JP2016059005A - Scene determination device, control method thereof, control program, and imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize an exposure control and a flash emission control by determining a specified photographic scene, such as a candle scene, with accuracy.SOLUTION: A photometry sensor 26 comprises: a first pixel group that has sensibility in a visible light region; and a second pixel group that has the sensibility in a deep red to a near-infrared region. By controlling the photometry sensor, a camera control section 41 measures a luminance value in accordance with an output of the first pixel group in each of a plurality of photometry regions in an image obtained by the photographic scene, and measures an infra-red value in accordance with the output of second pixel group in each photometry region. The camera control section determines whether or not that the photographic scene is a specified scene in accordance with the luminance value and the infra-red value.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a scene discrimination device, a control method thereof, a control program, and an imaging device, and more particularly to exposure control and flash light emission control according to a scene discrimination result.

  In general, in an imaging apparatus such as a digital camera, switching from natural light photography to flash photography is performed when the luminance of a subject is lower than a predetermined condition. When performing natural light photography, exposure conditions such as shutter speed (exposure time), aperture value, and photographing sensitivity (imaging gain) are determined according to the subject luminance value obtained by photometry.

  When determining the exposure conditions, in order to reduce the effects of camera shake or subject blur, it is necessary to consider the low speed limit of the shutter speed and the maximum aperture that is determined by the maximum aperture of the photographic lens and the maximum sensitivity that allows noise. is there. If exposure is insufficient even when the maximum aperture value and maximum sensitivity are set, the camera switches from natural light photography to flash photography.

  By the way, when switching from natural light shooting to flash shooting, switching is performed according to the maximum aperture value and maximum sensitivity without determining the shooting scene. As a result, a good image may not be obtained depending on the shooting scene.

  For example, in a so-called candle scene where the main subject is illuminated only by the light of the candle, when the flash photography is performed, the main subject may become too bright due to the flash light. Then, the reddish color due to the light from the candle is erased, resulting in an image different from the appearance.

  In order to solve the problem that occurs in a specific shooting scene by such control, it is necessary to provide a shooting mode for setting whether or not to perform flash shooting according to the user's designation in the specific shooting scene.

  For example, when a user sets a candlelight shooting mode, there is an image pickup apparatus in which the shutter speed in the image pickup device is decreased to further increase sensitivity and the white balance is adjusted to sunlight (about 5000K) (patent) Reference 1). As a result, this imaging apparatus obtains an image that leaves an atmosphere such as redness of candlelight without performing flash photography.

  Further, the first photometric result is obtained by measuring the visible light region, the second photometric result is obtained by measuring the infrared light region, and the first photometric result is corrected by the second photometric result. There is an imaging apparatus that determines the exposure amount (see Patent Document 2).

JP 2012-70300 A JP 2005-115145 A

  However, in the imaging apparatus described in Patent Document 1, the user needs to set the candlelight shooting mode each time a candle scene is shot. That is, it is impossible to automatically determine a specific shooting scene such as a candle scene and perform exposure control and flash light emission control.

  Furthermore, in the imaging apparatus described in Patent Document 2, the first photometric result is corrected with the second photometric result to improve the exposure shift caused by the difference in spectral characteristics between the photometric sensor and the image sensor. However, exposure control and flash emission control cannot be performed by automatically determining a specific shooting scene such as a candle scene.

  Accordingly, an object of the present invention is to determine a specific shooting scene such as a candle scene with high accuracy, and to perform exposure control and flash emission control according to the determination result, a control method thereof, and control A program and an imaging apparatus are provided.

  In order to achieve the above object, a scene discriminating apparatus according to the present invention is a scene discriminating apparatus that discriminates whether or not a shooting scene is a predetermined specific scene, and is a first discriminating device having sensitivity in a visible light region. A second sensor unit having sensitivity from a deep red to a near infrared region, receiving an image obtained in the shooting scene, dividing the image into a plurality of photometric regions, Photometric means for measuring the brightness value according to the output of the first sensor unit in each of the photometric areas, and measuring the infrared value according to the output of the second sensor unit in each of the photometry areas; Scene discrimination means for discriminating whether or not the shooting scene is the specific scene according to a luminance value and the infrared value.

  In the imaging device according to the present invention, when the scene determination device and the scene determination device determine that the shooting scene is the specific scene, the luminance value is equal to or higher than a predetermined luminance value in each of the photometry areas. Calculating means for obtaining a first average subject brightness value by averaging the brightness values in each of the photometry areas by increasing the weighting for the high brightness area, and the first average subject brightness value and a predetermined first Setting means for setting a first shutter speed, a first aperture value, and a first photographing sensitivity using a program diagram of one, the first subject luminance value, the first shutter speed, and the first And a light emission control means for determining whether or not to perform flash light emission in accordance with an aperture value of 1 and the first photographing sensitivity.

  A control method according to the present invention is a control method of a scene discrimination device that discriminates whether or not a shooting scene is a predetermined specific scene, and includes a first sensor unit having sensitivity in a visible light region and a dark red color. Using a photometric sensor having a second sensor unit having sensitivity in the near infrared region, receiving an image obtained in the shooting scene, dividing the image into a plurality of photometric regions, A photometric step of measuring the luminance value according to the output of the first sensor unit in each, and the photometric step of measuring the infrared value according to the output of the second sensor unit in each of the photometric regions; And a scene determination step of determining whether or not the shooting scene is the specific scene according to a luminance value and the infrared value.

  A control program according to the present invention is a control program used in a scene discriminating apparatus that discriminates whether or not a photographic scene is a predetermined specific scene, in a computer provided in the scene discriminating apparatus, in a visible light region. Using a photometric sensor comprising a first sensor unit having sensitivity and a second sensor unit having sensitivity from dark red to the near-infrared region, a plurality of the images are received by receiving an image obtained in the shooting scene. And measuring the luminance value in accordance with the output of the first sensor unit in each of the photometric regions, and in accordance with the output of the second sensor unit in each of the photometric regions. A metering step for metering an infrared value, and a scene discrimination step for discriminating whether or not the shooting scene is the specific scene according to the luminance value and the infrared value. Characterized in that to execute, when.

