JP2007081732A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the time required for detecting a face for focusing. <P>SOLUTION: In the imaging apparatus, the output of an imaging element which converts incident light into electric signals is converted into a digital value to provide an image data. An area setting part, region cutting-out processor, and face detection process read region data representing a plurality of partial regions in the image from a memory, and detect a face region from the image data in the partial region represented by a region data. The imaging apparatus, based on the image data in the detected face region, performs control of the imaging apparatus such as automatic focusing and automatic exposure. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an imaging device that obtains image data by converting an output of an imaging element that converts incident light into an electrical signal into a digital value.

  Conventionally, when taking a picture of a person, there is a problem that the focus is not on the person but on the background because of the contrast between the person who is the main subject and the background. In order to solve such a problem, an imaging apparatus that focuses on a person by detecting a face in the screen and focusing on the position of the detected face has been developed (see Patent Document 1).

As for face detection from image data, those described in Non-Patent Documents 1 and 2 are known. Further, the position and size of the face can be estimated by detecting eyes by the methods described in Patent Documents 2 to 5.
JP 2001-215403 A Japanese Patent Laid-Open No. 3-17696 JP-A-4-255015 JP-A-5-300601 Japanese Patent Laid-Open No. 9-251342 Television Society Journal Vol. 49, no. 6, pp. 787-797 (1995), “Proposal of Modified HSV Color System Effective for Face Area Extraction” The Institute of Electronics, Information and Communication Engineers Vol. 74-D-II, no. 11, pp. 1625-1627 (1991), “Method for extracting a face region from a still gray scene image”

  However, in such an imaging apparatus, the whole screen is set as a face detection area because it is not known where the person is on the screen. For this reason, the face detection process takes a long time. Since the time required for face detection directly affects the shutter time lag, it is necessary to reduce the time required for face detection.

  The present invention has been made in view of the above problems, and an object thereof is to reduce the shutter release time lag by reducing the time required for face detection in the imaging apparatus.

In an imaging device that obtains image data by converting the output of an imaging device that converts incident light into an electrical signal into a digital value,
Holding means for holding area data indicating a plurality of partial areas in the image data;
Clipping means for cutting out the partial area indicated by the area data held in the holding means from image data;
Detecting means for detecting a face area from the image data in the partial area cut out by the cutting means;
An imaging apparatus comprising: control means for controlling the imaging apparatus based on image data in the face area detected by the detection means.

  The time required for face detection in the imaging apparatus can be reduced, and the shutter release time lag can be reduced.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

<First Embodiment>
FIG. 1 is a block diagram illustrating a configuration example of an imaging apparatus according to the first embodiment. In FIG. 1, reference numeral 100 denotes the imaging apparatus of the first embodiment.

  In the imaging apparatus 100, the optical image that has passed through the photographing lens 10 and the shutter 12 having a diaphragm function reaches the imaging element 14. The image sensor 14 converts an optical image that has reached the imaging surface into an electrical signal, and outputs an analog signal. The A / D converter 16 converts an analog signal output from the image sensor 14 into a digital signal. The timing generation circuit 18 supplies a clock signal and a control signal to the image sensor 14, the A / D converter 16, and the D / A converter 26. The timing generation circuit 18 is controlled by the memory control circuit 22 and the system control circuit 50.

  The image processing circuit 20 performs predetermined pixel interpolation processing and color conversion processing on the data from the A / D converter 16 or the data from the memory control circuit 22. Further, predetermined calculation processing is performed using image data captured by the image processing circuit 20, and the system control circuit 50 controls the exposure control unit 40 and the distance measurement control unit 42 based on the calculation result. With this control, TTL (through the lens) AF (autofocus) processing, AE (automatic exposure) processing, and EF (flash pre-emission) processing are performed. Further, the image processing circuit 20 performs predetermined arithmetic processing using captured image data, and also performs TTL AWB (auto white balance) processing based on the obtained arithmetic result.

  The memory control circuit 22 controls the A / D converter 16, the timing generation circuit 18, the image processing circuit 20, the image display memory 24, the D / A converter 26, the memory 30, and the compression / decompression circuit 32. The data of the A / D converter 16 is written into the image display memory 24 or the memory 30 via the image processing circuit 20 and the memory control circuit 22 or the data of the A / D converter 16 is directly passed through the memory control circuit 22. It is. The display image data written in the image display memory 24 is displayed by the image display unit 28 via the D / A converter 26. Note that the image display unit 28 includes, for example, a TFT liquid crystal display.

