JP2011197266A - Digital camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve favorable blur correction and acquire images of which resolution deterioration in the peripheral area is not visually recognized by a user.SOLUTION: A digital camera includes: a blur correction means which include at least one of a blur correction optical system and an image pickup element displacing in a plane crossing the optical axis of an image pickup optical system and corrects blur of the image of an object; a drive means which drives the blur correction optical system or the image pickup element in a drive range of either a first drive range or a second drive range that is wider than the first drive range; a division photometric means which detects the intensity for each of a plurality of regions; and a setup means which, based on the detected intensity, sets the drive range to the second drive range if it estimates that the brightness when imaging the second region as the peripheral region of the first region including the center of an imaging screen is lower than predetermined brightness and which sets the drive region to the first drive range if it estimates that the brightness of the second region when imaging is higher than the predetermined brightness.

Description

  The present invention relates to a digital camera having a shake correction device.

  2. Description of the Related Art Conventionally, there has been known a camera that expands the drive range of a blur correction optical system when slow sync is set when the flash device emits light (for example, Patent Document 1).

JP 2008-2031312 A

  However, since the background subject is also photographed as a bright subject by the slow sync photography, the background subject whose resolution is lowered in the peripheral region of the photographed image is easily recognized by the user as the driving range of the blur correction optical system is expanded. There is.

  According to a first aspect of the present invention, there is provided a digital camera including at least one of a blur correction optical system and an image sensor that are displaced in a plane intersecting an optical axis of a photographing optical system, and blurring of an image of a subject on the image pickup surface of the image sensor. , A drive unit that drives the shake correction optical system or the image sensor in one of the first drive range and the second drive range that is wider than the first drive range, and a subject in a plurality of areas Divided photometry means for detecting the luminance for each of the plurality of areas, and a first area that is a peripheral area of the first area on the shooting screen including the center of the shooting screen based on the brightness detected by the divided photometry means. When it is estimated that the brightness at the time of shooting in the two areas is lower than the predetermined brightness, the driving range is set to the second driving range, and the brightness of the second area at the time of shooting is higher than the predetermined brightness. If a constant is characterized in that it comprises setting means for setting the driving range to the first driving range.

  ADVANTAGE OF THE INVENTION According to this invention, while realizing favorable blur correction | amendment, the image from which the resolution fall in a peripheral region is not visually recognized by a user is acquirable.

The figure which shows the external appearance of the digital camera by embodiment of this invention FIG. 2 is a block diagram illustrating a main configuration of a control system of a digital camera according to an embodiment The figure which shows an example of the drive range of a shift lens The figure which shows an example of the relationship between the brightness | luminance of the to-be-photographed object irradiated by pre light emission, and an assumed value The figure explaining an example of the positional relationship between an imaging | photography screen and various areas. The figure explaining the positional relationship between the peripheral area and the main subject area Flowchart for explaining operation of digital camera according to embodiment

  A digital camera according to an embodiment of the present invention includes a shake correction device for correcting image blur that occurs in a captured image due to a camera shake of a user. When shooting with light from the flash device in a dark environment, the digital camera is configured so that the drive range of the shake correction device can be set to one of two drive ranges with different areas. Yes. When the background and surrounding subjects different from the main subject are illuminated brightly by the light emitted from the flash device, the digital camera sets the drive range of the shake correction device to the normal drive range. When the background or surrounding subject is not sufficiently illuminated even when the flash device emits light and the image is taken dark, the digital camera expands the drive range of the shake correction device from the normal drive range. That is, even when shooting is performed with the drive range of the blur correction device enlarged, the reduction in image quality (for example, resolution) of the peripheral area on the captured image due to the increase of the drive range is not noticeable (it is difficult for the user to visually recognize) In addition, the digital camera corrects a large camera shake by expanding the drive range of the shake correction apparatus.

  A digital camera according to an embodiment of the present invention will be described in detail with reference to the drawings. As shown in FIG. 1A, the digital camera 1 is provided with a photographing lens 2, a release button 3, a power button 4, a mode dial 5 for performing a photographing mode setting operation, and a flash device 19. The photographic lens 2 includes a focusing lens (not shown) and other imaging lenses. Further, as shown in FIG. 1B, an operation button including a liquid crystal monitor 17, a cross key, a determination button, and the like is provided on the back of the digital camera 1.

  FIG. 2 is a block diagram illustrating a circuit configuration of the camera according to the embodiment. The digital camera 1 includes an image sensor 6, a control circuit 7, an SDRAM 8, a memory card interface 11, a shake detection sensor 14, a shake correction device 15, an operation unit 16, a liquid crystal monitor 17, an LCD drive circuit 171 and a flash device 19.

  The imaging element 6 is configured by a CCD or CMOS image sensor provided with a plurality of photoelectric conversion elements. The image sensor 6 captures a subject image formed on the imaging surface, and outputs a photoelectric conversion signal (image signal) corresponding to the subject image to the control circuit 7.

  Based on the control program, the control circuit 7 performs a predetermined calculation using signals input from each unit constituting the digital camera 1 and sends a control signal to each unit of the digital camera 1 to control the photographing operation. . The control program is stored in a nonvolatile memory (not shown) in the control circuit 7. The control circuit 7 functionally includes an image processing unit 71, an image recording unit 72, a focus adjustment unit 73, an exposure control unit 74, an area detection unit 75, a setting unit 77, and a shake correction control unit 78.

