JP2011064637A - Light source detection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accelerate the speed of processing for estimation of a spectrum or identification of the type of a light source by a simpler hardware configuration, even when the measurement luminance range is wide and measurement targets are the light sources of a large number of types. <P>SOLUTION: A light source detection system 400 includes: a light detecting section 408, having a plurality of photoelectric conversion sections each a having different spectral sensitivity characteristics; an illumination discriminating section 402, capable of discriminating illumination light from a measurement target into two or more types; an operation condition determining section 404 for determining the condition for a light detection operation, performed by the light detection section 408, based on the discrimination result by the illumination discriminating section 402; a measurement control section 406 for controlling the light detection operation performed by the light detection section 408, based on the operation condition; and an illumination estimation processing section 410 for performing at least one of an illumination detail discrimination processing and an illumination spectrum estimation processing, based on the light detection result obtained by the light detection operation by the light detecting section 408. The illumination estimation processing section 410 discriminates illumination light into types which are more than the types that the illumination discrimination section 402 can be discriminated. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a light source detection device, and more particularly to a light source detection device capable of determining the type of illumination or estimating an illumination spectrum based on signals obtained from sensors having a plurality of types of spectral sensitivity characteristics.

  In recent years, digital cameras have become widespread, and not only resolution but also color reproducibility is improving. Patent Document 1 discloses a multispectral camera as a device that can obtain further color reproducibility. This multispectral camera is configured to be able to photograph a subject as spectral data for each pixel. The multispectral camera also has a photographing light spectrum detection unit that detects a spectral distribution of illumination light that illuminates a place where the subject is photographed.

  The photographing light spectrum detection unit includes a plurality of color filters, a photodiode having a plurality of photoelectric conversion units arranged at positions to receive light transmitted through the respective color filters, and a white transmission unit arranged in front of the color filters. And a mold diffuser plate. The photographing light diffused by the diffusion plate passes through each of the color filters and enters the photodiode.

  As described above, the method of detecting the amount of light transmitted through a plurality of color filters with a photodiode is advantageous in terms of cost and size compared to a method using a diffraction grating or an interference filter, Spectral detection may be difficult due to the limitations described below in the spectral transmission characteristics that can be realized with a color filter. This will be described with reference to FIGS.

  FIG. 1 is a graph showing an example of spectral sensitivity characteristics of each of 14 sensors provided with color filters having different spectral sensitivity characteristics on the front side of the light receiving unit. In the graph of FIG. 1, the horizontal axis represents the wavelength and the vertical axis represents the relative sensitivity. In FIG. 1, 14 spectral transmission characteristic curves are drawn, and numbers 1 to 14 are assigned to the respective curves. Here, a sensor including a filter having the first spectral sensitivity characteristic is referred to as a first sensor. The same applies to the 2nd sensor to the 14th sensor. The spectral transmission characteristic of each sensor is obtained by multiplying the spectral sensitivity characteristic of each sensor by the spectral transmission characteristic of each filter. Assuming that the spectral sensitivity characteristics of the sensors themselves are substantially the same from the first sensor to the fourteenth sensor, the spectral transmission characteristics of each filter can be inferred from FIG.

  For example, the color filter of the first sensor exhibits a relatively wide spectral transmission characteristic with a peak wavelength of about 530 nm, and transmits a larger amount of light than other color filters. On the other hand, the filter of sensor No. 14 has a characteristic of slightly transmitting near-infrared light with a peak wavelength of about 750 nm. Assuming that the illumination light to be detected is white light, the amount of light detected by the 14th sensor is considerably smaller than the amount of light detected by the 1st sensor.

  FIG. 2 shows examples of output values obtained from the first sensor to the fourteenth sensor when the illumination light is sunlight or fluorescent lamp light. In FIG. 2, the horizontal axis represents the wavelength, and the vertical axis represents the sensor output value. The sensor output value on the vertical axis indicates the relative output value of each sensor logarithmically compressed when the maximum value among the outputs obtained from the 14 sensors is 1.

  When the illumination light is sunlight, there is a difference of about 2,400 times between the maximum value (1st sensor) and the minimum value (14th sensor) of the sensor output. Further, when the illumination light is not continuous in spectral spectrum such as a fluorescent lamp and includes a bright line spectrum, a large difference in incident light amount occurs between a sensor that receives this bright line spectrum component and other sensors. As a result, in the example shown in FIG. 2, there is a difference of about 63,000 times between the maximum value (1st sensor) and the minimum value (14th sensor) of the sensor output.

  As described above, the amount of light incident on the photodiode portion of each color sensor as a result of the difference in spectral transmission characteristics of the color filters provided corresponding to the respective color sensors and the spectral radiance characteristics of the illumination light itself. Make a big difference. Therefore, even if the illumination light has a constant luminance, a wide dynamic range is required for the photodiode and its readout circuit. Actually, since the brightness of the illumination light to be detected varies variously according to changes in the photographing situation, a wider dynamic range is required for the sensor and the circuit for processing the sensor output.

  When measurement is performed using a photosensor such as a CMOS sensor or a CCD that detects the amount of incident light by integrating the photocurrent generated by the photodiodes, sufficient accuracy can be obtained from all the sensors in one integration operation for the reasons described above. It is difficult to obtain an output signal. For example, in the example of FIG. 1, it is difficult to obtain a sufficiently large signal from the 14th sensor even if the integration operation is performed once with the longest integration time in a range where the 1st sensor is not saturated. In that case, it is necessary to perform the measurement a plurality of times while changing the integration time or changing the gain when amplifying the signal output from the sensor. For example, when a light source detection sensor is provided in a digital camera, if it takes a long time to measure, there is a problem that the photographing timing and the light source detection completion timing are greatly shifted and the light source detection result cannot be reflected well in the image data processing.

  As a technique that can cope with the above problems, Patent Document 2 discloses a technique in which the opening areas of the sensors differ from each other according to the sensitivity of the sensors of the respective colors. In other words, the sensitivity can be increased by increasing the opening area of the sensor having a relatively low sensitivity, so that the output difference between the sensors can be reduced.

JP-A-9-172649 JP 2004-31732 A

  However, in the technique disclosed in Patent Document 2, the configuration of the sensor circuit is complicated. In addition, since the types of light sources to be measured are diverse, it is difficult to configure hardware that can handle all types of light sources and usage conditions.

  The present invention has been made in view of the above-described problems, and does not require a complicated hardware configuration, has a wide measurement luminance range, and has many types of light sources to be measured. The purpose is to provide a technology capable of identifying the above.

(1) According to the first aspect of the present invention, the light source detection device comprises:
A light detection unit having a plurality of photoelectric conversion units having different spectral sensitivity characteristics;
An illumination discriminator capable of discriminating two or more types of illumination light to be measured;
An operation condition determination unit that determines an operation condition of a light detection operation performed in the light detection unit based on a determination result in the illumination determination unit;
A measurement control unit that controls the light detection operation performed by the light detection unit based on the operation condition determined by the operation condition determination unit;
An illumination estimation processing unit that performs at least one of the illumination detail determination process and the illumination spectrum estimation process based on a light detection result obtained by a light detection operation performed by the light detection unit;
The illumination detail determination process solves the above-described problem by including a process of determining the illumination light of the measurement object into a larger number of types than the number of types that can be determined by the illumination determination unit.

  According to the present invention, the illumination discriminating unit discriminates two or more types of illumination light to be measured, and based on the discrimination result, the operating condition of the light detection operation performed by the photodetecting unit is determined. Then, the light detection operation performed by the light detection unit is controlled based on the operation condition determined by the operation condition determination unit, and based on the light detection result obtained as a result, a type of type that can be determined by the illumination determination unit The illumination light to be measured is discriminated into a larger number of types than the number. This makes it possible to perform simple measurement of spectral characteristics when it is determined that the illumination light to be measured has a spectral profile that changes relatively slowly, such as sunlight or tungsten light. It becomes possible to improve the responsiveness by increasing the speed of the light source detection operation.

