JP5672922B2 - Imaging device - Google Patents

Description

  The present invention relates to an imaging apparatus such as a digital still camera or a digital video camera.

  In recent digital still cameras (hereinafter referred to as “digital cameras”), in addition to an autofocus (AF) function, an auto exposure (AE) function, and an auto white balance (AW) function, a person as a main subject in an imaging screen It has become common to have face detection means for automatically detecting the face of a person when there is a face (for example, see Patent Document 1).

  When a face detection means for detecting a person's face is provided as in the digital camera disclosed in Patent Document 1, when a subject image is formed on the light receiving surface of the image sensor through the photographing lens, the image is output from the image sensor. Image data is input to the face detection means. When the face detection unit detects the human face as a main subject from the input image data by a known method, the control unit focuses (focuses) on the position of the human face detected by the face detection unit. (Focus position) is determined, and an optimal exposure and white balance are determined using the human face as a photometric area.

  By the way, the face detection means is configured to detect a person's face as a main subject from the input image data as described above by a known method. For example, the face of the person who is the main subject is detected by extreme backlighting. If it is too dark for a predetermined time, it may be difficult to detect the face of a person. Also, even when the background around the face of the person who is the main subject is dark and the person's face is exposed to extremely bright illumination from the front and is too bright above a predetermined level, it is difficult to detect the person's face itself. May be.

  As described above, even when a person's face as a main subject is present in the imaging screen, if the person's face cannot be detected due to the above-described shooting conditions, the focus (focus position) is set relative to the position of the person's face. ) Cannot be determined, and the optimal exposure and white balance cannot be determined using the human face as the photometric area, so that a photographed image different from the photographer's intention may be obtained.

  Accordingly, the present invention is based on the main subject (for example, when the main subject is too dark due to backlighting, or when the main subject is exposed to strong illumination light from the front side and is overexposed). For example, an object of the present invention is to provide an imaging apparatus capable of detecting a main subject in an imaging screen even when a human face) cannot be detected.

In order to achieve the above object, an imaging apparatus according to claim 1, wherein an imaging device for main photographing that captures an image for main photographing through an optical system for main photographing, and auxiliary photographing through an optical system for auxiliary photographing. Generated by an auxiliary photographing image pickup device that picks up an image for use, first image data generated by an image signal output from the main photographing image pickup device, and an image signal output from the auxiliary photographing image pickup device Exposure control means for performing arbitrary exposure control on the second image data, and a main object for detecting a main subject located in the imaging screen from the first image data and the second image data, respectively. Subject detection means, wherein the main photographing optical system has a zoom function, and the angle of view of the auxiliary photographing optical system is set to be substantially the same as the angle of view on the wide angle end side of the main photographing optical system. The main photographing optical system When the angle of view being telephoto zoom than at the wide angle end, the main subject detection unit, if it can not detect the main object from the first image data by shooting conditions, the exposure control means Thus, the second image data is subjected to exposure shift control to the high luminance side or the low luminance side, and the second imaging data subjected to the exposure shift control by the main subject detection means is used for the auxiliary imaging. The main subject is detected from an area corresponding to the angle of view of the main imaging optical system in the entire imaging area of the element .

  The imaging apparatus according to claim 2, wherein when the main subject detection unit can detect the main subject from the second image data subjected to exposure shift control, the exposure control unit performs the exposure shift control. Based on the position information of the main subject detected from the second image data, photometry processing is performed using the corresponding position for the first image data as a photometry area, and the exposure of the main subject is performed based on the photometry result. It is characterized by performing control.

  The imaging apparatus according to claim 3 includes at least a pair of the auxiliary photographing optical system and the auxiliary photographing image sensor, and the exposure control unit outputs from one of the pair of auxiliary photographing image sensors. The second image data generated by the image signal output from the other auxiliary photographing image sensor is subjected to exposure shift control to the high luminance side with respect to the second image data generated by the image signal to be processed. In contrast, exposure shift control is performed on the low luminance side.

  The image pickup apparatus according to claim 4 has one auxiliary photographing optical system and the auxiliary photographing image sensor, and the exposure control unit is configured to output an image signal output from the one auxiliary photographing image sensor. The generated second image data can be switched between exposure shift control to the high luminance side and exposure shift control to the low luminance side.

  The image pickup apparatus according to claim 5 includes one auxiliary photographing optical system and the auxiliary photographing image sensor, and the exposure control unit is configured to output an image signal output from the one auxiliary photographing image sensor. Exposure shift control is performed on either the high luminance side or the low luminance side with respect to the generated second image data.

