JP2005184508A - Imaging device and control method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable detection of a person's face from a photographed image with accuracy, when the person is photographed in a situation of insufficient brightness, for example, against a background of a night scene. <P>SOLUTION: A light control region of a stroboscope is set in a photographing image including a subject, according to a distance measured by a distance measurement controller 42 for measuring the distance to the subject. Based on the photographed image produced under a pre-light emission, a face area in the photographed image is detected. According to the above detected face area, the light control region is determined. According to a photometric value in the above determined light control region being obtained under the pre-light emission, a main light-emission amount is calculated. Based on the calculated main light-emission amount, the stroboscope is controlled, and photographing is performed accordingly. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an imaging apparatus that captures, records, and reproduces still images and moving images, and a control method thereof.

  2. Description of the Related Art Conventionally, image processing apparatuses such as electronic cameras that can record still images and moving images and play back image data stored on a lossless medium using a memory card having a solid-state memory element as a storage medium are commercially available. An electronic camera equipped with an electronic viewfinder such as a color liquid crystal panel is also sold.

  These electronic cameras are designed to have a built-in strobe as auxiliary light for shooting in the dark or to be able to attach a separate strobe to the main body of the electronic camera. It is possible to take pictures.

  In such a strobe device of a conventional electronic camera, pre-flash is performed before actual imaging at the time of release, and the difference between the luminance level of the subject and the appropriate light control level is obtained from the pre-captured image, and according to the difference, Imaging is performed by determining the light emission amount at the time of actual imaging (see, for example, Patent Document 1).

  The light control range at this time is generally set around the distance measurement area.

  FIG. 10 is a diagram illustrating the relationship between the distance measurement area 912 and the light control area 911 on the shooting screen.

  In the same figure, since the distance measurement area 912 and the subject 910 overlap, a clear image having no problem is captured even if the light adjustment control is performed based on the light adjustment area 911 centering on the distance measurement area 912. be able to. However, for example, when the image capturing range by the camera is moved and the composition of FIG. 11 is changed after focusing on the subject 910 (focusing is performed), the subject 910 and the distance measurement area 912 do not match. In such a state, if dimming control is performed around the distance measuring area 912, the dimming control is performed in the area 920 where the subject 910 is not present, and thus an overexposed image may be captured.

  In order to avoid this, for example, as shown in FIG. 12, the AF area operation may be performed by setting the distance measurement area 912 to an area where the subject 910 exists, but in general, the distance measurement area 912 Rather than selecting the position, the AF operation is generally performed with the focus detection area 912 left in the center of the screen as shown in FIG. 11, and the composition is generally changed after this focusing. Therefore, there is a problem that the subject 910 and the light control region 911 do not match and an overexposed image is obtained.

Therefore, the face of the subject 910 is detected from the photographed image before AF, and exposure control is performed by weighting the detected face area of the subject (see, for example, Patent Document 2) or dimming control (for example, , See Patent Document 3). With such a configuration, it is possible to always focus on the face of the subject without performing the work of changing the composition after focusing.
JP 2001-091989 A JP 2003-107555 A JP 2003-107567 A

  However, for example, in a situation where the luminance is not sufficient (for example, when a person is photographed against a night view), it is difficult to accurately detect the person's face from the photographed image. There are two methods for detecting a human face: a method in which a skin color area with a size greater than or equal to a predetermined size is considered as a face area, and a method in which the face contour and eye shape are detected from luminance information and considered as a face area. However, the detection accuracy cannot be denied in the dark.

  The present invention has been made in view of the above problems, and provides an imaging apparatus capable of obtaining an appropriate flash image even when a subject and a preset light control area do not match, and a control method thereof. With the goal.

  An imaging device that detects a face position of a subject from a pre-flash imaging screen, and performs dimming control in an area centered on the face area when the preset dimming area and the detected face area are different; The control method is provided.

The imaging device of the present invention has the following configuration. That is,
An imaging device that performs pre-flash before main flash during shooting,
Ranging means for measuring the distance to the subject;
A dimming area setting means for setting a dimming control area of a strobe in a captured image including a subject according to the distance measured by the distance measuring means;
A face area detecting means for detecting a face area in the captured image based on a captured image by pre-emission;
Determining means for determining the dimming control area according to the face area detected by the face area detecting means;
A calculation means for calculating a main light emission amount according to a photometric value by the pre-light emission in the light control area determined by the determination means;
Control means for controlling the strobe to perform photographing based on the main light emission amount calculated by the calculating means.

Moreover, the control method of the imaging device of the present invention includes the following steps. That is,
A control method in an imaging device that performs pre-flash before main flash at the time of shooting,
A ranging process for measuring the distance to the subject;
A dimming area setting step for setting a dimming control area of a strobe in a captured image including a subject according to the distance measured in the ranging process;
A face area detection step of detecting a face area in the captured image based on a captured image by pre-emission;
A determining step of determining the dimming control region according to the face region detected in the face position detecting step;
A calculation step of calculating a main light emission amount according to a photometric value by the pre-light emission in the light control region determined in the determination step;
And a control step of controlling the strobe to perform photographing based on the main light emission amount calculated in the calculation step.

  According to the present invention, it is possible to detect a face area of a subject with high accuracy even when shooting in a situation where the brightness of the subject cannot be sufficiently obtained, and to perform appropriate strobe control based on the detected face area. Can be performed.