It is a figure explaining an example of the spectral sensitivity characteristic of the sensor which has a photoelectric conversion part from which spectral sensitivity differs mutually. It is a figure which shows the example of a sensor output in case illumination light is sunlight, such as fluorescence. It is a figure which shows the example of the spectral characteristic of a light source. It is a block diagram explaining the schematic structure of a light source detection system. It is a figure explaining the schematic structure of an imaging device and a light source detection system, (a) is a block diagram explaining the schematic structure of an imaging device, (b) and (c) are the structural examples of a light source detection part. (D) is a figure explaining the example of arrangement | positioning of the photoelectric conversion part provided in a spectrum sensor. It is a figure which shows an example of the spectral sensitivity characteristic of the photoelectric conversion part provided in a spectrum sensor. It is a figure which shows the example of a sensor output in case illumination light is sunlight, such as fluorescence. It is a schematic flowchart explaining the procedure of the illumination estimation process performed with a light source detection system. It is a schematic flowchart explaining the procedure of the illumination discrimination | determination process performed with a light source detection system. It is a table | surface explaining the operating conditions of a spectrum sensor. It is a schematic flowchart explaining another example of the illumination discrimination | determination processing procedure performed with a light source detection system. It is a schematic flowchart explaining another example of the illumination estimation processing procedure performed with a light source detection system, and is a schematic flowchart explaining the example which performs an illumination estimation process corresponding to the case where flash light emission is accompanied at the time of imaging | photography. It is a schematic flowchart explaining the process sequence performed following the process sequence shown by the flowchart of FIG. 12A. It is a table | surface explaining the operating condition of the spectrum sensor when not accompanied by flash emission.

  FIG. 3 shows the spectral characteristics of a typical light source. In FIG. 3, the horizontal axis indicates the wavelength, and the vertical axis indicates the relative intensity of light with respect to each wavelength. Sunlight and incandescent light bulbs have relatively gentle intensity changes with respect to wavelength changes, and have a relatively wide wavelength band from short wavelengths to long wavelengths. That is, these sunlight and incandescent bulb light have a continuous spectrum and do not have the bright line spectrum that fluorescent light has. Using another representation, these sunlight and incandescent bulb light have a spectral distribution close to that of blackbody radiation.

  In addition to sunlight and incandescent bulb light, FIG. 3 shows the spectral characteristics of three typical fluorescent lamp lights, that is, a three-wavelength day white fluorescent lamp, a white fluorescent lamp, and a daylight fluorescent lamp. All fluorescent lamp lights have a continuous spectrum, but some of the emission line spectra derived from mercury are included. As a further feature of the fluorescent lamp light, there is less light of wavelength components in the red to infrared region than sunlight and incandescent light. Moreover, it has the characteristic that there are few near ultraviolet-ultraviolet light components in fluorescent lamp light compared with sunlight.

  Here, consider a case where the spectral characteristics of light are measured over a predetermined band, for example, a band from a wavelength of 380 nm to 780 nm which is a human visible range. When the spectral distribution is similar to black body radiation and the intensity change with respect to the wavelength change is relatively gentle like the spectral characteristics of sunlight and incandescent bulb light, relatively large wavelengths such as 100 nm and 200 nm, for example. It is possible to measure spectral characteristics at intervals and then estimate spectral characteristics corresponding to unmeasured wavelengths by interpolation processing. By doing so, the time required for measurement can be greatly shortened. In this specification, such measurement is referred to as “simple measurement of spectral characteristics”.

  On the other hand, in the case of the fluorescent line light having an emission line spectrum, it has a discontinuous peak in the profile of spectral characteristics and is not gentle (the spectral intensity change with respect to the wavelength change is relatively large). It is difficult to apply the interpolation process. Therefore, it is required to measure at a relatively small wavelength interval. In addition, as described with reference to FIG. 2, the dynamic range required for measurement increases, so it is necessary to repeatedly measure by changing the integration time and gain, and time is required for measurement. In the present specification, such measurement is referred to as “detailed measurement of spectral characteristics”.

  As will be apparent from the following description, the embodiment of the present invention roughly determines what the illumination light to be measured is, and based on the determination result, the spectral characteristics can be simply measured or detailed. Measure.

  FIG. 4 is a block diagram schematically showing the configuration of the light source detection system 400 according to the embodiment of the present invention. The light source detection system 400 includes an illumination determination unit 402, an operation condition determination unit 404, a measurement control unit 406, a light detection unit 408, and an illumination estimation processing unit 410. The light source detection system 400 can perform spectrum estimation processing of illumination light to be measured (this is referred to as “measurement target light” in this specification) or detailed illumination determination processing.

  Here, the spectrum estimation process means a process for estimating the spectrum of the measurement target light. Further, the illumination detail determination process means a process for determining in detail the type of measurement target light. For example, if the light to be measured is a white fluorescent light, a light bulb color fluorescent light, a three-wavelength daylight white fluorescent light, a daylight color fluorescent light, an incandescent light bulb, sunlight, or sunlight, it will be The process of determining in detail the type of light to be measured, such as whether it is light, daylight, evening light, clear sky light, or cloudy light, is the detailed illumination determination process.

  The light source detection system 400 may be configured to operate as a single unit and display or output the light source detection processing result to the outside, for example, a digital photographing device such as a still camera or a movie camera. (Hereinafter simply referred to as “photographing apparatus”). In the present embodiment, the light source detection system 400 will be described as being incorporated in a photographing apparatus 500 described later with reference to FIG. In the embodiment of the present invention, the light source detection system 400 will be described below using illumination light that illuminates a subject at the time of photographing (referred to as “photographing illumination light” in this specification) as measurement target light. Thus, the spectrum estimation process or the detailed illumination determination process is configured.

  FIG. 5 is a diagram schematically illustrating a configuration of an imaging device 500 in which the light source detection system 400 is incorporated. FIG. 5A schematically shows the internal configuration of the photographing apparatus 500. 5B and 5C show examples of the internal configuration of the light detection unit 408 included in the light source detection system 400. FIG. FIG. 5D schematically shows the configuration of the spectrum sensor 420.

  The photographing apparatus 500 includes a photographing lens 502, an infrared cut filter 503, an optical low-pass filter 504, an image sensor 506, and a device control unit 450. A light source detection system 400 is incorporated in the photographing apparatus 500. Hereinafter, the light source detection system 400 will be described as being incorporated in the imaging apparatus 500, but the light source detection system 400 may be detachably attached to the imaging apparatus 500. In that case, the light source detection system 400 is configured to be able to communicate with the device control unit 450 via a connection cable or a wireless communication device.

  An image of the subject Obj is formed on the image sensor 506 by the photographing lens 502. The light detection unit 408 of the light source detection system 400 receives light that illuminates the subject Obj during photographing, that is, photographing illumination light. The light detection unit 408 includes a light receiving lens 440, a translucent milky white diffusion plate 430, and a spectrum sensor 420 as shown in FIG.

  The photographing illumination light enters the light receiving lens 440 and is collected by the light receiving lens 440. The photographing illumination light emitted from the light receiving lens 440 is diffused by the diffusion plate 430 and then enters the spectrum sensor 420. As an example, the spectrum sensor 420 includes nine photoelectric conversion units 422-1, 422-2,... 422-9 as shown in FIG. Each of the nine photoelectric conversion units 422-1, 422-2,..., 422-9 has filters having different spectral transmission characteristics, and is configured to be able to receive light in different wavelength bands. When it is not necessary to distinguish between these photoelectric conversion units in the following description, they are simply referred to as photoelectric conversion units 422. In the embodiment of the present invention, the photoelectric conversion unit 422 included in the spectrum sensor 420 has a rectangular shape, and an example in which they are arranged in a 3 × 3 tile shape is shown. However, the photoelectric conversion unit 422 may have a shape other than a rectangle, and the arrangement method and the number of arrangements can be freely set without departing from the gist of the present invention.