The imaging apparatus according to claim 6 , wherein when the main subject detection unit can detect the main subject from the first image data, the exposure control unit applies the second image data to the second image data. Exposure shift control is not performed, and the main subject detection means does not detect the main subject from the second image data.

The image pickup apparatus according to claim 7 , wherein the main subject detection unit does not perform an image pickup operation by the auxiliary imaging device when the main subject can be detected from the first image data. It is a feature.

The image pickup apparatus according to an eighth aspect is characterized in that the main subject is a person's face, and the main subject detecting means detects a person's face as the main subject.

  According to the imaging apparatus of the present invention, even when the main subject cannot be detected from the first image data generated by the image signal output from the main imaging element depending on the imaging situation, the high luminance side or low luminance The main subject can be detected from the second image data generated by the image signal output from the auxiliary photographing image sensor whose exposure shift is controlled to the side. Therefore, based on the position of the main subject detected from the second image data, the focus (focus position) can be determined with respect to the position corresponding to the first image data. It becomes possible to determine the balance.

1 is a front view showing a digital camera as an example of an imaging apparatus according to Embodiment 1 of the present invention. 1 is a block diagram illustrating an outline of a system configuration of a digital camera according to Embodiment 1. FIG. The figure which shows the time interval of exposure control and a face detection process at the time of monitoring operation | movement. (A) is a schematic sectional drawing which shows the auxiliary imaging unit in Embodiment 1, (b) is a top view which shows the 1st, 2nd auxiliary imaging element of this auxiliary imaging unit. (A) is a figure which shows an imaging | photography angle of view when the imaging lens is zoomed to the widest angle side, (b) is a figure which shows the angle of view of the lens for auxiliary image sensors. (A) is a view showing a shooting angle of view when the shooting lens is zoomed from the widest angle to the telephoto side, and (b) corresponds to the angle of view of the lens for the auxiliary image sensor and the shooting angle of view at this time. The figure which shows an area | region. 5 is a flowchart showing face detection processing and exposure control processing for detecting a human face during a monitoring operation according to the first embodiment of the present invention. (A) is a figure which shows an example of an image when a person's face has become too dark by backlight, (b) is an example of the image by which exposure shift control was carried out to the high-intensity side, and the person's face became bright FIG. FIG. 6 is a front view showing a digital camera as an example of an imaging apparatus according to Embodiments 2 and 3 of the present invention. FIG. 5 is a schematic cross-sectional view illustrating an auxiliary imaging unit according to Embodiments 2 and 3. The flowchart which shows the face detection process and exposure control process which detect the person's face at the time of the monitoring operation | movement of Embodiment 2 of this invention. The flowchart which shows the face detection process and exposure control process which detect the face of a person at the time of the monitoring operation | movement of Embodiment 3 of this invention.

  Hereinafter, the present invention will be described based on the illustrated embodiments.

<Embodiment 1>
FIG. 1 is a front view showing a digital camera as an example of an imaging apparatus according to Embodiment 1 of the present invention, and FIG. 2 is a block diagram showing an outline of a system configuration of the digital camera shown in FIG.

(Appearance structure of digital camera)
As shown in FIG. 1, on the front (front) side of the digital camera 1 according to the present embodiment, a photographing lens 2 for photographing a subject having an optical zoom function, and a lens array 4 on the front side of an auxiliary imaging unit 3 described later. Etc. are provided. On the surface of the lens array 4, a pair (two) of auxiliary imaging element lenses 5 a and 5 b provided in the left-right direction at a predetermined interval are integrally formed. The optical axes of the imaging lens 2 and the auxiliary imaging element lenses 5a and 5b are parallel to each other. Further, on the upper surface side of the digital camera 1, a release button 6, a shooting mode switching button 7, a power switch (not shown), a zoom switch, and the like are provided.

(System configuration of digital camera 1)
As shown in FIG. 2, the digital camera 1 includes a photographing lens 2 having a plurality of lens groups, a diaphragm unit 10 having a shutter function, and a CCD image in which a photographed image incident through the photographing lens 2 is formed on a light receiving surface. An imaging sensor 11 such as a sensor, and an image signal (electric signal) output from the imaging sensor 11 is digitally processed by an analog front end (AFE) unit 12 and captured to display or record a captured image. A control program stored in a ROM (not shown) is stored on the basis of operation input information from a signal processing unit 13 that performs conversion processing to data and an operation unit (release button 6, shooting mode switching button 7 (see FIG. 1), etc.). A control unit (CPU) 15 that performs system control of the entire digital camera 1 based on the image data (photographed image) generated by the signal processing unit 13 And includes a liquid crystal monitor (LCD) 16 to display, the lens driving unit 17 for driving the plurality of lens of the taking lens 2, aperture unit drive unit 18 drives the aperture unit 10, and the auxiliary image pickup unit 3 or the like. The image data generated by the signal processing unit 13 is recorded in a memory card 19 that can be stored in a memory card storage unit (not shown).

