JP4761039B2 - Imaging device - Google Patents

Description

  The present invention relates to an imaging apparatus, and more particularly to an imaging apparatus capable of emitting auxiliary light during an autofocus operation.

  Contrast AF is known as an autofocus (AF) method employed in digital cameras and the like. This contrast AF detects the position where the contrast of the image reaches its peak and moves the focus lens to that position for focusing. However, this contrast AF is accurate when the subject contrast is low or the subject is dark. There was a problem that proper focusing was not possible.

In view of this, there has been proposed a camera that enables the detection of contrast by irradiating auxiliary light toward a subject during the AF operation (for example, Patent Documents 1 to 4).
JP 2003-244535 A JP 200531290 A JP 2005-37519 A Japanese Patent Laid-Open No. 2003-140027

  However, when a person is photographed with a camera that emits auxiliary light during AF operation, there is a drawback in that the subject is distracted by the emission of auxiliary light, making it difficult to take pictures with natural expressions. In particular, when taking pictures of babies, there was a problem that they could not shoot well because they were surprised by the light emitted from the auxiliary light or they closed their eyes.

  The present invention has been made in view of such circumstances, and it is an object of the present invention to provide an imaging apparatus that can capture an image of a subject without feeling uncomfortable.

In order to achieve the above object, the invention according to claim 1 is an image pickup method in which light passing through a photographing lens is received by an image pickup device, an image signal obtained from the image pickup device is subjected to necessary signal processing and recorded on a storage medium. In the apparatus, means for detecting the luminance of the subject, auxiliary light emitting means for emitting auxiliary light toward the subject at the time of autofocus operation, mode setting means for setting a macro mode capable of macro photography, and the imaging device A face detecting means for analyzing the obtained image signal to detect a human face, and a control means for controlling the auxiliary light to be emitted from the auxiliary light emitting means at a low luminance equal to or lower than a predetermined luminance value, If the face of a person is detected in the face detecting means to the macro mode is set, shooting is characterized in that and a control means for stopping the emission of auxiliary light from the auxiliary light emitting means To provide a device.

  According to the first aspect of the present invention, when a human face is detected from an image captured by the image sensor at the time of macro photography, emission of auxiliary light is prohibited. Thereby, when photographing near a person, it is possible to prevent the auxiliary light from being inadvertently emitted and giving the subject an uncomfortable feeling.

According to a second aspect of the present invention, in order to achieve the above object, an image pickup device that receives light passing through a photographic lens by an image pickup device, performs necessary signal processing on an image signal obtained from the image pickup device, and records the image signal on a storage medium. In the apparatus, means for detecting the luminance of the subject, auxiliary light emitting means for emitting auxiliary light toward the subject during the autofocus operation, and a face for extracting a human face by analyzing an image signal obtained from the image sensor Extraction means, means for calculating the ratio of the face extracted by the face extraction means on the screen as a face dominance ratio, and auxiliary light emitting means emitting light from the auxiliary light emitting means when the luminance is lower than a predetermined luminance value control means for controlling, as the light amount of the auxiliary light is reduced to the face possession is emitted from the auxiliary light emitting means in accordance with increases, the auxiliary light emitting means in response to said face possession Providing a control means for controlling the amount of auxiliary light to be al emission, the imaging apparatus characterized by comprising a.

In the invention according to claim 2, when a person's face is included in an image captured by the image sensor, the amount of auxiliary light is adjusted in accordance with the ratio of the person's face to the screen. Thereby, it is possible to prevent strong light from being emitted in the vicinity of the person who is the subject and giving the subject a sense of incongruity.
According to a third aspect of the present invention, in order to achieve the above object, the means for calculating the face dominance ratio shows the largest image when a plurality of human faces are detected by the face extracting means. The imaging apparatus according to claim 2, wherein a person is specified and a face dominance ratio of the person is calculated.
The invention according to claim 4 is a look-up table in which the setting of the output of the auxiliary light emitting means according to the face dominance rate is determined in order to achieve the object, and the smaller the face dominance rate is A lookup table that is set so that the setting of the output of the auxiliary light emitting means is increased, and the control means is configured to calculate the auxiliary light emitting means based on the look-up table from the calculated face dominance rate. The imaging apparatus according to claim 2 or 3, wherein an output is determined and the amount of auxiliary light emitted from the auxiliary light emitting unit is controlled.

In order to achieve the above object, the invention according to claim 5 receives light that has passed through a photographic lens constituted by a zoom lens by an image sensor, and performs necessary signal processing on an image signal obtained from the image sensor. In an imaging apparatus for recording on a storage medium, means for detecting the luminance of a subject, auxiliary light emitting means for emitting auxiliary light toward the subject during autofocus operation, and analyzing the image signal obtained from the imaging element The face extraction means for extracting the face, means for calculating the ratio of the face extracted by the face extraction means on the screen as the face dominance ratio, and the face calculated according to a preset classification of the face dominance ratio Means for determining the rank of the control ratio, and means for determining the zoom position of the photographic lens currently set according to a preset zoom position classification A lookup table in which the setting of the output of the auxiliary light emitting means according to the rank of the face dominant rate and the zoom position is determined, and the output of the auxiliary light emitting means decreases as the face dominant rate decreases. A lookup table that is set so that the setting of the output of the auxiliary light emitting means becomes larger as the setting becomes larger and the focal length of the photographing lens becomes longer, and the auxiliary light emitting means when the luminance is lower than a predetermined luminance value Control means for controlling the auxiliary light to be emitted from the face dominance rate and the zoom position based on the look-up table to determine the output of the auxiliary light emitting means, and the auxiliary light emission There is provided an imaging apparatus comprising: control means for controlling the amount of auxiliary light emitted from the means .