  FIG. 6 shows an example of the spectral sensitivity characteristic of each of the photoelectric conversion units 422-1, 422-2,... 422-9. In FIG. 6, reference numerals 1, 2,..., 9 are attached to the spectral sensitivity characteristic curves corresponding to the photoelectric conversion units 422-1, 422-2,. It is desirable that the photoelectric conversion unit 422-1 responsible for the shortest wavelength band has sensitivity to at least part of light in the near ultraviolet region (wavelength of about 300 to 400 nm). On the other hand, it is desirable that the photoelectric conversion unit 422-9 having the longest wavelength band has sensitivity to at least part of light in the near infrared region (wavelength of about 700 to 800 nm). It is desirable that the photoelectric conversion units 422-2 to 422-8 set the spectral sensitivity so that almost all of the visible range is covered by these photoelectric conversion units.

  By the way, fluorescent lamp light and mercury lamp light have several emission line spectra derived from mercury. Although these emission line spectra differ slightly depending on the type of fluorescent lamp, they also have peak wavelengths around 400, 450, 550, and 610 nm as shown in FIG. Although not shown in FIG. 3, mercury lamp light has a peak wavelength in the vicinity of 405, 436, 546, and 777 nm. It is desirable to set the spectral sensitivity characteristics of the photoelectric conversion unit 422 so that these emission line spectra can be distinguished.

  FIG. 5C shows another example 408A of the light detection unit. The light detection unit 408A includes a dome-shaped cover 424 and a spectrum sensor 420 formed of a translucent milky white material. The light source detection system 400 incorporated in the photographing apparatus 500 may include any of the light detection units 408 and 408A.

  A description will be given with reference to FIG. 4 again. The device control unit 450 comprehensively controls the operation of the photographing apparatus 500. Then, the device control unit 450 can more accurately perform color balance processing and color correction processing of image data based on the processing result output from the illumination estimation processing unit 410. Alternatively, it is possible to add information related to photographing illumination light as tag data to the image data. The image data to which the tag data is added is transmitted from the photographing apparatus 500 to another information processing apparatus, and the information processing apparatus that has received the image data can perform processing for improving color reproducibility.

  The illumination discriminating unit 402 is configured to be capable of discriminating the types of photographing illumination light into two types or more types. For example, the illumination determination unit 402 determines whether the photographic illumination light is a type of light that does not include an emission line spectrum such as natural light or incandescent light, or a type of light that includes an emission line spectrum such as a fluorescent light or a mercury lamp. Is configured to be discriminable.

  In order for the illumination discrimination unit 402 to discriminate the type of photographic illumination light, it can be configured as follows. That is, the illumination determination unit 402 can determine the type of photographing illumination light based on the setting content set by the user in the photographing apparatus 500. For example, it is assumed that the white balance mode options that can be set by the photographing apparatus 500 include sunlight, shade, cloudiness, tungsten light, fluorescent light, auto, and user setting modes. Here, the illumination determination unit 402 is configured to be able to input white balance setting information, which is information related to the white balance mode set by the photographing apparatus 500, from the device control unit 450.

  Among the white balance modes described above, the user setting mode is a mode in which the user performs an operation of white balance setting using a chart. That is, this mode is a mode in which a white or neutral gray chart is imprinted on the entire photographing screen in the photographing environment, and the obtained B, G, R color image data is analyzed to set the white balance.

  When the white balance mode is set to sunlight, shade, cloudy, tungsten light, the illumination determination unit 402 determines that the photographic illumination light is a type of light that does not include a bright line spectrum, such as natural light or incandescent light. Is possible. On the other hand, when the white balance mode is set to fluorescent lamp light, the illumination determination unit 402 can determine that the type of photographing illumination light is a type of light including a bright line spectrum.

  When the white balance mode is set to auto or user setting, the illumination determination unit 402 is a well-known input that is input to the illumination determination unit 402 by the imaging apparatus 500 simply determining illumination light based on information from the image sensor 506. The type of photographic illumination light is determined based on the white balance correction information. For example, fluorescent lamp light has more green components than other color components due to the influence of the bright line spectral components. That is, in this case, if white is included in the photographic subject, a green color fog is generated in that portion when photographing without adjusting the white balance. The photographing apparatus 500 determines the color cast amount of the white portion based on a known white balance correction algorithm or the like, and the illumination determination unit 402 is based on the white balance information input from the device control unit 450, and the shooting illumination light It is possible to determine whether or not the type of light is a type of light including an emission line spectrum.

  Instead of the above, the light source detection system 400 itself may be provided with a switch or the like that can be operated by the user so that the user can set the type of illumination light to be detected. In that case, the illumination determination unit 402 can determine the type of illumination light in response to the user operating the switch.

  Further, the light source detection system 400 has a configuration that can detect a temporal change in luminance of photographing illumination light and can detect the presence or absence of flicker specific to a fluorescent lamp based on the cycle of the luminance change. It may be. In this case, the illumination discriminating unit 402 detects flicker having a flicker period of 10 milliseconds (power supply frequency: 50 Hz) and 8.3 milliseconds (power supply frequency: 60 Hz) which are flicker periods of the non-inverter type fluorescent lamp. When this is done, it is possible to determine that the type of photographic illumination light is a type of light that includes a bright line spectrum.

  Moreover, the illumination determination part 402 may be comprised so that the signal output from the light detection part 408 can be input. In this case, the light detection unit 408 is configured to be operable in an operation mode for outputting the light detection result to the illumination determination unit 402 and an operation mode for outputting the light detection result to the illumination estimation processing unit 410. In this specification, the operation for outputting the light detection result to the illumination determination unit 402 is referred to as a light detection preliminary operation, and the operation for outputting the light detection result to the illumination estimation processing unit 410 is referred to as a light detection main operation. The illumination discriminating unit 402 discriminates the type of photographing illumination light based on the light detection signal output as a result of the light detection preliminary operation performed by the light detection unit 408. This specific example will be described in detail later with reference to FIG. 9 or FIG.

  The operation condition determination unit 404 determines an operation condition for the main light detection operation performed by the light detection unit 408 based on the illumination determination result output from the illumination determination unit 402. Details of the operating conditions determined by the operating condition determining unit 404 will be described later with reference to FIG. 10 or FIG.

  Based on the operation condition determined by the operation condition determination unit 404, the measurement control unit 406 controls the light detection main operation performed by the light detection unit 408. The illumination estimation processing unit 410 performs spectrum estimation processing of imaging illumination light or detail determination processing of imaging illumination light based on the light detection result output as a result of the main light detection operation performed by the light detection unit 408.

  The illumination estimation processing unit 410 outputs the imaging illumination light spectrum estimation processing result or the imaging illumination light detail determination processing result to the device control unit 450. The device control unit 450 processes the image data using the spectrum estimation process result of the photographic illumination light or the detailed determination process result of the photographic illumination light input from the light source detection system 400.

  This image data processing includes, for example, white balance processing, color correction processing, subject color spectrum estimation processing, and the like (here, when applied to white balance processing, the following configuration is possible). That is, the imaging apparatus 500 makes a simple illumination determination by a known method based on the output from the imaging element 506. Based on the simple illumination determination result, the light source detection system 400 uses the spectrum of the imaging illumination light. It may be configured such that the estimation process or the detailed determination process of the photographic illumination light is performed, and based on the result, the imaging apparatus 500 performs the white balance correction process. The device control unit 450 also inserts the spectrum estimation processing result of the photographic illumination light input from the light source detection system 400 or the detailed determination processing result of the photographic illumination light into the tag information added to the image data obtained by photographing. Can do.

