordingly, the correction may be made accordingly. In this way, the calculation unit 204c calculates an RGB value for each predetermined wavelength based on the image data acquired by the acquisition unit 204b. The RGB values are recorded in the RAM 203.

  Note that the RGB value for each wavelength may be calculated based on the position of the xy coordinates of the captured image (imaging device). And you may compare with the RGB value of the same xy coordinate in the picked-up image (imaging element) used as the reference | standard of adjustment.

  The calculation unit 204c calculates each RGB value obtained by multiplying the RGB value calculated for each predetermined wavelength by a predetermined coefficient. Furthermore, the calculation unit 204c calculates a difference from each RGB value corresponding to each wavelength of the spectral sensitivity characteristic that is a reference for adjustment, and obtains a coefficient that minimizes the average value of the sum of the differences (details will be described later). ).

  Next, an example of the operation of the adjustment device in the first embodiment will be described. A method for adjusting the electronic camera 1 will be described.

  Here, first, an outline of an adjustment method of the electronic camera 1 will be described. In the present embodiment, spectral sensitivity characteristics serving as a reference for adjustment are prepared in advance for a plurality of electronic cameras to be adjusted. This spectral sensitivity characteristic may be obtained by measurement or calculation.

  FIG. 6 is a schematic view illustrating the spectral sensitivity characteristic that is a reference for adjustment. Here, it is drawn as a schematic diagram for convenience of explanation. The adjustment device 1 according to the present embodiment is configured so that the electronic camera 100 to be adjusted is close to the spectral sensitivity characteristic (each RGB value for each wavelength) that is a reference for adjustment, and the image sensor between the electronic camera models. An adjustment method for suppressing variations in spectral sensitivity characteristics is provided. Hereinafter, a specific description will be given using a flowchart.

  FIG. 7 is a flowchart illustrating an example of the operation of the adjustment device.

  This flowchart is started when the computer CPU 204 receives an instruction to start the adjustment method program from the keyboard 206 after the electronic camera 100 to be adjusted is arranged in the adjustment apparatus 1 shown in FIG. It is assumed that the power source of the electronic camera 1 is turned on in advance. The light source 2 is also turned on in response to an instruction from the computer CPU 204 via a communication cable (not shown).

  As an example of analog waveform image data that is the basis of the spectral sensitivity characteristics of the image sensor 103 used for adjustment, the range from 380 nm to 780 nm (780-380 = 400 nm) is divided into 40 equal parts, and the wavelength Image data of spectral lines corresponding to a bandwidth of 10 nm is acquired.

  Step S101: Upon receiving an instruction to start shooting from the keyboard 206, the shooting control unit 204a of the computer CPU 204 turns on the light source 2 of the adjustment device 1 and then causes the electronic camera 100 to perform still image shooting. . The shooting control unit 204 a issues a shooting start instruction to the CPU 108 of the electronic camera 100 via the communication interface (I / F) 201. As a result, the CPU 108 of the electronic camera 100 sends a drive signal to the image sensor 103 via a timing generator (not shown) to perform still image shooting. Then, image data (analog data) of an analog waveform representing the light intensity of visible light subjected to spectrum spectroscopy is acquired. When the still image shooting is completed, the computer CPU 204 turns off the light source 2.

  FIG. 8 is a diagram illustrating an example of image data of an analog waveform. The imaging element 103 images continuous spectral lines from 380 nm to 780 nm via the prism 3. The CPU 108 captures a still image of one frame of continuous spectral lines, and then extracts image data for each wavelength (wavelength band: 10 nm). For easy understanding, light intensity distribution is extracted for each wavelength from one frame of still image data, and a still image of 40 frames (n is a natural number from 1 to 40) as shown in FIG. The image data is created. In FIG. 8, the light intensity for each wavelength (wavelength band: 10 nm) is shown. Image data (digital data) of a still image output from the AFE 104 is recorded in the RAM 105.

  Step S102: The acquisition unit 204b of the computer CPU 204 acquires the image data recorded in the RAM 105 of the electronic camera 100 via the communication interface (I / F) 201. Then, the acquisition unit 204b records the image data in the RAM 203. Further, the calculation unit 204c calculates each RGB value for each wavelength based on the image data recorded in the RAM 203. These RGB values are recorded in the RAM 203.