  According to the present invention, since it is determined whether or not a shooting scene is a specific scene according to the luminance value and infrared value for each photometric area, a specific shooting scene such as a candle scene is accurately determined. can do. As a result, exposure control and flash emission control can be performed according to the determination result.

It is sectional drawing which shows the structure about an example of an imaging device provided with the scene discrimination device by the 1st Embodiment of this invention. It is a figure which shows the structure about an example of the sensor for focus detection shown in FIG. FIGS. 2A and 2B are diagrams for explaining the configuration of an example of the photometric sensor shown in FIG. 1, in which FIG. 1A shows a photometric area obtained by dividing the light receiving surface of the photometric sensor into a plurality of areas, and FIG. It is a figure which shows an example of the color filter arrange | positioned at each of these. It is a block diagram for demonstrating an example of the control system in the camera shown in FIG. 5 is a flowchart for explaining an example of a photographing process in the camera shown in FIG. 6 is a flowchart for explaining an exposure calculation process and a flash use determination process shown in FIG. 5. It is a figure for demonstrating the spectral characteristic of a light source, (a) is a figure which shows the spectral characteristic of a light source schematically, (b) is B (blue), G (green), R (red), and IR ( It is a figure which shows the spectral characteristics of dark red-near-infrared). It is a figure for demonstrating the periodic change of the emitted light intensity of a light source, (a) is a figure which shows the periodic change of the emitted light intensity of the fluorescent lamp which is one of the light sources, (b) is tungsten which is one of the light sources. It is a figure which shows the periodic change of the emitted light intensity of a light bulb. It is a figure which shows an example of the 1st diagram which is a program diagram for candle scenes used with the camera shown in FIG. It is a figure which shows an example of the 2nd diagram which is a program diagram for normal use used with the camera shown in FIG.

  Hereinafter, an example of a scene discrimination device according to an embodiment of the present invention will be described with reference to the drawings.

[First Embodiment]
FIG. 1 is a cross-sectional view illustrating the configuration of an example of an imaging apparatus including a scene discrimination device according to the first embodiment of the present invention.

  The illustrated imaging device is, for example, a single-lens reflex camera (hereinafter simply referred to as a camera) with interchangeable lenses, a camera body 1, an interchangeable lens unit (hereinafter simply referred to as an interchangeable lens) 2, and a light emitting device (hereinafter referred to as a flash device). 3).

  The camera body 1 is provided with an image sensor 12. The image sensor 12 is an area storage type image sensor such as a CMOS or CCD. An optical low-pass filter 11 is disposed on the front side of the image sensor 12, and a mechanical shutter 10 is disposed in front of the optical low-pass filter 11.

  A semi-transmissive main mirror 13 is disposed in front of the mechanical shutter 10. A first reflection mirror 14 is disposed between the mechanical shutter 10 and the main mirror 13. The main mirror and the first reflecting mirror 14 jump upward in the figure when photographing. In other words, the main mirror and the first reflection mirror 14 are retracted from the optical axis during shooting.

  A paraxial imaging plane 15 is defined on the optical axis of the light reflected by the first reflection mirror 14, and this paraxial imaging plane 15 forms an image of the imaging device 12 with respect to the first reflection mirror 14. It is in a position conjugate with the surface.

  The second reflecting mirror 16 reflects the light reflected by the first reflecting mirror 14 and guides it to a focus detection sensor (AF sensor) 20. Between the second reflection mirror 16 and the focus detection sensor 20, an infrared cut filter 17, a diaphragm 18, and a secondary imaging lens 19 are arranged.

  The aperture 18 is formed with two openings. The focus detection sensor 20 includes an area storage photoelectric conversion element such as a CMOS or a CCD.

  FIG. 2 is a diagram showing the configuration of an example of the focus detection sensor 20 shown in FIG.

  The focus detection sensor 20 has light receiving sensor portions 20A and 20B corresponding to the two openings of the diaphragm 18 shown in FIG. Each of the light receiving sensor portions 20A and 20B is divided into a large number of light receiving portions.

  Further, although not shown, the focus detection sensor 20 includes peripheral circuits for signal accumulation and signal processing, and these peripheral circuits are integrated on the same chip together with the light receiving sensor portions 20A and 20B.

  Note that the configuration of the first reflection mirror 14, the second reflection mirror 16, the infrared cut filter 17, the diaphragm 18, the secondary imaging lens 19, and the focus detection sensor 20 is disclosed in Japanese Patent Laid-Open No. 9-184965. As described in the above, focus detection by a so-called image shift method can be performed at an arbitrary position on the photographing screen.

  A diffusive focus plate 21 is disposed above the main mirror 13, and a pentaprism 22 is disposed above the focus plate 21. Then, the light that has passed through the prism 22 enters the eyepiece lens 23.

  A third reflecting mirror 24 is disposed in the vicinity of the prism 22, and the light reflected by the third reflecting mirror 24 is guided to a photometric sensor 26 through a condenser lens 25. The photometric sensor 26 is for obtaining luminance information indicating the luminance of the subject and color information indicating the color. The photometric sensor 26 includes an area storage type photoelectric conversion element such as a CMOS or a CCD.

  FIG. 3 is a diagram for explaining the configuration of an example of the photometric sensor 26 shown in FIG. FIG. 3A is a diagram showing a photometry area obtained by dividing the light receiving surface of the photometry sensor 26 into a plurality of areas, and FIG. 3B shows an example of a color filter arranged in each of the photometry areas. FIG.

  In FIG. 3A, the light-receiving surface of the photometric sensor 20 is divided into a plurality of areas to define a plurality of photometric areas. The photometric sensor 20 outputs luminance information and color information related to the subject for each photometric area. In the illustrated example, the light receiving surface is divided into 35 areas of 5 rows × 7 columns, and photometric areas PD1 to PD35 are formed.

  As shown in FIG. 3B, each of the photometric areas PD1 to PD35 has a plurality of light receiving unit pixels, and a color filter having a predetermined arrangement is arranged in each of the photometric areas PD1 to PD35. ing.

  In the illustrated example, a primary color filter 261 in which four primary colors of B (blue), G (green), and R (red) and four spectral colors of IR (dark red to near infrared) are arranged in a stripe shape is a photometric region. It arrange | positions at each of PD1-PD35.