  FIG. 8 and FIG. 9 are flowcharts schematically showing a procedure of illumination estimation processing executed in the light source detection system 400. The contents of the illumination determination process performed in S800 of FIG. 8 are shown in FIG. The processing shown in FIGS. 8 and 9 may be implemented by hardware logic or software. When implemented by software, the light source detection system 400 includes a ROM that stores a program for executing the processes shown in FIGS. 8 and 9, and a controller such as a CPU that executes the program. Alternatively, it may be executed by a controller including a ROM, a CPU, or the like included in the imaging apparatus 500.

  The processes shown in FIGS. 8 and 9 can be performed intermittently at appropriate time intervals when the imaging apparatus 500 is turned on. Alternatively, it can be executed when the user performs an operation for instructing the operation start of the light source detection system 400. First, the illumination discrimination processing procedure will be described with reference to FIG. The example of discriminating the type of photographing illumination light based on the light detection signal output as a result of the light detection preliminary operation performed by the light detection unit 408 has been described above. This is the process shown in FIG.

  In S900, the light source detection system 400 sets initial operating conditions of the spectrum sensor 420. The initial operation condition includes a time of integration operation (integration time) performed by the spectrum sensor 420, a gain when a signal read from the spectrum sensor 420 is amplified, and the like. In the embodiment of the present invention, the spectrum sensor 420 includes an analog front end unit that amplifies an analog signal read from the photoelectric conversion unit 422 with a preset gain, and converts the amplified analog signal into a digital signal. A / D converter unit to be included.

  The initial operating conditions of the spectrum sensor 420 can be set as follows as an example. That is, the light source detection system 400 can obtain subject luminance information from a photometric unit (not shown) included in the photographing apparatus 500 and set initial operating conditions of the spectrum sensor 420 based on the subject luminance information. Alternatively, when the photographing apparatus 500 operates in a so-called live view mode, an aperture value set by the photographing lens 502, an integration time of the image sensor 506, an amplifier gain when amplifying an image signal read from the image sensor 506, It is possible to set an initial operation condition of the spectrum sensor 420 based on a value of an image signal obtained from the image sensor 506 or the like. Further, a predetermined initial operation condition corresponding to general brightness may be recorded and the condition may be followed. In step S <b> 902, the light source detection system 400 acquires an output from the spectrum sensor 420. The processes in S900 and S902 described above correspond to the light detection preliminary operation.

  In subsequent S <b> 904, the light source detection system 400 corrects the output from the spectrum sensor 420. The correction processing will be described. Each of the photoelectric conversion units 422-1, 422-2,..., 422-9 may have variations in sensitivity characteristics, and in addition, there is a difference in spectral transmittance of the filters. So there is a sensitivity difference. That is, even if the photographic illumination light is white light, the signal values output from the photoelectric conversion units 422-1, 422-2, ..., 422-9 are not equal.

  Therefore, in order to correct the sensitivity difference due to the above-described variation in sensitivity characteristics and the difference in spectral transmittance of the filters, the signals corresponding to the photoelectric conversion units 422-1, 422-2,. Individual correction processing is performed in S904.

  In S906, the light source detection system 400 determines whether or not a relatively large amount of near-infrared light component is included in the photographic illumination light. Specifically, it is determined whether or not the result obtained from the photoelectric conversion unit 422-9 and corrected (referred to as No. 9 data) exceeds a predetermined reference value 1. If the determination result is affirmative, the process proceeds to S908, where it is determined that the photographic illumination light is light other than a fluorescent lamp, the illumination determination process is completed, and the process returns. If the determination in S906 is negative, the process branches to S910, where it is determined that the imaging illumination light is fluorescent light, the illumination determination process is completed, and the process returns. Here, in S906, no. Although an example in which determination is made based only on the size of 9 data has been described, for example, No. 9 is used instead. No. 6 for data. It is also possible to obtain a ratio of 9 data (No. 9 data ÷ No. 6 data) and determine whether or not this ratio exceeds the reference value in S906. In this case, a value different from the reference value 1 is used as the reference value. By doing so, it is possible to eliminate the influence of subject brightness.

  The reference value 1 will be described. The photoelectric conversion unit 422-9 has a spectral sensitivity characteristic denoted by reference numeral 9 in FIG. That is, it has a peak sensitivity in the vicinity of about 640 nm and has a sensitivity in the wavelength band of 600 nm to 700 nm. When attention is paid to the vicinity of 640 nm in FIG. 3 showing the spectral characteristics of the light source, the relative intensity of incandescent light and sunlight is greater than the relative intensity of the fluorescent lamp. The three-wavelength daylight white fluorescent lamp light has an emission line spectrum in the vicinity of 610 nm, but deviates from the peak sensitivity of the photoelectric conversion unit 422-9. That is, by setting the reference value 1 to an appropriate value, it is possible to determine whether the photographing illumination light is fluorescent lamp-based illumination or non-fluorescent lamp-based illumination.

  The illumination estimation processing procedure will be described with reference to FIG. In S800, the light source detection system 400 performs the illumination determination process described above with reference to FIG. In S802, it is determined whether or not the illumination discrimination result obtained in S800 is a fluorescent lamp system, that is, whether or not the illumination discrimination is “fluorescent lamp system” in S910. If the determination in S802 is affirmed, the process proceeds to S804, and the light source detection system 400 sets the operation condition 1 as the operation condition of the main light detection operation performed by the light detection unit 408. This operating condition 1 is an operating condition suitable when the photographing illumination light is a fluorescent lamp system. In S814, which is a branch destination when the determination in S802 is negative, the light source detection system 400 sets the operation condition 2 as the operation condition of the main light detection operation performed by the light detection unit 408.

  Here, the operating conditions 1 and 2 will be described with reference to FIG. FIG. 10 summarizes the contents set as the operating conditions 1 and 2 as a list. The operation condition 1, which is an operation condition corresponding to the case where the illumination discrimination result is a fluorescent lamp system, is set as follows. The integration operation is set to perform the first integration operation, the second integration operation, the third integration operation, and the fourth integration operation defined in the right half portion in the table of FIG. The sensor used is no. 1 to No. All sensors are up to 9. That is, it is set so that the illumination estimation process is performed by acquiring all the signals output from the photoelectric conversion units 422-1, 422-2, ..., 422-9.

  The first to fourth integration operations described above will be described. For the first integration operation, the integration time is set to 100 microseconds, the amplification factor is 1, and the flicker reduction process is set to “Yes”. For the second integration operation, the integration time is set to 5 milliseconds, the amplification factor is 1, and the flicker reduction process is set to “Yes”. For the third integration operation, the integration operation is set to 100 milliseconds, the amplification factor is 1, and the flicker reduction process is set to “none”. For the fourth integration operation, the integration operation is set to 100 milliseconds, the amplification factor is 10, and the flicker reduction process is set to “none”. In the present embodiment, “amplification factor of 1” does not necessarily mean 1 time, but it means “1 unit”.

  The flicker reduction process in the first integration operation and the second integration operation will be described. Fluorescent lamps cause flicker, that is, periodic luminance fluctuations. In non-inverter fluorescent lamps, the flicker frequency is twice the power supply frequency. For example, when the power supply frequency is 50 Hz, the flicker frequency is 100 Hz, and thus the flicker cycle is 10 milliseconds. When the integration operation is performed in the photoelectric conversion unit 422, luminance fluctuation due to flicker adversely affects the measurement result. Therefore, flicker reduction processing described below is performed in the first integration operation and the second integration operation in which the integration time is shorter than the flicker cycle.

The flicker reduction process is a process of obtaining an appropriate waiting time that satisfies the following conditions and appropriate integers n and m, repeating an integration operation and a read operation n times, and obtaining an average value thereof.