According to the fifth aspect of the present invention, when the photographing lens is a zoom lens, if an image captured by the image sensor includes a person's face, the ratio of the person's face to the entire screen, and the photographing lens The amount of auxiliary light is adjusted according to the focal length. As a result, when shooting near the subject, strong light is emitted toward the subject, which can prevent the subject from feeling uncomfortable. Thus, it is possible to focus accurately.

  According to the imaging apparatus of the present invention, it is possible to shoot without giving a sense of incongruity to a subject when shooting a person.

  The best mode for carrying out an imaging apparatus according to the present invention will be described below with reference to the accompanying drawings.

  1 and 2 are a front perspective view and a rear perspective view of a digital camera to which the present invention is applied, respectively.

  As shown in the figure, the camera body 12 of the digital camera 10 of the present embodiment is formed in a thin and square box shape.

  As shown in FIG. 1, a photographing lens 14, a strobe 16, a self-timer lamp 18, an AF auxiliary light lamp 20, and the like are provided on the front surface of the camera body 12, and a shutter button 22 and a mode lever 24 are disposed on the upper surface. A power button 26 and the like are provided.

  On the other hand, as shown in FIG. 2, a monitor 28, a zoom button 30, a playback button 32, a photo mode button 34, a cross button 36, a MENU / OK button 38, a BACK button 40, and the like are provided on the back of the camera body 12. ing.

  Although not shown, a USB terminal and a battery cover are provided on the bottom surface of the camera body 12 so as to be openable and closable. A battery storage chamber for storing the battery inside the battery cover and a memory card are provided. A memory card slot for loading is provided.

  The taking lens 14 is composed of a retractable zoom lens having a macro mechanism, and is extended from the camera body 12 when the power of the digital camera 10 is turned on. As will be described later, when the macro mode is set, the macro mechanism is activated, and macro photography (proximity photography) becomes possible.

  In addition, since the zoom mechanism, the retracting mechanism, and the macro mechanism of the photographing lens 14 are known techniques, a specific description thereof is omitted here.

  The shutter button 22 is constituted by a two-stage stroke type switch composed of so-called “half press” and “full press”. The digital camera 10 performs AE (Automatic Exposure), AF (Auto Focus), and AWB (Automatic White Balance) by half-pressing the shutter button 22, and full-pressing the image. Make a record.

  The mode lever 24 is used for setting the shooting mode. The mode lever 24 is provided so as to be rotatable around the shutter button 22 and can be set at the “SP position”, “AUTO position”, “M position”, and “moving picture position”. The digital camera 10 is set to the “scene program shooting mode” by setting the mode lever 24 to the “SP position”, and set to a mode for performing exposure control according to the shooting scene. Also, by setting the “AUTO position”, the “auto shooting mode” is set, and the mode is set to perform the exposure control fully automatically. Also, by setting the “M position”, the “manual shooting mode” is set, and the exposure setting is manually set. Also, by setting the “moving image position”, the “moving image shooting mode” is set, and the moving image shooting mode is set.

  The monitor 28 is composed of a color LCD. The monitor 28 is used as an image display unit for displaying captured images, and is used as a GUI during various settings. Further, at the time of shooting, an image captured by the image sensor is displayed as a through view and used as an electronic viewfinder.

  The zoom button 30 is used for a zoom operation of the photographic lens 14 and includes a zoom tele button for instructing zooming to the telephoto side and a zoom wide button for instructing zooming to the wide angle side.

  The playback button 32 is used for an instruction to switch to the playback mode. That is, the digital camera 10 is switched to the playback mode when the playback button 32 is pressed during shooting.

  The photo mode button 34 is used to call up various setting screens for shooting and reproduction. That is, when the photo mode button 34 is pressed during shooting, a setting screen for image size (number of recording pixels) and sensitivity is displayed on the monitor 28. When the photo mode button 4 is pressed during playback, the monitor 28 is displayed. A print reservation (DPOF) setting screen is displayed.

  The cross button 36 is provided so that it can be pressed in four directions, up, down, left, and right, and a function corresponding to the setting status of the camera is assigned to the button in each direction.

  That is, for example, at the time of shooting, a function for switching the macro mode ON / OFF is assigned to the left button, and a function for switching the strobe mode is assigned to the right button. In addition, a function for changing the brightness of the monitor 28 is assigned to the upper button, and a function for switching ON / OFF of the self-timer is assigned to the lower button.

  Further, during playback, a frame advance function is assigned to the left button, and a frame return function is assigned to the right button. Also, a function for changing the brightness of the monitor 28 is assigned to the upper button, and a function for deleting the image being reproduced is assigned to the lower button.

  Also, at the time of various settings, a function for moving the cursor in the direction of each button is assigned.

  The MENU / OK button 38 is used for calling up a menu screen, and is used for confirming selection contents, executing a process, and the like. The BACK button 42 is used for an instruction such as canceling an input operation.