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

  FIG. 1 is a block diagram showing a configuration of an electronic camera (image processing apparatus) 100 according to an embodiment of the present invention.

  In the figure, 10 is a photographing lens, 12 is a shutter, 14 is an image sensor that converts an optical image into an electrical signal, and 16 is an A / D converter that converts an analog signal output of the image sensor 14 into a digital signal. The timing generator 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 to control their operations. The timing generator 18 is controlled by the memory controller 22 and the system controller 50. The image processing unit 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 unit 22. The image processing unit 20 performs predetermined calculation processing using the captured image data, and the system control unit 50 controls the shutter control unit 40 and the distance measurement control unit 42 based on the calculation result obtained therefrom. TTL (through-the-lens) AF (autofocus) processing, AE (automatic exposure) processing, and EF (strobe preflash) processing are performed. The image processing unit 20 performs predetermined calculation processing using the captured image data, and also performs TTL AWB (auto white balance) processing based on the obtained calculation result. Furthermore, a face detection process is also performed in which features of eyes and mouth edges are extracted from the captured image data to detect a human face.

  The memory control unit 22 controls the A / D converter 16, the timing generation unit 18, the image processing unit 20, the image display memory 24, the D / A converter 26, the memory 30, and the compression / decompression unit 32. As a result, the data A / D converted by the A / D converter 16 can be directly memory-controlled via the image processing unit 20 and the memory control unit 22, or the data A / D converted by the A / D converter 16 can be directly memory controlled. The data is written into the image display memory 24 or the memory 30 via the unit 22.

  The image display memory 24 stores data to be displayed on the image display unit 26, and the data stored in the image display memory 24 is sent to an image display unit such as a TFT or LCD via the D / A converter 26. It is output to 28 and displayed. If the captured image data is sequentially displayed by the image display unit 28, a function as an electronic viewfinder can be realized. Further, the image display unit 28 can arbitrarily turn on / off the display according to an instruction from the system control unit 50. When the display is turned off, the power consumption of the image processing apparatus 100 can be greatly reduced. 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 unit 50. The compression / decompression unit 32 can compress and decompress the image data by, for example, adaptive discrete cosine transform (ADCT) or the like, and reads the image data stored in the memory 30 to perform the compression process or the compressed image Data can be read and decompressed, and the processed data can be written into the memory 30.

  The shutter control unit 40 controls the shutter 12. The distance measurement control unit 42 controls the focusing of the photographing lens 10. The distance measurement control unit 43 detects the distance of the subject from the focusing position of the photographic lens 10. The zoom control unit 44 controls zooming of the taking lens 10. A diaphragm control unit 46 controls the operation of the diaphragm 102. The strobe unit 48 also has an AF auxiliary light projecting function and a strobe light control function. The shutter control unit 40 and the distance measurement control unit 42 are controlled using the TTL method, and the system control unit 50 controls the shutter control unit 40 and the aperture control based on the calculation result obtained by calculating the captured image data by the image processing unit 20. The unit 46 and the distance measurement control unit 42 are controlled.

  The system control unit 50 controls the overall operation of the image processing apparatus 100. The memory 52 stores constants, variables, programs, and the like for operating the system control unit 50. The display unit 54 includes a liquid crystal display unit, 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 the program by the system control unit 50. The display unit 54 is installed in a single or a plurality of positions near the operation unit 70 of the image processing apparatus 100 so as to be easily visible, and is configured by, for example, a combination of an LCD, an LED, a sounding element, and the like. In addition, a part of the function of the display unit 54 is 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, recording pixel number display, recording number display, remaining image number display, Shutter speed display, aperture value display, exposure compensation display, strobe display, red-eye reduction display, macro shooting display, buzzer setting display, battery level display for clock, battery level display, error display, multi-digit number information display, There are a display state of the storage 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 on the optical viewfinder 104 includes in-focus display, camera shake warning display, strobe charge display, shutter speed display, aperture value display, exposure correction display, and the like.

  The nonvolatile memory 56 is an electrically erasable and recordable memory. For example, an EEPROM or the like is used. A mode dial 60, shutter switches 62 and 64, an image display ON / OFF switch 66, a quick review ON / OFF switch 68, and an operation unit 70 are operation units for inputting various operation instructions of the system control unit 50. It is composed of one or a plurality of combinations such as a switch, dial, touch panel, pointing by line of sight detection, and a voice recognition device.

  Next, these operation units will be specifically described here.