(Integration time + reading time + waiting time) × n = flicker cycle × m

For example, if the integration time is 0.1 milliseconds, the readout time is 2 milliseconds, and the flicker cycle is 10 milliseconds, a waiting time of 1.9 milliseconds, n = 5, and m = 2 is derived. In the integration operation, the integration / reading operation is repeated five times, and the average value is derived. Similarly, when the integration time is 5 milliseconds, the readout time is 2 milliseconds, and the flicker period is 10 milliseconds, a waiting time of 1 millisecond, n = 5, and m = 4 are derived. The average value is derived by repeating the integration / reading operation five times. Here, the appropriate waiting time and the appropriate integers n and m may be set so that the influence of flicker is reduced while the amount of measurement time and the amount of memory used is reduced.

  Regarding the flicker cycle, it is estimated that the flicker cycle has a flicker cycle fixed to some extent in the case of fluorescent lamp-based artificial lighting, and the value (for example, 10 milliseconds) may be used.

  In the third integration operation and the fourth integration operation, the integration time is set to 100 milliseconds. Since this integration time is sufficiently longer than the flicker cycle, there is almost no influence of flicker. Therefore, flicker reduction processing is not performed in the third integration operation and the fourth integration operation.

  In the first, second,..., Fourth integration operation corresponding to the operating condition 1, the integration time and the amplification factor are set as shown in FIG. Then, a signal value of 50 is obtained in the second integration operation, 1,000 in the third integration operation, and 10,000 in the fourth integration operation. By setting the integration time and the amplification factor in this way, it is possible to cope with the need for a wide dynamic range when measuring fluorescent lamp light.

  When it is determined that the illumination determination result is a fluorescent lamp system, the illumination light includes a bright line spectrum, and thus a wide dynamic range is required for measurement. In addition, the spectral spectrum curve of the imaging illumination light has a spike-like distribution due to the bright line spectrum. Therefore, in order to obtain a more accurate measurement result, as described above, No. 1 to No. It is desirable to use all the sensors up to 9 and shorten the measurement wavelength interval when measuring the spectrum. In addition, since there is a high possibility that flicker exists, flicker reduction processing is required. The operating condition 1 described above corresponds to detailed measurement of spectral characteristics.

  Here, the meaning of the “fluorescent lamp system” during the processing shown in FIGS. 8 and 9 will be supplementarily described. There is a possibility that artificial illumination such as high-pressure illumination is included in the illumination light to be determined as the “fluorescent lamp system” in the above processing. The reason is as follows. In other words, when considering whether the high-pressure illumination is a fluorescent lamp system or a natural light system, it has spectral characteristics close to those of the fluorescent lamp system. In addition, the degree of the spectral characteristic is close to that of a fluorescent lamp depending on the type of high-pressure illumination.

  Therefore, by setting the reference value 1 so that all or part of the high-pressure illumination is included in the illumination light to be classified as “fluorescent lamp system”, the spectral transmission characteristic is fluorescent even in high-pressure illumination. A thing close to a lamp can be intentionally determined to be a “fluorescent lamp system”. Conversely, if the reference value 1 is set so that almost all fluorescent lamps are reliably determined as “fluorescent lamp system” in the determination in S906, a part of the high-pressure illumination may be determined as “fluorescent lamp system”. There is.

  The operation condition 2 which is an operation condition corresponding to the case where the illumination determination result is determined to be other than the fluorescent lamp system is set as follows. The integration operation is set to perform only the first integration operation. The sensor used is no. 1, 2, 3, 6, 7, 9 and 6 out of 9 sensors are targeted. That is, it is set to perform illumination estimation processing by acquiring signals output from the photoelectric conversion units 422-1, 422-2, 422-3, 422-6, 422-7, and 422-9. The integration time for the first integration operation is determined according to the magnitude of the output obtained from the spectrum sensor 420 in the light detection preliminary operation in S900 and S902 of FIG. The amplification factor when a signal output from the spectrum sensor 420 is amplified is set to 1.

  When it is determined that the illumination determination result is other than the fluorescent lamp system, the bright line spectrum is not included in the illumination light, so that a wide dynamic range is not necessary for measurement. Further, since there is no flicker, flicker reduction processing is not required. Further, since the spectral spectrum curve of the photographic illumination light can be considered to be relatively smooth, the sensor used is No. 1 as described above. Even if only some sensors 1, 2, 3, 6, 7, 9 are used, sufficient measurement accuracy can be obtained. The operating condition 2 described above corresponds to simple measurement of spectral characteristics.

  Referring to FIG. 8 again, the illumination estimation processing procedure will be described. The light source detection system 400 is set after setting to operation condition 1 which is an operation condition for fluorescent lamp system illumination in S804 or after setting to operation condition 2 which is an operation condition for illumination other than the fluorescent lamp system in S814. In step S806, the process of controlling the operation of the spectrum sensor 420 under any of the above conditions is performed.

  In step S808, the light source detection system 400 acquires an output from the sensor set in the operation condition 1 or 2. That is, when the operating condition 1 is set, the light source detection system 400 acquires all the signals output from the photoelectric conversion units 422-1, 422-2,. On the other hand, when the operating condition 2 is set, the light source detection system 400 is output from the six photoelectric conversion units 422-1, 422-2, 422-3, 422-6, 422-7, and 422-9. Get the signal.

  In S810, the light source detection system 400 corrects the output acquired from the spectrum sensor 420. That is, the photoelectric conversion units 422-1, 422-2,..., 422-9 may have a sensitivity difference due to individual variations in manufacturing, etc., and may also exhibit a sensitivity difference due to a difference in spectral transmittance of the filter. Have. In addition, the output obtained from the spectrum sensor 420 differs depending on the difference in integration time and amplification factor. In step S810, correction is performed so as to eliminate non-uniformity in output due to individual differences among the spectrum sensors caused by these factors.

  Based on the spectrum sensor output corrected in S810, the light source detection system 400 performs processing (illumination estimation processing) for estimating the spectrum of the photographic illumination light in S812. In the illumination estimation process, for example, the spectral spectrum shape (spectral profile) of the illumination light is estimated based on the spectrum sensor output obtained in S810. In addition to the illumination estimation process in S812 or instead of the illumination estimation process, the light source detection system 400 may perform the detailed illumination determination process described above.

  Here, an example of the illumination estimation process and the detailed illumination determination process will be described. The light source detection system 400 can have a lookup table therein. This lookup table is a database of combinations of relative values of outputs from the photoelectric conversion units 422-1, 422-2,..., 422-9 of the spectrum sensor 420 and spectral profiles corresponding to the combinations. be able to. From this look-up table, the one closest to the combination of the relative values of the outputs from the photoelectric conversion units 422-1, 422-2,... 422-9 is selected to estimate the spectral profile of the corresponding illumination or It can be derived.

  Similarly, in response to a combination of relative values of outputs from the photoelectric conversion units 422-1, 422-2,. The light source detection system 400 may include a database including information that can identify a fluorescent lamp, a daylight fluorescent lamp, a light bulb color fluorescent lamp, a three-wavelength fluorescent lamp, a high color rendering fluorescent lamp, and the like. From this database, by selecting the one closest to the combination of the relative values of the outputs from the photoelectric conversion units 422-1, 422-2,... 422-9, the detailed type of illumination corresponding thereto is estimated or derived. It becomes possible.

  If the light source detection system 400 is connectable to a network, the lookup table and database may not be in the light source detection system 400. Instead, the light source detection system 400 may access an external database to obtain information necessary for the illumination estimation process and the detailed illumination determination process.

  When the process of estimating the spectrum of the imaging illumination light is performed in S812, it is possible to insert information related to the spectrum of the imaging illumination light into the tag information added to the image data generated by the imaging apparatus 500. Become. When this image data is output to a personal computer or a video recorder, and the image reproduction process is performed by the personal computer or the video recorder, the color reproducibility of the reproduced image can be improved by using information related to the spectrum of the photographing illumination light. It becomes possible to raise.