  FIG. 3 is a block diagram showing an electrical configuration of the digital camera 10. As shown in the figure, the digital camera 10 includes a CPU 110, an operation unit (shutter button 22, mode lever 24, power button 26, zoom button 30, playback button 32, photo mode button 34, cross button 36, MENU / OK button. 38, BACK button 40, etc.) 112, ROM 114, RAM 116, EEPROM 118, VRAM 120, clock / calendar unit 122, imaging optical system 124, imaging optical system driving unit 126, imaging device 128, timing generator 130, analog signal processing unit 132, A / D converter 134, image input controller 136, image signal processing unit 138, compression / decompression processing unit 140, face detection unit 142, media controller 144, memory card M, USB controller 146, encoder 148, OSD unit 150, A / AWB detection unit 152, AF detection unit 154, the flash control unit 156, the power supply control unit 158, and a battery 160, AF auxiliary light emission control unit 162, AF auxiliary light lamp 20 or the like.

  The CPU 110 functions as a control unit that performs overall control of the overall operation of the digital camera 10 and also functions as an arithmetic processing unit that performs various arithmetic processes. Each circuit is configured according to a predetermined control program based on an input from the operation unit 112. Control.

  The ROM 114 stores a control program executed by the CPU 110 and various data necessary for control. The EEPROM 118 stores various setting information such as user setting information.

  The RAM 116 is used as a calculation work area for the CPU 110 and is also used as a temporary storage area for image data, and the VRAM 120 is used as a temporary storage area dedicated for image data for display.

  The clock / calendar unit 122 counts the current date and time, and outputs the current time information measured according to a command from the CPU 110 to the CPU 110.

  The photographing optical system 124 includes a photographing lens 14, a diaphragm, and a shutter, and the photographing lens 14 includes a focus lens and a zoom lens.

  The photographing optical system driving unit 126 drives a focus lens and a zoom lens constituting the photographing lens 14 in accordance with a command from the CPU 110, and performs focusing and zooming. Further, in response to a command from the CPU 110, the diaphragm is driven to adjust the amount of light incident on the image sensor 128, and the shutter is driven to control exposure / light shielding of the image sensor 128.

  The image sensor 128 is composed of a color CCD, and a large number of photodiodes (light receiving elements) are arranged on the light receiving surface thereof. Light incident on the light receiving surface of the image sensor 128 via the imaging optical system 124 is converted into signal charges of an amount corresponding to the amount of incident light by each photodiode and accumulated in each photodiode.

  A timing generator (TG) 130 generates a timing signal mainly for driving the image sensor 128 in accordance with a command from the CPU 110. The image sensor 128 reads the signal charge accumulated in each photodiode in accordance with the timing signal applied from the timing generator 130 and outputs it as a voltage signal (image signal).

  The analog signal processing unit 132 performs correlated double sampling processing on image signals sequentially output from the image sensor 128 (for the purpose of reducing noise (particularly thermal noise) included in the output signal of the image sensor). (A process for obtaining accurate pixel data by taking the difference between the feedthrough component level and the pixel signal component level included in the output signal for each pixel) and amplifying and outputting.

  The A / D converter 134 converts the R, G, and B analog image signals output from the analog signal processing unit 132 into digital image signals.

  The image input controller 136 includes a line buffer having a predetermined capacity, accumulates image signals for one image output from the A / D converter 134, and stores them in the RAM 116.

  The image signal processing unit 138 includes a synchronization circuit (a processing circuit that interpolates a spatial shift of the color signal associated with the color filter array of the single CCD and converts the color signal into a simultaneous expression), a white balance correction circuit, and a gamma correction. Circuit, contour correction circuit, luminance / color difference signal generation circuit, etc., and performs necessary signal processing on the image signal input in accordance with a command from the CPU 110 to obtain luminance data (Y data) and color difference data (Cr, Cb data). Image data (YUV data) consisting of:

  The compression / decompression processing unit 140 performs compression processing on the image data input in accordance with a command from the CPU 110, and generates compressed image data in a predetermined format (for example, JPEG). Further, the input compressed image data is decompressed to generate non-compressed image data.

  The face detection unit 142 analyzes image data input in accordance with a command from the CPU 110 and detects a human face image. That is, a face region is extracted from image data, and its position (center of gravity coordinates) and size (range) are detected. This process is performed, for example, by extracting pixels having a color close to the color designated as the skin color from the input image data and extracting the extracted area as a face area. In the skin color extraction process, for example, in the color space for distinguishing the skin color from other colors, the skin color range on the color space is determined from the pre-sampled skin color information, and the color of each pixel falls within the specified range. It is performed by determining whether or not. Note that other known techniques can be used for the face detection process.

  The media controller 144 controls reading and writing of data with respect to the memory card M loaded in the media slot according to a command from the CPU 110.

  In the digital camera 10 of the present embodiment, the image is stored in the memory card M that can be detached from the camera body 12, but the image may be stored in a built-in memory.

  The USB controller 146 transmits / receives data to / from an external device (such as a personal computer or a printer) connected to the USB terminal 147 according to a command from the CPU 110.

  The encoder 148 converts an image signal input in accordance with a command from the CPU 110 into a video signal (for example, an NTSC signal, a PAL signal, or a SCAM signal) for display on the monitor 28 and outputs the video signal to the monitor 28.