  In addition to displaying image data (captured image), the liquid crystal monitor (LCD) 16 can display various operation contents such as a shooting mode at the time of shooting, and can also display a monitoring image (moving image) as an electronic viewfinder. it can. A liquid crystal monitor (LCD) 16 is provided on the back side of the digital camera 1. At the time of monitoring before actual shooting, an image obtained by thinning the number of pixels with respect to the image signal from the image pickup device 11 is displayed on the liquid crystal monitor (LCD) 16.

  The control unit (CPU) 15 uses an AF (automatic focus) evaluation value, an AE (automatic exposure) evaluation value, and an AWB (AWB) based on an image signal captured from the image pickup device 11 for imaging via the analog front end (AFE) unit 12. (Auto white balance) Evaluation value is calculated.

  The AF evaluation value is calculated by, for example, the output integrated value of the high frequency component extraction filter or the integrated value of the luminance difference between adjacent pixels. When in the in-focus state, the edge portion of the subject is clear, so the high frequency component is the highest. By utilizing this, at the time of AF operation (at the time of focus detection operation), an AF evaluation value at each focus lens position along the optical axis direction of the photographing lens 2 is acquired, and the point at which the maximum is obtained is focused. An AF operation is executed as a detection position.

  The AE evaluation value and the AWB evaluation value are calculated from the integrated values of the RGB values in the captured image signal from the imaging element 11 for photographing. For example, the imaging screen corresponding to the light receiving surfaces of all the pixels of the imaging element 11 for photographing is equally divided into 1024 areas (horizontal 32 divisions and vertical 32 divisions), and the RGB integration of each area is calculated.

  Then, the control unit 15 reads out the AE evaluation value (calculated RGB integrated value), calculates the luminance of each area in the imaging screen, and determines the appropriate exposure amount from the luminance distribution (AE processing). I do. Then, the control unit 15 sets exposure conditions (the number of electronic shutters of the image pickup device 11, the aperture value of the aperture unit 10, etc.) based on the determined exposure amount, and performs exposure control. Further, the control unit 15 reads the AWB evaluation value (calculated RGB integrated value), determines the subject color and the light source color from the RGB distribution of each area in the imaging screen, and controls the AWB according to the color of the light source. Processing for determining a value (AWB processing) is performed.

  The control unit 15 has a face detection unit 15a.

  The face detection unit 15a, for example, reads out luminance data of each area in the imaging screen and performs matching between a human face eye and a nose luminance pattern template stored in advance, so that the person who is the main subject To detect the face. Plural types of brightness pattern templates are stored in advance in a ROM (not shown), and a person's face is obtained by pattern matching in each area in the imaging screen with the brightness pattern templates of each size. Detection is performed. When the face of a person is detected, even if the face of the person moves within the imaging screen, it is tracked and the detection state is maintained.

  As shown in FIG. 3, during the monitoring operation before the subject is actually photographed after being set to the photographing mode (an image (moving image) to be photographed is displayed on the liquid crystal monitor 16 in order to confirm the composition or the photo opportunity). The control unit 15 performs the exposure control at a constant time interval, and the face detection unit 15a performs the face detection process at a constant time interval (a constant time for exposure control). The face detection result information is notified to the exposure control side.

  Then, when a human face is detected in the imaging screen, the control unit 15 calculates an AE evaluation value using the face as a photometric area, and determines an exposure amount based on the calculated AE evaluation value. Based on the determined exposure amount, exposure conditions (such as the number of electronic shutters of the image pickup device 11 and the aperture value of the aperture unit 10) are set and exposure control is performed.

  In the case of a shooting situation where face detection is not possible even though there is a person's face in the imaging screen, when there is no person's face in the imaging screen, or when the face detection mode is OFF, for example, split photometry (imaging screen) Is divided into a plurality of areas, the average value of the luminance is calculated for each area, and the luminance data is determined from the distribution pattern of the calculated luminance average value) to perform exposure control.

  In this monitoring operation, the AF operation is performed at a fixed time interval (longer than the fixed time interval of the exposure control) asynchronously with the exposure control. For example, the face of the person who is the main subject is detected in the face detection process. If detected, an AF operation is performed on the detected face position.