  When the detailed illumination determination process is performed in step S812, the photographing apparatus 500 can perform more accurate color balance and white balance adjustment based on the detailed illumination determination process result. Further, it is possible to insert information (illumination detailed information) obtained as a result of the detailed illumination determination process into tag information added to image data generated by the imaging apparatus 500. When the image generated by the photographing apparatus 500 is subjected to image reproduction processing with a personal computer or a video recorder, the color reproducibility of the reproduced image can be improved by using the detailed illumination information.

  In the above, an example in which the light detection preliminary operation is performed and the illumination determination process is performed to determine whether the photographing illumination light is fluorescent or non-fluorescent illumination will be described with reference to FIG. However, the number of types when determining illumination may be three or more. Here, an example in which the number of types when determining the illumination by performing the light detection preliminary operation is 3 or more will be described with reference to FIG. FIG. 11 is a flowchart for explaining an example of the illumination discrimination process different from that shown in FIG. This process is executed by the light source detection system 400 when the illumination determination process is called in S800 of FIG.

  In the processing of FIG. 11, processing steps having the same contents as the processing steps in the processing of FIG. 9 (S900 to S906 in FIG. 11) are denoted by the same reference numerals as those in the flowchart of FIG. 9. The description is omitted. Then, the description starts from the processing of S920 and S928 following the determination processing in S906. In S920, which is a branch destination when the determination in S906 determines that the near-infrared light component is included in the photographing illumination light, the light source detection system 400 is No. No. 9 for the signal value of 9 sensors. It is determined whether or not the ratio of signal values of 6 sensors (No. 6 data ÷ No. 9 data) is smaller than a predetermined reference value 2.

  No. 6 data, that is, the signal value of the photoelectric conversion unit 422-6 is No. 9 data, that is, the value divided by the signal value of the photoelectric conversion unit 422-9 is smaller than the reference value 2, so that the spectral intensity in the vicinity of 640 nm is relative to the spectral intensity in the vicinity of 550 nm of the photographing illumination light. The reference value 2 is determined so that the determination in S920 is affirmed when the value is large (the amount of the near-infrared light component is relatively large). That is, if the determination in S920 is affirmed, it can be estimated that the spectral characteristics of the light source shown in FIG. 3 have characteristics close to the spectral characteristics of incandescent light. As light having such characteristics, incandescent bulb light and evening natural light can be considered.

  If the determination in S920 is affirmed, the process of S922 is performed, and if the determination is negative, the process of S926 is performed. In S922, the light source detection system 400 is No. It is determined whether or not the signal value (No. 1 data) of one sensor is lower than a predetermined reference value 3. No. One sensor, that is, the photoelectric conversion unit 422-1 has a spectral sensitivity characteristic numbered 1 in FIG. That is, it has a peak sensitivity in the vicinity of about 440 nm and has a sensitivity in the wavelength band of 410 nm to 490 nm. If attention is paid to the vicinity of 440 nm in FIG. 3 showing the spectral characteristics of the light source, the relative intensity of sunlight is larger than the relative intensity of incandescent light (the amount of near-ultraviolet light components is relatively large in sunlight). That is, by setting the reference value 3 to an appropriate value, when the photographic illumination light is non-fluorescent light, it can be determined whether it is incandescent light or sunlight. It becomes possible. If the determination in S922 is affirmed, the process proceeds to S924, whereas if the determination is negative, the process branches to S926.

  If the determinations in both S920 and S922 are negative, the light source detection system 400 determines in S926 that the photographic illumination light is natural light and returns. If the determination in S922 is affirmed, the light source detection system 400 determines in S924 that the photographic illumination light is incandescent bulb system light and returns.

  In S928, which is the branching destination when the determination in S906 is negative, the light source detection system 400 is No. 4 sensor signal value (No. 4 data) exceeds a predetermined reference value 4, No. 5 signal value (No. 5 data) exceeds a predetermined reference value 5 and It is determined whether the signal value (No. 8 data) of the 8 sensors is below a predetermined reference value 6 or not.

  No. The four sensors, that is, the photoelectric conversion units 422-4 have spectral sensitivity characteristics denoted by reference numeral 4 in FIG. That is, it has a peak sensitivity in the vicinity of about 510 nm and has a sensitivity in the wavelength band of 450 nm to 560 nm. When attention is paid to the vicinity of 500 nm in FIG. 3 showing the spectral characteristics of the light source, in the case of a fluorescent lamp, there is almost no spectrum, and it is possible to capture a portion of the fluorescent lamp having a small spectrum. On the other hand, many high-pressure illuminations have a spectrum peak around this area. It can help to determine whether or not the illumination is a high-pressure system from the signal values of the four sensors.

  No. The five sensors, that is, the photoelectric conversion units 422-5 have spectral sensitivity characteristics denoted by reference numeral 5 in FIG. That is, it has a peak sensitivity in the vicinity of about 550 nm and has a sensitivity in the wavelength band of 500 nm to 600 nm. When attention is paid to the vicinity of 550 nm in FIG. 3 showing the spectral characteristics of the light source, there is an emission line spectrum peculiar to fluorescent lamp light. That is, by setting the reference value 5 to an appropriate value, it is possible to capture the bright line spectrum that is characteristic when the photographing illumination light is fluorescent light. Many high-pressure illuminations do not have a spectrum peak around here, or even if there is a peak, the level is not high. Therefore, it can help to determine whether or not the illumination is a high voltage system from the signal value of the sensor.

  No. The eight sensors, that is, the photoelectric conversion units 422-8 have spectral sensitivity characteristics denoted by reference numeral 8 in FIG. That is, it has a peak sensitivity in the vicinity of about 590 nm and has a sensitivity in the wavelength band of 540 nm to 650 nm. When attention is paid to the vicinity of 590 nm in FIG. 3 showing the spectral characteristics of the light source, in the case of a fluorescent lamp, there is almost no spectrum, and it is possible to capture a portion of the fluorescent lamp having a small spectrum. Many high-pressure illuminations have a spectral peak around this area. It can help to determine whether or not the illumination is a high voltage system from the signal values of the eight sensors.

  If the determination in S928 is affirmed based on the determination criteria described above, the light source detection system 400 determines in S930 that the imaging illumination light is fluorescent light and returns. On the other hand, if the determination in S928 is negative, the light source detection system 400 determines in S932 that the photographic illumination light is light of a high-pressure illumination system, and returns.

  As described above, by performing the illumination determination process exemplified in the flowchart of FIG. 9 or FIG. 11, two or more types of illumination light to be measured can be determined based on the result of the light detection preliminary operation. it can.

  In addition, regarding the illumination determination process, when the number of types when performing the illumination determination is 3 or more as described with reference to FIG. 11, it is desirable to change the content of the illumination estimation process described with reference to FIG. 8. . That is, in the above description, only the example in which the process of S804 or S814 is performed in the process of FIG. 8 in response to the determination of whether or not the illumination is a fluorescent lamp system in the process of FIG. On the other hand, when the processing of FIG. 11 instead of FIG. 9 is performed in S800, it is desirable to perform the following processing. That is, according to the processing shown in FIG. 11, the number of types of illumination to be determined increases, so that the number of types of operating conditions can be increased in accordance with the number of types of illumination to be determined. It is desirable to do

  By the way, when the photographing apparatus 500 is a still camera, a flash may be used as auxiliary light, that is, flash photographing may be performed. In such a case, the photographing illumination light is a mixture of flash light and steady light. Illumination estimation processing in the case of shooting with flash emission will be described with reference to FIG. FIG. 12A and FIG. 12B are flowcharts for explaining the illumination estimation processing procedure performed by the light source detection system 400 before (immediately before) the photographing operation when flash emission is scheduled at the time of photographing.