  The spectral characteristics of the photometric sensor 26 will be described later. In the photometric sensor 26, peripheral circuits for signal amplification and signal processing are integrated on the same chip in addition to the light receiving unit pixels.

  Referring again to FIG. 1, a finder optical system is formed by the focus plate 21, the pentaprism 22, and the eyepiece lens 23. A part of the light metering sensor (AE sensor) 26 that is reflected by the main mirror 13 and further diffused by the focus plate 21 is incident outside the optical axis.

  The camera body 1 is provided with a mount portion 27 for attaching an interchangeable lens (also referred to as a photographing lens) 2. The mount portion 27 is formed with a contact portion 28 for communicating with the photographic lens 2. Further, a connection portion 29 for attaching the flash device 3 is provided on the upper surface of the camera body 1.

  The interchangeable lens 2 includes optical lenses 30 a to 30 e and a diaphragm 31. Further, a contact portion 32 for communicating with the camera body 1 is provided on the rear end surface of the interchangeable lens 2, and a mount portion 33 for attaching the interchangeable lens 2 to the camera body 1 is provided.

  The flash device 3 includes a xenon tube 34 that is a light emitting unit, and the xenon tube 34 is disposed, for example, at a focal position of a reflection shade 35. A condensing Fresnel lens 36 is disposed on the front side of the xenon tube 34.

  The flash device 3 includes a monitor sensor (also referred to as a light emission monitor unit) 37 for monitoring the light emission amount of the xenon tube 34. The flash device 3 is formed with an attachment portion 38 for attaching the flash device 3 to the camera body 1.

  FIG. 5 is a block diagram for explaining an example of a control system in the camera shown in FIG. In FIG. 5, the same components as those shown in FIG. 1 are denoted by the same reference numerals.

  The camera body 1 is provided with a camera control unit 41. The camera control unit 41 is, for example, a one-chip microcomputer that includes an arithmetic unit (ALU), ROM, RAM, A / D converter, timer (Timer), and serial communication port (SPI). The camera control unit 41 controls the entire camera.

  The timing generator (TG) 42 generates a timing signal for controlling charge accumulation and charge reading in the photometric sensor (AE sensor) 26 under the control of the camera control unit 41. Output signals from the focus detection sensor (AF sensor) 20 and the photometry sensor (AE sensor) 26 are input to an input terminal of an A / D converter provided in the camera control unit 41.

  The signal processing circuit 43 drives and controls the image sensor 12 under the control of the camera control unit 41 to A / D convert an image signal (imaging signal) that is an output of the image sensor 12, and then performs predetermined signal processing. Let it be image data. Furthermore, the signal processing circuit 43 performs predetermined image processing such as compression processing when recording image data.

  The memory 44 is, for example, a DRAM and is used as a work memory at the time of signal processing by the signal processing circuit 43. Further, the memory 44 is used as a VRAM for displaying an image on the display unit 45.

  The display unit 45 is constituted by, for example, a liquid crystal panel, and various types of shooting information and images obtained as a result of imaging are displayed on the display unit 45. The camera control 41 controls the lighting of the display unit 45. The storage unit 46 includes, for example, a flash memory or an optical disk, and the signal processing circuit 43 stores image data in the storage unit 46.

  As shown in the figure, a first motor driver 47, a release switch (SW) 49, and a shutter drive unit 50 are connected to the camera control unit 41. The first motor driver 47 drives the first motor 48 for up / down the main mirror 13 and the first reflecting mirror 14 and charging the mechanical shutter 10 under the control of the camera control unit 41. To do.

  The release SW 49 is a switch for instructing the camera control unit 41 to start photographing. The shutter drive unit 50 drives the mechanical shutter 10 under the control of the camera control unit 41.

  The contact portion 28 provided in the camera body 1 is connected to the SPI provided in the camera control unit 41. Further, the connection unit 29 provided in the camera body 1 is connected to an SPI provided in the camera control unit 41.

  The interchangeable lens 2 is provided with a lens control unit 51. The lens control unit 51 is, for example, a one-chip microcomputer incorporating an ALU, ROM, RAM, timer, and SPI. The second motor driver 52 drives a second motor 53 for performing focus adjustment under the control of the lens control unit 51. The third motor driver 54 drives a third motor 55 for driving the diaphragm 31 under the control of the lens control unit 51.

  A distance encoder 56 and a zoom encoder 57 are connected to the lens control unit 51. The distance encoder 56 obtains subject distance information indicating the extension amount of the focus adjustment lens (that is, the focus lens), that is, the subject distance. The zoom encoder 57 obtains focal length information indicating the focal length at the time of shooting according to the movement of the zoom lens provided in the interchangeable lens 2. The contact part 32 is connected to an SPI provided in the lens control part 51.

  When the interchangeable lens 2 is attached to the camera body 1, the contact portions 28 and 32 are connected. Thereby, the lens control unit 51 can perform data communication with the camera control unit 41. Then, the lens control unit 51 sends the lens-specific optical information, subject distance information, and focal length information necessary for performing focus detection (that is, distance measurement) and exposure calculation (that is, photometry) to the camera control unit 41. send.

  The camera control 41 sends focus adjustment information and aperture information obtained by focus detection and exposure calculation to the lens control unit 51. The lens control unit 51 controls the second motor driver 52 according to the focus adjustment information and also controls the third motor driver 54 according to the aperture information.

  The flash device 3 includes a flash control unit 61. Although not shown, the flash control unit 61 is, for example, a one-chip microcomputer incorporating an ALU, ROM, RAM, A / D converter, timer, and SPI. The boosting unit 62 generates a high voltage of about 300 V necessary for light emission of the xenon tube that is the light emitting unit 34, and performs charging with the high voltage.

  When the flash device 3 is attached to the camera body 1, the connection units 38 and 29 are connected, and the flash control unit 61 can perform data communication with the camera control unit 41. The flash controller 61 controls the booster 62 under the control of the camera controller 41 to start and stop the emission of the xenon tube 34. Further, the flash control unit 61 sends the detection result by the monitor sensor 37 to the camera control 41.

  FIG. 5 is a flowchart for explaining an example of photographing processing in the camera shown in FIG. Note that the processing according to the illustrated flowchart is performed under the control of the camera control unit 41.

