JP4839750B2 - Imaging apparatus, imaging method, and program - Google Patents

Description

  The present invention relates to an imaging apparatus, an imaging method, and a program suitable for application to, for example, a digital still camera that records captured image files on an external recording medium.

Conventionally, when a subject is imaged with a digital still camera in a low illuminance or backlight environment, a strobe is emitted, and the subject is illuminated with the light, whereby a darkly sinking subject can be imaged brightly. Appropriate exposure during strobe emission is defined by the strobe guide number (GNo), aperture (FNo), and distance (m) to the subject. When a digital still camera capable of obtaining a sensitivity equivalent to ISO (International Organization for Standardization) 100 is used, proper exposure is defined by the following equation.
GNo = FNo × (distance to subject)

  For example, when shooting an object 2 m away using a GNo. 5 strobe, if the aperture is set to F2.5, proper exposure can be obtained.

  Japanese Patent Application Laid-Open No. 2004-228561 describes an imaging technique that performs uniform and appropriate light emission regardless of the background of the subject.

  Japanese Patent Application Laid-Open No. 2004-228688 describes a technique that enables a subject including a background to be photographed with appropriate brightness in a dark place.

Patent Document 3 describes a technique for suppressing noise at the time of shooting against a night scene.
JP 2002-277721 A (FIG. 7) Japanese Patent Laid-Open No. 2004-32681 (FIG. 3) Japanese Patent Laying-Open No. 2005-86488 (FIG. 1)

  By the way, there were the following problems during flash photography. For example, when shooting in a dark background such as a night view, if you take a strobe shot at a relatively high shutter speed that can prevent camera shake, the main subject will be kept at a proper exposure with strobe light, but the background will be Because it becomes dark due to insufficient exposure, the photographer looks different. In order to make up for this problem, a technique called slow sync, which makes the background exposure appropriate by increasing the shutter speed, is used.

  However, when performing strobe shooting in an environment where the background is dark, such as a night view, the shutter speed becomes long, so it is necessary to prevent camera shake using a tripod or the like. However, carrying a tripod is cumbersome for a user who uses a camera with a compact and excellent portability.

  Further, when a night scene and a person image are simultaneously photographed, the photographed image is too bright or too dark unless the person image as the main subject is located at an appropriate distance of the strobe light. Also, the night view as the background also becomes a dark image because an appropriate exposure amount cannot be obtained. Even if the photographer sets strobe light emission, unnecessary power is consumed due to wasteful strobe light emission when shooting a night scene or the like where strobe illumination does not make sense.

  In addition, when shooting with a film camera (or a digital still camera that cannot be controlled without using a light control sensor, such as a digital single-lens reflex camera) when shooting a dark background such as a night view, exposure information and subject Since a dimming sensor for detecting distance information is required, there is a problem that the cost is increased and an extra space for providing the dimming sensor is required. In addition, there is a technique in which the main subject and the background are photographed by changing the setting of the strobe, gain, and shutter speed, and are combined after shooting. In this case as well, there are memory circuits and control circuits for compositing digital images. This requires not only increased complexity but also extra space.

  The present invention has been made in view of such circumstances, and an object thereof is to photograph a subject with an appropriate exposure amount and shutter speed.

The present invention picks up image light imaged through an optical system and outputs it as an image pickup signal, and also picks up image light imaged through an optical system when illuminating a subject side obtained as image light. The first gain amount is calculated by the first operation of the shutter operation unit that instructs the capturing timing of the imaging signal output by the unit, and is instructed by the second operation of the shutter operation unit that is performed following the first operation. The received light amount is detected as the first luminance evaluation value in the non-lighting state of the illumination in accordance with the captured timing , the illumination is pre-flashed with the first light amount, and the reflected light amount reflected from the subject is subjected to the second luminance evaluation. When the first and second luminance evaluation values are substantially equal, the light emission of the illumination is prohibited, the first and second luminance evaluation values are different, and the distance at which the first light amount of the pre-light emission reaches is reached. If there is a subject, The second light quantity at which proper exposure is obtained is the main light emission quantity. When the first and second luminance evaluation values are different and there is no subject at the distance where the first light quantity of the pre-light emission reaches, the light quantity is adjusted to the maximum. Based on the differential gain amount obtained by subtracting the first gain amount from the second gain amount, calculating the second gain amount up to the position where the light reaching the proper exposure of the subject reaches the third light amount. Thus, a second shutter speed higher than the first shutter speed set in advance as 1 / focal length is determined, and imaging is performed with each light emission amount and gain amount in accordance with an instruction to start capturing an imaging signal. It is a thing.