  The image processing unit 71 converts the image signal input from the image sensor 6 into a digital image signal, and performs various image processing on the digital image signal to generate image data. The image recording unit 72 performs JPEG compression processing on the generated image data and records it on the memory card 12 in a format such as EXIF. The focus adjustment unit 73 calculates a known focus evaluation value, for example, using the image signal input from the image sensor 6 and adjusts the focus state of the photographic lens 2.

  The exposure control unit 74 detects the luminance of the subject using the imaging signal output from the imaging device 6, performs exposure calculation, and determines the shutter speed and the aperture value. In the present embodiment, the exposure control unit 74 detects the luminance of the subject using a known divided photometry method. The area detection unit 75 uses the luminance detected by the exposure control unit 74 to detect an area corresponding to the main subject or the high luminance subject on the captured image. The setting unit 77 predicts the brightness of the peripheral area of the photographed image when photographing with the main light emission is performed by the flash device 19.

  The setting unit 77 determines whether or not the brightness of the predicted peripheral region of the captured image satisfies a predetermined brightness condition. And the setting part 77 sets the drive range of the shift lens 151 contained in the blurring correction apparatus 15 mentioned later based on a determination result. Note that the predetermined brightness condition is that, as will be described later, when the shift lens 151 of the shake correction device 15 is driven within a wide driving range, a reduction in resolution occurring in the peripheral region of the captured image is not visually recognized by the user. This is a condition corresponding to the brightness that is possible. In other words, the predetermined brightness condition is determined in relation to the resolution in the peripheral area of the captured image. The shake correction control unit 78 controls driving of a shake correction device 15 described later. Details of the exposure control unit 74, the region detection unit 75, the setting unit 77, and the shake correction control unit 78 will be described later.

  The SDRAM 8 is used to temporarily store data during or after image processing, image compression processing, and display image data creation processing. The display image data is generated by the image processing unit 72 based on the image data generated by the image processing unit 71 using the image signal output from the image sensor 6 or the image data recorded on the memory card 12. The The generated display image data is stored in the SDRAM 8 by the image recording unit 72. The control circuit 7 drives the liquid crystal monitor 17 via the LCD drive circuit 171 and displays an image on the liquid crystal monitor 17. The liquid crystal monitor 17 displays a menu screen for performing various settings of the digital camera.

  The memory card interface 11 is an interface to which the memory card 12 can be attached and detached. The memory card interface 11 is an interface circuit that writes image data to the memory card 12 and reads image data recorded on the memory card 12 under the control of the control circuit 7. The memory card 12 is a semiconductor memory card such as a compact flash (registered trademark) or an SD card.

  The shake detection sensor 14 is composed of, for example, a gyro sensor, and detects the shake that occurs in the X direction and the Y direction (see FIG. 1) of the main body of the digital camera 1 at the time of shooting by dividing it into pitching and yawing. A shake amount signal representing pitching and yawing detected by the shake detection sensor 14 is output to the control circuit 7. The shake correction control unit 78 performs shake correction by driving a shake correction device 15 described later based on the input shake amount signal.

  The blur correction device 15 includes a shift lens 151, an actuator 153, and a position detection sensor 154. The shift lens 151 is driven by an actuator 153 in a plane that intersects the optical axis of the photographing lens 2.

  FIG. 3 shows an example of the driving range of the shift lens 151 of the present embodiment. The range defined by the drive limiting member 151c indicated by the solid line in FIG. 3 includes a first drive range A surrounded by a broken line and a second drive range B surrounded by a one-dot chain line. The shift lens 151 is configured to be driven by an actuator 153 within one of the first drive range A and the second drive range B that is larger than the first drive range A. The driving range of the shift lens 151 is normally set to the first driving range A by the setting unit 77. However, in the case where shooting is performed in a dark situation and the subject in the periphery of the shot image satisfies the brightness condition as described later, the drive range is set to the second drive range B by the setting unit 77. Is done. FIG. 3 shows a state where the shift lens 151 is located at the center of the driving range, that is, a case where the optical axis of the shift lens 151 and the optical axis of the photographing lens 2 coincide. In addition, a description will be given later of whether the driving range of the shift lens 151 is set to the first driving range A or the second driving range B. Note that the size in the X-axis direction and the size in the Y-axis direction of the first drive range A shown in FIG. 3 may be the same or different. Similarly, the size in the X-axis direction and the size in the Y-axis direction of the second drive range B may be the same or different from each other.

  The actuator 153 in FIG. 2 is, for example, a voice coil motor having a coil, a magnet, and a yoke. The actuator 153 drives the shift lens 151 by generating a driving force by driving with a voltage applied from the shake correction control unit 78. As a result, the relative position between the shift lens 151 and the image sensor 6 changes in a direction perpendicular to the optical axis of the photographic lens 2, and the subject light that has passed through the photographic lens 2 is refracted in a direction that cancels the blur.