  If the image data captured using the image display unit 28 is sequentially displayed, the electronic viewfinder function can be realized. The image display unit 28 can arbitrarily turn on / off the display according to an instruction from the system control circuit 50. When the display is turned off, the power consumption of the image processing apparatus 100 can be greatly reduced. I can do it.

  The memory 30 is a memory for storing captured still images and moving images, and has a sufficient storage capacity for storing a predetermined number of still images and moving images for a predetermined time. Thereby, even in the case of continuous shooting or panoramic shooting in which a plurality of still images are continuously shot, it is possible to write a large amount of images to the memory 30 at high speed. The memory 30 can also be used as a work area for the system control circuit 50.

  The compression / decompression circuit 32 compresses and decompresses image data by adaptive discrete cosine transform (ADCT) or the like. The compression / decompression circuit 32 reads an image stored in the memory 30, performs a compression process or an expansion process, and writes the processed data to the memory 30.

  The exposure control unit 40 controls the shutter 12 having a diaphragm function, and also has a flash light control function in cooperation with the flash 48. The distance measuring unit 42 controls the focusing of the photographic lens 10. The zoom control unit 44 controls zooming of the taking lens 10. The barrier control unit 46 controls the operation of the protection unit 102 that is a barrier. The flash 48 also has an AF auxiliary light projecting function and a flash light control function.

  The exposure control unit 40 and the distance measurement control unit 42 are controlled using the TTL method. That is, the system control circuit 50 controls the exposure control unit 40 and the distance measurement control unit 42 based on the calculation result obtained by calculating the captured image data by the image processing circuit 20.

  A system control circuit 50 controls the entire imaging apparatus 100. The memory 52 is a memory for storing constants, variables, programs and the like for operating the system control circuit 50. The display unit 54 includes a liquid crystal display device, a speaker, and the like that display an operation state, a message, and the like using characters, images, sounds, and the like according to execution of a program in the system control circuit 50. The display unit 54 is installed at a single or a plurality of locations near the operation unit of the imaging apparatus 100 where it can be easily seen, and is configured by, for example, a combination of an LCD, an LED, a sounding element, and the like. The display unit 54 has a part of its function installed in the optical viewfinder 104.

  Among the display contents of the display unit 54, what is displayed on the LCD or the like includes single shot / continuous shooting display, self-timer display, compression rate display, number of recorded pixels, number of recorded pixels, number of remaining images that can be captured, shutter Speed display, Aperture value display, Exposure compensation display, Flash display, Red-eye reduction display, Macro shooting display, Buzzer setting display, Clock battery level display, Battery level display, Error display, Multi-digit number information display and recording There are a display state of the media 200 and 210, a communication I / F operation display, a date / time display, and the like. Among the display contents of the display unit 54, what is displayed in the optical viewfinder 104 includes in-focus display, camera shake warning display, flash charge display, shutter speed display, aperture value display, exposure correction display, and the like.

  The nonvolatile memory 56 is electrically erasable and recordable, and is composed of, for example, an EEPROM. Reference numerals 60, 62, 64, 66, 68 and 70 constitute an instruction input unit for inputting various operation instructions of the system control circuit 50. The instruction input unit is configured by a single or a combination of a switch, dial, touch panel, pointing by line-of-sight detection, a voice recognition device, and the like. Here, the instruction input unit will be specifically described.

  The mode dial switch 60 can switch and set various function modes such as power-off, automatic shooting mode, shooting mode, panoramic shooting mode, playback mode, multi-screen playback / erase mode, and PC connection mode.

  The shutter switch 62 is turned on during the operation of the shutter button (half-pressing the shutter button) to generate the SW1 signal. The system control unit 50 starts operations such as face detection processing, AF (autofocus) processing, AE (automatic exposure) processing, AWB (auto white balance) processing, and EF (flash pre-emission) processing based on the SW1 signal. . The shutter switch 64 is turned on when the operation of the shutter button is completed (the shutter button is fully pressed) to generate the SW2 signal. The SW2 signal instructs the start of a series of processing operations including exposure processing, development processing, and recording processing. In the exposure process, a signal read from the image sensor 12 is written into the memory 30 as image data via the A / D converter 16 and the memory control circuit 22. In the development processing, image processing using calculation in the image processing circuit 20 and the memory control circuit 22 is performed. In the recording process, image data is read from the memory 30, compressed by the compression / decompression circuit 32, and written to the recording medium 200 or 210.