  An OSD (On Screen Display) unit 150 outputs a signal indicating characters and graphics to be displayed on the monitor 28 to the encoder 148 in accordance with a command from the CPU 110.

  The AE / AWB detection unit 152 calculates a physical quantity necessary for AE control and AWB control from the input image signal in accordance with a command from the CPU 110. For example, as a physical quantity required for AE control, one screen is divided into a plurality of areas (for example, 16 × 16), and an integrated value of R, G, and B image signals is calculated for each divided area. The CPU 110 detects the brightness of the subject (subject brightness) based on the integrated value obtained from the AE / AWB detector 152, calculates an exposure value (shooting EV value) suitable for shooting, and calculates the calculated shooting EV. An aperture value and a shutter speed are determined from the value and a predetermined program diagram. Further, as a physical quantity necessary for AWB control, one screen is divided into a plurality of areas (for example, 16 × 16), and an average integrated value for each color of R, G, and B image signals is calculated for each divided area. . The CPU 110 obtains the ratio of R / G and B / G for each divided area from the obtained R accumulated value, B accumulated value, and G accumulated value, and R of the obtained R / G and B / G values. The light source type is discriminated based on the distribution in the / G, B / G color space. Then, according to the white balance adjustment value suitable for the determined light source type, for example, the value of each ratio is approximately 1 (that is, the RGB integration ratio is R: G: B≈1: 1: 1 in one screen). Then, a gain value (white balance correction value) for the R, G, and B signals of the white balance adjustment circuit is determined.

  The AF detection unit 154 calculates a physical quantity necessary for AF control from the input image signal in accordance with a command from the CPU 110. In the digital camera 10 of the present embodiment, AF control is performed based on the contrast of the image, and the AF detection unit 154 calculates a focus evaluation value indicating the sharpness of the image from the input image signal. The CPU 110 moves the focus lens to a position where the focus evaluation value calculated by the AF detection unit 154 is maximized. That is, the focus lens is moved from the closest distance to infinity, the focus evaluation value is acquired in the entire area, and the position where the focus evaluation value reaches a peak is detected. Then, the focus lens is moved to a position where the focus evaluation value is a peak.

  The strobe control unit 156 controls the light emission of the strobe 16 in accordance with a command from the CPU 110.

  The power control unit 158 controls power supply from the battery 160 to each unit in accordance with a command from the CPU 110.

  The AF auxiliary light emission control unit 162 controls the light emission of the AF auxiliary light lamp 20 in accordance with a command from the CPU 110. The AF auxiliary light lamp 20 is composed of, for example, a high-brightness LED.

  The digital camera 10 of the present embodiment is configured as described above.

  Next, basic photographing and reproduction processing by the digital camera 10 of the present embodiment will be described.

  First, a basic processing operation of the digital camera 10 at the time of shooting will be described.

  When the power button 26 is pressed and the digital camera 10 is turned on, an image captured by the image sensor 128 is displayed on the monitor 28 as a through display. That is, when the digital camera 10 is turned on, images are continuously picked up by the image pickup device 128, and image data is continuously generated by the image signal processing unit 138 from image signals obtained continuously from the image pickup device 128. Is done. The generated image data is sequentially added to the encoder 148 via the VRAM 120 and output from the encoder 148 to the monitor 28. As a result, the image captured by the image sensor 128 is displayed through on the monitor 28. The photographer determines the composition by operating the zoom button 30 as necessary while viewing the through image displayed on the monitor 28. When the composition is determined, the shutter button 22 is half-pressed.

  When the shutter button 22 is half-pressed, an S1 ON signal is input to the CPU 110. The CPU 110 executes AE, AF, and AWB processes in response to the S1 ON signal.

  First, an image signal output from the image sensor 128 is captured via the analog signal processing unit 132, the A / D converter 134, and the image input controller 136, and is added to the AE / AWB detection unit 152 and the AF detection unit 154.

  The AE / AWB detection unit 152 calculates a physical quantity necessary for AE control and AWB control from the input image signal, and outputs it to the CPU 110. Based on the output from the AE / AWB detection unit 152, the CPU 110 determines an aperture value and a shutter speed, and also determines a white balance correction value.

  Further, the AF detection unit 154 calculates a physical quantity necessary for AF control from the input image signal, and outputs it to the CPU 110. The CPU 110 controls the driving of the photographing optical system driving unit 126 based on the output from the AF detection unit 154 and adjusts the focus of the photographing lens 14. That is, the focus lens is moved from the close range to infinity, the focus evaluation value is acquired in the entire area, and the position where the focus evaluation value reaches a peak is detected (AF scan). Then, the focus lens is moved to a position where the focus evaluation value is a peak.

  At this time, when the subject is dark, that is, when the subject brightness obtained from the AE / AWB detector 152 is equal to or lower than a predetermined brightness value, the CPU 100 causes the AF auxiliary light lamp 20 to emit light, performs AF scan, and performs focus evaluation. The value detects the position of the peak. The emission of the AF auxiliary light will be described in detail later.

  The photographer confirms the through image displayed on the monitor 28, confirms the focus state of the photographing lens 14, and executes photographing. That is, the shutter button 22 is fully pressed.

  When the shutter button 22 is fully pressed, an S2ON signal is input to the CPU 110, and the CPU 110 executes an image recording process in response to the S2ON signal.