  The position detection sensor 154 is a magnetic sensor having, for example, a magnet and a magnetic detection element, and outputs a voltage (position detection voltage) corresponding to the position of the shift lens 151 to the shake correction control unit 78 of the control circuit 7. The blur correction controller 78 detects the position of the shift lens 151 based on the value of the position detection voltage input from the position detection sensor 154. It is assumed that the position detection voltage value and the position of the shift lens 151 are associated with each other in advance and recorded in a predetermined recording area.

  When the shift lens 151 is driven within the first drive range A, the blur correction control unit 78 has the position detection voltage of the shift lens 151 output from the position detection sensor 154 as Va1 to Va2 [V] (however, The drive of the shift lens 151 is controlled so as to be within the range of Va1 <Va2). In addition, when the shift lens 151 is driven within the second drive range B, the blur correction control unit 78 detects that the position detection voltage of the shift lens 151 output from the position detection sensor 154 is Vb1 to Vb2 [V] (however, , Va2 <Vb2, Va1> Vb1) to control the driving of the shift lens 151.

  The operation unit 16 includes various buttons such as a release button 3, a power button 4, a mode dial 5, and an operation button 18 shown in FIG. The operation unit 16 outputs an operation signal corresponding to the operation of the various buttons by the user to the control circuit 7. The flash device 19 includes a light source unit 191. The light source unit 191 is a discharge light-emitting type light source configured to emit subject illumination light, for example, composed of an Xe tube or the like. The light emission operation of the light source unit 191 is controlled according to the light emission command output from the control circuit 7. The flash device 19 in the present embodiment is configured to be capable of pre-emission (preliminary emission) for illuminating the subject with a predetermined amount of light before photographing.

  Hereinafter, the pre-light emission and main light emission processing of the flash device 19 by the control circuit 7 will be described. When the pre-flash is performed, the control circuit 7 calculates the distance to the subject using the result of the focus adjustment processing by the focus adjustment unit 73 and performs setting for the pre-flash of the flash device 19. First, the exposure control unit 74 of the control circuit 7 determines whether or not the illumination light at the time of pre-emission of the flash device 19 reaches the subject, using the calculated distance to the subject. When the illumination light at the time of pre-emission of the flash device 19 does not reach the subject, that is, when the distance to the subject is far, the exposure control unit 74 sets the imaging sensitivity of the imaging element 6 to be, for example, 1 than the reference sensitivity. Increase the stage.

  When the illumination light at the time of pre-emission of the flash device 19 reaches the subject, the exposure control unit 74 sets the imaging sensitivity of the image sensor 6 at the time of pre-emission to the reference sensitivity. However, when the subject is closer than a preset distance, that is, when macro photography is performed, the exposure control unit 74 reduces the aperture (not shown), for example, by one stage. When the digital camera 1 includes an ND filter, the control circuit 7 may set the ND filter in the optical path instead of the diaphragm.

  When the pre-flash setting of the flash device 19 is performed as described above, the exposure control unit 74 determines a range of values assumed as the luminance of the subject irradiated by the pre-flash as an assumed value. Note that the assumed value is a value having a predetermined range determined by the imaging sensitivity, the aperture value, and the distance to the subject of the image sensor 6 and is recorded in a predetermined recording area in advance. . A subject having the brightness included in the assumed value among subjects irradiated by the pre-flash can be appropriately exposed by photographing with the main flash of the flash device 19.

  FIG. 4 shows an example of the luminance and the assumed value of the subject irradiated by the pre-light emission. In FIG. 4, the vertical axis represents the luminance of the subject. In FIG. 4, the luminance included in the range X is an assumed value. As described above, a subject having a luminance within the range X can obtain a proper exposure by photographing with the main light emission of the flash device 19. When the above setting is completed, the control circuit 7 outputs a light emission command instructing the flash device 19 to perform pre-light emission, and causes the flash device 19 to perform pre-light emission.

  When the image sensor 6 captures an image of a subject irradiated by the pre-flash of the flash device 19 and outputs an image signal, the exposure control unit 74 detects the luminance for each of a plurality of partial areas of the subject using the output image signal. . Then, the exposure control unit 74 sets, as an evaluation value (reference luminance), the luminance included in the range of the assumed value described above among the detected luminance for each partial region. The exposure control unit 74 uses this evaluation value as data for main light emission when determining the light emission amount during main light emission by the flash device 19. In addition, the exposure control unit 74 uses the evaluation value as a main subject detection threshold for detecting the main subject as described later, and a high brightness subject for determining whether or not a high brightness subject exists in the surrounding area. Also used to determine the detection threshold.

  Further, the exposure control unit 74 uses the above-described evaluation value, imaging sensitivity at the time of actual photographing (recording image data generation) of the image sensor 6, and the aperture value, and the light emission amount at the time of main light emission of the flash device 19. That is, the light emission time is determined. The exposure control unit 74 determines the imaging sensitivity of the image sensor 6 at the time of actual shooting according to the distance to the subject calculated using the result of the focus adjustment process by the focus adjustment unit 73. That is, when the subject is present at a position less than the predetermined distance, the exposure control unit 74 sets the imaging sensitivity of the imaging device 6 to the reference sensitivity. When the subject is present at a position separated by a predetermined distance or more, the exposure control unit 74 increases the imaging sensitivity of the image sensor 6. The predetermined distance described above is set in advance as a distance that the illumination light from the flash device 19 can irradiate the subject during the main light emission.