  Step S103: The calculation unit 204c of the computer CPU 204 calculates a coefficient based on each RGB value for each wavelength of the spectral sensitivity characteristic that is a reference for adjustment and each RGB value for each wavelength obtained by still image shooting. To do. The calculation of the coefficient will be described specifically with reference to FIG.

  FIG. 9 is a diagram for explaining a flow until a coefficient is calculated in the first embodiment.

  First, the arithmetic unit 204c reads out from the ROM 202 each RGB value (R, G, B) serving as an adjustment reference (target) as shown in FIG.

  Here, n is a natural number from 1 to 40. That is, the calculation unit 204c prepares 40 sets of RGB values (R, G, B) that are the reference for adjustment. Next, as shown in FIG. 9 (b), the calculation unit 204c has a determinant (coefficient) of 3 rows and 3 columns for each RGB value for each wavelength obtained by shooting a still image according to an instruction from the shooting control unit 204a. To calculate output values (R ′, G ′, B ′).

  Here, n is a natural number from 1 to 40.

  Next, as shown in FIG. 9C, the calculation unit 204c calculates the difference between each RGB value (R, G, B) serving as a reference for adjustment and the output value (R ′, G ′, B ′). Calculate for each wavelength.

  Here, n is a natural number from 1 to 40.

  Next, the arithmetic unit 204c calculates the average value of the sum of the differences from n = 1 to 40 as shown in FIG.

  Next, the calculation unit 204c adjusts the determinant (coefficient) of 3 rows and 3 columns so that the average value of the sum of the differences approaches the minimum (zero), and again, FIG. 9B and FIG. ), The process of FIG. 9D is repeated, and the calculation is repeated until the coefficients converge. Since this calculation itself is a known matrix calculation, its details are omitted. In this way, the calculation unit 204c finally calculates the coefficient.

  This coefficient is recorded in the RAM 203.

  Step S104: The computer CPU 204 reads the coefficient from the RAM 203, and transmits the coefficient (data) to the electronic camera 100 via the communication interface (I / F) 201. The electronic camera 100 receives the coefficient (data) via the communication interface (I / F) 109 and writes the coefficient (data) in the ROM 106. Then, the processing routine of the flowchart shown in FIG. 7 ends. In the case where the other electronic camera is continuously adjusted, the flowchart shown in FIG. 7 may be executed after the other electronic camera is installed in the adjusting device 1 again.

  As described above, according to the adjustment device 1 and the adjustment method of the first embodiment, it is possible to accurately adjust the variation in spectral sensitivity characteristics of the image sensor 103 that may occur for each product. Note that the variation in spectral sensitivity characteristics of the image sensor 103 is affected by the spectral characteristics of the IR cut filter and the color filter used in the image sensor 103. In the adjustment method of the first embodiment, it is possible to compensate for variations in spectral sensitivity characteristics caused by the IR cut filter and the color filter.

  Further, according to the adjustment method of the first embodiment, the coefficient can be easily obtained by using the determinant of 3 rows and 3 columns as the coefficient. Note that the 3 × 3 determinant is an example, and is not limited to the 3 × 3 determinant.

Furthermore, according to the electronic camera 100 of the first embodiment, the coefficient is recorded in the electronic camera 100 during the adjustment work, so that the spectral sensitivity characteristic of the image sensor 103 can be matched with the reference spectral sensitivity characteristic.
(Second Embodiment)
Next, a second embodiment of the present invention will be described. In the second embodiment, the computing unit 204c minimizes the average value of the sum of the differences by combining the determinant of 3 rows and 3 columns and the correction value calculated from the nonlinear gamma function. Note that the first embodiment of the present invention and the second embodiment of the present invention differ only in the mathematical processing (step S103 in FIG. 7) of the arithmetic unit 204c. Are denoted by the same reference numerals and description thereof is omitted. In the second embodiment, it is assumed that a coefficient (a determinant of 3 rows and 3 columns) is obtained in advance as in the first embodiment.

  Next, an example of operation | movement of the adjustment apparatus 1 in 2nd Embodiment is demonstrated.