  The image display ON / OFF switch 66 can set ON / OFF of the image display unit 28. With this function, when taking an image using the optical viewfinder 104, the current supply to the image display unit including a TFT liquid crystal display or the like can be cut off, and power saving can be achieved. The quick review ON / OFF switch 68 sets a quick review function for automatically reproducing image data taken immediately after photographing. In the present embodiment, it is assumed that a function for setting the quick review function when the image display unit 28 is turned off is also provided.

  The operation unit 70 includes various buttons and a touch panel. The operation buttons provided in the operation unit 70 include, for example, a menu button, a set button, a macro button, a multi-screen playback page break button, a flash setting button, a single shooting / continuous shooting / self-timer switching button, and a menu movement + (plus) button. , Menu movement-(minus) button, Playback image movement + (plus) button, Playback image-(minus) button, Shooting image quality selection button, Exposure compensation button, Date / time setting button, Image deletion button, Image deletion cancel button, etc. There is.

  The power supply control unit 80 is configured by a battery detection circuit, a DC-DC converter, a switch circuit that switches blocks to be energized, and the like. With these configurations, the power control unit 80 detects the presence / absence of a battery, the type of battery, and the remaining battery level, and controls the DC-DC converter based on the detection result and the instruction of the system control circuit 50, and is necessary. A sufficient voltage is supplied to each part including the recording medium for a necessary period. The power supply unit 86 includes a primary battery such as an alkaline battery or a lithium battery, a secondary battery such as a NiCd battery, a NiMH battery, or a Li battery, an AC adapter, and the like, and is connected to the power control unit 80 via connectors 82 and 84. .

  Interfaces 90 and 94 connect a recording medium such as a memory card or a hard disk to a bus in the apparatus. Connectors 92 and 96 are connectors for connecting to a recording medium such as a memory card or a hard disk. The recording medium attachment / detachment detection unit 98 detects whether the recording medium 200 or the recording medium 210 is attached to the connector 92 and / or the connector 96. In the present embodiment, it is assumed that there are two interfaces and connectors for attaching the recording medium. Of course, the interface and the connector for attaching the recording medium may have a single or a plurality of systems, any number of systems. Moreover, it is good also as a structure provided with combining the interface and connector of a different standard.

  The interface and the connector may be configured using a PCMCIA card, a CF (Compact Flash (registered trademark)) card, or the like that conforms to a standard.

  Furthermore, when the interfaces 90 and 94 and the connectors 92 and 96 are configured in accordance with a standard such as a PCMCIA card or a CF card, a communication card that enables communication with an external device can be used. That is, image data and management information attached to the image data can be transferred to and from other peripheral devices such as other computers and printers. Examples of the communication card include a LAN card, a modem card, a USB card, an IEEE 1394 card, a P1284 card, a SCSI card, a PHS card, and the like.

  The protection unit 102 functions as a barrier that prevents the imaging unit from being dirty or damaged by covering the imaging unit including the lens 10 of the image processing apparatus 100. The optical viewfinder 104 enables photographing without using the electronic viewfinder function of the image display unit 28. In the optical viewfinder 104, some functions of the display unit 54, for example, a focus display, a camera shake warning display, a flash charge display, a shutter speed display, an aperture value display, an exposure correction display, and the like are installed.

  The communication unit 110 has various communication functions such as RS232C, USB, IEEE1394, P1284, SCSI, modem, LAN, and wireless communication. Reference numeral 112 denotes a connector (an antenna in the case of wireless communication) for connecting the imaging apparatus 100 to another device through the communication unit 110.

  Reference numerals 200 and 210 denote recording media such as a memory card and a hard disk. Each of the recording media 200 and 210 includes recording units 202 and 212 configured by a semiconductor memory, a magnetic disk, and the like, interfaces 204 and 214 with the image processing apparatus 100, and connectors 206 and 216 for connecting with the image processing apparatus 100. Yes.