  Furthermore, the exposure control unit 74 detects the brightness of each of the plurality of partial areas by split photometry using the image signal that is captured and output by the imaging device 6 without causing the flash device 19 to emit light. Then, the exposure control unit 74 performs an exposure calculation according to the detected luminance, and determines the shutter speed and the aperture value so that the subject has an appropriate exposure amount.

  The digital camera 1 having the above-described configuration performs processing for determining the driving range of the shift lens 151 when shooting is performed by emitting light from the flash device 19 and driving the shift lens 151. As described above, the setting unit 77 determines the driving range of the shift lens 151 as one of the first driving range A and the second driving range B. In the following description, it is divided into a case where the first drive range A is set and a case where the second drive range B is set.

(1) When Setting the First Driving Range A The setting unit 77 sets the driving range of the shift lens 151 to the first driving range A in the following cases. In other words, when the shift lens 151 is driven in the second driving range B wider than the first driving range A, a reduction in image quality due to a reduction in resolution or the like in the peripheral region of the captured image can be visually recognized by the user. In addition, the setting unit 77 sets the first drive range A. In other words, the setting unit 77 prohibits setting the drive range of the shift lens 151 to the second drive range B.
(A) When shooting in a bright situation.
(B) A main subject that is photographed in a dark situation exists in the periphery of the photographed image.
(C) When the peripheral portion of a photographed image photographed in a dark situation is photographed brightly by irradiation of the flash device 19 or the like.

(1-A) When Shooting in a Bright Situation The exposure control unit 74 performs known divided photometry using an image signal imaged and output by the imaging device 6 without the pre-emission of the flash device 19. (Hereinafter referred to as normal division metering). Then, the exposure control unit 74 determines whether or not shooting is performed in a bright situation. That is, the exposure control unit 74 determines whether or not the luminance of the subject detected by the normal split photometry is equal to or higher than the first threshold value. When the exposure control unit 74 determines that the luminance of the subject is equal to or higher than the first threshold, the setting unit 77 sets the drive range of the shift lens 151 to the first drive range A. In other words, the setting unit 77 prohibits expansion of the drive range of the shift lens 151. In this case, the shake correction control unit 78 drives the shift lens 151 so that the position detection voltage of the shift lens 151 output from the position detection sensor 154 falls within the range of Va1 to Va2 [V] (where Va1 <Va2). Control.

(1-B) When a main subject photographed in a dark situation exists in the peripheral portion of the photographed image The exposure control unit 74 determines that the subject brightness detected by the above-described normal division metering is less than the first threshold. It is determined that shooting is performed in a dark situation. In this case, the exposure control unit 74 performs split photometry using the image signal captured and output by the imaging device 6 in accordance with the pre-flash of the flash device 19 (hereinafter referred to as pre-flash split photometry). That is, the image sensor 6 receives the light reflected by the subject from the flash device 19 and outputs an image signal, and the exposure controller 74 uses the input image signal to correspond to a plurality of portions of the captured image. The luminance for each (partial area) is detected.

  The area detection unit 75 detects a main subject area corresponding to a main subject such as a person on the photographed image using the luminance value for each partial area obtained by the pre-photometric division photometry. Further, the region detection unit 75 determines whether at least a part of the detected main subject region overlaps with the peripheral region on the shooting screen, that is, whether the main subject exists in the peripheral portion of the captured image. The peripheral area is an area where the resolution is, for example, 70% or less compared to the central portion of the captured image when the shift lens 151 is driven in the second drive range B. Hereinafter, after showing an example of a captured image and a partial region corresponding to a plurality of portions, detection of a main subject region and determination of overlap with a peripheral region will be described.

  First, a plurality of partial areas and peripheral areas on a captured image will be described with reference to FIG. FIG. 5 shows an example of a captured image and partial areas corresponding to a plurality of parts. FIG. 5 shows that the captured image is divided into, for example, a plurality of 48 partial areas R1 to R48 (hereinafter, the partial areas are generically referred to as “R”). Further, in FIG. 5, if the partial region R included in the region surrounded by the thick line is a central region Rc, the partial region R indicated by the oblique lines provided around the central region Rc is represented by the symbol Rp as the peripheral region in the captured image. .

  The area detection unit 75 detects the main subject area occupied by the main subject such as a person on the captured image using the luminance of each of the partial areas R detected by the exposure control unit 74. In order to detect each of the above areas, the present embodiment uses a main subject detection threshold for determining whether or not the subject is a main subject. This main subject detection threshold is set by the exposure control unit 74 as a value that is lower by a predetermined value with the above-described evaluation value as the reference luminance. The area detection unit 75 determines the partial area R corresponding to the luminance equal to or higher than the main subject detection threshold as the main subject area Rs occupied by a person or the like on the shooting screen. That is, the area detection unit 75 detects the position of the main subject on the shooting screen.