(Configuration of auxiliary imaging unit 3)
As shown in FIGS. 4A and 4B, the auxiliary imaging unit 3 of the present embodiment includes a housing 20 having an open front side (upper side in FIG. 4A) and a front side of the housing 20. A pair of auxiliary imaging lenses 5a and 5b are integrally formed in a line (left and right direction of the digital camera 1) in a single lens array 4 made of a transparent resin material, and a rear side in the housing 20 facing the lens array 4 ( A thin plate-like imaging element substrate 21 disposed on the lower side of FIG. 4A and first and second planar (two-dimensional) CCDs formed on the imaging element substrate 21 at equal intervals. Auxiliary imaging devices 22a and 22b and an analog front that converts image signals (electrical signals) output from the first and second auxiliary imaging devices 22a and 22b disposed on the back surface of the imaging device substrate 21 into digital signals. An end (AFE) section 23 and the like are provided. The image signal converted into a digital signal by the analog front end unit 23 is input to the signal processing unit 13.

  The first and second auxiliary imaging elements 22a and 22b are arranged so as to face the auxiliary imaging element lenses 5a and 5b, respectively. The size of the first and second auxiliary imaging elements 22a and 22b is smaller than that of the imaging imaging element 11, and the number of pixels in each of the imaging regions 22a1 and 22b1 of the first and second auxiliary imaging elements 22a and 22b is, for example, This is the same level as during monitoring when the number of pixels of the image sensor 11 for photographing is thinned out.

  The optical axes of the first and second auxiliary imaging element lenses 5a and 5b are parallel to each other, and the diagonal centers of the imaging areas 22a1 and 22b1 and the lights of the first and second auxiliary imaging element lenses 5a and 5b. The axes are positioned so that they are substantially coincident. In the present embodiment, the field angles of the first and second auxiliary imaging element lenses 5a and 5b correspond to the shooting field angles in the vicinity of the widest zoom side of the shooting lens 2. The auxiliary imaging element lenses 5a and 5b have focal lengths such that subject light incident on the auxiliary imaging element lenses 5a and 5b forms an image on the imaging regions 22a1 and 22b1. The portions other than the auxiliary imaging element lenses 5a and 5b on the front side of the lens array 4 are covered with a light shielding member (not shown).

  The control unit (CPU) 15 uses the image signals captured from the first and second auxiliary imaging elements 22a and 22b (the respective imaging regions 22a1 and 22b1) via the analog front end (AFE) unit 23 to each imaging region 22a1. , 22b1 can be divided into a plurality of areas, and an AE evaluation value can be calculated in each area.

  And the control part 15 performs exposure control shifted to the high-intensity side with respect to the image signal from the 1st auxiliary image sensor 22a (imaging area 22a1), and the 2nd auxiliary image sensor 22b (image area 221). The exposure control shifted to the low luminance side is performed on the image signal from. When exposure control is performed on the high luminance side, for example, the gain value in the analog front end unit 23 that converts the image signals output from the first and second auxiliary imaging elements 22a and 22b into digital signals is increased, Conversely, when exposure is controlled to the low luminance side, the gain value is lowered.

  Note that image signals from the first and second auxiliary imaging elements 22a and 22b (imaging areas 22a1 and 22b1) are input to the signal processing unit 13, but are displayed on the liquid crystal monitor 16 as images, or the memory card 19 Will not be recorded.

  If the face detection unit 15a cannot detect the face of a person due to shooting conditions such as backlighting when performing face detection processing based on the image signal from the image pickup device 11 during the monitoring operation, the face detection unit 15a performs first and second auxiliary operations. Face detection processing is performed based on image signals from the imaging elements 22a and 22b (imaging areas 22a1 and 22b1) (details will be described later).

  5A is a shooting field angle when the shooting lens 2 is zoomed to the widest angle side, and FIG. 5B is a field angle of the auxiliary imaging element lenses 5a and 5b of the auxiliary imaging unit 3. The angle of view of both is substantially the same. In this case, the images on the screen are approximately the same size. Therefore, when the photographing lens 2 is zoomed to the widest angle side, the face of the person who is the main subject is detected from the entire imaging areas 22a1 and 22b1 of the first and second auxiliary imaging elements 22a and 22b.

  6A shows a shooting angle of view when the taking lens 2 is zoomed from the widest angle to the telephoto side, and FIG. 6B shows the auxiliary imaging element lenses 5a and 5b of the auxiliary imaging unit 3. The angle of view is shown, and the shooting angle of view of the taking lens 2 is narrower. Therefore, in this case, the face of the person who is the main subject is detected from the area A corresponding to the shooting angle of view of the shooting lens 2 in the imaging areas 22a1 and 22b1 of the first and second auxiliary imaging elements 22a and 22b. To do.