  FIG. 2 is a perspective view showing an electronic camera as an example of the imaging apparatus 100. The power button 201 is a button for turning on / off the power to the imaging apparatus 100. A mode switching lever 202 is a lever for switching and setting each function mode such as a shooting mode, a playback mode, a moving image shooting mode, and a still image shooting mode. The shutter button 203 constitutes shutter switches 62 and 64. A liquid crystal display (LCD) 204 constitutes an image display unit 28 that displays a photographed image of the camera. A screen for reproducing a still image and / or a moving image is also displayed on the LCD 204.

  A menu button 205 is a button for starting and ending display of a menu screen for changing shooting parameters and camera settings. The set button 206 is used to determine setting contents on the menu screen. A delete button 207 is used for a field for designating image deletion. The DISP button 208 is a button for switching ON / OFF of display on the LCD 204, and constitutes an image display ON / OFF switch 66. The cross button 209 is used, for example, to instruct movement of an item on the menu screen by using the up / down / left / right buttons. In the playback mode, the left and right buttons of the cross button 209 are used for image forwarding.

  An imaging operation by the imaging apparatus 100 having the above configuration will be described below. FIG. 4 is a flowchart illustrating the imaging operation according to the first embodiment. The process shown in FIG. 4 is executed by the system control unit 50. For example, the system control unit 50 includes a CPU (not shown), and realizes the processing shown in FIG. 4 by executing a control program stored in the memory 52, for example.

  In FIG. 4, when the user presses the shutter button 203, the shutter switch 62 is first turned on and the signal SW1 is turned on. When the signal SW1 is turned on, the process proceeds from step S401 to step S402, and the image processing unit 20 in FIG.

  Now, since the time required for the face detection process directly affects the shutter time lag, it is necessary to reduce the time required for the face detection process. For example, FIG. 3 is a diagram schematically showing an example of how the camera looks in the viewfinder of a camera that performs three-point autofocus (hereinafter abbreviated as AF). The camera determines where to focus on the three AF frames 301a to 301c, and displays the AF frame to be focused. In such a three-point AF system, it is not necessary to detect a human face over the entire screen. Face detection is performed by performing face detection in the areas indicated by the three face detection area frames 302a to 302c. The camera may be controlled so that the selected area is in focus. That is, by setting the face detection area frames 302a to 302c corresponding to the AF frames 301a to 301c and performing face detection on these face detection area frames, it is effective for controlling the imaging apparatus (AF, AE, etc.). Certain face detection can be performed.

  FIG. 5 is a flowchart for explaining face area detection processing by the image processing unit 20. FIG. 6 is a block diagram showing a functional configuration for face area detection processing by the image processing unit 20. Hereinafter, the operation of the face area detection process performed by the image processing unit 20 will be described with reference to FIGS. 5 and 6.

  When the face detection process is started by an instruction from the system control unit 50, the area setting unit 601 sets the number of cutout areas and the cutout area coordinates in step S501. In the present embodiment, as shown in FIG. 3, the number of cutout areas is set to 3 and the cutout area coordinates are set to face detection frames 302a, 302b, and 302c. The face detection area frame is stored in advance in the memory 52, for example, as shown in FIG. The face detection area frame is specified by, for example, the upper left and lower right coordinates of the frame.

  In step S502, the area setting unit 601 performs area segmentation processing on the segmentation coordinates of the face detection frame 302a (for example, defined by the upper right corner (Xs, Ys) and lower left corner (Xe, Ye) of the face detection region frame 302a). To part 602. Next, in step S503, the region cutout processing unit 602 cuts out a region according to the cutout region coordinates passed from the area setting unit 601. In the above example, the area of the face detection area frame 302a is first cut out from the image data. The extracted image data is sent to the face detection processing unit 603. In step S504, the face detection processing unit 603 performs face detection processing on the image data cut out by the region cutout processing unit 602 (image data in the face detection frame 301a). In step S <b> 505, the information storage unit 604 stores the number of faces detected by the face detection processing unit 603, each size, and coordinate data in the memory 30.