  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 and deletion mode, and PC connection mode. The shutter switch (SW1) 62 is turned on during the operation of a shutter button (not shown), and instructs to start operations such as AF (autofocus) processing, AE (automatic exposure) processing, and AWB (auto white balance) processing. The shutter switch (SW2) 64 is turned on when the operation of a shutter button (not shown) is completed. In the flash photography mode, the light emission control of the flash unit 48 and the signal read from the image sensor 14 are converted to the A / D converter 16 and the memory. Exposure processing to be written as image data in the memory 30 via the control unit 22, development processing using calculation in the image processing unit 20 and the memory control unit 22, image data read out from the memory 30, and compression in the compression / decompression unit 32 And instructing the start of a series of processing operations such as recording processing for writing image data in the storage medium 200 or 210. The image display ON / OFF switch 66 can set ON / OFF of image display on the image display unit 28. With this function, when photographing using the optical viewfinder 104, it is possible to save power by cutting off the current supply to the image display unit 28 including TFT, LCD, and the like. The quick review ON / OFF switch 68 sets a quick review function for automatically reproducing the captured image data immediately after shooting. In the present embodiment, it is assumed that a function for setting a quick review function when the image display unit 28 is turned off is provided. The operation unit 70 has various buttons, a touch panel, and the like. These switches and buttons include a menu button, a set button, a macro button, a multi-screen playback page break button, a strobe setting button, single shooting / continuous shooting / self-timer switching. Button, menu movement + (plus) button, menu movement-(minus) button, playback image movement + (plus) button, playback image-(minus) button, shooting image selection button, exposure compensation button, date / time setting button, etc. There is.

  The power control unit 80 includes a battery detection unit, a DC-DC converter, a switch unit that switches a block to be energized, and the like, detects whether or not a battery is installed, the type of battery, and the remaining battery level, and the detection result and The DC-DC converter is controlled based on an instruction from the system control unit 50, and a necessary voltage is supplied to each unit including the storage medium for a necessary period. Reference numerals 82 and 84 denote connectors, and the power source 86 includes primary batteries such as alkaline batteries and lithium batteries, secondary batteries such as NiCd batteries, NiMH batteries, and Li batteries, and AC adapters.

  Reference numerals 90 and 94 denote interfaces with a storage medium such as a memory card or a hard disk, and reference numerals 92 and 96 denote connectors for connecting to a storage medium such as a memory card or a hard disk. The storage medium attachment / detachment detection unit 98 detects whether the storage medium 200 or 210 is attached to the connector 92 or 96.

  In the present embodiment, it is assumed that there are two systems of interfaces and connectors for attaching a storage medium. Of course, the interface and connector to which this storage medium is attached may have a single or plural 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) card, or the like that conforms to a standard.

  Further, when the interfaces 90 and 94 and the connectors 92 and 96 are configured using a PCMCIA card, a CF (Compact Flash (registered trademark)) card, or the like, a LAN card, a modem card, a USB card, IEEE1394. Image data and management information attached to image data are transferred to and from peripheral devices such as other computers and printers by connecting various communication cards such as cards, P1284 cards, SCSI cards, and PHS communication cards. I can meet each other.

  The aperture 102 determines the exposure amount to the image sensor 14 in combination with the shutter 12. The optical viewfinder 104 can perform photographing using only the optical viewfinder without using the electronic viewfinder function of the image display unit 28. The optical viewfinder 104 is provided with some functions of the display unit 54, such as a focus display, a camera shake warning display, a strobe charge display, a shutter speed display, an aperture value display, and an exposure correction display. The communication unit 110 has various communication functions such as RS232C, USB, IEEE1394, P1284, SCSI, modem, LAN, and wireless communication. An antenna (connector) 112 is used to connect the image processing apparatus 100 to another device by the communication unit 110, and is a connector in the case of wired connection, and an antenna in the case of wireless communication. The storage medium 200 is a storage medium such as a memory card or a hard disk. The storage medium 200 includes a storage unit 202 composed of a semiconductor memory, a magnetic disk, or the like, an interface 204 with the image processing apparatus 100, and a connector 206 for connecting to the image processing apparatus 100. The storage medium 210 is a storage medium such as a memory card or a hard disk. The storage medium 210 is also connected to the storage unit 212 including a semiconductor memory or a magnetic disk, the interface 214 with the image processing apparatus 100, and the image processing apparatus 100. A connector 216 is provided.

  FIG. 2 is a block diagram for explaining the strobe unit 48 according to the present embodiment in more detail.

  The DC / DC converter 300 boosts a relatively low voltage output from the power source 86 to a high voltage of about 300V. The capacitor 301 is connected in parallel to the output of the DC / DC converter 300 to charge the light emission energy. The voltage dividing resistors 302 and 303 divide the charging voltage to a low voltage in order to monitor the charging voltage of the capacitor 301. The light emitting unit 305 such as an Xe tube emits light when excited by the trigger voltage from the trigger unit 304. The current interruption element 306 is an element for controlling light emission of the Xe tube 305, and is, for example, an IGBT. The light receiving element 307 is composed of a photodiode, for example, and monitors the light emission amount of the Xe tube 305. The compression integration unit 308 receives and amplifies the photocurrent output from the light receiving element 307, performs logarithmic compression, and detects the light emission amount of the Xe tube 305. The light emission amount comparator 309 detects whether or not the light emission amount of the Xe tube 305 is equal to or greater than a predetermined amount, and outputs the detection result. Reference numerals 310 to 314 are connection terminals for the system controller 50.

  The terminal 310 is a light emission control terminal that controls the start / stop of light emission of the Xe tube 305. A terminal 311 is a trigger control terminal for inputting a trigger control signal for controlling the trigger unit 304. A terminal 312 is a voltage monitor terminal for monitoring the voltage of the capacitor 301. A terminal 313 is a comparator voltage terminal of the comparator 309 for controlling the light emission amount, and a terminal 314 is an output terminal of the comparator.