  Note that a flowchart showing an example of the operation of the adjustment apparatus 1 will also be described with reference to FIG. For this reason, the processing in step S101 and step S102 is the same procedure as in the first embodiment, and a description thereof will be omitted.

  FIG. 10 is a diagram for explaining a flow until a coefficient is calculated in the second embodiment.

  Step S103: The computing unit 104c reads out from the ROM 202 each RGB value (R, G, B) serving as a reference for adjustment, as shown in FIG.

  Next, as shown in FIG. 10B, the calculation unit 204c calculates the coefficients (determinants of 3 rows and 3 columns) obtained in the first embodiment for each RGB value obtained by capturing a still image. To calculate output values (R ′, G ′, B ′).

Next, the calculation unit 204c performs so-called gamma correction on R ′, G ′, and B ′ individually for the output values (R ′, G ′, and B ′) for each wavelength. This gamma correction corrects the value of γ when y = ax ^{γ with} respect to the input x (FIG. 10C). A is a proportionality constant. In this case, the calculation unit 204c adjusts the gamma coefficients (γ _R , γ _G , γ _B ) for each RGB with respect to the input x (R ′, G ′, B ′) and outputs the output values (R ″, G ″, B ″) is calculated.

  Next, the arithmetic unit 204c calculates the average value of the sum of the differences from n = 1 to 40 as shown in FIG.

Next, the calculation unit 204c adjusts the gamma coefficient so that the average value of the sum of differences approaches the minimum (zero), and again in FIGS. 9C, 9D, and 9E. Repeat the process until the gamma coefficient converges. Since this calculation itself is a well-known mathematical process, details are omitted. In this way, the arithmetic unit 204c calculates the gamma coefficients (γ _R , γ _G , γ _B ) as correction values. The gamma coefficients (γ _R , γ _G , γ _B ) are recorded in the RAM 203.

Step S104: The computer CPU 204 reads out a coefficient (a determinant of 3 rows and 3 columns and a gamma coefficient (γ _R , γ _G , γ _B ) from the RAM 203 and transmits it to the electronic camera 100. The electronic camera 100 outputs the coefficient. The data is written in the ROM 106. Then, the processing routine of the flowchart shown in FIG.

  As described above, according to the adjustment device 1 and the adjustment method of the second embodiment, similarly to the first embodiment, the variation in spectral sensitivity characteristics of the image sensor 103 that may occur for each product can be adjusted with high accuracy. Further, according to the adjustment method of the second embodiment, it is possible to adjust more accurately than the first embodiment by combining the determinant of 3 rows and 3 columns and the gamma coefficient.

Furthermore, according to the electronic camera 100 of the second embodiment, since the coefficient is recorded in the electronic camera 100 during the adjustment operation, the spectral sensitivity characteristic of the image sensor 103 can be matched with the reference spectral sensitivity characteristic.
<Supplementary items of the embodiment>
(1) In the second embodiment, the calculation unit 204c combines the determinant of 3 rows and 3 columns with the correction value (gamma coefficient) of each RGB value calculated from the non-linear gamma function. Although the average value of the sum is minimized, the average value of the sum of the differences may be minimized by using only the correction value (gamma coefficient) calculated from the nonlinear gamma function.

  (2) In the first embodiment and the second embodiment, spectral sensitivity characteristics serving as a reference for adjustment are obtained by calculation. For example, when the spectral sensitivity characteristic of a predetermined electronic camera is adopted as a reference machine, preprocessing is performed in advance so that the spectral sensitivity characteristic of the reference machine is matched with the spectral sensitivity characteristic serving as a reference for adjustment. Thus, the other electronic camera for adjustment may be adjusted to the spectral sensitivity characteristic of the reference machine.

  (3) In the first embodiment and the second embodiment, the prism 3 is employed as the spectroscope. However, as shown in FIG. 4B, only visible light having a specific wavelength is transmitted without using the prism 3. You may make it selectively permeate | transmit visible light from the light source 2 using a filter. Even in this case, the same effect as the first embodiment and the second embodiment can be obtained.

  (4) In the first embodiment and the second embodiment, the computer CPU 204 includes the imaging control unit 204a, the acquisition unit 204b, and the calculation unit 204c, but may be included in the CPU 108 of the electronic camera 100.