By doing so, the presence / absence of the subject is determined based on the received light amount in the state where no light is emitted and the received light amount in the pre-light emission, and shooting is performed with an appropriate exposure amount and gain amount based on the determination. It became possible to do.

According to the present invention, the presence / absence of the subject and whether or not the predetermined amount of light reaches the subject can be determined based on the reflected light amount measured from the pre-flash, and the subject can be imaged with an appropriate exposure amount and gain amount. However, there is an effect that it is not necessary to perform complicated settings.

  Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. The present embodiment is an example applied to a digital still camera that records (stores) photographed image data in a built-in recording medium or a removable external recording medium.

  First, an internal configuration example of the digital still camera of this example will be described. FIG. 1 is a block diagram showing an example of the internal configuration of the digital still camera 100 of this example. The digital still camera 100 includes a lens unit 1 including optical system parts such as a plurality of lenses, and forms image light incident through the lens unit 1 on an imaging surface of a CCD (Charge Coupled Device) imaging device 4. This is a configuration to be made. The CCD imaging device 4 also has a function of measuring external light such as pre-light emission described later. The lens unit 1 includes a zoom control mechanism unit (not shown) and a focus control mechanism unit. The lens unit 1 also includes an iris mechanism 2 that controls the aperture amount and a shutter mechanism 3 that performs shutter control. The iris mechanism 2 controls the size of an aperture through which light incident through the lens unit 1 is transmitted by a control signal supplied from a main control unit 10 that controls each unit. The shutter mechanism 3 is driven by a control signal supplied from the main control unit 10 in response to a pressing operation of the shutter release button 20 and controls a time (exposure time) for transmitting light incident through the lens unit 1. . Thus, the amount of exposure light is controlled by the control of the iris mechanism 2 and the shutter mechanism 3. The CCD imaging device 4 can obtain an imaging output signal corresponding to the subject image formed on the imaging surface.

  The analog signal processing circuit 5 that performs analog processing performs processing such as sampling processing (S / H) and amplification processing (AGC), and performs predetermined analog processing on the imaging output signal supplied from the CCD imaging device 4 to generate an image. Output a signal. The image signal output from the analog signal processing circuit 5 is supplied to the analog / digital conversion circuit 6. The analog / digital conversion circuit 6 samples the analog image signal supplied from the analog signal processing circuit 5 at a predetermined sampling rate and converts it into a digital image signal. The digital image signal output from the analog / digital conversion circuit 6 is supplied to a digital signal processing circuit 7 that performs digital processing.

  The digital signal processing circuit 7 generates various signals necessary for framing, still image capturing, autofocus, photometry, and the like from the digital image signal supplied from the analog / digital conversion circuit 6. For example, at the time of framing, a display image signal is generated from the input image signal and supplied to the display unit 15 that displays an image. Further, at the time of capturing a still image, one still image signal is generated from the input image signal, subjected to processing such as compression, and then supplied to the removable recording medium 16. The recording medium 16 may be a recording medium such as an HDD (Hard Disk Drive) built in the digital still camera 100. Further, at the time of autofocus, a high frequency component in a predetermined area in the screen is detected from the input image signal, a parameter indicating the level of the high frequency component is generated, and supplied to the main control unit 10. Further, at the time of photometry, a light amount component (referred to as an AE (Auto Exposure) signal) in a predetermined area in the screen is detected from the input image signal, a parameter indicating the light amount level is generated, and supplied to the main control unit 10.