  Hereinafter, the operation of the electronic camera according to the present embodiment will be described with reference to the flowcharts of FIGS. A program for executing this processing (900 in FIG. 9) is stored in the memory 52 and is executed under the control of the system control unit 50. An example of the memory map of the memory 52 is shown in FIG. In FIG. 9, reference numeral 907 denotes face data for one face area including the face position data and the average luminance of the image data of the face area when the face area is detected as will be described later. Therefore, when a plurality of face areas are detected in one image, as many face data 907 as the number of face areas are stored. Reference numeral 908 denotes an area in which when there are a plurality of faces, the average luminance of these face areas is obtained and stored.

  3 and 4 are flowcharts for explaining the operation in the main processing routine in the electronic camera (image processing apparatus) according to the present embodiment.

  This process is started when the power is turned on, for example after battery replacement. First, in step S101, the system control unit 50 initializes various flags and control variables in the memory 52, and in step S102, the image on the image display unit 28 is displayed. Initialize the display to the off state. Next, in step S103, the setting position of the mode dial 60 is determined. If the mode dial 60 is set to power off, the process proceeds to step S105, the display on each display unit is changed to the end state, and a flag or control variable is set. Necessary parameters, setting values, and setting modes including the above and the like are recorded in the nonvolatile memory 56, and a predetermined end process such as cutting off unnecessary power sources of the respective units of the image processing apparatus 100 including the image display unit 28 by the power control unit 80. Then, the process returns to step S103 again.

  In step S103, if the mode dial 60 is set to the shooting mode, the process proceeds to step S106. If the other mode is set, the process proceeds to step S104, and the mode dial 60 is selected according to the mode selected by the mode dial 60. The process is executed, and when the process is finished, the process returns to step S103.

  If the shooting mode is set, the process proceeds to step S106, and the remaining capacity and operation status of the power source 86 constituted by a battery or the like has a problem in the operation of the image processing apparatus 100 based on a signal from the power control unit 80. Determine whether or not. If it is determined that there is a problem, the process proceeds to step S108, where a predetermined warning is displayed by an image or sound using the display unit 54, and then the process returns to step S103.

  If it is determined in step S106 that there is no problem with the power source 86, the process proceeds to step S107, and whether or not the operation state of the storage medium 200 or 210 has a problem in the operation of the image processing apparatus 100, in particular, the recording / reproducing operation of image data with respect to the storage medium. If it is determined that there is a problem, the process proceeds to step S108 described above, and a predetermined warning is displayed by image or sound using the display unit 54, and then the process returns to step S103.

  If it is determined in step S107 that there is no problem, the process proceeds to step S109, and the display unit 54 is used to display a UI of various setting states of the image processing apparatus 100 using images and sounds. If the image display of the image display unit 28 is on, the UI display of various setting states of the image processing apparatus 100 may be performed using the image display unit 28 by an image or sound. In this way, various settings are made by the user.

  Next, in step S110, the state of the quick review on / off switch 68 is checked. If the quick review is set to on, the process proceeds to step S111, and the quick review flag 901 in the memory 52 is set to on. On the other hand, if the quick review on / off switch 68 is set to quick review off, the process proceeds to step S112, and the quick review flag 901 in the memory 52 is turned off. The quick review flag 901 is stored in the internal memory of the system control unit 50 or the memory 52. Here, the case where the quick review flag 901 is set in the memory 52 as shown in FIG. The same applies to other flags.

  In step S113, the setting state of the image display on / off switch 66 is checked. If the image display is set to on, the process proceeds to step S114, and the image display flag 902 in the memory 52 is set to on. In step S115, the image display of the image display unit 28 is set to an on state. Furthermore, in step S116, the captured image data is set to a through display state for sequentially displaying, and the process proceeds to step S119 (FIG. 4). In this through display state, the data sequentially written in the image display memory 24 via the image sensor 14, the A / D converter 16, the image processing unit 20, and the memory control unit 22 are transferred to the memory control unit 22, the D / D The electronic finder function is realized by sequentially displaying images on the image display unit 28 via the A converter 26.

  On the other hand, if the image display on / off switch 66 is set to image display off in step S113, the process proceeds to step S117, and the image display flag 902 is turned off. In step S118, the image display unit 28 displays the image. The off state is set and the process proceeds to step S119. When the image display is off, the image is taken using the optical viewfinder 104 without using the electronic viewfinder function of the image display unit 28. In this case, it is possible to reduce power consumption of the image display unit 28, the D / A converter 26, and the like that consume a large amount of power. The image display flag 902 is stored in the internal memory or the memory 52 of the system control unit 50.

  In step S119, it is checked whether or not the shutter switch (SW1) 62 has been pressed. If not, the process returns to step S103. If the shutter switch (SW1) 62 has been pressed, the process proceeds to step S120, and the system control unit. It is checked whether the image display flag 902 stored in the internal memory 50 or the memory 52 is set to ON. If it is set to ON, the process proceeds to step S121, the display state of the image display unit 28 is set to the freeze display state, and the process proceeds to step S122. In this freeze display state, rewriting of image data in the image display memory 24 via the image sensor 14, A / D converter 16, image processing unit 20, and memory control unit 22 is prohibited, and the last written image data Is displayed by the image display unit 28 via the memory control unit 22 and the D / A converter 26, thereby displaying the frozen image on the optical viewfinder 104.