  Next, a face detection process and an exposure control process for detecting a human face in the monitoring operation before the main photographing in the first embodiment will be described with reference to a flowchart shown in FIG. Note that the face detection process and the exposure control process in the flowchart shown in FIG. 7 are based on the premise that the face of the person who is the main subject is within the imaging angle of view (the same applies to the flowcharts of Embodiments 2 and 3 described later). Is).

  When the photographer turns on the power switch (not shown) of the digital camera 1 to set the photographing mode and the face detection mode, a monitoring operation is started, and a photographed image is formed on the photographing image sensor 11 through the photographing lens 2. An image signal is output from the imaging element 11 for imaging to the signal processing unit 13 via the analog front end unit 12, and image data is generated.

  Then, the face detection unit 15a performs a process of detecting the face of a person as a main subject based on the image data generated by the image signal from the image pickup device 11 captured by the signal processing unit 13 (step S1). .

  Then, during the face detection process in step S1, the shooting situation (when the face of the person is too dark due to backlighting or when the person's face is exposed to strong illumination light from the front side and is overexposed) If the face cannot be detected (step S2: NO), the control unit 15 first controls the exposure shift to the high luminance side by the image signal from the first auxiliary imaging element 22a (imaging region 22a1). Image data is generated, and the face detection unit 15a performs processing for detecting a human face from the image data (step S3).

  When the face cannot be detected from the image data subjected to the exposure shift control to the high luminance side during the face detection process in step S3 (step S4: NO), the control unit 15 next uses the second auxiliary image sensor. Based on the image signal from 22b (imaging region 22b1), image data that has been subjected to exposure shift control on the low luminance side is generated, and the face detection unit 15a performs processing for detecting a human face from this image data (step S5).

  In the face detection process in step S5, when a face is detected from the image data subjected to exposure shift control on the low luminance side (step S6: YES), the control unit 15 is based on the detected face position information. Photometric processing is performed using the image data generated from the image signal from the image pickup device 11 (step S7). Then, exposure control is performed based on the photometric result in step S7 (step S8).

  In step S2, if a face can be detected from the image data generated from the image signal from the imaging element 11 for shooting (step S2: YES), it is a normal shooting situation, and the control unit 15 has detected it. Using the face position as the photometric area, photometric processing is performed using the image data generated from the image signal from the image pickup device 11 (step S7).

  In addition, in step S4, when a face can be detected from the image data subjected to exposure shift control to the high luminance side (step S4: YES), for example, as shown in FIG. When the face F is too dark to detect the face, it is possible to detect the person's face F by generating an image whose exposure shift is controlled to the high luminance side as shown in FIG. Then, the control unit 15 performs photometric processing based on the image data generated from the image signal from the imaging element 11 based on the detected face position information (step S7).

  FIG. 8A is an example of an image displayed on the liquid crystal monitor 16 by the image signal from the imaging element 11 when the face F of the person who is the main subject is too dark due to backlight. . FIG. 8B shows an image generated by an image signal from the first auxiliary imaging element 22a (imaging region 22a1) (an image in which the face F of the person is brightly exposed and shifted to the high luminance side). However, this image is not displayed on the liquid crystal monitor 16.

  Therefore, the image displayed on the liquid crystal monitor 16 during the monitoring operation does not change, for example, the person's face that is too dark suddenly shifts to the high luminance side and becomes brighter, and the photographer feels uncomfortable. Never give.

  In addition, when the face cannot be detected from the image data subjected to exposure shift control to the low luminance side during the face detection process in step S5 (step S6: NO), the face of the person who is the main subject in the imaging screen This is an adverse condition where face detection is not possible even if there is a face. In this case, the control unit 15 performs a photometric process using a normal photometric method (for example, a divided photometric method) based on the image data generated from the image signal from the image pickup device 11 (step S9). Then, exposure control is performed based on the photometric result in step S9 (step S10).

  As described above, according to the digital camera 1 of the present embodiment, the first imaging unit 3 of the auxiliary imaging unit 3 can be used even in a shooting situation in which face detection cannot be performed with the image data generated from the image signal from the imaging sensor 11 during the monitoring operation. The image data subjected to the exposure shift control on the high luminance side and the low luminance side are generated by the image signals from the two auxiliary imaging elements 22a and 22b (imaging regions 22a1 and 22b1), and the image data subjected to the exposure shift control. The position of the face can be obtained by detecting the face of the person.