  Now, when a power switch (not shown) provided in the camera is turned on, the camera control unit 41 becomes operable. Then, the camera control unit 41 obtains lens information necessary for distance measurement and photometry from the lens control unit 51 (step S101: lens communication).

  Subsequently, the camera control unit 41 controls the focus detection sensor 20 by the TG 42 to perform charge accumulation (signal accumulation), and when the signal accumulation is completed, reads a signal (that is, charge) accumulated in the focus detection sensor 20. (Step S102). The camera control unit 41 performs A / D conversion on the signal charge to obtain focus detection data, and performs data correction such as shading correction on the focus detection data.

  Next, the camera control unit 41 performs focus detection for each focus detection area in accordance with the lens information and focus detection data, and obtains a focus detection result (step S103). Then, the camera control unit 41 determines a focus detection area to be focused.

  In determining the focus detection area, for example, the camera control unit 41 determines the focus detection area designated by the user as the focus detection area to be focused. The camera control unit 41 may determine the main subject area as a focus detection area to be focused.

  The camera control unit 41 calculates a lens movement amount for achieving a focus state according to a focus detection result in a focus detection region to be focused. Then, the camera control unit 41 sends the lens driving amount to the lens control unit 51. The lens control unit 51 controls the second motor driver 52 based on the lens driving amount and drives the focus adjustment lens by the second motor 53 (step S103). As a result, the interchangeable lens 2 is brought into focus with respect to the main subject.

  At this time, since the subject distance information is changed by driving the focus adjustment lens, the lens control unit 51 updates the lens information.

  Subsequently, the camera control unit 41 controls the TG 42 to perform accumulation control and signal readout control for the photometric sensor 26 (step S104). As a result, the photometric sensor 26 accumulates charges for a predetermined time and outputs signal charges. The camera control unit 41 A / D converts the signal charge and stores it in the RAM as photometric data.

  Next, the camera control unit 41 performs predetermined exposure calculation processing and determination processing for determining whether or not flash photography is performed based on the photometry data stored in the RAM as described later (step S105). ).

  In accordance with the processing in step S105, the camera control unit 41 determines whether to perform flash photography, that is, whether to use the flash (step S106). If it is determined that the flash is to be used (YES in step S106), the camera control unit 41 controls the flash control unit 61 to operate the boosting unit 62 to charge a high voltage sufficient for flash emission (step S107: Flash charge).

  Next, the camera control unit 41 confirms whether or not the release SW 49 has been turned on (step S108). If release SW 49 is not turned on (NO in step S108), camera control unit 41 returns to the process in step S101.

  When the release SW 49 is turned on (YES in step S108), the camera control unit 41 checks whether or not it is determined to perform flash photography in step S105 described above (step S109). If it is determined that flash photography is to be performed (YES in step S109), the camera control unit 41 instructs the flash control unit 61 to perform flash preliminary light emission (step S110).

  As a result, the flash controller 61 causes the xenon tube 34 to emit light (preliminary light emission). The flash control unit 61 monitors the output signal from the monitor sensor 37 and controls the light emission of the xenon tube 34 so that the light emission amount of the xenon tube 34 becomes a preset preliminary light emission amount.

  When the preliminary light emission is performed, the camera control unit 41 controls the TG 42 to perform predetermined charge accumulation control and signal readout control for the photometric sensor 26. As a result, the photometric sensor 26 accumulates charges for a predetermined time and outputs a signal charge. Then, the camera control unit 41 performs A / D conversion on the signal charge, and performs a main light emission amount calculation for determining the flash main light emission amount by a known method in accordance with the light emission photometric data (step S110).

  Subsequently, the camera control unit 41 drives the first motor 48 by the first motor driver 47 to jump up (retract from the optical axis) the main mirror 13 and the first reflection mirror 14. Then, the camera control unit 41 sends to the lens control unit 51 aperture control information indicating the opening of the aperture 31 obtained by the exposure calculation process described above.

  The lens control unit 51 drives and controls the third motor 55 by the third motor driver 54 based on the diaphragm control information to drive the diaphragm 31 (step S111). As a result, the interchangeable lens (photographing lens) 2 is in a narrowed state.

  If it is determined not to perform flash photography (NO in step S109), the camera control unit 41 proceeds to the process of step S111.

  Subsequently, the camera control unit 41 causes the shutter driving unit 50 to open the shutter 10 (step S112). As a result, a light beam (optical image) enters the imaging element 12 from the photographing lens 2 and imaging is performed (step S112).

  Here, the camera control unit 41 sets the charge accumulation time and the readout gain according to the shutter control time and the imaging sensitivity obtained by the exposure calculation process described above, and the signal processing circuit 43 controls the charge accumulation of the image sensor 12. And signal readout control is performed.

  When performing flash photography, the camera control unit 41 sends a flash emission instruction to the flash control unit 61 in synchronization with the imaging timing. The flash control unit 61 causes the xenon tube 34 to emit light according to the flash emission instruction and monitors the output signal of the monitor sensor 37 so that the light emission amount of the xenon tube 34 becomes the main light emission amount obtained in step S110. The light emission of the xenon tube 34 is controlled. Thereby, imaging using flash light emission is performed.

  When the imaging is completed, the camera control unit 41 causes the shutter driving unit 50 to put the shutter 10 in a light shielding state (step S113). Thereby, the optical image incident on the image sensor 12 is blocked.

  Further, the camera control unit 41 instructs the lens control unit 51 to open the aperture 31. As a result, the lens control unit 51 drives and controls the third motor 55 by the third motor driver 54 to open the diaphragm 31 (step S113). Further, the camera control unit 41 drives and controls the first motor 48 by the first motor driver 47, and lowers the main mirror 13 and the first reflection mirror 14 (step S113).

  Subsequently, the camera control unit 41 performs A / D conversion on the image signal output from the image sensor 12 by the signal processing circuit 43, and then performs predetermined correction processing and interpolation processing (step S114). Further, the camera control unit 41 performs white balance processing by the signal processing circuit 43 (step S115).

  For example, the signal processing circuit 43 divides the image into a plurality of areas, and extracts a white area of the subject according to the color difference signal for each area. Then, the signal processing circuit 43 performs white balance processing by performing gain correction on the red channel and the blue channel in the entire image based on the white region.