  If the image display flag 902 is off in step S120, the process proceeds to step S122. In step S122, a distance measurement process is performed to focus the photographing lens 10 on the subject, and a photometry process is performed to determine an aperture value and a shutter speed. In this photometric process, the strobe is set if necessary. The details of the distance measurement and photometry processing S122 will be described later in detail with reference to the flowchart of FIG.

  When the distance measurement and photometry processing is completed in step S122, the process proceeds to step S123, and the state of the image display flag 902 stored in the internal memory of the system control unit 50 or the memory 52 is determined. If the image display flag 902 is set to ON, the process proceeds to step S124, the display state of the image display unit 28 is set to the through display state, and the process proceeds to step S125. The through display state in step S124 is the same operation as the through state in step S116.

  Next, in step S125, if the shutter switch (SW1) 62 is also released without pressing the shutter switch (SW2) 64, the process returns to step S103 (FIG. 3).

  On the other hand, when the shutter switch (SW2) 64 is pressed in step S125, the process proceeds to step S127, where it is determined whether the image display flag 902 stored in the internal memory of the system control unit 50 or the memory 52 is on, and the image display flag 902 is determined. If ON, the process proceeds to step S128, the display state of the image display unit 28 is set to the fixed color display state, and the process proceeds to step S129. In this fixed color display state, instead of the captured image data written in the image display memory 24 via the image sensor 14, the A / D converter 16, the image processing unit 20, and the memory control unit 22, the fixed color replaced. Is displayed on the image display unit 28 via the memory control unit 22 and the D / A converter 26. In this way, a fixed color image is displayed on the electronic viewfinder 104.

  If the image display flag 902 is off in step S127, the process proceeds to step S129. In this step S129, the captured image data is acquired via the image sensor 14, the A / D converter 16, the image processing unit 20, the memory control unit 22, or directly from the A / D converter 16 via the memory control unit 22. Exposure processing for writing the image data into the memory 30, and photographing processing including development processing for reading out the image data written in the memory 30 and performing various processing using the memory control unit 22 and, if necessary, the image processing unit 20. Execute.

  Details of the photographing process (S129) will be described later with reference to FIGS.

  When the photographing process of step S129 is executed in this way, the process proceeds to step S130, where it is determined whether or not the image display flag 902 stored in the internal memory of the system control unit 50 or the memory 52 is on, and the image display flag 902 is on. In step S133, a quick review display is performed. In this case, the image display unit 28 is always displayed as an electronic viewfinder even during shooting, and quick review display immediately after shooting is also performed.

  If it is determined in step S130 that the image display flag 902 is off, the process advances to step S131 to check whether the quick review flag 901 stored in the internal memory of the system control unit 50 or the memory 52 is on. If the quick review flag 901 is on, the process proceeds to step S132, the image display of the image display unit 28 is set to the on state, the quick review display is performed, and then the process proceeds to step S134.

  If the image display flag 902 is off in step S130 and the quick review flag 901 is also off in step S131, the process proceeds to step S134 while the image display unit 28 remains off. In this case, the image display unit 28 remains off even after shooting, and no quick review display is performed. This is a usage method that places importance on power saving without using the electronic viewfinder function of the image display unit 28 without the need to check the photographed image immediately after photographing, as in the case of continuing photographing using the optical viewfinder 104. .

  In step S134, the captured image data written in the memory 30 is read out, and various image processing is executed using the memory control unit 22 and, if necessary, the image processing unit 20, and the compression / decompression unit 32 is executed. After performing the image compression process according to the mode set by using, the recording process for writing the compressed image data to the storage medium 200 or 210 is executed. Details of the recording process (S134) will be described later in detail with reference to the flowchart of FIG.

  After the recording process in step S134 is completed, in step S135, it is checked whether the shutter switch (SW2) 64 has been pressed. If so, the process proceeds to step S136, and the internal control memory 50 or the memory 52 of the system control unit 50 is checked. The state of the continuous shooting flag 903 stored is determined. If the continuous shooting flag 903 is ON, the process proceeds to step S129 to continuously shoot, and the next video is shot. If the continuous shooting flag 903 is not on in step S136, the process proceeds to step S137, and the processes in steps S135 and S136 are repeated until the shutter switch (SW2) 64 is released.

  As described above, according to the present embodiment, in the operation setting state in which the quick review display is performed immediately after shooting, the shutter is pressed if the shutter switch (SW2) is pressed when the recording process (S134) is completed. The quick review display on the image display unit 28 is continued until the switch (SW2) 64 is released. Thereby, it is possible to carefully check the captured image.

  In this way, when the shutter switch (SW2) 64 is turned off immediately after the recording process of step S134, or after the recording process of step S134, the shutter switch (SW2) is kept pressed and the quick review display is continued to be taken. When the shutter switch (SW2) is turned off after confirming the above, the process proceeds from step S135 to step S137, and waits for a predetermined minimum review time to elapse, and then proceeds to step S138. In step S138, it is checked whether the image display flag 902 is on. If it is on, the process proceeds to step S139, the display state of the image display unit 28 is set to the through display state, and the process proceeds to step S141. Thereby, after confirming the captured image by the quick review display on the image display unit 28, it is possible to enter a through display state in which image data captured for the next imaging is sequentially displayed. If the image display flag 902 is off in step S138, the process proceeds to step S140, the image display of the image display unit 28 is set to the off state, and the process proceeds to step S141. Thus, after confirming the captured image by the quick review display on the image display unit 28, the function of the image display unit 28 is stopped for power saving, and the image display unit 28 or D / A conversion with large power consumption is stopped. It is possible to reduce the power consumption of the device 26 and the like.