  In step S506, it is determined whether face detection processing has been performed for all face detection frames set by the area setting unit 601. For example, the number of processed face detection frames may be counted, and it may be determined whether face detection processing has been performed for all face detection frames based on whether or not this matches the number of cutout areas set in step S501. If there is an unprocessed face detection frame, the process returns to step S502, and the above-described process is repeated for the unprocessed face detection frame. For example, when the area setting unit 601 sets the cutout coordinates indicating the face detection region frame 302b to be processed next in the region cutout unit 602, the region cutout unit 602 and the face detection processing unit 603 are connected to the face detection frame 302b. Perform face detection processing.

  As described above, when face detection processing is completed for all of the face detection frames 302a to 302c in FIG. 3, the face detection processing of the image processing unit 20 shown in FIG. 5 is ended from step S506. Thus, at the end of the face detection process, the face detection process is performed for all face detection frame regions of the face detection frames 302a to 302c, and the result is stored in the memory 30 by the information storage unit 604.

  The face detection processing unit 603 detects the face position and coordinates and the face size. As a method for detecting the position and coordinates of a face, “Proposal of a modified HSV color system effective for face region extraction” (Non-patent Document 1) or “Method of extracting a face region from a still gray scene image” (Non Patent The method disclosed in Document 2) can be used. Face detection and coordinate position detection are performed by these methods. Alternatively, the size and position of the face can be estimated using the distance between the left eye and the right eye obtained by detecting the eyes. For eye detection, JP-A-3-17696 (Patent Document 2), JP-A-4-255015 (Patent Document 3), JP-A-5-300601 (Patent Document 4), JP-A-9-251342. The technique of gazette (patent document 5) can be used.

  As described above, when the face area detection in step S402 ends, in step S403, the AE process is performed based on the face detection information for each clipped area (face detection frame). The AE process using the face detection result will be described below. For example, when the face detection area is only the face detection area frame 302b of FIG. 3, the aperture and the shutter speed are determined so that the brightness of the area of the face detection area frame 302b is appropriate. Further, when a face is detected in the face detection area frames 302a and 302b, the aperture and the shutter speed are determined so that the average luminance in the face detection area frames 302a and 302b is appropriate. Further, when a face is detected in the face detection area frames 302a, 302b, and 302c, the aperture and shutter speed are determined so that the average brightness of the face detection area frames 302a, 302b, and 302c is appropriate. If no face is detected in any face detection area frame, the aperture and shutter speed are determined so that the average luminance in the face detection area frames 302a, 302b, and 302c is appropriate. Note that the AE process itself is realized by the cooperation of the image processing unit 20, the system control unit 50, and the exposure control unit 42 as described above.

  As described above, when the AE process ends, the process proceeds to step S404, and the AF process is performed. The AF process using the face detection result will be described below. The distance measurement control unit 44 in FIG. 1 sequentially performs imaging while moving the focus lens position within the imaging lens 10 by a certain amount. Then, an AF signal is created by band-pass filter processing from the image data in the face detection area frame where the face is detected in the captured image data. The focus lens position where the created AF signal is the largest is determined, and the focus lens position is set as the in-focus position.

  For example, when the face detection area is only the face detection area frame 302b, an AF signal is created using image data in the face detection area frame 302b, and the focus lens position with the largest AF signal is obtained. When a face is detected in the face detection area frames 302a and 302b, the focus lens position with the largest AF signal is obtained using the image data of the area obtained by combining the face detection area frames 302a and 302b. Further, when a face is detected in the face detection area frames 302a, 302b, and 302c, the focus lens position with the largest AF signal is determined using the image data of the area including the face detection area frames 302a, 302b, and 302c. Desired. If a face is not detected by the face area detection process, an AF signal is created using image data of the area including the face detection area frames 302a, 302b, and 302c, and the focus lens position with the largest AF signal is created. Is required.

  When the AF process ends, the system waits for SW2 to turn on (step S405). When the user presses the shutter button 303 and the shutter switch 64 is turned on, an ON signal of SW2 is input to the system control unit 50. When SW2 is turned on, the process proceeds to step S406, and the system control unit 50 performs main exposure with the aperture, shutter speed, and focus lens position obtained in steps S403 and S404. The analog signal output from the image sensor 14 by the main exposure is converted into a digital signal by the A / D converter 16 and sent to the image processing unit 20. In step S407, the image processing unit 20 converts the digital signal into a YUV signal, further converts it into a JPEG format, and stores it in the memory 30. In step S408, the JPEG format converted data is recorded in the recording unit 202 (or 212) as an image file.