  The camera control unit 41 compresses and converts the image data after the white balance processing into a recording file format by the signal processing circuit 43, and then stores it in the storage unit 46. Then, the camera control unit 41 ends the shooting process.

  FIG. 6 is a flowchart for explaining the exposure calculation process and the flash use determination process shown in FIG.

  As described with reference to FIG. 5, photometric data is stored in the RAM. The camera control unit 41 adds the B, G, and R components (spectral components) for each of the photometric areas (blocks) PD1 to PD35 to obtain integrated values B (i), G (i), and R (i). Obtained (step S151). Then, the camera control unit 41 multiplies the integral values B (i), G (i), and R (i) by predetermined coefficients (y1 to y3), respectively, as shown in the following equation (1). Then, subject luminance information Yr (i) for each photometric area is obtained.

Yr (i) = y1 * B (i) + y2 * G (i) + y3 * R (i) (1)
However, i = 1 to 35 and y1 + y2 + y3 = 1.

  Here, the coefficient y1 is set to about 0.2, the coefficient y2 is set to about 0.5, and y3 is set to about 0.3 so that the spectral characteristic of the detection luminance of the photometric sensor 26 approaches the visual sensitivity or the spectral sensitivity of the image sensor 12. To. In calculating the subject luminance information Yr (i), infrared IR (i) may be considered.

  As shown in the following formula (2), the camera control unit 41 performs a conversion function process on the subject luminance information Yr (i) for each of the photometric areas PD1 to PD35 into a logarithmic compression system with 2 as a base. Further, the camera control unit 41 obtains subject luminance information Y (i) in the logarithmic compression system by performing correction processing for correcting the luminance information S (i) for each photometric area based on the optical characteristics corresponding to the lens information. .

Y (i) = log ₂ {Yr (i)} × S (i) (2)
In general, since the shutter speed and the aperture value are set in logarithmic series of steps, the camera control unit 41 obtains subject luminance information Y (i) in the logarithmic compression system as described above.

  Subsequently, the camera control unit 41 determines whether each of the photometry areas PD1 to PD35 is a high brightness area based on the subject brightness information Y (i). That is, the camera control unit 41 detects a high brightness area for each of the photometry areas PD1 to PD35 based on the subject brightness information Y (i) (step S152).

  Here, for example, the camera control unit 41 obtains the average value (row average value) of the luminance values indicated by the subject luminance information Y (i) in the row direction, and is positioned in the row indicating the maximum value among these row average values. The photometric area to be used is a high brightness area. Furthermore, the camera control unit 41 obtains an average value (column average value) of the luminance values indicated by the subject luminance information Y (i) in the column direction, and a photometric area located in the column indicating the maximum value among these column average values Is a high luminance region.

  The camera control unit 41 determines the luminance value indicated by the subject luminance information Y (i) for a total of nine areas (photometric area group) including three areas in the horizontal direction (row direction) and three areas in the vertical direction (column direction). The average value is obtained according to. Then, the camera control unit 41 may detect a photometric area group showing the maximum value among these average values as a high luminance area.

  Next, the camera control unit 41 obtains the average luminance value Ya of the entire image using the subject luminance information Y (i) (step S153). Here, for example, the camera control unit 41 calculates the average luminance value Ya by simply averaging the luminance values indicated by the subject luminance information Y (i). Note that the camera control unit 41 may obtain the average luminance value Ya by setting the weight in the central portion of the image or the above-described in-focus area larger than the weight in the other photometry areas.

  Subsequently, the camera control unit 41 calculates average color values Ba, Ga, Ra, and IRa in the entire image based on the integral values B (i), G (i), and R (i) (step S154). ). The average color value IRa is obtained by simply averaging the infrared value IR (i). Furthermore, the average color value IRa may be obtained by making the weighting in the central portion of the image or the above-described in-focus area larger than the weighting in other photometry areas. And it calculates | requires similarly about each of average color value Ba, Ga, and Ra.

  Next, the camera control unit 41 satisfies the first condition in which the average luminance value Ya is determined in advance, and the second in which the average color value IRa (hereinafter also referred to as average IR value (average infrared value)) is determined in advance. It is determined whether or not the above condition is satisfied (step S155).

  In the process of step S155, the camera control unit 41 determines whether or not the shooting scene is a scene that seems to be a candle scene (a scene in which the main subject is illuminated only by candle light) according to subject brightness and IR spectral sensitivity. To do. Here, it is assumed that the camera control unit 41 does not satisfy the first condition when the average luminance value Ya is a high luminance value (greater than a predetermined luminance value), for example, outdoors in the daytime. That is, the camera control unit 41 determines that the predetermined condition is satisfied when the average luminance value Ya is smaller than the predetermined luminance value. Further, the camera control unit 41 determines that the average color value IRa satisfies the second condition when the ratio to the average luminance value Ya is equal to or greater than a predetermined value.

  FIG. 7 is a diagram for explaining the spectral characteristics of the light source. FIG. 7A schematically shows the spectral characteristics of the light source, and FIG. 7B shows B (blue), G (green), R (red), and IR (dark red to near red). FIG.

  In FIG. 7A, the horizontal axis indicates the wavelength of light, and its unit is nm. The vertical axis indicates the relative light intensity. A spectral characteristic 81 indicated by a solid line indicates a spectral characteristic of candle light. The light intensity on the short wavelength side in the visible light region is low, and the light intensity increases as the wavelength increases. The spectral characteristic 81 has a high light intensity in the near infrared region.

  A spectral characteristic 82 indicated by a broken line indicates a spectral characteristic of tungsten light bulb light. Like the candle light, the light intensity on the short wavelength side in the visible light region is low, and the light intensity increases as the wavelength becomes longer. The spectral characteristic 82 tends to have higher light intensity even in the near infrared region.

  A spectral characteristic 83 indicated by a broken line indicates a spectral characteristic of the light bulb color fluorescent lamp, and the light bulb color fluorescent light emits light by combining several bright line spectra by the phosphor. Thereby, in the light bulb color fluorescent lamp, the emission line spectrum peak of red is relatively increased with respect to blue and green so as to obtain a warm emission color. The spectral characteristic 83 contains very little deep red to infrared wavelength component exceeding 650 nm.