  The shutter release button 20 which is a momentary type push switch operated by the photographer can be operated in a plurality of pressed states. The shutter release button 20 switches between three states: a state where the switch is not pressed at all (off), a state where the switch is fully pressed (deep press), and a state where the switch is pressed halfway (half press). A function is provided. The deeply pressed state is a state for instructing shutter timing (imaging timing) for capturing an image, and the half-pressed state is a state for instructing preparation for capturing an image. The main control unit 10 determines the three pressed states (off, half-pressed, and deep-pressed) of the shutter release button 20.

  A timing signal generation circuit 9 that generates a predetermined timing signal generates various drive pulses that the CCD image sensor 4 needs to store and read image signals for each screen. Various pulses generated from the timing signal generation circuit 9 are supplied to the CCD imaging device 4 and used as timing signals for image signal imaging processing and output processing.

  A main control unit 10 that controls each unit in the digital still camera 100 includes a microcomputer, a CPU (Central Processing Unit), a program ROM (Read Only Memory), a work area RAM (Random Access Memory), and various I's (not shown). / O port and interface. The main control unit 10 performs various processes such as exposure amount calculation, lens zoom control, strobe light emission control, capture image storage, and image processing such as resizing. The main control unit 10 is connected to a lens control unit 8 that drives and controls the zoom mechanism and the focus mechanism of the lens unit 1. A control signal from the main control unit 10 is supplied to the zoom control mechanism unit and the focus control mechanism unit of the lens unit 1 via the lens control unit 8 to drive and control zoom and focus. The digital still camera 100 of this example is supplied from a power supply unit (not shown) and always performs loop control while the power is on. When the brightness changes, the iris and shutter mechanisms are changed to achieve proper exposure. Yes. The main control unit 10 is connected to a strobe 12 that emits strobe light through a charging / light emission circuit control unit 11 that performs charging and control until the necessary strobe light amount is obtained. In addition, the main control unit 10 includes an operation input unit 14 including menu keys and operation cursors for a user to perform various operation inputs, and an LCD (Liquid Crystal Display) panel, for example, and can display image data. Display unit 15, removable recording medium 16, external interface 17 having an output terminal compliant with, for example, the USB (Universal Serial Bus) standard, and electrically rewritable EEPROM (Electrically Erasable and Programmable Read Only Memory) ) 18 and a RAM (Random Access Memory) 19 for temporarily storing generated data and the like.

  A strobe 12 that emits strobe light on a subject is attached, for example, to the front or upper portion of the casing, and is provided so as to irradiate light on the subject to be imaged. That is, the strobe 12 is provided so as to irradiate light in the direction of the optical axis of the lens and in the forward direction from the lens. The strobe 12 is a discharge device such as a xenon lamp, and can emit strong light for a moment and irradiate a subject with strong flash light. The strobe 12 is driven by the charge / light emission control unit 11 that controls the charging and light emission of the strobe 12, and the light emission timing is controlled by the main control unit 10. In addition, the strobe 12 can be pre-flashed with a predetermined light emission amount before the main light emission. The luminance level of the entire imaging screen is detected from the CCD imaging device 4 from the photometric data in the pre-emission, and compared with the target luminance level at which proper exposure can be obtained, the emission amount as the main emission of the strobe 12 is controlled by the main control unit. 10 is determined.

  Next, with regard to exposure control processing for automatically performing proper exposure when a strobe mode that emits pre-flash or main flash light is used in still image shooting such as a night scene where the background is dark, FIG. Will be described with reference to FIG. FIG. 2 is a flowchart of processing for performing exposure correction, for example, in a mode in which a night scene and a person are simultaneously photographed. In this example, it is possible to switch between a mode for allowing strobe light emission, a mode for prohibiting strobe light emission, and a mode for automatically permitting or prohibiting strobe light emission depending on the presence or absence of a subject depending on the shooting conditions.

  First, when a strobe mode that allows the strobe light to be emitted from the strobe 12 to the subject at the time of shooting is selected, the shutter speed is set to a shutter speed (1 / focal length) second T1 that can prevent camera shake (step S100). ).