  First, the image sensor 128 is exposed with the aperture value and shutter speed obtained in the above AE process, and an image signal for recording is captured. At this time, the strobe 16 emits light as necessary.

  The image signal for one frame output from the image sensor 128 is taken into the image input controller 136 via the analog signal processing unit 132 and the A / D converter 134 and stored in the RAM 116. The image signal stored in the RAM 116 is added to the image signal processing unit 138 under the control of the CPU 110, and image data (YUV data) including luminance data and color difference data is generated. The generated image data is temporarily stored in the RAM 116 and then added to the compression / decompression processing unit 140. The compression / decompression processing unit 140 compresses the input image data according to a predetermined compression format.

  The compressed image data is stored in the RAM 116 and recorded on the memory card M via the media controller 144 as a still image file (for example, Exif) in a predetermined format.

  In the digital camera 10 of the present embodiment, the photographer can arbitrarily set the size and compression rate of the image to be recorded. This point will be described in detail later.

  Next, a basic processing operation of the digital camera 10 during reproduction will be described.

  The captured image is played back by pressing the playback button 32. When the play button 32 is pressed, the CPU 110 reads the compressed image data of the image file last recorded on the memory card M via the media controller 144. The read compressed image data is added to the compression / decompression processing unit 140, converted into uncompressed image data, and then added to the VRAM 120. Then, it is output from the VRAM 120 to the monitor 28 via the encoder 148. As a result, the image recorded on the memory card M is reproduced and displayed on the monitor 28.

  The frame advance of the image is performed by operating the left and right buttons of the cross button 36. When the right button is operated, the next image is read from the memory card M and reproduced and displayed on the monitor 28. When the left button of the cross button 36 is operated, the previous image is read from the memory card M and is reproduced and displayed on the monitor 28.

  As described above, in the digital camera 10 according to the present embodiment, AF is possible even under low luminance. When the luminance of the subject falls below a predetermined luminance value, the AF auxiliary light lamp 20 is directed toward the subject. AF assist light is emitted.

  However, when AF assist light is emitted from a short distance when shooting a person, there is a problem that the subject is uncomfortable and a picture with a natural expression cannot be taken.

  Therefore, in the digital camera 10 according to the present embodiment, the emission of AF auxiliary light is prohibited when a human face is detected during macro photography. Hereinafter, the procedure of the emission control of the AF auxiliary light will be described.

  FIG. 4 is a flowchart showing a procedure of emission control of AF auxiliary light at the time of AF search.

  When the shutter button 22 is pressed halfway and execution of AF search is instructed, first, the CPU 110 determines whether or not the digital camera 10 is in the macro mode (step S10). The macro mode is set by operating the cross button 36 as described above. That is, when the left button of the cross button 36 is pressed, the macro mode is turned on, and when the left button is pressed again, the macro mode is turned off.

  The CPU 110 determines whether or not the digital camera 10 is in the macro mode based on the input from the operation unit 112.

  If it is determined that the macro mode is set as a result of the determination, the CPU 110 determines whether or not a face image is detected from the image captured by the image sensor 128 (step S11). That is, the image data obtained from the image sensor 128 is added to the face detection unit 142 to perform face image detection processing, and it is determined whether a face image is detected based on the detection result.

  If it is determined that the face image is detected as a result of the determination, the CPU 110 turns off (prohibits) the AF auxiliary light (step S12) and executes an AF search (step S13).

  On the other hand, when determining that the face image is not detected, the CPU 110 determines whether or not the subject has low luminance (step S14). That is, the subject luminance obtained from the AE / AWB detection unit 152 is compared with a predetermined luminance value stored in the ROM 114, and it is determined whether or not the subject luminance obtained from the AE / AWB detection unit 152 is equal to or lower than the predetermined luminance value. judge.

  If it is determined that the brightness is low (the subject brightness is equal to or less than a predetermined brightness value), the CPU 110 causes the AF auxiliary light lamp 20 to emit light via the AF auxiliary light emission control unit 162 (step S15). A search is executed (step S16).

  If the macro mode is not set, the AF auxiliary light is emitted and the AF search is executed when the subject luminance falls below a predetermined luminance value as usual.

  As described above, in the digital camera 10 according to the present embodiment, when the macro mode is set, if a face image of a person is included in the image to be photographed, the AF auxiliary light emission is prohibited. Thereby, when shooting near the subject, the AF auxiliary light is inadvertently emitted to prevent the subject from feeling uncomfortable, and an image with a natural expression can be taken.

  In the above embodiment, when a human face is detected in the macro mode, the AF auxiliary light emission is completely stopped, but the ratio of the detected human face image to the entire screen (face control) The light emission amount may be adjusted according to the rate. That is, when the face dominance rate is small, it is considered that the camera is away from the subject, so AF auxiliary light is emitted with a relatively large light emission amount and AF search is performed. On the other hand, when the face dominance rate is large, it is considered that the camera is close to the subject. Therefore, the AF auxiliary light is emitted with a relatively small light emission amount, or the light emission is stopped, and the AF search is performed. That is, the light emission amount is changed in proportion to the face control rate. Thereby, it is possible to take a picture without giving the person a sense of incongruity.