  In step S141, it is checked whether the shutter switch (SW1) 62 is turned on. If so, the process proceeds to step S125 to prepare for the next shooting. If it is determined in step S141 that the shutter switch (SW1) 62 has been turned off, the series of photographing operations is terminated and the process returns to step S103 (FIG. 3).

  FIG. 5 is a flowchart showing details of the distance measurement and photometry processing in step S122 of FIG.

  First, in step S <b> 201, a charge signal is read from the image sensor 14, converted into digital data via the A / D converter 16, and the digital data is input to the image processing unit 20. Using the input image data, the image processing unit 20 performs predetermined calculations used for TTL AE (automatic exposure) processing, EF (strobe pre-emission) processing, and AF (autofocus) processing. In each process here, a specific portion of the total number of captured pixels is extracted according to necessity and extracted for use. Thereby, in each process of TTL method AE, EF, AWB, and AF, it is possible to perform an optimal calculation for each different mode such as the center weight mode, the average mode, and the evaluation mode.

  Using the calculation result in the image processing unit 20 in step S201, the exposure (AE) is determined to be appropriate in step S202, and the process proceeds to night step S203. AE control is performed by a combination of the aperture control unit 46 and the electronic shutter of the image sensor 14. I do. Using measurement data 905 (FIG. 9) obtained by this AE control, it is determined in step S204 whether or not a strobe is necessary. If strobe is necessary, the process proceeds to step S205, and a strobe flag 904 is set. The strobe 48 is charged and the process proceeds to step S201.

  If it is determined in step S202 that the exposure (AE) is appropriate, the process proceeds to step S206, and the measurement data 905 and / or the setting parameter 906 are stored in the internal memory of the system control unit 50 or in the memory 52 (in FIG. 9, stored in the memory 52). Example). Then, using the calculation result in the image processing unit 20 and the measurement data obtained by the AE control, it is determined whether or not the white balance (AWB) is appropriate. The AWB control is performed by adjusting the parameters of the color processing using, and the process proceeds to step S201.

  When it is determined in step S206 that the white balance (AWB) is appropriate, the process proceeds to step S208, and the measurement data 905 and / or the setting parameter 906 in the memory 52 are stored in the internal memory or the memory 52 of the system control unit 50. Then, using the measurement data 905 obtained by the AE control and the AWB control, it is determined whether or not the distance measurement (AF) is in focus. If not in focus, the process proceeds to step S209, AF control is performed using the distance measurement control unit 42, and the process proceeds to step S201. When it is determined in step S208 that the distance measurement (AF) is in focus, the measurement data 905 and / or the setting parameter 906 are stored in the internal memory or the memory 52 of the system control unit 50, and the distance measurement and photometry processing ends.

  6 and 7 are flowcharts showing details of the photographing process in S129 of FIG.

  The aperture value is set by the aperture control unit 46 in accordance with the photometry data 905 obtained by the above-described distance measurement and photometry processing and stored in the internal memory of the system control unit 50 or the memory 52, and the shutter control unit 40 also sets the aperture value. The shutter 12 is opened to expose the image sensor 10 (S301 and S302).

  Next, in step S303, it is determined whether or not the strobe 48 is necessary based on the strobe flag 904. If the strobe is necessary, the process proceeds to step S304, and the strobe unit 80 is pre-flashed with a predetermined light emission amount. The amount of pre-emission is determined based on the aperture value of the lens 10, the distance to the subject detected by the distance detection unit 43, and the set sensitivity of the image sensor 14. In step S305, the exposure of the image sensor 14 is awaited according to the photometric data 905. When the exposure end timing comes, the shutter 12 is closed in step S306. In step S307, the charge signal is read out from the image sensor 14, and the A / D converter 16, the image processing unit 20, the memory control unit 22, or the A / D converter 16 directly through the memory control unit 22 is read. The captured image data is written into the memory 30.

  Next, the process proceeds to step S308, where it is determined whether it is necessary to perform frame processing according to the set shooting mode. If it is necessary to perform frame processing, the process proceeds to step S309, where the memory control unit 22 and the necessary processing are performed. Accordingly, the image processing unit 20 is used to read the image data written in the memory 30 and execute vertical addition processing. Next, in step S310, color processing is sequentially performed, and then face detection processing is performed in step S311. Do. As described above, the face detection process by the image processing unit 20 detects the position of a person's face by extracting features of the edges of the eyes and mouth from the captured image data, and includes the eyes and mouth. The contour of the face is detected, the position of the center of gravity is obtained, and the luminance (image signal level) of the area within the contour is calculated. In this face detection process, the size of a human face is predicted from the focusing position of the lens 10 based on the distance detected by the distance detection unit 43 and the focal length of the lens, thereby improving detection accuracy.