The strobe 12 detects a luminance evaluation value YS obtained in a pre-emission state with a fixed pre-emission amount P and compares it with a target luminance level YT at which proper exposure is obtained. In other words, a pre-emission dimming method is used, in which the emission amount Q during main emission is determined from the luminance evaluation value YS, the target luminance level YT, and the pre-emission amount P. Further, the light emission amount Q during the main light emission can be obtained by the following equation.
Q = P × √ (YT / YS)
P: fixed pre-emission amount Q: emission amount during main emission YS: luminance evaluation value obtained in the pre-emission state YT: target luminance level at which proper exposure is obtained

  In photometry, it is necessary to determine the exposure with respect to the reference brightness. Therefore, an LV value indicating brightness is calculated based on the AE signal (step S101). Then, the LV value is compared with a reference threshold value (step S102), and when the LV value is equal to or greater than the reference threshold value, the exposure correction amount 1 processing is selected (step S103). This is an AGC process in which when the amount of light is too large, the aperture amount is increased, the shutter speed amount is increased, or the image signal is lowered.

  If the LV value is smaller than the reference threshold value, the exposure correction amount 2 process is selected (step S115). This is AGC processing in which, when the amount of light is too small, the aperture amount is decreased, the shutter speed amount is decreased, or the image signal is increased. These exposure correction amounts may be provided in three or more types, or may be configured to perform correction calculation according to individual LV values without providing the exposure correction amount.

  Next, when the exposure amount in the background such as a night view is properly maintained and the user presses the shutter button 20 halfway (step S104), the appropriate exposure amount is determined and the gain amount G1 is calculated (step S105). The shutter button 20 in this example has two pressed states, half pressed and deep pressed. The appropriate exposure amount is a value calculated by the main control unit 10 such as the aperture amount F1, the shutter speed T1, and the gain amount G1. If the shutter button 20 is not half-pressed, the process returns to step S101 again to calculate the LV value.

  Next, the photographing sequence is entered by pressing the shutter button 20 deeply (step S106). If the shutter button 20 is not pressed deeply, the process returns to step S105 again to determine the proper exposure amount.

  If the shutter button 20 is pressed deeply in step S106, then pre-emission with a fixed emission amount is performed (step S107). Then, it is determined whether or not the main subject is present by pre-emission (step S108). Here, the main subject refers to, for example, a person image in the night view + person mode. In step S108, whether or not the main subject is present is determined by comparing the luminance evaluation value Y0 obtained by the main control unit 10 in the non-light emitting state with the luminance evaluation value YS obtained in the pre-light emitting state, and if Y0 = YS. It can be determined that there is no main subject. This means a case where reflected light from a person who should be obtained by pre-emission cannot be obtained.

  Normally, it is assumed that the main subject is present when the user selects the strobe mode, but the main subject is not necessarily present. For example, if the flash mode was selected by mistake, the user would like to capture only the background of the night view, but the flash would fire, resulting in a different image from the image the user expected In order to prevent such an erroneous operation, the luminance evaluation value Y0 and the luminance evaluation value YS are compared. For this reason, the CCD imaging device 4 detects the amount of reflected light obtained from the main subject by pre-flash, and detects the presence or absence of the main subject, for the strobe mode that emits strobe light by forcibly performing pre-flash and main flash. If it is determined that there is no main subject, the mode is set to prohibit the main flash.

  If it is determined in step S108 that there is no main subject, main light emission is stopped and exposure is started, and a main light emission prohibition flag F1 = 1 described later is set (step S116). Here, the main light emission prohibition flag F1 is a binary flag for controlling the main light emission of the strobe light. If the main light emission inhibition flag F1 = 0, the main light emission is performed. On the other hand, if the main light emission prohibition flag F1 = 1, the main light emission is not performed. The main light emission prohibition flag F1 is stored in the work area of the main control unit 10 and is rewritten as needed.

  Thus, an image shot when there is no main subject can be obtained as a properly exposed image of only the background. Further, by preventing such erroneous light emission, useless light emission can be eliminated and power consumption can be suppressed.

  On the other hand, if it is determined in step S108 that the main subject is present, whether or not the strobe light reaches the position where the main subject is present is determined based on the luminance level (step S109). When it is determined that the strobe light reaches the position where the main subject is present, the main control unit 10 adjusts the light emission amount Q of the strobe light (step S110), thereby obtaining an image with proper exposure. In this case, the final exposure amount is determined with the aperture amount F1, the shutter speed T1, and the gain amount G1 (step S111).