  Note that in the case of a digital camera using a zoom lens, even if the distance to the subject is the same, the face dominance rate varies depending on the focal length (zoom position). Therefore, it is preferable to adjust the light emission amount in consideration of the zoom position.

  In the above embodiment, the case where the AF search is performed only once (so-called one-shot AF) has been described as an example. However, when the AF search is continuously performed (so-called continuous AF), the face is continuously detected. An image is detected, and the emission of AF auxiliary light is continuously controlled based on the detection result. That is, the emission of the AF auxiliary light is stopped while the face is detected, and when the face is no longer detected, the AF auxiliary light is emitted (only when the brightness is low).

  Further, when a face is detected, it is preferable to display a frame so as to overlap the through image and surround the face detected by the frame as shown in FIG. This makes it clear to the photographer that the face has been detected.

  In the embodiment described above, the emission of the AF auxiliary light is controlled only when the macro mode is set. However, there are cases where shooting is performed relatively close to the subject other than the macro shooting.

  Therefore, a case where the emission of AF auxiliary light is controlled regardless of the macro mode setting will be described next.

  In the present embodiment, when a person's face is included in the captured image, the emission of AF auxiliary light is controlled according to the ratio of the person's face to the entire screen (face control ratio). In other words, it is assumed that the higher the face control rate is, the closer the subject is to the image, so the amount of AF auxiliary light emitted is controlled according to the face control rate.

  FIG. 6 is a flowchart showing a procedure for controlling the emission of AF auxiliary light when the emission of AF auxiliary light is controlled in accordance with the face dominance rate.

  When the shutter button 22 is pressed halfway and execution of AF search is instructed, the CPU 110 first determines whether or not the subject has low luminance (step S20). That is, it is determined whether or not the subject brightness obtained from the AE / AWB detection unit 152 is equal to or less than a predetermined brightness value.

  If the CPU 110 determines that the brightness is not low as a result of this determination, the CPU 110 outputs 0% of the AF auxiliary light lamp 20, that is, does not emit AF auxiliary light (step S21), and executes an AF search (step S22). ).

  On the other hand, when determining that the brightness is low, the CPU 110 determines whether or not a face image is detected from the image captured by the image sensor 128 (step S23). That is, the image data obtained from the image sensor 128 is added to the face detection unit 142 to perform face image detection processing, and it is determined whether a face image is detected based on the detection result.

  If it is determined that the face image is not detected as a result of the determination, the CPU 110 sets the output of the AF auxiliary light lamp 20 to 100% and emits AF auxiliary light (full light emission) (step S24). A search is executed (step S22).

  On the other hand, if it is determined that a face image has been detected, CPU 110 calculates a face dominance rate based on the output from face detection unit 142, and determines whether the face dominance rate is 10% or less (step S25). If the face dominating rate is determined to be 10% or less, the output of the AF auxiliary light lamp 20 is set to 90% based on a lookup table (LUT) stored in the ROM 114, and the AF auxiliary light lamp is set at the set output. 20 is emitted (step S26), and AF search is executed (step S22). That is, in this case, it is determined that the subject is relatively far from the subject, and strong AF auxiliary light is emitted to perform AF search.

  On the other hand, when determining that the face dominance rate is not 10% or less, the CPU 110 determines whether or not the face dominance rate is 20% or less (step S27). If it is determined that the face control rate is 20% or less, the CPU 110 sets the output of the AF auxiliary light lamp 20 to 75% based on the LUT, and causes the AF auxiliary light lamp 20 to emit light with the set output (step S28). ), AF search is executed (step S22). That is, also in this case, it is determined that the subject is relatively far from the subject, relatively strong AF auxiliary light is emitted, and AF search is executed.

  On the other hand, when determining that the face dominance rate is not 20% or less, the CPU 110 determines whether or not the face dominance rate is 40% or less (step S29). If it is determined that the face control rate is 40% or less, the CPU 110 sets the output of the AF auxiliary light lamp 20 to 55% based on the LUT, and causes the AF auxiliary light lamp 20 to emit light with the set output (step S30). An AF search is executed (step S22). That is, in this case, it is determined that the subject is slightly away from the subject, and the AF auxiliary light is emitted with approximately half the light emission amount, and the AF search is executed.

  On the other hand, when determining that the face dominance rate is not 40% or less, the CPU 110 determines whether or not the face dominance rate is 60% or less (step S31). If it is determined that the face control rate is 60% or less, the CPU 110 sets the output of the AF auxiliary light lamp 20 to 30% based on the LUT, and causes the AF auxiliary light lamp 20 to emit light with the set output (step S32). An AF search is executed (step S22). That is, in this case, it is determined that the subject is slightly close to the subject, and the AF search is executed by emitting slightly weak AF auxiliary light.

  On the other hand, when determining that the face dominating rate is not 60% or less, the CPU 110 sets the output of the AF auxiliary light lamp 20 to 20% based on the LUT, and causes the AF auxiliary light lamp 20 to emit light with the set output (step S33). ), AF search is executed (step S22). That is, in this case, it is determined that the object is close to the subject, weak AF auxiliary light is emitted, and AF search is executed.

  In this way, by predicting the distance from the face control rate to the subject and controlling the amount of AF auxiliary light emitted, strong AF auxiliary light is emitted near the subject to prevent the subject from feeling uncomfortable. it can. In addition, when the subject is far away, the AF auxiliary light can be accurately emitted to perform accurate focusing.