  As will be described in detail below, the light source detection system 400 performs processing in the following flow prior to flash photography. First, the illumination determination described above with reference to FIGS. 9 and 11 is performed. When there is no plan to perform flash photography, the illumination estimation process is performed by the same process as described with reference to FIG. On the other hand, if there is a plan to shoot with flash, the so-called pre-flash, that is, the flash is emitted prior to the main shooting, and the mixed light that mixes the flash light reflected by the subject and the steady light is used as the shooting illumination light. And measure the illumination.

  By the way, the shutter time set in the main photographing with flash emission can be changed to various values depending on the photographing scene and the user setting. On the other hand, the light emission time of the flash light is about 0.1 milliseconds in the short case and about several milliseconds at the longest. That is, even if the flash is emitted with the same amount of light, the ratio between the steady light component and the flash light component in the exposure amount obtained by one exposure operation differs depending on the set shutter speed. As the shutter time increases, the ratio of the steady light component to the flash light component in the total exposure amount increases.

  Therefore, in the illumination estimation process shown in FIG. 12, the light source detection system 400 performs the light source detection process both when the flash is not emitting light and when the light is emitted. Based on the light source detection process result of the steady light and the light source detection result of the mixed light obtained as a result, the illumination estimation process corresponding to the set shutter time is performed.

  In S1200, the light source detection system 400 performs illumination discrimination processing. This illumination discrimination process can be the same as that described with reference to FIGS. 9 and 11. Here, it is assumed that the processing shown in FIG. 9 is performed. That is, it is assumed that it is determined whether the photographing illumination light is of a fluorescent lamp system or a non-fluorescent lamp system by the illumination determination process of S1200.

  In S1202, the light source detection system 400 acquires information related to the exposure operation of the photographing apparatus 500 from the device control unit 450, and determines whether or not flash emission is scheduled in the exposure operation to be performed. If this determination is affirmed, the process proceeds to S1204, and if not, the process proceeds to S802 in FIG. 12B.

  The process shown in FIG. 12B is a process when the flash emission is not scheduled in the exposure operation to be performed, and is the same process as described with reference to FIG. Therefore, in FIG. 12B, the same processing steps as those shown in FIG. 8 are given the same step numbers as those shown in the processing steps in FIG.

  In S1204 which is a branch destination when the determination in S1202 is affirmed, the light source detection system 400 determines whether or not the result of the illumination determination process in S1200 is a fluorescent lamp system. If the determination result in S1204 is affirmative, that is, if it is determined that the photographing illumination light is a fluorescent lamp system, the process proceeds to S1206. On the other hand, if the determination result in S1204 is negative, that is, if it is determined that the photographing illumination light is other than the fluorescent lamp system, the process branches to S1224.

  The processing of S1206, S1208, S1210, and S1212 described below is the same as the processing of S804, S806, S808, and S810 described above with reference to FIG.

  In step S <b> 1206, the light source detection system 400 sets the operation condition 1 as the operation condition of the light detection main operation performed by the light detection unit 408. Regarding the operating conditions, four operating conditions 1 to 4 are prepared as will be described below with reference to FIG. Of these operating conditions, operating condition 1 and operating condition 2 are assumed to be the same as those described above with reference to FIG. The operation condition 1 is an operation condition suitable when the photographing illumination light is a fluorescent lamp system.

  In S1208, the light source detection system 400 performs a process of controlling the operation of the spectrum sensor 420 under the operation condition 1 set in S1206. In S1210, the light source detection system 400 acquires all the signals output from the sensors set under the operating condition 1, that is, the photoelectric conversion units 422-1, 422-2, ..., 422-9. In step S <b> 1212, the light source detection system 400 corrects the output acquired from the spectrum sensor 420.

  As described above, the light source detection processing of the steady light component in the photographing illumination light is performed by the processing of S1206, S1208, S1210, and S1212.

  In S <b> 1214, the light source detection system 400 sets the operation condition of the main operation of light detection performed by the light detection unit 408 to an operation condition 3 that is an operation condition involving flash emission under fluorescent lamp illumination. As shown in FIG. 13, the operating condition 3 is set so that only the first integration operation is performed as the integration operation. The sensor used is no. 1, 2, 3, 4, 5, 6, 7, 8, 9 sensors. That is, it is set so that the illumination estimation processing is performed by acquiring all the signals output from the photoelectric conversion units 422-1, 422-2, ..., 422-9.

  The integration time for the first integration operation is preferably set to the same time as the light emission time in synchronization with the light emission period when the flash is pre-emitted. In this embodiment, since the pre-flash time is 0.8 / 10,000 seconds, that is, about 80 microseconds, the flash is pre-flashed in synchronism with the integration operation by setting the integration time to 100 microseconds. The amplification factor is determined according to the magnitude of the output obtained when the spectrum sensor 420 operates under the initial operating conditions when the illumination discrimination process is performed in S1200.

  Under the above operating condition 3, flicker reduction processing is performed. The flicker reduction process is desirably determined according to the number of times the flash can be pre-flashed. For example, when the flicker cycle is 10 milliseconds, the flicker reduction process can be performed by performing the first integration operation with flash emission (pre-emission) twice at intervals of 5 milliseconds.

  In the present embodiment, in the operating condition 1, in addition to the first integrating operation, the second, third, and fourth integrating operations are performed, but in the operating condition 3, only the first integrating operation is performed. This is because the flash emission time is limited. However, if the light emission per light emission is reduced and the flash light emission is repeated intermittently, if the light emission time as long as 5 milliseconds or 100 milliseconds can be generated in a pseudo manner, the second light is emitted as necessary. The third and fourth integration operations may also be performed. In addition, when an LED or the like can be used instead of flash light as auxiliary light at the time of photographing, it is easy to adjust the light emission time to the integration time. It is also possible to set operation conditions for performing the first, second, third, and fourth integration operations.

  In S1216, the light source detection system 400 controls the operation of the spectrum sensor 420 so as to synchronize with flash emission under the operation condition 3 set in S1214. In step S <b> 1218, the light source detection system 400 acquires an output from the sensor set in the operation condition 3. That is, the light source detection system 400 acquires all signals output from the photoelectric conversion units 422-1, 422-2, ..., 422-9. In step S <b> 1220, the light source detection system 400 corrects the output acquired from the spectrum sensor 420. This process is the same as the process of S810 described with reference to FIG.

  The processing of S1224, which is a branch destination when the determination result in S1204 is negative, that is, it is determined that the photographing illumination light is other than the fluorescent lamp system, and the subsequent processing will be described.

  The processing of S1224, S1226, S1228, and S1230 described below is the same as the processing of S814, S806, S808, and S810 described above with reference to FIG.

  In S <b> 1224, the light source detection system 400 sets the operation condition 2 as the operation condition of the main operation of light detection performed by the light detection unit 408. The operating condition 2 is assumed to be the same as that described above with reference to FIG. That is, the operating condition 2 is an operating condition suitable when the photographing illumination light is other than a fluorescent lamp system.

  In S1226, the light source detection system 400 performs a process of controlling the operation of the spectrum sensor 420 under the operation condition 2 set in S1224. In S <b> 1228, the light source detection system 400 outputs a signal output from the sensor set in the operation condition 2, that is, the photoelectric conversion units 422-1, 422-2, 422-3, 422-6, 422-7, and 422-9. get. In S1230, the light source detection system 400 corrects the output acquired from the spectrum sensor 420.

  As described above, the light source detection processing of the steady light component in the photographing illumination light is performed by the processing of S1224, S1226, S1228, and S1230.