  If it is determined in step S109 that the strobe light does not reach the position where the main subject is present, the amount of light is insufficient, and if the image is taken as it is, the main subject becomes dark. Therefore, the main control unit 10 calculates the gain amount G2 up to the position where the strobe light reaches so that the main subject is properly exposed with the strobe light emission amount Q set to the maximum (step S117). In this way, the problem that the captured image of the main subject becomes dark is prevented.

  Then, based on the calculated gain amount G2 and the difference gain amount G2-G1 between the gain amount G1 in the background, the shutter speed T2 that further increases the shutter speed amount is determined (step S118). In this case, the final exposure amount is determined by the aperture amount F1, the shutter speed T2, and the gain amount G2 (step S111).

  When the final exposure amount is determined in step S111, exposure is started, the main light emission prohibition flag F1 = 0 is set (step S112), the strobe light is actually emitted (step S113), and the exposure is ended (step S114).

  The digital still camera 100 of this example has a guidance function for presenting appropriate shooting to the user in addition to the process of controlling exposure. Since the main light emission is performed in the exposure in step S112 for automatic determination of the guidance function, the main light emission prohibition flag F1 = 0 is set. On the other hand, since the main light emission is prohibited in the exposure in step S116, the main light emission inhibition flag F1 = 1 is set.

  If the main light emission is stopped and exposure is started in step S116, the exposure is terminated after a predetermined time (step S114). In this way, a properly exposed image can be obtained by balancing the subject and the background.

  Here, for example, when the strobe light of the guide number 10 is used, if the distance of 3 m to the subject is the recommended distance, the background and the subject are both dimmed by hardware if the subject is located within the distance of 3 m. Is possible. When the subject is located farther than 3 m, the camera extends the recommended distance by improving the gain amount using software such as a dimming program. By the way, if the gain amount increases, the background noise also increases. Therefore, the noise is suppressed by increasing the shutter speed. In this way, both the subject and the background can be photographed with good balance. Explaining using specific numerical values, as the shutter speed T1 capable of preventing camera shake, for example, if the focal length of the lens is 38 mm, the shutter speed T1 is set to 1/40 seconds. It is assumed that the gain amount G1 at this time is ISO = 100. If the gain amount G2 at which the subject is exposed properly is set to ISO = 200, the gain difference amount G2-G1 = 200-100 = 100, so the gain amount G2 is twice the gain amount G1. I understand that As a result, the final exposure amount can be determined by setting the shutter speed T2 to T2 = T1 × 1/2 = 1/80 seconds.

  Next, an example of strobe shooting processing that prompts the user to use or not use the strobe light emission by the guidance function during strobe shooting will be described with reference to FIGS. FIG. 3 is a flowchart illustrating an example of a control display process of strobe shooting performed after shooting of the first image. 4 to 7 show display examples of guidance messages to be displayed on the display unit 15.

  Even if the digital still camera 100 of this example determines that there is no main subject, the user may select the strobe mode without noticing and continue shooting. In such cases, guidance functions such as “Please cancel the flash mode” and “Please switch to the night view shooting mode” are automatically used to prevent the camera from continuing to shoot a scene without the main subject in the flash mode. The user is alerted by performing control in the guidance mode that is determined and displayed on the display unit 15.

  First, it is determined whether or not the mode setting of the digital still camera 100 is the strobe mode (step S200). If not in the strobe mode, the process is terminated. If it is the strobe mode, it is determined whether or not it is a guidance mode for displaying a guidance message on the display unit 15 (step S201). If not in the guidance mode, the process ends.

  Subsequently, it is determined whether or not the main light emission prohibition flag F1 = 1 (step S202). When the main light emission prohibition flag F1 = 0, strobe light emission is performed, and the process ends. When the main flash prohibition flag F1 = 1, the digital still camera 100 determines that there is no main subject and prohibits the main flash. In this case, since it is highly likely that the user selects the strobe mode without noticing and continues shooting, the guidance display process is started. First, it is determined whether or not the auto mode is set (step S203). Here, the exposure is controlled using an auto mode (auto strobe mode) that automatically determines whether or not the strobe emits light. The auto mode is a mode in which pre-light emission is performed, exposure is corrected based on the amount of light detected by the CCD image pickup device 4, and a decision to permit or prohibit the main light emission of the strobe 12 is automatically performed.