  As described above, according to the first embodiment, face detection processing is performed on a limited region called a face detection region frame, rather than performing face detection processing on the entire image captured from the image sensor. Therefore, the face detection processing time is shortened and the shutter time lag can be reduced.

  It should be noted that the user may be able to select in advance one or more desired face detection area frames to be subjected to face detection processing from among the plurality of face detection area frames. In this case, in step S401, the face area detection process is performed only on the selected face detection area frame. Alternatively, in the case of an imaging apparatus that allows the user to select an AF frame, face detection may be performed using a face detection area frame corresponding to the selected AF frame. In this case, the number of areas and the cut-out area coordinates set by the area setting unit 601 relate to the face detection area frame selected by the user or the face detection area frame selected according to the AF frame selection.

Second Embodiment
In the first embodiment, as shown in the flowchart of FIG. 4, after face switch, AE process, and AF process are not completed after the shutter switch SW1 is turned on, it is not possible to shift to ON detection of the shutter switch SW2. For this reason, a problem that the shutter release time lag increases may be considered. Therefore, in the second embodiment, it is possible to further reduce the shutter release time lag.

  Since the configuration and the like of the imaging device are the same as those in the first embodiment, description thereof is omitted here. Hereinafter, mainly the same parts as in the first embodiment will be described. FIG. 7 is a flowchart for explaining face area detection processing by the image processing unit 20 of the second embodiment. FIG. 8 is a block diagram showing a functional configuration for face area detection processing by the image processing unit 20 of the second embodiment. In FIG. 7, the same steps as those in FIG. 5 are given the same step numbers. In FIG. 8, the same reference numerals are assigned to the same functional blocks as those shown in FIG. Also, the flow of processing of the photographing operation is as shown in the flowchart of FIG.

  When the shutter button 303 is pressed halfway and the signal SW1 is turned on, the process proceeds from step S401 to step S402, and face area detection processing is performed. In the second embodiment, this face detection process is shown in the flowchart of FIG.

  In step S501, the area setting unit 802 sets the number of cutout areas and the cutout area coordinates. Also in the second embodiment, as shown in FIG. 3, it is assumed that the number of cut-out areas is 3, and the cut-out area coordinates are set to face detection frames 302a, 302b, and 302c.

  Next, in step S701, the priority setting unit 801 (FIG. 8) sets the priority of the cutout area. An example of data indicating the face detection area frame and the set priority is shown in FIG. 8 (table 810). Here, description will be made assuming that the priority is set in the order of the face detection area frames 302b, 302a, and 302c. The priority setting unit 801 sets a desired priority for the face detection area frame in accordance with an operation of the cross key or the like. Accordingly, the priority setting state is stored in the rewritable memory 30. When the priority of each area is set, in step S702, the area setting unit 802 sets the coordinates of the cut-out area frame to the area cut-out processing unit 602 in descending order of the set priority. That is, in this example, first, the area of the face detection area frame 302b is cut out from the image data. Then, the cut out image data is sent to the face detection unit 603, and the number of faces in the cut out image data, the size, and coordinate data are output (steps S503 and S504). The data output by the face detection processing unit 603 is stored in the memory 30 as face detection information by the information storage unit 604 (step S505).

  Next, in step S703, it is determined whether or not the signal SW2 has been turned ON during the processing in steps S702 and S503 to S505. If the signal SW2 is ON, the face detection process is immediately terminated. On the other hand, if the signal SW2 is not ON, it is determined in step S506 whether face detection processing has been performed for all the areas set by the area setting unit 802. Here, since the face detection of the face detection area frames 302a and 302c has not been completed yet, the process returns to step S702. Then, the area setting unit 802 sets the cutout region coordinates indicating the region of the next priority in the region cutout processing unit 602. In this way, face detection is performed for the face detection area frame 302a. Thus, when the face detection processing of the face detection area frames 302a and 302c is finished and the face detection information of each area is stored in the memory 30 by the information storage unit 604, the face area detection process is finished in step S506.

  If the signal SW2 is turned on before face detection processing is performed for all face detection area frames, the area where face detection has not been performed is handled as if no face was detected. Returning to FIG. 4, when the face area detection processing in step S <b> 402 ends, AE processing and AF processing using the face area detection information are performed. Since the operation after step S403 in FIG. 4 is exactly the same as in the first embodiment, the description thereof is omitted here.