  (5) In the first embodiment and the second embodiment, three types of RGB color filters are employed, but the present invention is not limited to this, and a similar adjustment method may be performed using a complementary color filter.

DESCRIPTION OF SYMBOLS 1 ... Adjustment apparatus, 2 ... Light source, 3 ... Prism, 20 ... Filter, 9 ... Stage, 106, 202 ... ROM, 204b ... Acquisition part, 204c ... Arithmetic unit, 100 ... electronic camera

JP 2001-197511 A

Claims (8)

A light source that emits visible light;
A spectroscopic unit for spectrally spectrally analyzing the visible light;
A holding unit that holds an imaging device having an imaging element whose spectral sensitivity characteristics are to be adjusted;
A memory for recording data of the spectral sensitivity characteristics as a reference for adjustment;
An acquisition unit that acquires image data including a combination of R (red), G (green), and B (blue) color components by photoelectrically converting visible light spectrally separated by the spectroscopic unit with the imaging device;
Each RGB value obtained by multiplying a predetermined coefficient by an RGB value calculated for each predetermined wavelength based on the image data acquired by the acquisition unit, and for each wavelength of the spectral sensitivity characteristic that serves as a reference for adjustment Calculating a difference with each corresponding RGB value, and calculating the coefficient that minimizes the average value of the sum of the differences;
An adjustment device comprising: A light source that emits visible light;
Among the visible light, filters each having a different pass wavelength band;
A holding unit that holds an imaging device having an imaging element whose spectral sensitivity characteristics are to be adjusted;
A memory for recording data of the spectral sensitivity characteristics as a reference for adjustment;
An acquisition unit that acquires image data including a combination of R (red), G (green), and B (blue) color components by photoelectrically converting visible light that has passed through the filter with the imaging device;
Each RGB value obtained by multiplying a predetermined coefficient by an RGB value calculated for each predetermined wavelength based on the image data acquired by the acquisition unit, and for each wavelength of the spectral sensitivity characteristic that serves as a reference for adjustment Calculating a difference with each corresponding RGB value, and calculating the coefficient that minimizes the average value of the sum of the differences;
An adjustment device comprising: The adjustment device according to claim 1 or 2,
The adjustment apparatus is characterized in that the coefficient is a determinant of N rows and N columns. The adjustment device according to claim 1 or 2,
The adjustment device is characterized in that the coefficient is a correction value calculated from a nonlinear gamma function. The adjustment device according to claim 1 or 2,
The said calculating part combines the determinant of the said N row N column and the correction value calculated from a nonlinear gamma function, The adjustment apparatus characterized by the above-mentioned. An imaging step of irradiating an imaging device having an imaging device whose spectral sensitivity characteristic is to be adjusted with spectrally visible light, and performing photoelectric conversion with the imaging device;
An acquisition step of acquiring image data composed of a combination of R (red), G (green), and B (blue) color components generated by the photoelectric conversion;
Based on the image data acquired in the acquisition step, each RGB value obtained by multiplying the RGB value calculated for each predetermined wavelength by a predetermined coefficient, and for each wavelength of the spectral sensitivity characteristic that is a reference for adjustment A calculation step of calculating a difference between each corresponding RGB value and obtaining the coefficient that minimizes an average value of the sum of the differences;
The adjustment method characterized by comprising. An imaging step of irradiating an imaging apparatus having an imaging element whose spectral sensitivity characteristics are to be adjusted selectively with visible light that has been selectively passed by filters having different pass wavelength bands, and performing photoelectric conversion with the imaging element;
An acquisition step of acquiring image data composed of a combination of R (red), G (green), and B (blue) color components generated by the photoelectric conversion;
Based on the image data acquired in the acquisition step, each RGB value obtained by multiplying the RGB value calculated for each predetermined wavelength by a predetermined coefficient, and for each wavelength of the spectral sensitivity characteristic that is a reference for adjustment A calculation step of calculating a difference between each corresponding RGB value and obtaining the coefficient that minimizes an average value of the sum of the differences;
The adjustment method characterized by comprising. An image sensor that generates image data by photoelectric conversion;
A coefficient recording unit that records the coefficient calculated by the adjustment device according to any one of claims 1 to 5,
An imaging apparatus comprising:

Images