  In the auto mode, since there is a high possibility that the main subject will not be captured in the next and subsequent shootings, the digital still camera 100 automatically switches the setting to another mode in which the flash emission is prohibited (step S204). Here, a guidance message 15c as shown in FIG. 4 is displayed on the display unit 15 in order to automatically notify the user that the shooting mode has changed. In this example, the guidance message 15c is displayed as “Night view mode is determined to be appropriate. Switch to night view mode”. At the same time, the display unit 15 shows an icon 15a indicating the switched shooting mode (in this example, a night scene mode in which strobe light emission is prohibited and pre-flash and main light emission are not performed), and a strobe light emission prohibition state. The icon 15b is displayed (step S205).

  If the auto mode is not set in step S203, the guidance mode is set in which the user manually selects the operation / prohibition of the strobe light emission. Here, a guidance message recommending prohibition of strobe light emission is displayed on the display unit 15 according to a command from the main control unit 10, the current state is appropriately displayed to the user, and the user can select whether to actually prohibit light emission. (Step S206). Since the digital still camera 100 determines that there is no main subject, the guidance message 15e is displayed as shown in FIG. In this example, the guidance message 15e is displayed on the display unit 15 as follows: “It is determined that there is no person. In this case, it is recommended to disable flash firing. At the same time, the display unit 15 displays an option 15 f for selecting “Yes” or “No” with the operation input unit 14 and an icon 15 d indicating the flash emission state.

  The user selects “Yes” or “No” in the option 15f as to whether or not to prohibit the light emission (step S207). When “Yes” in the option 15f is selected, the mode is switched to the light emission inhibition mode, and the guidance message 15g is displayed as shown in FIG. In this example, the guidance message 15g is displayed on the display unit 15 as “Strobe flash prohibited. At the same time, the display unit 15 displays an icon 15b indicating the strobe emission prohibition state (step S208), and the process ends.

  On the other hand, when “No” in the option 15f is selected, since the light emission is not prohibited, the guidance message 15h is displayed as shown in FIG. In this example, a guidance message 15h is displayed on the display unit 15 as “Strobe flash. Please shoot with a person in the lower frame”. At the same time, the display unit 15 displays an icon 15d indicating the flash emission state and a person frame 15i serving as a photographing guide for the subject (step S209), and the process ends. In this case, the mode is, for example, a slow sync mode.

  In this way, appropriate exposure control is performed on the subject, the digital still camera 100 automatically determines and switches to the light emission prohibition mode, and the light emission prohibition mode and light emission when the user switches to manual operation. By providing a guidance function that supports each mode, it is possible to support shooting appropriate for the user.

  According to the embodiment of the present invention, even when the strobe mode is used in still image shooting where the background is dark, such as a night scene, the main subject and the background are minimized by an appropriate shutter speed. Therefore, there is an effect that an image with proper exposure can be obtained.

  Further, since the pre-emission dimming method is used, a dimming sensor that detects exposure amount information and subject distance information is not required. Therefore, there is an effect that no extra space is required and cost is low, and it is possible to cope with a small-sized digital still camera that is mainstream today.

  Further, when a strobe mode is used when shooting a still image in a dark background such as a night view, it is possible to automatically determine whether or not the main subject is at the position where the strobe light reaches. For this reason, even if the strobe light does not reach, the main subject to be photographed is not darkened by appropriate processing of the shutter speed and AGC, so that it is possible to reduce the possibility that the user will fail to photograph.

  In addition, it is possible to automatically determine whether or not the main subject is present by the pre-flash, and when the main subject is not present, by stopping the main flash, it is possible to cope with the case where the user does not need the strobe light. There is an effect that an image of only the background of the night view can be taken without camera shake.