  FIG. 6A shows a photographing screen for photographing the main subject, and FIG. 6B shows a relationship between the main subject region Rs and the partial region R corresponding to FIG. As shown in FIG. 6A, when the main subject S exists in the vicinity of the center of the shooting screen, as shown in FIG. 6B, the portion arranged near the center of the shot image as the main subject region Rs. Regions R12, R13, R20, R21, R28, R29, R36, and R37 are detected by the region detector 75.

  When detecting the main subject region Rs, the region detection unit 75 determines whether or not the main subject region Rs overlaps with the peripheral region Rp. That is, the region detection unit 75 determines whether or not there is a partial region R having a luminance equal to or higher than the main subject detection threshold among the partial regions R included in the peripheral region Rp. If there is even one partial region having a luminance equal to or higher than the main subject detection threshold, the region detection unit 75 determines that the main subject exists in the peripheral region Rp.

  FIG. 6C shows a photographing screen for photographing the main subject, and FIG. 6D shows the relationship between the main subject region Rs and the partial region R corresponding to FIG. As shown in FIG. 6C, when the main subject S is present in the periphery of the shooting screen, as shown in FIG. 6D, the main subject region Rs is the partial regions R15, R16, R23, R24, R31. , R32, R39. R40 is detected by the area detector 75. In the case shown in FIG. 6D, the partial areas R16, R24, R32, and R40 of the main subject area Rs are partial areas R included in the peripheral area Rp. In such a case, the area detection unit 75 determines that the main subject exists in the peripheral area Rp.

  When the main subject region Rs and the peripheral region Rp partially overlap, the region detection unit 75 captures the main subject with appropriate exposure. It is determined that the image can be visually recognized by the user. The setting unit 77 sets the drive range of the shift lens 151 to the first drive range A when the region detection unit 75 determines that the main subject Rs and the peripheral region Rp partially overlap. In other words, the setting unit 77 prohibits expansion of the drive range of the shift lens 151.

(1-C) When the periphery of a captured image captured in a dark situation is captured brightly by irradiation of the flash device 19 or the like The region detection unit 75 determines whether the main subject region Rs and the peripheral region Rp described above overlap. As a result, if it is determined that the main subject does not exist in the peripheral region Rp, the exposure control unit 74 sets an exposure control value so that the main subject has an appropriate exposure amount, and exposure conditions (shutter speed and aperture value). To decide. At this time, the exposure control unit 74 determines the light emission amount, that is, the light emission time, of the flash device 19 during the main light emission, using the evaluation value described above, the imaging sensitivity of the image pickup device 6 during the main photographing, and the aperture value. . The setting unit 77 calculates the exposure amount of the peripheral region Rp during the main light emission of the flash device 19 as the predicted exposure amount. Then, the setting unit 77 estimates that the peripheral region Rp of the captured image is brighter than the predetermined brightness when the calculated predicted exposure amount is equal to or greater than the second threshold value. When the region detection unit 75 detects that a high-luminance subject (for example, a white wall) exists in the peripheral region Rp, the setting unit 77 estimates the predicted exposure amount for the peripheral region Rp excluding the high-luminance subject. Is calculated.

  It should be noted that when the shift lens 151 is driven in the second drive range B, the second threshold value is visually recognized by the user as to a decrease in image quality due to a decrease in resolution or the like in the peripheral region Rp when the main subject is photographed with proper exposure. This value corresponds to the brightness (exposure amount) that is impossible. It is assumed that the second threshold is determined in advance based on experiments or the like.

  First, the process of detecting a high-luminance subject by the area detection unit 75 will be described. The area detection unit 75 detects the high luminance area Rh occupied by the high luminance subject using the luminance of each of the partial areas R included in the peripheral area Rp. In order to detect the high luminance region Rh, the region detection unit 75 uses a high luminance subject detection threshold. The high-luminance subject detection threshold is set by the exposure control unit 74 as a value higher by a predetermined value with reference to the evaluation value described above, that is, a value higher than the main subject detection threshold described above. The region detection unit 75 detects a partial region R corresponding to a luminance equal to or higher than the high luminance subject detection threshold among the partial regions R included in the peripheral region Rp as the high luminance region Rh.

  FIG. 6 (e) shows a photographing screen for photographing the main subject and the high-intensity subject, and FIG. 6 (f) shows the relationship among the main subject region Rs, the high-intensity region Rh, and the partial region R corresponding to FIG. 6 (e). Show. As shown in FIG. 6E, when a high-intensity subject Sh different from the main subject S exists in the peripheral part of the shooting screen, as shown in FIG. R24, R31, R32, R39, R40, R47, and R48 are detected by the region detector 75. In the case shown in FIG. 6F, the partial regions R24, R32, R40, R47, and R48 of the high luminance region Rh are partial regions R included in the peripheral region Rp. In such a case, the region detection unit 75 determines that the high brightness subject Sh is present in the peripheral region Rp.

  Next, calculation of the predicted exposure amount by the setting unit 77 will be described. The setting unit 77 calculates the exposure amount of the subject existing in the peripheral region Rp as the predicted exposure amount when the main subject is photographed at the appropriate exposure determined by the exposure control unit 74 so as to have the appropriate exposure amount. . The setting unit 77 sets the exposure amount for each partial region R relative to the appropriate exposure amount according to the difference between the luminance of the main subject region Rs detected by the normal division metering and the luminance of each partial region R included in the peripheral region Rp. Calculated as the predicted exposure amount.