  Then, the control unit 15 determines a focus (focus position) with respect to the detected position of the person's face, and further performs a process of determining an optimum exposure and white balance using the person's face as a photometric area. Take a picture.

  In the digital camera 1 of the present embodiment, when a face can be detected from the image data generated from the image signal from the imaging element 11 in step S2 in the flowchart of FIG. 7 (step S2: YES), It is preferable that the control unit 15 does not perform exposure shift control on the second image data, and the face detection unit 15a does not detect a human face from the second image data. Thereby, it is possible to prevent unnecessary arithmetic processing from being executed and to reduce power consumption.

  Further, in step S2 of the flowchart of FIG. 7, when a face can be detected from the image data generated from the image signal from the imaging element 11 for shooting (step S2: YES), the power supply to the auxiliary imaging unit 3 is turned off. In addition, the imaging operation by the first and second auxiliary imaging elements 22a and 22b may not be performed. Thereby, it is possible to prevent unnecessary arithmetic processing from being executed, and to further reduce power consumption.

<Embodiment 2>
FIG. 9 is a front view showing a digital camera according to Embodiment 2 of the present invention, and FIG. 10 is a cross-sectional view showing an auxiliary imaging unit provided in the digital camera.

  As shown in FIGS. 9 and 10, the auxiliary imaging unit 3 a provided in the digital camera 1 a of the present embodiment has one auxiliary imaging element lens 5 and an auxiliary imaging element 24. The auxiliary imaging element 24 is positioned so that the diagonal center of the imaging region 24a and the optical axis of the auxiliary imaging element lens 5 are substantially aligned. Other configurations of the auxiliary imaging unit 3a are the same as those in the first embodiment shown in FIG. The system configuration of the digital camera 1a is the same as that of the first embodiment shown in FIG. 2, and the following flowchart will be described with reference to FIG.

  In the present embodiment, the control unit 15 (see FIG. 2) of the digital camera 1a controls the exposure control shifted to the high luminance side with respect to the image data generated by the image signal from the auxiliary imaging element 24 (imaging region 24a). The exposure control shifted to the low luminance side can be switched. Note that the image signal from the auxiliary imaging element 24 (imaging region 24 a) is input to the signal processing unit 13, but is not displayed as an image on the liquid crystal monitor 16 or recorded on the memory card 19.

  When the face detection unit 15a cannot detect the face of a person due to bad conditions such as backlighting when performing face detection processing based on the image signal from the image pickup imaging element 11 during the monitoring operation, the face detection unit 15a Face detection processing is performed on the image data generated from the image signal from 24a) (details will be described later).

  Next, face detection processing and exposure control processing for detecting a person's face during a monitoring operation before actual photographing in the present embodiment will be described with reference to a flowchart shown in FIG.

  When the photographer turns on the power switch (not shown) of the digital camera 1a to set the photographing mode and the face detection mode, the monitoring operation is started, and the photographed image is formed on the photographing image sensor 11 through the photographing lens 2, An image signal is output from the imaging element 11 for imaging to the signal processing unit 13 via the analog front end unit 12, and image data is generated.

  Then, the face detection unit 15a performs a process of detecting the face of a person as a main subject based on the image data generated by the image signal from the image pickup device 11 captured by the signal processing unit 13 (step S11). .

  Then, during the face detection process in step S11, the shooting situation (when a person's face is too dark due to backlighting or when a strong illumination light hits the person's face from the front side is overexposed) If the face cannot be detected (step S12: NO), the control unit 15 first outputs image data whose exposure shift is controlled to the high luminance side by the image signal from the auxiliary imaging element 24 (imaging region 24a). The face detection unit 15a generates the person's face from the image data (step S13).

  In the face detection process in step S13, if a face cannot be detected from the image data subjected to exposure shift control to the high luminance side (step S14: NO), the control unit 15 next performs the auxiliary imaging element 24 (imaging). Based on the image signal from the region 24a), image data subjected to exposure shift control so as to switch to the low luminance side is generated, and the face detection unit 15a performs processing for detecting a human face from this image data (step S15).

  In the face detection process in step S15, when a face is detected from the image data subjected to exposure shift control on the low luminance side (step S16: YES), the control unit 15 is based on the detected face position information. Photometric processing is performed using the image data generated from the image signal from the image pickup device 11 (step S17). Then, exposure control is performed based on the photometric result in step S17 (step S18).