  In addition, by providing a guidance function that supports each of the light emission prohibition mode and the light emission mode, the user can switch the strobe light manually, and the strobe light can be appropriately emitted according to the scene. effective. In addition, since the power consumption can be suppressed by performing the control to stop the main light emission, there is an effect that it is possible to extend the usage time in which the digital still camera 100 can be used.

  In addition, when there is no main subject, control for switching to an appropriate shooting state while automatically displaying the guidance function in order not to continue shooting in the strobe mode, and control for the user to select according to the guidance function, it is possible for the user to It is possible to easily set a desired shooting mode and to reduce the possibility that the user will fail to shoot.

  In the above-described embodiment, the light control of the strobe is performed without using a sensor such as a light control sensor or a distance measuring sensor. However, with respect to the light control of the strobe, other exposure information and distance are used. Similar functions and effects can be obtained by using a sensor for detecting information. Further, the exposure may be controlled using an auto strobe mode that automatically determines whether or not the strobe emits light without using the strobe mode.

  In the above-described embodiment, the exposure control technique applied when shooting a night scene and a person at the same time has been described. However, the exposure control of this example is not limited to a shooting scene with a dark background such as a night scene. Technology can be applied. For example, even when shooting in backlit conditions, strobe light emission, shutter speed, and gain can be appropriately set by pre-dimming, so that an image intended by the user can be obtained.

  The exposure control when using the strobe mode may be manually switched on / off by the operation input unit 14. Further, the auto mode on / off may be configured to include a control for manually turning on / off by the operation input unit 14. Further, the guidance mode may be always turned on without determining the guidance mode, or the guidance mode may be manually turned off by the operation input unit 14.

  As for the guidance function control, the same functions and effects can be obtained even if various notification functions such as a vibration function and an alarm function are used together to prompt the user to switch the strobe light emission control.

It is the block diagram which showed the internal structural example of the digital still camera in one embodiment of this invention. It is the flowchart which showed the example of a process of flash photography in one embodiment of this invention. It is the flowchart which showed the example of a process of flash photography (guidance function) in one embodiment of this invention. It is explanatory drawing which showed the example of a display of the guidance function (night view mode switching) in one embodiment of this invention. It is explanatory drawing which showed the example of a display of the guidance function (strobe light emission selection) in one embodiment of this invention. It is explanatory drawing which showed the example of a display of the guidance function (strobe light emission prohibition) in one embodiment of this invention. It is explanatory drawing which showed the example of a display of the guidance function (strobe light emission) in one embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Lens part, 2 ... Iris, 3 ... Shutter, 4 ... CCD, 5 ... Analog signal processing part, 6 ... Analog / digital conversion circuit, 7 ... Digital signal processing part, 8 ... Lens control part, 9 ... Timing signal generation Circuit 10, Main control section 11, Charge / light emission control section 12, Strobe 14, Operation input section 15, Display section 15 a-15 g Guidance menu 16, Recording medium 17, External interface 18 EEPROM, 19 ... RAM, 20 ... Shutter release button, 100 ... Digital still camera

Claims (4)