  When the calculated predicted exposure amount of the peripheral region Rp is equal to or greater than the second threshold value, the setting unit 77 displays image quality due to a decrease in resolution or the like in the peripheral region Rp when the surrounding subject is photographed brightly by the main light emission of the flash device 19. Is estimated to be visible to the user. Then, the setting unit 77 sets the driving range of the shift lens 151 to the first driving range A. In other words, the setting unit 77 prohibits expansion of the drive range of the shift lens 151. In this case, the shake correction control unit 78 drives the shift lens 151 so that the position detection voltage of the shift lens 151 output from the position detection sensor 154 falls within the range of Va1 to Va2 [V] (where Va1 <Va2). Control.

(2) When setting the second drive range B When the main subject does not exist in the peripheral region Rp and the setting unit 77 estimates that the peripheral region Rp of the captured image is darker than the predetermined brightness The setting unit 77 sets the drive range of the shift lens 151 to the second drive range B. That is, even if the flash device 19 emits light, the peripheral area Rp is not photographed brightly, and when the deterioration of the image quality due to a decrease in resolution or the like in the peripheral area Rp cannot be visually recognized by the user, the setting unit 77 sets the shift lens 151. Is set to the second drive range B.

  Also in this case, as described above, when the area detection unit 75 determines whether the main subject area Rs and the peripheral area Rp overlap with each other and determines that the main subject does not exist in the peripheral area Rp, the exposure control unit 74 The exposure control value is set so that the main subject has an appropriate exposure amount, and the exposure condition is determined. The setting unit 77 calculates the exposure amount of the peripheral region Rp during the main light emission of the flash device 19 as the predicted exposure amount. Then, the setting unit 77 estimates that the peripheral region Rp of the captured image is darker than the predetermined brightness when the calculated predicted exposure amount is less than the second threshold value. When the region detection unit 75 detects that a high-luminance subject exists in the peripheral region Rp, the setting unit 77 calculates a predicted exposure amount for the peripheral region Rp excluding the high-luminance subject. When the predicted exposure amount of the peripheral region Rp is less than the second threshold, the setting unit 77 determines that the user cannot visually recognize a decrease in image quality even if the resolution of the peripheral region Rp is reduced. The drive range is set to the second drive range B. In this case, the blur correction control unit 78 drives the shift lens 151 so that the position detection voltage of the shift lens 151 output from the position detection sensor 154 is within the range of Vb1 to Vb2 [V] (Va1 <Va2). Control.

  When the processing for determining the drive range is completed, the shake correction control unit 78 applies a voltage to the actuator 153 so that the shift lens 151 performs the shake correction operation. In this case, the blur correction control unit 78 applies the voltage necessary for driving the shift lens 151 to the initial position based on the value of the position detection voltage input from the position detection sensor 154, that is, the voltage necessary for centering before exposure. Apply to 153. The initial position is a position where the optical axis of the shift lens 151 coincides with the optical axis of the photographing lens 2 as shown in FIG. In this way, the blur correction control unit 78 applies a voltage to the actuator 153 until it is determined that the shift lens 151 has been driven to the initial position based on the value of the position detection voltage input from the position detection sensor 154. As a result, the imaging shift lens 151 is centered at the initial position.

  When it is confirmed that the shift lens 151 is centered before exposure based on the value of the position detection voltage from the position detection sensor 154, the control circuit 7 controls the image sensor 6 to start imaging. Furthermore, the shake correction control unit 78 calculates the drive amount of the shift lens 151 based on the shake amount signal output from the shake detection sensor 14 and the value of the position detection voltage output from the position detection sensor 154. Then, the blur correction control unit 78 applies a voltage according to the calculated drive amount to the actuator 153, and the shift lens 151 is placed inside the first drive range A or the second drive range B shown in FIG. Drive in the plane that intersects the optical axis. As a result, the relative position between the shift lens 151 and the image sensor 6 changes in the direction intersecting the optical axis of the photographic lens 2, and the subject light that has passed through the photographic lens 2 is refracted in a direction that cancels out the blur.

  The operation of the digital camera 1 according to the embodiment described above will be described with reference to the flowchart shown in FIG. A program for executing each process of the flowchart of FIG. 7 is recorded in a memory (not shown). This program is activated and executed by the control circuit 7 when a full-press operation signal is input from the operation unit 16 in response to a full-press operation of the release button 3 by the user.

  In step S101, a flash command for instructing pre-flash to the flash device 19 is output, and pre-flash is performed. Then, the subject illuminated by the pre-flash illumination light from the flash device 19 is imaged by the imaging device 6, pre-emission divided photometry is performed using the image signal output from the imaging device 6, and a plurality of portions on the photographed image are obtained. A luminance value is calculated for each region R, and the process proceeds to step S102. In step S102, the subject is imaged by the image sensor 6 without performing pre-flash by the flash device 19, normal division photometry is performed using the image signal output from the image sensor 6, and the process proceeds to step S103.