  Note that the spectral characteristics of a light bulb color LED that emits light by combining several emission line spectra of phosphors are also similar to the spectral characteristics of a light bulb color fluorescent lamp.

  In FIG.7 (b), a horizontal axis shows the wavelength of light and the unit is nm. The vertical axis indicates relative light intensity. A spectral characteristic 91 indicated by a broken line indicates a spectral characteristic of a B (blue) spectral pixel, and a spectral characteristic 92 indicated by a broken line indicates a spectral characteristic of a G (green) spectral pixel. A spectral characteristic 93 indicated by a one-dot chain line indicates a spectral characteristic of an R (red) spectral pixel, and a spectral characteristic 94 indicated by a solid line indicates a spectral characteristic of an IR (dark red to near infrared) spectral pixel. As shown in the figure, the IR (dark red to near infrared) spectroscopic pixel selects light in a long wavelength region exceeding about 650 nm.

  In general, a photometric sensor (color imaging sensor) has three spectral pixels of B (blue), G (green), and R (red). In such a color imaging sensor, when a subject illuminated with three types of light sources shown in FIG. 7A is measured, B (blue), G (green), and R (red) under any light source. It is difficult to distinguish the light sources because the output ratio becomes a similar value.

  On the other hand, when the color imaging sensor has an IR (dark red to near infrared) spectral pixel, a light bulb color fluorescent lamp and a light bulb color LED having almost no dark red to near infrared component, and dark red to near infrared. It becomes easy to distinguish from candlelight or tungsten bulb light in which the component is present above a certain level.

  Referring to FIG. 6 again, when average luminance value Ya satisfies the first condition and average color value IRa satisfies the second condition (YES in step S155), camera control unit 41 determines that the shooting scene is Suppose there is a possibility of a candle scene. And the camera control part 41 calculates | requires ratio Ra / Ga and Ba / Ga using average color value Ba, Ga, and Ra. Thereafter, the camera control unit 41 determines whether or not the ratio Ra / Ga is greater than or equal to a predetermined value (determination threshold) with respect to the ratio Ba / Ga (step S156). Whether or not the ratio Ra / Ga is equal to or higher than a predetermined value (determination threshold) with respect to the ratio Ba / Ga is, for example, that the absolute value of the difference between the ratio Ba / Ga and the ratio Ra / Ga is constant. What is necessary is just to determine whether it is more than a value (determination threshold value). Alternatively, the ratio Ra / Ba is obtained using the average color values Ba and Ra instead of whether or not the ratio Ra / Ga is equal to or higher than a predetermined value (determination threshold) with respect to the ratio Ba / Ga. The determination may be made based on whether the ratio Ra / Ba is equal to or greater than a certain value (determination threshold).

  Here, in the case of a shooting scene candle scene, the entire image is reddish and bluish, and if the ratio Ra / Ga is greater than or equal to a predetermined value with respect to the ratio Ba / Ga, The shooting scene is determined to be a candle scene. However, since the above ratio varies depending on the color of the subject such as the color of clothes, the determination threshold is set in consideration of the color of the subject.

  If the ratio Ra / Ga is greater than or equal to the determination threshold with respect to the ratio Ba / Ga (YES in step S156), the camera control unit 41 obtains the temporal change in the average luminance value Ya and changes the luminance of the average luminance Ya over time. It is checked whether or not there is periodicity (step S157). That is, the camera control unit 41 checks whether or not the temporal change in the average luminance Ya is irregular and there is a low-frequency light / dark change.

  FIG. 8 is a diagram for explaining a periodic change in the light emission intensity of the light source. FIG. 8A is a diagram showing a periodic change in the emission intensity of a fluorescent lamp, which is one of the light sources, and FIG. 8B is a periodical change in the emission intensity of a tungsten bulb, which is one of the light sources. FIG.

  It is known that a fluorescent lamp driven by a commercial power source has a periodic change in emission intensity called flicker. 8A and 8B, the horizontal axis represents time (seconds), and the vertical axis represents relative light emission intensity. In a fluorescent lamp driven by a commercial power supply of 50 Hz, the light intensity changes bright / dark with regularity of 100 Hz which is twice the power supply frequency, that is, a period of 0.1 second (see FIG. 8A).

  On the other hand, in a tungsten light bulb driven by a commercial power source, no clear flicker is observed like a fluorescent lamp due to the afterglow effect of the filament, and there is a periodic light / dark change in light emission intensity with a small amplitude (Fig. 8 (b)).

  In addition, since the candle is not driven by a commercial power supply, there is no bright / dark change in light emission intensity with periodicity that depends on the power supply frequency, and it is not caused by fluctuations in the flame caused by convection of the surrounding air. There are regular and low frequency light / dark changes.

  If the time change of the average luminance value Ya is detected for a certain period of time, for example, at intervals of about 1 ms to 2 ms, and the intensity and period of the light intensity / dark change of the emission intensity is observed, the period depending on the shooting scene depends on the commercial power supply It can be determined whether there is a dynamic flicker or irregular light / dark changes.

  Referring to FIG. 6 again, when the average luminance value Ya changes irregularly and there is a low-frequency light / dark change (YES in step S157), the camera control unit 41 performs the above-described process. In order to prevent the detected high brightness area from becoming too bright, the high brightness area is weighted according to the subject brightness information Y (i) of the photometry areas PD1 to PD35. Then, the camera control unit 41 performs a weighted average calculation to obtain an average subject luminance value (hereinafter simply referred to as subject luminance value) Bv (A) (step S158).

  When obtaining the subject brightness value Bv (a), the camera control unit 41 selects a photometric area in a predetermined range including the high brightness area from the photometric areas PD1 to PD35, and the subject only in the selected photometric area. The subject brightness value Bv (A) may be obtained using the brightness information. Furthermore, the camera control unit 41 obtains a difference between the average luminance value Ya and the luminance value in the high luminance area. Then, the camera control unit 41 may multiply the difference by a predetermined coefficient, and an addition value obtained by adding the multiplication result and the average luminance value Ya may be set to the subject luminance value Bv (A).