  When a plurality of human faces are detected, the person whose face is most greatly photographed is specified, and the output of the AF auxiliary light lamp 20 is determined using the control ratio of the face images of the persons. And

  By the way, in the case of a zoom lens, even if the distance to the subject is the same, there is a problem that if the focal length (zoom position) is changed, the face dominance rate also changes.

  Therefore, when a zoom lens is used, the emission of AF auxiliary light is controlled based on the zoom position and the face dominance rate as follows.

  FIG. 7 is a flowchart showing a procedure of AF auxiliary light emission control when a zoom lens is used.

  When the shutter button 22 is pressed halfway and execution of AF search is instructed, first, the CPU 110 determines whether or not the subject has low luminance (step S40). That is, it is determined whether or not the subject brightness obtained from the AE / AWB detection unit 152 is equal to or less than a predetermined brightness value. If it is determined that the brightness is not low as a result of the determination, the CPU 110 performs an AF search without emitting the AF auxiliary light (step S41).

  On the other hand, when determining that the brightness is low, the CPU 110 determines whether or not a face image is detected from the image captured by the image sensor 128 (step S42). That is, the image data obtained from the image sensor 128 is added to the face detection unit 142 to perform face image detection processing, and it is determined whether a face image is detected based on the detection result.

  If it is determined that the face image is not detected as a result of the determination, the CPU 110 sets the face control rate to A (step S43).

  On the other hand, when determining that a face image has been detected, the CPU 110 calculates a face dominance rate based on the output from the face detection unit 142, and determines whether the face dominance rate is 10% or less (step S44). If it is determined that the face dominance rate is 10% or less, the face dominance rate is set to B (step S45).

  If it is determined that the face control rate is not 10% or less, the CPU 110 determines whether or not the face control rate is 20% or less (step S46). (Step S47).

  If it is determined that the face dominance rate is not 20% or less, the CPU 110 determines whether the face dominance rate is 40% or less (step S48). If the face dominance rate is determined to be 40% or less, the CPU 110 determines the face dominance rate as D. (Step S49).

  If it is determined that the face dominance rate is not 40% or less, the CPU 110 determines whether or not the face dominance rate is 60% or less (step 50). When the face control rate is determined to be 60% or less, the face control rate is set to E (step S51), and when it is determined that the face control rate is not 60% or less, the CPU 110 sets the face control rate to F ( Step S52).

  When a face is detected in this way, the rank (A to F) is set according to the ratio of the face to the entire screen (face dominance rate). Then, the current zoom position (Z1 to Z10) is determined (step S53).

  Here, the determination of the zoom position is performed by determining to which region of the focal length range divided into 10 the currently set focal length belongs. For example, in the case of a zoom lens having a focal length of 30 mm to 330 mm in terms of 35 mm, 30 to 60 mm is Z1, 61 to 90 mm is Z2, 91 to 120 mm is Z3, 121 to 150 mm is Z4, 151 to 180 mm is Z5, 181 to 210 mm Is Z6, 211 to 240 mm is Z7, 241 to 270 mm is Z8, 271 to 300 mm is Z9, and 301 to 330 mm is Z10. When the current focal length setting is 50 mm, the zoom position is set to Z1.

  In this way, the zoom position is determined based on the current focal length setting (step S53). Then, the light emission amount of the AF auxiliary light lamp 20 is determined based on the determined zoom position and the rank of the face control rate (step S54).

  Here, the light emission amount of the AF auxiliary light 20 is set with reference to a lookup table (LUT) stored in the ROM 114. In this LUT, as shown in FIG. 8, the output of the AF auxiliary light lamp corresponding to the zoom position is set for each rank of the face dominance rate, and the CPU 110 refers to this LUT and the zoom position and the face dominance. The light emission amount of the AF auxiliary light lamp 20 is determined from the rank of the rate (step S54). Then, the AF auxiliary light lamp 20 is caused to emit light with the set output (step S55), and AF search is executed (step S41).

  As described above, according to the AF auxiliary light emission control method of the present embodiment, the AF auxiliary light emission is controlled in accordance with the set focal length and face dominance rate. Thus, the AF auxiliary light can be appropriately emitted. That is, when shooting a person at a short distance, it is possible to shoot without giving a sense of incongruity to the subject, and when shooting other than a person, it is possible to focus accurately even under low luminance.

  In the present embodiment, the rank of the face dominance rate is divided into six levels. However, the method of dividing the rank of the face dominance rate is not limited to this, and is divided in more detail or in a simplified manner. May be. Similarly, the zoom position classification method may be classified in more detail or may be simplified.

  In the above-described embodiment, an AF auxiliary light lamp made of an LED is used to emit AF auxiliary light. However, the means for emitting AF auxiliary light is not limited to this. For example, it may be configured to emit AF auxiliary light using a strobe. Alternatively, an external light emitting unit may emit light and be used for AF auxiliary light.

  In this embodiment, the case where the present invention is applied to a digital camera has been described as an example. However, the application of the present invention is not limited to this. The present invention can be applied to all imaging apparatuses provided with AF auxiliary light emitting means. For example, the present invention can be similarly applied to a camera-equipped mobile phone, a video camera, and the like having a function of emitting AF auxiliary light.