  In step S103, it is determined whether or not the luminance value of the subject calculated based on the result of the normal division photometry performed in step S102 is less than the first threshold value. That is, it is determined whether shooting is performed in a bright environment or a relatively dark environment. If the luminance value of the subject is less than the first threshold value, an affirmative determination is made in step S103 and the process proceeds to step S104. If the luminance value of the subject is greater than or equal to the first threshold, a negative determination is made in step S103 and the process proceeds to step S109 described later.

  In step S104, the position of the main subject on the captured image, that is, the main subject region Rs is determined, and the process proceeds to step S105. At this time, when a high brightness subject is detected, the high brightness area Rh is determined. In step S105, it is determined whether or not the main subject region Rs overlaps with the peripheral region Rp. If there is a partial region R where the main subject region Rs and the peripheral region Rp overlap, an affirmative determination is made in step S105 and the process proceeds to step S109 described later. If the main subject region Rs and the peripheral region Rp do not overlap, a negative determination is made in step S105 and the process proceeds to step S106. Note that if the main subject region Rs is not detected in step S104, that is, if the main subject cannot be detected, a negative determination is made in step S105 and the process proceeds to step S106. In step S106, based on the result of the normal division metering in step S102, the exposure condition is determined so that the main subject has an appropriate exposure amount, and the process proceeds to step S107.

  In step S107, the exposure amount of each partial region R of the peripheral region Rp is calculated as the predicted exposure amount for the main subject for which the exposure condition for the appropriate exposure amount has been determined in step S106, and the process proceeds to step S108. In step S108, it is determined whether or not the calculated predicted exposure amount is equal to or greater than a second threshold value. If the predicted exposure is greater than or equal to the second threshold, an affirmative determination is made in step S108 and the process proceeds to step S109. In step S109, the driving range of the shift lens 151 is set to the first driving range A, and the process proceeds to step S111. If the calculated predicted exposure amount is less than the second threshold value, a negative determination is made in step S108 and the process proceeds to step S110. In step S110, the driving range of the shift lens 151 is set to the second driving range B, and the process proceeds to step S111.

  In step S111, the blur correction device 15 is controlled to perform blur correction. That is, after the shift lens 151 is centered, the shift lens 151 is driven based on the shake amount signal output from the shake detection sensor 14 and the position detection voltage value output from the position detection sensor 154. In a succeeding step S112, charge accumulation for the image pickup device 6, that is, a photographing operation is started, and the process proceeds to step S113. In step S113, a light emission command for instructing the main light emission is output to the flash device 19 to perform the main light emission, and the process proceeds to step S114. In step S114, an image signal is output to the image sensor 6 and the photographing operation is terminated. Further, the blur correction operation is ended for the blur correction device 15, and the processing shown in this flowchart is ended.

According to the digital camera 1 of the embodiment described above, the following operational effects can be obtained.
(1) The blur correction device 15 includes a shift lens 151 that is displaced in a plane that intersects with the optical axis of the photographing optical system, and corrects blurring of a subject image on the imaging surface of the image sensor 6. The shake correction control unit 78 drives the shift lens 151 in one of the first drive range A and the second drive range B wider than the first drive range A. The exposure control unit 74 divides the subject into a plurality of partial areas R, and detects the luminance for each of the plurality of partial areas R. Based on the brightness detected by the exposure calculation unit 74, the setting unit 77 has a predetermined brightness at the time of shooting in the peripheral region Rp provided on the shooting screen and around the region including the center of the shooting screen. When it is estimated that the brightness is lower than the brightness, the driving range of the shift lens 151 is set to the second driving range B. Further, the setting unit 77 sets the drive range of the shift lens 151 to the first drive range A when it is estimated that the brightness of the peripheral region Rp is higher than the predetermined brightness. That is, when the driving range of the shift lens 151 is enlarged as in the prior art, the shift lens 151 is noticeable when the deterioration of the image quality of the subject in the peripheral region Rp irradiated on the flash device 19 is noticeable to the user. Do not expand the drive range. Therefore, it is possible to obtain an image in which the deterioration of the image quality of the peripheral region Rp accompanying the driving of the shift lens 151 is suppressed.

(2) The area detecting unit 75 detects a main subject among the subjects, and the exposure control unit 74 is an exposure control value for photographing the main subject with an appropriate exposure amount based on the luminance detected by the normal division photometry. To decide. The setting unit 77 calculates the predicted exposure amount by predicting the exposure amount at the time of shooting of the peripheral region Rp based on the luminance detected by the normal division metering and the exposure control value determined by the exposure control unit 74. . Then, the setting unit 77 estimates that the brightness of the peripheral region Rp is lower than the predetermined brightness when the predicted exposure amount of the peripheral region Rp is less than the second threshold value. Accordingly, it is possible to improve the accuracy when estimating whether or not the subject in the peripheral region Rp satisfies the brightness condition during the main photographing.

(3) The region detection unit 75 determines whether or not the detected main subject region Rs overlaps with the peripheral region Rp. The setting unit 77 sets the drive range of the shift lens 151 to the first drive range A when it is determined that the main subject region Rs and the peripheral region Rp overlap. That is, the flash device 19 emits irradiation light toward the subject (pre-emission), and the exposure controller 74 determines the luminance for each of the plurality of partial regions R based on the reflected light from the subject irradiated by the flash device 19. Is detected. When the setting unit 77 determines that there is a partial region R whose predicted brightness is higher than the main subject detection threshold among the plurality of partial regions R included in the peripheral region Rp, the setting unit 77 drives the shift lens 151. The range is set to the first drive range A. Therefore, it is possible to reliably detect the main subject existing in the peripheral region Rp and prevent the image quality of the main subject from being deteriorated due to the expansion of the drive range of the shift lens 151.