  In step S12, when a face can be detected from the image data generated from the image signal from the imaging element 11 for shooting (step S12: YES), and in step S14, the image data subjected to exposure shift control on the high luminance side. When the face can be detected from the image (step S14: YES), the control unit 15 generates the image signal from the image sensor 11 for photographing using the detected face position as the photometric area, as in the first embodiment. Photometric processing is performed based on the image data (step S17).

  In addition, in the face detection process in step S15, when a face cannot be detected from the image data subjected to exposure shift control to the low luminance side (step S16: NO), the face of the person who is the main subject in the imaging screen This is an adverse condition where face detection is not possible even if there is a face. In this case, the control unit 15 performs a photometric process using a normal photometric method (for example, a divided photometric method) based on the image data generated from the image signal from the image pickup device 11 (step S19). Then, exposure control is performed based on the photometric result in step S19 (step S20).

  Thus, according to the digital camera 1a of the present embodiment, the auxiliary imaging unit 3 can be used even in a shooting situation in which the face that is the main subject cannot be detected from the image data generated from the image signal from the imaging device 11 during the monitoring operation. The exposure control shifted to the high luminance side and the exposure control shifted to the low luminance side are switched for the image data generated by the image signal from the auxiliary imaging element 24 (imaging region 24a), and these exposure shifts are performed. By detecting the face of a person from the controlled image data, face position information can be obtained.

  Then, the control unit 15 determines a focus (focus position) with respect to the detected position of the person's face, and further performs a process of determining an optimum exposure and white balance using the person's face as a photometric area. Take a picture.

<Embodiment 3>
The digital camera of the present embodiment includes an auxiliary imaging unit 3 a having one auxiliary imaging element lens 5 and an auxiliary imaging element 24 as in the second embodiment shown in FIGS. 9 and 10. The system configuration of the digital camera of this embodiment is the same as that of the first embodiment shown in FIG.

  In the present embodiment, the control unit 15 (see FIG. 2) of the digital camera 1a sets the exposure to a predetermined luminance for the image data generated by the image signal from the auxiliary imaging device 24 (imaging region 24a) (for example, , Exposure setting shifted to high brightness side). Note that the image signal from the auxiliary imaging element 24 (imaging region 24 a) is input to the signal processing unit 13, but is not displayed as an image on the liquid crystal monitor 16 or recorded on the memory card 19.

  If the face detection unit 15a cannot detect the face of the person who is the main subject due to bad conditions such as backlighting when face detection processing is performed based on the image signal from the imaging image sensor 11 during the monitoring operation, the auxiliary image sensor Face detection processing is performed on the image data generated by the image signal from 24 (imaging area 24a) (details will be described later).

  Next, a face detection process and an exposure control process for detecting a person's face during a monitoring operation before the actual photographing in the present embodiment will be described with reference to a flowchart shown in FIG.

  When the photographer turns on the power switch (not shown) of the digital camera 1a to set the photographing mode and the face detection mode, the monitoring operation is started, and the photographed image is formed on the photographing image sensor 11 through the photographing lens 2, An image signal is output from the imaging element 11 for imaging to the signal processing unit 13 via the analog front end unit 12, and image data is generated.

  Then, the face detection unit 15a performs a process of detecting the face of a person as a main subject based on the image data generated by the image signal from the image pickup device 11 captured by the signal processing unit 13 (step S21). .

  Then, during the face detection process in step S21, the shooting situation (when a person's face is too dark due to backlighting or when a strong illumination light hits the person's face from the front side is overexposed) If the face cannot be detected (step S22: NO), the control unit 15 sets the exposure to a predetermined luminance (for example, shifts to the high luminance side) by the image signal from the auxiliary imaging element 24 (imaging region 24a). The exposure detection) image data is generated, and the face detection unit 15a performs a process of detecting a human face from the image data (step S23).

  When the face is detected from the image data set to the predetermined brightness (for example, the exposure setting shifted to the high brightness side) during the face detection process in step S23 (step S24: YES), the control unit 15 Then, based on the detected position information of the face, photometric processing is performed using the image data generated from the image signal from the imaging element 11 (step S25). Then, exposure control is performed based on the photometric result in step S25 (step S26).

  In step S22, when the face can be detected from the image data generated from the image signal from the imaging element 11 for shooting (step S22: YES), the control unit 15 detects the same as in the first embodiment. Using the face position as the photometric area, photometric processing is performed using the image data generated from the image signal from the imaging element 11 for photographing (step S25).