  Subsequently, the camera control unit 41 determines an exposure factor (control value) such as a shutter speed, an aperture value, and a photographing sensitivity using a program diagram for a candle scene based on the subject luminance value Bv (A) ( Step S159). Further, the camera control unit 41 determines whether or not to use the flash as described later.

  FIG. 9 is a diagram illustrating an example of a first diagram which is a program diagram for a candle scene used in the camera illustrated in FIG. 4.

  In FIG. 9, the horizontal axis indicates the subject luminance value Bv (A), and the vertical axis indicates the shutter speed (Tv), the aperture value (Av), and the photographing sensitivity (ISO), respectively.

  If the subject brightness value Bv (A) = 4, in FIG. 9, the shutter speed (Tv) is 1/60 seconds, the aperture value (Av) is F2.8, and the photographing sensitivity (ISO) is ISO100. Is done.

  On the other hand, when the subject brightness value Bv (A) is brighter than 4, the photographing sensitivity is fixed at ISO 100, and the subject brightness Bv (A) is one step brighter for each of the shutter speed (Tv) and the aperture value (Av). Each time, it is changed by 0.5 steps. In the range where the subject brightness value Bv (A) is −1 or more and less than 4, the shutter speed (Tv) is fixed to 1/60 seconds, the aperture value (Av) is fixed to F2.8, and the photographing sensitivity is set to ISO3200 to ISO100. Change in range.

  When the subject brightness value Bv (A) is −1 or more, the camera control unit 41 determines that the proper exposure can be performed by natural light photography and does not perform flash emission. When the subject brightness value Bv (A) is less than −1, the camera control unit 41 sets the shutter speed (Tv) to 1/60 seconds, the aperture value (Av) to F2.8, and the photographing sensitivity to ISO 3200. It is determined that flash photography will be performed.

  In the illustrated example, the upper limit of the photographing sensitivity in the candle scene is ISO 3200, the low speed limit of the shutter speed (Tv) is set to 1/60 seconds in consideration of camera shake and subject shake, etc., depending on the opening of the photographing lens or the subject depth. The maximum F value is 2.8.

  When the process of step S159 ends, the camera control unit 41 proceeds to the process of step S106 shown in FIG.

  If the average luminance value Ya satisfies the first condition and the average color value IRa does not satisfy the second condition (NO in step S155), the camera control unit 41 weights the center portion of the image or the focus area. And subject weight value Bv (A) is obtained by performing a weighted average calculation according to the subject brightness information Y (i) of the photometry areas PD1 to PD35 (step S160).

  Subsequently, based on the subject brightness value Bv (A), the camera control unit 41 determines an exposure factor (control value) such as a shutter speed, an aperture value, and a photographing sensitivity using a program diagram for a normal scene ( Step S161). Further, the camera control unit 41 determines whether or not to use the flash as described later.

  FIG. 10 is a diagram showing an example of a second diagram which is a normal program diagram used in the camera shown in FIG.

  In FIG. 10, the horizontal axis represents the subject luminance value Bv (A), and the vertical axis represents the shutter speed (Tv), the aperture value (Av), and the photographing sensitivity (ISO), respectively.

  Now, if the subject luminance value Bv (A) = 4, the shutter speed (Tv) is 1/60 seconds, the aperture value (Av) is F2.8, and the photographing sensitivity (ISO) is ISO100 in FIG. Is done.

  On the other hand, when the subject brightness value Bv (A) is brighter than 4, the photographing sensitivity is fixed at ISO 100, and the subject brightness Bv (A) is one step brighter for each of the shutter speed (Tv) and the aperture value (Av). Each time, it is changed by 0.5 steps. When the subject brightness value Bv (A) is 1 or more and less than 4, the shutter speed (Tv) is fixed to 1/60 seconds, the aperture value (Av) is fixed to F2.8, and the photographing sensitivity is in the range of ISO 800 to ISO 100. Change with.

  When the subject luminance value Bv (A) is 1 or more, the camera control unit 41 determines that the proper exposure can be performed by natural light photography and does not perform flash emission. When the subject brightness value Bv (A) is less than 1, the camera control unit 41 sets the shutter speed (Tv) to 1/60 seconds, the aperture value (Av) to F2.8, and the shooting sensitivity to ISO800, and the flash It is determined that shooting is to be performed.

  In the illustrated example, the upper limit of the shooting sensitivity in a normal scene is ISO800, the shutter speed (Tv) is set to a low speed limit of 1/60 seconds in consideration of camera shake and subject shake, etc. The maximum F value is 2.8.

  When the process of step S161 ends, the camera control unit 41 proceeds to the process of step S106 shown in FIG.

  If the ratio Ra / Ga is less than the determination threshold with respect to the ratio Ba / Ga (NO in step S156), the camera control unit 41 proceeds to the process of step S160. If the average luminance value Ya is irregular in time and there is no low-frequency light / dark change (NO in step S157), the camera control unit 41 proceeds to the process in step S160.

  Here, when the second diagram shown in FIG. 10 is compared with the first diagram shown in FIG. 9, the subject luminance value Bv (A) for switching between the natural light photography and the flash photography is different. In the second diagram, the upper limit of the photographing sensitivity is ISO800, so when the subject brightness value Bv (A) is less than 1, the flash photography is switched. However, in the first diagram, the upper limit of the photographing sensitivity is ISO3200. However, when the subject brightness value Bv (A), which has a lower brightness, becomes less than -1, the flash photography is switched.

  When the shooting sensitivity is increased, image noise and the like may increase accordingly. However, in a candle scene, it is possible to obtain an image with a better atmosphere that looks better when natural light shooting is performed.

  As described above, in the embodiment of the present invention, it is determined whether or not the shooting scene is a specific scene such as a candle scene, and the program line used for the exposure control and the flash control according to the determination result. Change the figure. This makes it possible to perform exposure control and flash emission control according to whether or not the scene is a specific scene.

  In the above-described embodiment, the flash device 3 is detachable from the camera body 1, but the flash device 3 may be fixed to the camera body 1. Further, in FIG. 6, the average luminance value of the entire image is obtained in step S153, but the average luminance value may be obtained for a high luminance region in the image. In step S154, an average color value in the high luminance area may be obtained.