  In S1232, the light source detection system 400 sets the operation condition of the light detection main operation performed by the light detection unit 408 to an operation condition 4 that is an operation condition involving flash emission under illumination other than the fluorescent lamp system. As shown in FIG. 13, the operating condition 4 is set so that only the first integration operation is performed as the integration operation. The sensor used is no. 1, 2, 3, 6, 7, and 9 sensors. That is, it is set to perform illumination estimation processing by acquiring signals output from the photoelectric conversion units 422-1, 422-2, 422-3, 422-6, 422-7, and 422-9.

  The integration time for the first integration operation can be set in the same manner as the first integration operation in the operation condition 3. The amplification factor can be determined according to the light emission amount of the flash. For example, when the flash light emitting device is built in the photographing device 500 and the light emission amount is relatively small, the amplification factor may be increased. On the other hand, when a flash light emitting device with an external type and a relatively large amount of light emission is used, the amplification factor may be reduced. Under operating condition 4, flicker reduction processing is not performed.

  In S1234, the light source detection system 400 controls the operation of the spectrum sensor 420 to synchronize with the flash emission under the operation condition 4 set in S1232. In S <b> 1236, the light source detection system 400 acquires an output from the sensor set in the operation condition 4. That is, the light source detection system 400 acquires signals output from the photoelectric conversion units 422-1, 422-2, 422-3, 422-6, 422-7, and 422-9. In S <b> 1238, the light source detection system 400 corrects the output acquired from the spectrum sensor 420. This process is the same as the process of S810 described with reference to FIG.

  Following the processing of S1220 or S1238, the light source detection system 400 performs illumination estimation processing in S1222. In the illumination estimation processing in S1222, the weighted distribution of the light source detection result with flash emission and the light source detection result without flash emission is adjusted based on the set aperture value of the taking lens 502, etc. at the time of the shutter speed in the next shooting. To perform illumination estimation processing.

  That is, with respect to the combination of the relative values of the outputs from the photoelectric conversion units 422-1, 422-2,... 422-9, the weighted distribution of the result with flash emission and the result without flash emission is adjusted. . Then, by the same method as described for the illumination estimation processing in S812 with reference to FIG. 8, processing such as reading from the look-up table, access to the database, and the like is performed, and the spectrum estimation processing of the imaging illumination light and the imaging illumination are performed. At least one of the detailed light determination processes is performed to complete a series of illumination estimation processes.

  Processing when the determination in S1202 is negative will be described. If it is determined in step S1202 that there is no plan to perform flash emission in the next shooting, the processing shown in FIG. 12B is performed. After the illumination estimation processing is performed in step S812, a series of illumination estimation processing is performed. To complete. That is, after a process similar to that described with reference to FIG. 8 is performed, a series of illumination estimation processes is completed.

  As described above, the light source detection system 400 according to the embodiment of the present invention discriminates two or more types of illumination light to be measured, and the operation of the light detection operation performed by the light detection unit based on the discrimination result. Determine the conditions. This makes it possible to perform simple measurement of spectral characteristics when it is determined that the illumination light to be measured has a spectral profile that changes relatively slowly, such as sunlight or tungsten light. It is possible to increase the response speed of the light source detection system 400 by increasing the speed of the light source detection operation. And it becomes possible to discriminate | determine illumination light in detail based on an illumination estimation process result.

  On the other hand, when it is determined that the illumination light to be measured contains a bright line spectral component such as a fluorescent lamp or a high-pressure illumination system and has a spike-like spectral profile, a detailed measurement of spectral characteristics is performed. By doing so, the spectral profile of the illumination light can be grasped more accurately.

  Although the example in which the light source detection system 400 is built in the imaging apparatus 500 has been described above, the light source detection system 400 may be configured to be operable alone. Further, the light source detection system 400 may be configured to be externally attached to the photographing apparatus 500. The photographing apparatus 500 can be configured to be capable of photographing at least one of a still image and a moving image. The photographing apparatus 500 in which the light source detection system 400 is built-in or externally attached is not limited to a general one, and may be a television camera capable of outputting a video signal, or obtained with a microscope, an endoscope, or the like. It may be a device capable of taking an image.

  Further, the light source detection system 400 may be built in or externally attached to a monitor display device or the like, and may be configured to be able to measure light for illuminating the environment for observing the monitor (observation illumination light, ambient light). In this case, the color balance of the image observed by the viewer appears to be lost due to the adaptation of the ambient light of the viewer who observes the image and the ambient light is reflected (tube reflection) by the image display unit of the monitor display device. It becomes possible to deal with the problem. Furthermore, using so-called illumination conversion technology, it is possible to display images on the monitor display device by reproducing the color as if the subject was illuminated with observation illumination light, thereby displaying images with increased reality. It becomes.

  The embodiment of the present invention has been described above, but the present invention is not limited to this, and it is needless to say that various improvements and modifications can be made without departing from the spirit of the present invention.

  The present invention is applicable to a light source detection system and a photographing device such as a still camera or a movie camera, a television camera, a monitor display device, a microscope photographing device, an endoscope photographing device, and the like.

400 ... Light source detection system 402 ... Illumination discrimination unit 404 ... Operating condition determination unit 406 ... Measurement control unit 408, 408A ... Light detection unit 410 ... Illumination estimation processing unit 420 ... Spectrum sensor 422 ... Photoelectric conversion unit 430 ... Diffuser 440 ... Light reception Lens 450 ... Device control unit 500 ... Imaging device 502 ... Imaging lens 503 ... Infrared cut filter 504 ... Optical low-pass filter 506 ... Imaging element

Claims (7)

A light detection unit having a plurality of photoelectric conversion units having different spectral sensitivity characteristics;
An illumination discriminator capable of discriminating two or more types of illumination light to be measured;
An operation condition determination unit that determines an operation condition of a light detection operation performed in the light detection unit based on a determination result in the illumination determination unit;
A measurement control unit that controls the light detection operation performed by the light detection unit based on the operation condition determined by the operation condition determination unit;
An illumination estimation processing unit that performs at least one of the illumination detail determination process and the illumination spectrum estimation process based on a light detection result obtained by a light detection operation performed by the light detection unit;
The illumination detail determination process includes a process of determining the illumination light of the measurement object into a number of types larger than the number of types that can be determined by the illumination determination unit.   The illumination determination unit is further configured to be able to determine the illumination light to be measured based on a result of a light detection preliminary operation performed under a predetermined preliminary operation condition in the light detection unit. Item 4. The light source detection device according to Item 1.   The operation condition determination unit determines at least one of an integration time of the light detection unit, the number of integration operations, an operation time interval when the integration operation is performed a plurality of times, and an amplification factor as the operation conditions. The light source detection device according to claim 1, wherein the light source detection device is a light source detection device.   Which output is used when the operation condition determination unit obtains the light detection result among the plurality of outputs output from each of the plurality of photoelectric conversion units included in the light detection unit as the operation condition. The light source detection device according to claim 3, wherein the light source detection device is configured to be able to determine the light source.   The operation condition determination unit determines, as the operation condition, that the integration operation is performed a plurality of times by the light detection unit, and at that time, expands a dynamic range of the light detection operation performed by the light detection unit. The light source detection device according to claim 3, wherein the number of integration operations, the operation time interval, the integration time in each of the plurality of integration operations, and the amplification factor are determined. It further has an emission line spectral light detector having a spectral sensitivity characteristic capable of detecting an emission line spectral component derived from mercury,
The illumination discriminating unit is configured to be able to discriminate whether or not the illumination light to be detected has an emission line spectrum derived from the mercury based on a signal obtained by the emission line spectrum light detection unit. The light source detection device according to claim 1 or 2. A luminance fluctuation period detection unit capable of detecting the luminance fluctuation period when the luminance of the illumination light to be detected fluctuates periodically;
The illumination determination unit is configured to be able to determine whether or not the illumination light to be detected is fluorescent light based on the luminance variation period detected by the luminance variation period detection unit. Item 3. The light source detection device according to Item 1 or 2.

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