  In addition, when the face cannot be detected from the image data set to the predetermined brightness (for example, the exposure setting shifted to the high brightness side) during the face detection process in step S24 (step S24: NO), This is an adverse condition in which face detection cannot be performed even if the face of a person who is the main subject is present in the imaging screen. In this case, the control unit 15 performs a photometric process using a normal photometric method (for example, a divided photometric method) based on the image data generated from the image signal from the image pickup device 11 (step S27). Then, exposure control is performed based on the photometric result in step S27 (step S28).

  As described above, according to the digital camera 1a of the present embodiment, the auxiliary imaging element of the auxiliary imaging unit 3 even in a photographing situation in which face detection cannot be performed with the image data generated from the image signal from the photographing imaging element 11 during the monitoring operation. The image data generated by the image signal from the image sensor 24 (the imaging region 24a) is set to an exposure setting (for example, an exposure setting shifted to the high brightness side) at a predetermined brightness, and the image is set to an exposure setting at a predetermined brightness. The position information of the face can be obtained by detecting the face of the person from the data.

  In each of the above-described embodiments, the face detection unit 15a serving as a main subject detection unit detects the face of a person as a main subject. A frame for detecting a main subject may be displayed on the 16 screens, and an image in the frame may be detected as a main subject.

1. Digital camera (imaging device)
2 Imaging lens 3, 3a Auxiliary imaging unit 5 Auxiliary imaging element lens 5a First auxiliary imaging element lens 5b Second auxiliary imaging element lens 11 Imaging imaging element 13 Signal processing unit 15 Control unit (exposure control means)
15a Face detection unit (main subject detection means)
22a First auxiliary imaging element 22b Second auxiliary imaging element 24 Auxiliary imaging element

JP 2003-107335 A

Claims (8)

An imaging element for main imaging that captures an image for main imaging via an optical system for main imaging;
An auxiliary imaging device that captures an image for auxiliary imaging via an optical system for auxiliary imaging;
Arbitrary with respect to the first image data generated by the image signal output from the main photographing image sensor and the second image data generated by the image signal output from the auxiliary photographing image sensor Exposure control means for performing exposure control of
Main subject detection means for detecting a main subject located in the imaging screen from each of the first image data and the second image data,
The main photographing optical system has a zoom function, and the angle of view of the auxiliary photographing optical system is set to be substantially the same as the angle of view on the wide-angle end side of the main photographing optical system,
When the main photographing optical system has an angle of view that is zoomed to the telephoto side from the wide-angle end, the main subject detection unit cannot detect the main subject from the first image data depending on the shooting situation In
The exposure control means controls the exposure shift to the high luminance side or the low luminance side with respect to the second image data,
The main image is detected from within the area corresponding to the angle of view of the main imaging optical system in the entire imaging area of the auxiliary imaging device from the second image data subjected to exposure shift control by the main subject detection means. An imaging apparatus for detecting a subject .   When the main subject detection means can detect the main subject from the second image data subjected to exposure shift control, the exposure control means detects the second image data detected from exposure shift control. The photometric processing is performed using a position corresponding to the first image data as a photometric area based on position information of the main subject, and exposure control of the main subject is performed based on the photometric result. The imaging apparatus according to 1. Having at least a pair of the auxiliary photographing optical system and the auxiliary photographing image sensor;
The exposure control unit performs exposure shift control to the high luminance side for the second image data generated by the image signal output from one of the auxiliary imaging elements, and the other auxiliary The image pickup apparatus according to claim 1 or 2, wherein exposure shift control is performed to a low luminance side with respect to the second image data generated by an image signal output from the image pickup device for photographing. One auxiliary photographing optical system and the auxiliary photographing image sensor;
The exposure control means controls the exposure shift to the high luminance side and the exposure shift to the low luminance side with respect to the second image data generated by the image signal output from the one auxiliary photographing image sensor. The imaging apparatus according to claim 1, wherein the imaging apparatus can be switched to control. One auxiliary photographing optical system and the auxiliary photographing image sensor;
The exposure control unit performs exposure shift control on either the high luminance side or the low luminance side with respect to the second image data generated by the image signal output from one auxiliary photographing image sensor. The imaging apparatus according to claim 1 or 2, wherein When the main subject detection unit can detect the main subject from the first image data, the exposure control unit does not perform exposure shift control on the second image data, and object detecting means imaging apparatus to any one of claims 1 to 5, characterized in that does not perform detection of the main object from the second image data. Wherein the main subject detection unit, either when said first and can detect the main object from the image data, according to claim 1 to 5, characterized in that does not perform the imaging operation by the auxiliary photographic image-capturing element An imaging device in one item. The main subject is a face of a person, the main object detecting means, the imaging apparatus in any one of claims 1 to 7, wherein the detecting the face of a person as the main subject.