  Next, in step S312, the number of faces detected in step S311 is determined. If the number is “0”, the process proceeds to step S313. If “1”, the process proceeds to step S314. If more than one, the process proceeds to step S318. Branch. If face detection has not been performed, that is, if the number of detected faces is “0”, in step S313, as previously set, the luminance (image signal in the dimming area that matches the distance measuring point). Level) average value is calculated, and the process proceeds to step S321 (FIG. 7).

  If the number of detected faces is “1”, in step S314, it is determined whether or not the position of the detected face matches a preset dimming area. If they match, the process proceeds to step S315. The dimming area is corrected according to the detected face area. If they do not match, the process branches to step S316, the detected face position (area based on the face position data in FIG. 9) is set as a new dimming area, and the dimming area is set according to the detected face area. Set. When step S315 or S316 is executed in this way, the process proceeds to step S317, and the average value of the luminance (image signal level) in the light control region set in step S315 or step S316 (average luminance of the face region in FIG. 9) is calculated. Then, the process proceeds to step S321 (FIG. 7).

  On the other hand, if a plurality of faces are detected in the face detection process in step S312, the process proceeds to step S318 (FIG. 7), and a plurality of face position data for each detected face and a plurality of faces corresponding to each face region are detected. Set the dimming area. Next, in step S319, the average value of the brightness (image signal level) of each face area (in the light control area) is calculated and stored in the average brightness 907 of each face shown in FIG. Further, in step S320, the average brightness of the detected plurality of light control areas is further averaged and stored in the plurality of face average brightness areas 908 of FIG. 9, and the process proceeds to step S321.

  In this way, in step S321, the main light emission amount (light emission amount at the time of actual photographing) at which the luminance (image signal level) in the dimming area becomes appropriate luminance (appropriate signal level) is calculated. For example, when the image signal level of pre-imaging by pre-emission is an appropriate level, the same amount of light emission as that of pre-emission is sufficient. For example, when the image signal level of pre-emission is one step lower, Processing such as setting the light emission amount to double is performed.

  Next, in step S322, the shutter 12 is opened again by the shutter control unit 40 for the main imaging, and the image sensor 10 is exposed in step S323. Then, the process proceeds to step S324, and the strobe unit 80 is caused to emit light with the main light emission amount obtained in step S321.

  In step S325, the time until the exposure of the image sensor 14 is completed according to the photometric data, and the shutter 12 is closed in step S326. In step S327, the charge signal is read out from the image sensor 14, and the A / D converter 16, the image processing unit 20, the memory control unit 22 or directly from the A / D converter 16 through the memory control unit 22. The captured image data is written in the memory 30. In step S328, it is determined whether frame processing needs to be performed according to the set shooting mode. If frame processing needs to be performed, the process proceeds to step S329, and the memory control unit 22 and, if necessary, the image are processed. The processing unit 20 is used to read the image data written in the memory 30 and execute vertical addition processing. In step S330, color processing is sequentially performed, and then the processed image data is written to the memory 30. In step S331, the image data is read from the memory 30, and the display image data is transferred to the image display memory 24 via the memory control unit 22. When the series of processing is thus completed, the photographing processing routine (S129) is terminated.

  FIG. 8 is a flowchart showing details of the imaging recording process in S134 of FIG.

  First, in step S401, the captured image data written in the memory 30 is read out using the memory control unit 22 and, if necessary, the image processing unit 20, and the vertical / horizontal pixel ratio of the image sensor is interpolated to “1: 1”. A pixel square process is performed, and the processed image data is written in the memory 30. Next, in step S402, the image data written in the memory 30 is read out and image compression processing according to the set mode is performed by the compression / decompression unit 32. Then, in step S403, the interface 90 or 94, the connector 92 or The compressed image data is written to the storage medium 200 or 210 such as a memory card or a compact strobe card via 96. When the writing to the storage medium is thus completed, the recording processing routine S134 is ended.

  In this embodiment, the dimming area is set according to the face position detected by the image processing apparatus 100 and its size. However, since there is a possibility of erroneous detection, the distance to the subject is set. Based on the subject distance, the pre-emission light quantity, the aperture value, and the ISO sensitivity detected by the distance detection unit 40 to be detected, an appropriate luminance value is calculated when the reflectance of the face is 25%, and the luminance value If it is within the desired range, the detected face position is used as it is as the dimming area, and if it is out of the range, it is judged as a false detection, and the preset dimming area is used. Alternatively, an area with the highest luminance on the screen may be used as the dimming area.

  At this time, the appropriate brightness value according to the subject distance is compared with the high brightness area in the screen, and if it is higher than the desired brightness range, the dimming area is used as an abnormal reflection area such as glass or a mirror. By eliminating from the above, it becomes possible to set the light control region more accurately. In the face detection, the face area can be detected more accurately by recognizing the hue of the subject.

(Other examples)
Note that the present invention can be applied to a system (for example, a copier, a facsimile machine, etc.) composed of a single device even if it is applied to a system composed of a plurality of devices (for example, a host computer, interface device, reader, printer, etc.). May be.

  Another object of the present invention is to supply a storage medium (or recording medium) in which a program code of software that realizes the functions of the above-described embodiments is recorded to a system or apparatus, and to perform a computer (or a computer) This can also be achieved by the CPU and MPU) reading and executing the program code stored in the storage medium. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the program code constitutes the present invention. Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also an operating system (OS) running on the computer is actually executed based on the instruction of the program code. This includes a case where part or all of the processing is performed and the functions of the above-described embodiments are realized by the processing.