  As described above, according to the second embodiment, face detection processing is performed in the order of face area detection frames with higher priority. In the middle of this, when the shutter button 303 is fully pressed and the signal SW2 is turned on, the face area detection immediately ends after the process for the face area detection frame during the face detection process is completed. Since the face detection process is terminated when the signal SW2 is turned on, the shutter release time lag can be reduced. In addition, since the face detection area frame to be face detection processing is selected according to the priority order and the face detection process is performed, an effective face area detection result can be obtained even if an unprocessed face detection area frame remains. It will be. In addition, the number of detected face areas can be adjusted by adjusting the half-pressed state (the signal SW1 is ON), and the accuracy of AE and AF can be adjusted.

  The priority order of the face detection area frames may be fixed, or the user may set the order as desired. When the priority order is fixed, a table 810 as shown in FIG. In addition, when the face detection area is selectively used (when the face detection area frame selected by the user or the face detection area frame corresponding to the AF frame selected by the user is used), this book for setting the priority order It is clear that the embodiments are applicable. When the priority order is fixed and the face detection area frame is selectively used, the priority order is set for the selected face detection area so that the relative order relationship of the priority order is maintained. do it.

  In the second embodiment, as shown in the flowchart of FIG. 7, even if the signal SW2 is turned on immediately after the signal SW1 is turned on, the face detection process is always performed for the first priority area. Done. However, the present invention is not limited to such processing. For example, as shown in FIG. 10, whether the signal SW <b> 2 is ON is determined before image cutout and face detection (step S <b> 702). Good. In this case, depending on the timing at which the signal SW2 is turned ON, the face area detection process ends before the face detection process is performed at all.

<Third Embodiment>
In the second embodiment, the configuration in which the face area detection process is terminated by the signal SW2 from the shutter switch 64 has been described. In the third embodiment, face detection processing is performed in descending order of priority for a plurality of face detection region frames, and the face region detection processing (step S402) ends when a face is detected.

  Since the configuration and the like of the imaging device are the same as those in the first embodiment, description thereof is omitted here. Hereinafter, mainly the same parts as in the first embodiment will be described. FIG. 10 is a flowchart illustrating face area detection processing by the image processing unit 20 according to the third embodiment. The operation sequence of the imaging apparatus is the same as that of the first embodiment (FIG. 4), and the functional configuration of the face detection process in the image processing unit 20 is the same as that of the second embodiment (FIG. 8).

  When the signal SW1 is turned on, face area detection processing in step S402 is performed. The operation of this face detection process will be described using the flowchart of FIG.

  In step S501, the area setting unit 802 sets the number of clip areas and the clip area coordinates. Also in the third embodiment, as illustrated in FIG. 3, it is assumed that the number of cutout areas is set to 3 and the cutout area coordinates are set to face detection frames 302a, 302b, and 302c.

  Next, in step S701, the priority setting unit 801 (FIG. 8) sets the priority of the clip region. Here, description will be made assuming that the priority is set in the order of the face detection area frames 302b, 302a, and 302c. When the priority of each area is set, in step S702, the area setting unit 802 sets the coordinates of the cut-out area frame to the area cut-out processing unit 602 in descending order of the set priority. Therefore, in this example, first, the area of the face detection area frame 302b is cut out from the image data. Then, the cut out image data is sent to the face detection unit 603, and the number of faces in the cut out image data, the size, and coordinate data are output (steps S503 and S504). The data output by the face detection processing unit 603 is stored in the memory 30 as face detection information by the information storage unit 604 (step S505).

  Next, in step S1001, it is determined whether or not a face has been detected by the processing in steps S702 and S503 to S505. Here, if a face is detected, the face detection process is immediately terminated. On the other hand, if it is determined in step S1001 that no face has been detected, it is determined in step S506 whether face detection processing has been performed for all the areas set by the area setting unit 802. Here, since the face detection of the face detection area frames 302a and 302c has not been completed yet, the process returns to step S702. Then, the area setting unit 802 sets the cutout region coordinates indicating the region of the next priority in the region cutout processing unit 602. In this way, face detection is performed for the face detection area frame 302a. Thus, when the face detection processing of the face detection area frames 302a and 302c is finished and the face detection information of each area is stored in the memory 30 by the information storage unit 604, the face area detection process is finished in step S506.