  As is clear from the above description, in the example shown in FIG. 4, the photometric sensor (AE sensor) 26, the TG 42, and the camera control unit 41 function as photometry means, and the camera control unit 41 functions as scene discrimination means. .

  Further, the camera control unit 41 functions as a calculation unit and a setting unit, and the camera control unit 41 and the flash control unit 61 function as a light emission control unit.

  In the illustrated example, at least the photometric sensor (AE sensor) 26, the TG 42, and the camera control unit 41 constitute a scene discrimination device.

  As mentioned above, although this invention was demonstrated based on embodiment, this invention is not limited to these embodiment, Various forms of the range which does not deviate from the summary of this invention are also contained in this invention. .

  For example, the function of the above embodiment may be used as a control method, and this control method may be executed by the scene determination device. Further, a program having the functions of the above-described embodiment may be used as a control program, and the control program may be executed by a computer included in the scene determination device. The control program is recorded on a computer-readable recording medium, for example.

  The present invention can also be realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various recording media, and the computer (or CPU, MPU, etc.) of the system or apparatus reads the program. To be executed.

DESCRIPTION OF SYMBOLS 1 Camera main body 2 Interchangeable lens 3 Flash apparatus 12 Image sensor 20 Focus detection sensor 26 Photometric sensor 41 Camera control part 43 Signal processing circuit 51 Lens control part 61 Flash control part

Claims (12)

A scene discriminating apparatus that discriminates whether or not a shooting scene is a predetermined specific scene,
A first sensor unit having sensitivity in a visible light region and a second sensor unit having sensitivity in a deep red region to a near infrared region are received, and an image obtained in the shooting scene is received, and the image is subjected to a plurality of photometry. The luminance value is divided according to the output of the first sensor unit in each of the photometry regions, and the infrared value is measured in accordance with the output of the second sensor unit in each of the photometry regions. A metering means for metering the value;
Scene discriminating means for discriminating whether or not the shooting scene is the specific scene according to the luminance value and the infrared value;
A scene discrimination device characterized by comprising:   The scene discriminating means obtains an average luminance value by averaging the luminance values in each of the photometric areas, obtains an average infrared value by averaging the infrared values in each of the photometric areas, and calculates the average luminance value 2. The scene determination according to claim 1, wherein if the average infrared value does not satisfy a predetermined first condition and a second condition, the scene is determined not to be the specific scene. apparatus.   The scene determination unit determines that the first condition is not satisfied when the average luminance value is equal to or greater than a predetermined luminance value, and a ratio between the average infrared value and the average luminance value Ya is less than a predetermined value. The scene determination device according to claim 2, wherein if there is, it is determined that the second condition is not satisfied. The first sensor unit has sensitivity to a predetermined first spectrum, second spectrum, and third spectrum,
The scene determination means averages the first spectrum, the second spectrum, and the third spectrum in each of the photometry areas, and averages the first average color value, the second average color value, and The third average color value is obtained, and the first average color value / second average color value is obtained as the first ratio, and the third average color value / second average color value is obtained as the second ratio. 3. The ratio according to claim 2, wherein the shooting scene is determined not to be the specific scene when the second ratio is less than a predetermined determination threshold with respect to the first ratio. 4. The scene discrimination device according to 3.   The scene determination unit detects a temporal change in the average luminance value, and determines that the shooting scene is not the specific scene when the temporal change has a predetermined regularity. The scene discrimination device according to claim 4.   The scene determination apparatus according to claim 1, wherein the specific scene is a candle scene in which a subject is illuminated with light from a candle.   The scene determination apparatus according to claim 4, wherein the first spectrum, the second spectrum, and the third spectrum are blue, green, and red, respectively. A scene discrimination device according to claim 5;
When the scene discriminating apparatus determines that the shooting scene is the specific scene, the photometry area is set by increasing the weighting for the high brightness area where the brightness value is equal to or higher than a predetermined brightness value in each of the photometry areas. Calculating means for averaging the luminance values in each of the two to obtain a first average subject luminance value;
Setting means for setting a first shutter speed, a first aperture value, and a second photographing sensitivity using the first average subject luminance value and a predetermined first program diagram;
Light emission control means for determining whether to perform flash light emission according to the first subject luminance value, the first shutter speed, the first aperture value, and the first photographing sensitivity;
An imaging device comprising: When the scene discriminating apparatus determines that the shooting scene is not the specific scene, the calculation means increases the weight for at least one predetermined photometry area in the photometry area, and the luminance value in each of the photometry areas To obtain a second average subject luminance value,
The setting means sets a second shutter speed, a second aperture value, and a second photographing sensitivity using the second average subject luminance value and a predetermined second program diagram,
The light emission control means determines whether to perform flash light emission according to the second subject luminance value, the second shutter speed, the second aperture value, and the second photographing sensitivity. The imaging apparatus according to claim 8, wherein the imaging apparatus is characterized.   The imaging apparatus according to claim 9, wherein the predetermined at least one photometric area is an area located in the center of the image or an in-focus area in the image. A control method of a scene discrimination device for discriminating whether or not a shooting scene is a predetermined specific scene,
Using a photometric sensor comprising a first sensor unit having sensitivity in the visible light region and a second sensor unit having sensitivity in the near-infrared region from dark red, receiving an image obtained in the shooting scene, The image is divided into a plurality of photometric areas, and the luminance value is measured in accordance with the output of the first sensor unit in each of the photometric areas, and the output of the second sensor unit in each of the photometric areas. A metering step for metering the infrared value according to
A scene determination step of determining whether or not the shooting scene is the specific scene according to the luminance value and the infrared value;
A control method characterized by comprising: A control program used in a scene discriminating apparatus for discriminating whether or not a shooting scene is a predetermined specific scene,
In the computer provided in the scene discrimination device,
Using a photometric sensor comprising a first sensor unit having sensitivity in the visible light region and a second sensor unit having sensitivity in the near-infrared region from dark red, receiving an image obtained in the shooting scene, The image is divided into a plurality of photometric areas, and the luminance value is measured in accordance with the output of the first sensor unit in each of the photometric areas, and the output of the second sensor unit in each of the photometric areas. A metering step for metering the infrared value according to
A scene determination step of determining whether or not the shooting scene is the specific scene according to the luminance value and the infrared value;
A control program characterized by causing

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