An imaging unit that outputs image light imaged through an optical system as an imaging signal;
A light emitting unit that illuminates the subject side obtained as the image light;
A shutter operation unit for instructing timing of capturing an imaging signal output by the imaging unit;
A light amount detection unit for detecting a received light amount from the subject direction;
A first gain amount is calculated by a first operation of the shutter operation unit;
In accordance with the capture timing instructed by the second operation of the shutter operation unit performed subsequent to the first operation, the light amount detection unit uses the light amount as a first luminance evaluation value in a non-light emitting state of the light emitting unit. And the pre-emission of the first light amount from the light emitting unit, the reflected light amount reflected from the subject is detected by the light amount detection unit as a second luminance evaluation value,
When the first and second luminance evaluation values are substantially equal, the light emission of the light emitting unit is prohibited,
When the first and second luminance evaluation values are different and the subject is at a distance that the first light amount of the pre-light emission reaches, the main light emission amount is a second light amount at which the subject is properly exposed,
When the first and second luminance evaluation values are different and the subject is not at a distance that the first light amount of the pre-light emission reaches, the third light amount adjusted to the maximum light amount is set as the main light emission amount, and the subject The second gain amount to the position where the light reaching the proper exposure reaches is calculated, and the 1 / focal length is set in advance based on the difference gain amount obtained by subtracting the first gain amount from the second gain amount. Determining a second shutter speed higher than the first shutter speed to be
Wherein in operation of the shutter operation section, wherein each of the light emission amount and the gain amount imaging device Ru and a control unit that performs imaging at. The imaging device according to claim 1,
A display unit that displays a predetermined guidance message is provided.
The controller is
A first mode for displaying a guidance message for photographing with main flash on the display unit when allowing the pre-flash and the main flash;
A second mode for displaying a guidance message for prohibiting main flash on the display unit when prohibiting the pre-flash and the main flash;
It performs the pre-emission, based on the amount of light detected by the light amount detector, and corrects the exposure automatically have rows decision to allow or prohibit the emission of the light emitting portion, prohibiting the emission of the light emitting portion A third mode for displaying a guidance message that recommends prohibiting the main flash on the display unit ,
Guidance that prohibits the main light emission and prohibits the main light emission on the display unit when the pre-light emission is performed and the first and second luminance evaluation values are substantially equal based on the light amount detected by the light amount detection unit. Prepare a fourth mode to display messages ,
The first to fourth selection to be that the imaging apparatus sets the one of the modes of mode. An imaging method for imaging image light imaged through an optical system and outputting it as an imaging signal, and illuminating a subject side obtained as the image light,
The first gain amount is calculated by the first operation of the shutter operation unit that instructs the capturing timing of the imaging signal output by the imaging unit to output the image light imaged through the optical system,
In accordance with the capture timing instructed by the second operation of the shutter operation unit performed following the first operation , the received light amount is detected as the first luminance evaluation value in the non-light-emitting state of the illumination,
Pre-lighting the illumination with a first light amount, detecting a reflected light amount reflected from a subject as a second luminance evaluation value;
If the first and second luminance evaluation values are substantially equal, the light emission of the illumination is prohibited,
When the first and second luminance evaluation values are different and the subject is at a distance that the first light amount of the pre-light emission reaches, the main light emission amount is the second light amount at which the subject is properly exposed,
When the first and second luminance evaluation values are different and there is no subject at a distance that the first light amount of the pre-light emission reaches, the third light amount adjusted to the maximum light amount is set as the main light emission amount,
Based on a differential gain amount obtained by subtracting the first gain amount from the second gain amount, a 1 / focal length is calculated in advance. And determining a second shutter speed that is faster than the first shutter speed set,
In instruction acquisition start timing of the image signal, the row cormorants imaging methods imaging in light emission amount and the gain of the respective. In the program for controlling the imaging for illuminating the subject side obtained as the image light while imaging the image light imaged through the optical system and outputting it as an imaging signal.
The first gain amount is calculated by the first operation of the shutter operation unit that instructs the capturing timing of the imaging signal output by the imaging unit to output the image light imaged through the optical system,
A process of detecting the received light amount as a first luminance evaluation value in the non-light-emitting state of the illumination in accordance with the capture timing instructed by the second operation of the shutter operation unit performed subsequent to the first operation. When,
Processing to pre-emit the illumination with the first light amount and detecting the reflected light amount reflected from the subject as the second luminance evaluation value;
If the first and second luminance evaluation values are substantially equal, the light emission of the illumination is prohibited,
When the first and second luminance evaluation values are different and the subject is at a distance that the first light amount of the pre-light emission reaches, the main light emission amount is the second light amount at which the subject is properly exposed,
When the first and second luminance evaluation values are different and there is no subject at a distance where the first light amount of the pre-light emission reaches, the third light amount adjusted to the maximum light amount is set as the main light emission amount, and the subject The second gain amount to the position where the light reaching the proper exposure reaches is calculated, and the 1 / focal length is set in advance based on the difference gain amount obtained by subtracting the first gain amount from the second gain amount. A light emission amount setting process for determining a second shutter speed higher than the first shutter speed ,
In instruction acquisition start timing of the image signal, the light emission amount setting set light emission amount and row cormorants program an imaging process for imaging a gain amount in the process.

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