  Returning to FIG. 4, when the face area detection processing in step S <b> 402 ends, AE processing and AF processing using the face area detection information are performed. Since the operation after step S403 in FIG. 4 is exactly the same as in the first embodiment, the description thereof is omitted here.

  As described above, according to the third embodiment, since the face area detection process is completed when a face is detected, the shutter release time lag can be reduced. In addition, since the face detection region frame to be face detection processing target is selected according to the priority order and the face detection processing is performed, even if the face detection processing is terminated when the face is detected, face detection suitable for shooting can be performed. Will be done. In other words, since the minimum necessary face area detection is performed and the shooting operation is performed, it is possible to achieve both reduction of the release time lag and detection of an appropriate face area.

<Other embodiments>
In the first to third embodiments, the example in which the face is detected by dividing the image into three regions as shown in FIG. 3 has been described. However, the setting of the face detection area frame is not limited to this, and may be any number as long as one or more areas are set. Further, as shown in FIG. 11, the face detection area frame may be set to overlap with other face detection area frames.

  As described above, according to the above-described embodiment, in the camera that performs face detection and obtains an optimal shooting condition and performs shooting, face detection is performed only for a necessary area portion of the screen. The release time lag can be reduced. In addition, it is possible to further reduce the release time lag by interrupting the face detection by the user's shutter switch operation and performing the minimum necessary face area detection.

It is a block diagram which shows the structure of the imaging device by 1st Embodiment. It is a schematic diagram which shows the external appearance of the imaging device by 1st Embodiment. It is a figure which shows the example of the face detection area frame by 1st Embodiment. It is a flowchart which shows the imaging operation by the imaging device of 1st Embodiment. It is a flowchart explaining the face area detection process by 1st Embodiment. It is a block diagram which shows the function structural example for the face area detection process of the image process part 20 by 1st Embodiment. It is a flowchart explaining the face area detection process by 2nd Embodiment. It is a block diagram which shows the function structural example for the face area detection process of the image process part 20 by 2nd Embodiment. It is a flowchart explaining the modification of the face area detection process by 2nd Embodiment. It is a flowchart explaining the face area detection process by 3rd Embodiment. It is a figure which shows the other example of a face detection area frame.

Claims (10)

An imaging device that obtains image data by converting an output of an imaging device that converts incident light into an electrical signal into a digital value,
Holding means for holding area data indicating a plurality of partial areas in the image;
Detecting means for detecting a face area from image data in a partial area indicated by the area data held in the holding means;
An imaging apparatus comprising: control means for controlling the imaging apparatus based on image data in the face area detected by the detection means.   The imaging apparatus according to claim 1, wherein the detection unit performs face area detection for all of the plurality of partial areas indicated by the area data. A selection means for selecting a desired partial area from the plurality of partial areas;
The imaging apparatus according to claim 1, wherein the detection unit performs face region detection for all of the partial regions selected by the selection unit. Priorities are set for the plurality of partial areas,
2. The detection unit according to claim 1, wherein the detection unit selects a partial area in descending order of priority, executes face area detection, and ends detection of the face area in response to an input of a predetermined operation signal. The imaging device described.   The imaging apparatus according to claim 4, wherein the predetermined operation signal is an operation signal instructing shutter release. Priorities are set for the plurality of partial areas,
2. The detection unit according to claim 1, wherein the detection unit selects a partial region in descending order of priority, executes detection of a facial region, and terminates detection of the facial region when the facial region is detected. The imaging device described in 1. The imaging apparatus has a plurality of autofocus frames,
The imaging apparatus according to claim 1, wherein the plurality of partial areas are set corresponding to the plurality of autofocus frames.   The imaging apparatus according to claim 1, wherein the control unit performs focus position control based on image data in the face area detected by the detection unit.   The imaging apparatus according to claim 1, wherein the control unit performs exposure control based on image data in the face area detected by the detection unit. A method for controlling an imaging apparatus that obtains image data by converting an output of an imaging element that converts incident light into an electrical signal into a digital value,
A detection step of accessing a memory holding area data indicating a plurality of partial areas in an image, acquiring the area data, and detecting a face area from the image data in the partial area indicated by the acquired area data;
A control step of controlling the imaging device based on image data in the face area detected in the detection step.

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