Front perspective view of digital camera Rear perspective view of digital camera Block diagram showing the electrical configuration of the digital camera Flowchart showing the procedure of emission control of AF auxiliary light during AF search The figure which shows the example of a display of the detection frame of a face The flowchart which shows the procedure of the light emission control of AF auxiliary light in the case of controlling light emission of AF auxiliary light according to the face control rate Flowchart showing the procedure of AF auxiliary light emission control when using a zoom lens Diagram showing an example of a lookup table

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Digital camera, 12 ... Camera body, 14 ... Shooting lens, 16 ... Strobe, 20 ... AF auxiliary light lamp, 22 ... Shutter button, 24 ... Power / mode switch, 26 ... Mode dial, 30 ... Speaker, 32 ... Viewfinder Eyepiece, 34 ... Monitor, 36 ... Zoom button, 38 ... Cross button, 40 ... MENU / OK button, 42 ... DISP button, 44 ... BACK button, 46 ... Battery cover, 110 ... CPU, 112 ... Operation unit, 114 ... ROM, 116 ... RAM, 118 ... EEPROM, 120 ... VRAM, 122 ... clock / calendar unit, 124 ... imaging optical system, 126 ... imaging optical system drive unit, 128 ... imaging device, 130 ... timing generator, 132 ... analog signal Processing unit 134... A / D converter, 136... Image input controller DESCRIPTION OF SYMBOLS 138 ... Image signal processing part, 140 ... Compression / decompression processing part, 142 ... Face detection part, 144 ... Media controller, M ... Memory card, 146 ... USB controller, 147 ... USB terminal, 148 ... Encoder, 150 ... OSD part, 152 ... AE / AWB detection unit, 154 ... AF detection unit, 156 ... Strobe control unit, 158 ... Power supply control unit, 160 ... Battery

Claims (5)

In an imaging device that receives light passing through a photographing lens by an imaging device, performs necessary signal processing on an image signal obtained from the imaging device, and records it on a storage medium.
Means for detecting the brightness of the subject;
Auxiliary light emitting means for emitting auxiliary light toward the subject during autofocus operation;
Mode setting means for setting to a macro mode capable of macro shooting;
A face detection means for detecting a human face by analyzing an image signal obtained from the image sensor;
A control for controlling means so auxiliary light from the auxiliary light emitting means when a predetermined luminance value or lower intensity is emitted, if the face of a person is detected in the face detecting means to the macro mode is set Control means for stopping emission of auxiliary light from the auxiliary light emitting means;
An imaging apparatus comprising: In an imaging device that receives light passing through a photographing lens by an imaging device, performs necessary signal processing on an image signal obtained from the imaging device, and records it on a storage medium.
Means for detecting the brightness of the subject;
Auxiliary light emitting means for emitting auxiliary light toward the subject during autofocus operation;
A face extraction means for analyzing an image signal obtained from the image sensor and extracting a person's face;
Means for calculating a ratio of the face extracted by the face extraction means on the screen as a face dominance rate;
Control means for controlling the auxiliary light emitting means to emit auxiliary light when the luminance is lower than a predetermined luminance value, wherein the auxiliary light emitting means emits light from the auxiliary light emitting means as the face dominance rate increases. Control means for controlling the amount of auxiliary light emitted from the auxiliary light emitting means according to the face control rate so that the amount of light is reduced ;
An imaging apparatus comprising: The means for calculating the face dominance rate, when a plurality of human faces are detected by the face extraction means, specifies a person whose face is most greatly photographed, and calculates the face dominance rate of the person The imaging apparatus according to claim 2, characterized in that: A look-up table in which the setting of the output of the auxiliary light emitting means according to the face dominating rate is determined, and the setting of the output of the auxiliary light emitting means is increased as the face dominating rate decreases. The control means determines an output of the auxiliary light emitting means based on the look-up table from the calculated face dominance rate, and outputs auxiliary light emitted from the auxiliary light emitting means. The imaging apparatus according to claim 2, wherein the amount of light is controlled. In an imaging device that receives light passing through a photographing lens constituted by a zoom lens by an imaging device, performs necessary signal processing on an image signal obtained from the imaging device, and records the image signal on a storage medium.
Means for detecting the brightness of the subject;
Auxiliary light emitting means for emitting auxiliary light toward the subject during autofocus operation;
A face extraction means for analyzing an image signal obtained from the image sensor and extracting a person's face;
Means for calculating a ratio of the face extracted by the face extraction means on the screen as a face dominance rate;
Means for determining a rank of the calculated face dominance rate according to a preset classification of the face dominance rate;
Means for determining the currently set zoom position of the taking lens according to a preset zoom position classification;
A look-up table in which the setting of the output of the auxiliary light emitting unit is determined according to the rank of the face control rate and the zoom position, and the setting of the output of the auxiliary light emitting unit as the face control rate decreases A look-up table determined so that the setting of the output of the auxiliary light emitting means increases as the focal length of the photographic lens increases.
Control means for controlling the auxiliary light emitting means to emit auxiliary light at a low luminance of a predetermined luminance value or less, and based on the look-up table from the face dominance rate and the zoom position, Control means for determining the output of the auxiliary light emitting means and controlling the amount of auxiliary light emitted from the auxiliary light emitting means;
An imaging apparatus comprising:

Images