  Furthermore, after the program code read from the storage medium is written into a memory provided in a function expansion card inserted into the computer or a function expansion unit connected to the computer, the function is determined based on the instruction of the program code. The case where the CPU of the expansion card or the function expansion unit performs part or all of the actual processing and the functions of the above-described embodiments are realized by the processing is also included. For example, it goes without saying that this processing is performed by a driver on a PC.

It is a block diagram which shows the structure of the electronic camera which concerns on embodiment of this invention. It is a block diagram which shows the structure of the flash part of the electronic camera which concerns on this Embodiment. It is a flowchart which shows the process of the main routine in the electronic camera which concerns on this Embodiment. It is a flowchart which shows the process of the main routine in the electronic camera which concerns on this Embodiment. It is a flowchart which shows the ranging and photometry process in the electronic camera which concerns on this Embodiment. It is a flowchart explaining the imaging | photography process in the electronic camera which concerns on this Embodiment. It is a flowchart explaining the imaging | photography process in the electronic camera which concerns on this Embodiment. It is a flowchart explaining the recording process in the electronic camera which concerns on this Embodiment. It is a figure which shows the memory map example of the memory of the electronic camera which concerns on this Embodiment. It is a figure explaining a to-be-focused area | region and a light control area | region when a to-be-photographed object and a focusing area | region correspond. It is a figure explaining a to-be-photographed object, a focus area | region, and a light control area | region when a to-be-photographed object and a focus area | region do not correspond. It is a figure explaining a to-be-focused area | region and a light control area | region when a to-be-photographed object and a focusing area | region correspond.

Claims (14)

An imaging device that performs pre-flash before main flash during shooting,
Ranging means for measuring the distance to the subject;
A dimming area setting means for setting a dimming control area of a strobe in a captured image including a subject according to the distance measured by the distance measuring means;
A face area detecting means for detecting a face area in the captured image based on a captured image by pre-emission;
Determining means for determining the dimming control area according to the face area detected by the face area detecting means;
A calculation means for calculating a main light emission amount according to a photometric value by the pre-light emission in the light control area determined by the determination means;
Control means for controlling the strobe to perform shooting based on the main light emission amount calculated by the calculating means;
An imaging device comprising:   2. The imaging according to claim 1, wherein the strobe irradiation light amount at the time of the pre-light emission is determined based on the distance measured by the distance measuring unit, a set aperture, and sensitivity of an imaging device. apparatus.   The said calculating means calculates | requires the average brightness | luminance by the said pre light emission in the changed said light control area, and calculates the said main light emission amount based on the said average brightness | luminance. Imaging device.   The arithmetic means obtains an average brightness in each face area by the pre-emission when there are a plurality of face areas detected by the face position detecting means, and an average value of the brightness in the plurality of face areas from the average brightness The imaging apparatus according to claim 1, wherein the main light emission amount is calculated based on the average value. Comparing means for comparing whether the dimming control area set by the dimming area setting means and the face area detected by the face position detecting means match,
The determining means determines that the dimming control area set by the dimming area setting means is matched with the face area detected by the face position detecting means when it does not match by the comparing means. The imaging apparatus according to claim 1, wherein the imaging apparatus is characterized.   The imaging apparatus according to claim 1, wherein the distance is determined based on a focusing position of a lens. A control method in an imaging device that performs pre-flash before main flash at the time of shooting,
A ranging process for measuring the distance to the subject;
A dimming area setting step for setting a dimming control area of a strobe in a captured image including a subject according to the distance measured in the ranging process;
A face area detection step of detecting a face area in the captured image based on a captured image by pre-emission;
A determining step of determining the dimming control region according to the face region detected in the face position detecting step;
A calculation step of calculating a main light emission amount according to a photometric value by the pre-light emission in the light control region determined in the determination step;
A control step for controlling the strobe to perform shooting based on the main light emission amount calculated in the calculation step;
A control method characterized by comprising:   8. The control according to claim 7, wherein the amount of stroboscopic irradiation at the time of the pre-flash is determined based on the distance measured in the distance measuring step, a set aperture, and sensitivity of an image sensor. Method.   The said calculating process calculates | requires the average brightness | luminance by the said pre light emission in the changed said light control area, and calculates the said main light emission amount based on the said average brightness | luminance. Control method.   In the calculation step, when there are a plurality of face regions detected in the face position detection step, an average luminance in each face region by the pre-emission is obtained, and an average value of the luminances in the plurality of face regions from the average luminance The control method according to claim 7, wherein the main light emission amount is calculated based on the average value. Further comprising a comparison step for comparing whether or not the dimming control region set in the dimming region setting step matches the face region detected in the face position detection step;
If it is determined in the determination step that they do not coincide with each other in the comparison step, the dimming control region set in the dimming region setting step is determined to be matched with the face region detected in the face position detection step. The control method according to claim 7, wherein the control method is any one of claims 7 to 10.   The control method according to claim 7, wherein the distance is determined based on a focusing position of the lens.   The program which performs the control method of any one of Claims 7 thru | or 12.   A computer-readable storage medium storing the program according to claim 13.

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