(4) The exposure control unit 74 sets the luminance included in the predetermined luminance range X among the luminances of the plurality of partial regions R detected according to the pre-light emission of the flash device 19 as the evaluation value, and sets the evaluation A value lower than the value by a predetermined value is determined as the main subject detection threshold. Therefore, the detection accuracy of the main subject existing in the peripheral region Rp of the captured image can be maintained.

(5) Based on the luminance detected by the exposure control unit 74, the region detection unit 75 defines, as the high luminance region Rh, a region occupied by a high luminance subject having a luminance higher than the high luminance subject detection threshold in the peripheral region Rp. To detect. Then, when the high luminance region Rh is detected by the region detecting unit 75, the setting unit 77 excludes the high luminance region Rh from the peripheral region Rp, and the brightness of the peripheral region Rp is lower than the predetermined brightness. Whether to estimate whether or not. As a result, when there is a high-luminance subject that is likely to be whitened in the entire dark peripheral region Rp, the peripheral region Rp is higher than a predetermined brightness due to the influence of a part of the high-luminance subject. Can be prevented, and the determination accuracy can be improved.

The digital camera 1 of the embodiment described above can be modified as follows.
(1) The setting unit 77 assumes that the brightness in the peripheral region Rp satisfies the predetermined brightness condition when the predicted exposure amount is less than the second threshold, and instead of the brightness of the main subject and the brightness of the background When the difference is large, it may be estimated that the brightness in the peripheral region Rp of the captured image satisfies a predetermined brightness condition. In this case, the area detection unit 75 determines the main subject area Rs and the high luminance area Rh using the respective luminances of the partial areas R detected by the exposure control unit 74, as in the embodiment. Then, when the region detection unit 75 determines that the main subject region Rs does not exist in the peripheral region Rp, the setting unit 77 determines whether the brightness in the peripheral region Rp of the captured image satisfies a predetermined brightness condition. Estimate.

  In this case, the setting unit 77 calculates a difference between the luminance (that is, the evaluation value) of the main subject region Rs and the luminance of the peripheral region Rp, and the setting unit 77 determines whether the calculated difference value is equal to or greater than a third threshold value. To do. When the high luminance region Rh is detected, the setting unit 77 uses the luminance of the partial region R obtained by excluding the high luminance region Rh from the peripheral region Rp to calculate the difference from the luminance of the main subject region Rs. calculate. Note that the third threshold value is a brightness at which, when the shift lens 151 is driven in the second drive range B, similarly to the second threshold value, a decrease in image quality due to a decrease in resolution or the like in the peripheral region Rp is invisible to the user. It is a value corresponding to the size. It is assumed that this third threshold is determined in advance based on experiments or the like.

  When the difference value is equal to or larger than the third threshold, that is, when the background is sufficiently dark, the setting unit 77 estimates that the degradation in image quality is invisible to the user even if the resolution is decreased in the peripheral region Rp. To do. In addition, when the difference value is less than the third threshold, that is, when the background is not so dark, the setting unit 77 estimates that the user can visually recognize the deterioration in image quality due to the decrease in resolution in the peripheral region Rp. .

  The setting unit 77 sets the drive range of the shift lens 151 to the second drive range B when the difference value between the brightness of the main subject region Rs and the brightness of the peripheral region Rp is greater than or equal to the third threshold value. The setting unit 77 sets the drive range of the shift lens 151 to the first drive range A when it is determined that the luminance difference value is less than the third threshold value. When the region detection unit 75 determines that the main subject region Rs exists in the peripheral region Rp, the setting unit 77 sets the drive range of the shift lens 151 to the first regardless of the difference value in luminance. Set to drive range A.

  The operation of the digital camera 1 of the modified example described above is as follows. In the flowchart shown in FIG. 7, the difference between the luminance value of the main subject region Rs and the luminance value of the peripheral region Rp is calculated in step S107, and in step S108. It is determined whether or not the calculated difference value is greater than or equal to a third threshold value. If the difference value is greater than or equal to the third threshold value, an affirmative determination is made in step S108 and the process proceeds to step S109. If the difference value is less than the third threshold value, a negative determination is made in step S108 and the process proceeds to step S110. Good.

(2) The setting unit 77 estimates that the brightness in the peripheral area of the captured image satisfies the predetermined brightness condition when the brightness of the peripheral area Rp detected by the normal division photometry is equal to or less than a predetermined threshold. May be. The area detection unit 75 determines the main subject area Rs, the peripheral area Rp, and the high-brightness area Rh using the luminances of the partial areas R calculated by the exposure control unit 74 in the same manner as in the embodiment. When the region detection unit 75 determines that the main subject region Rs does not exist in the peripheral region Rp, the setting unit 77 determines whether the brightness in the peripheral region Rp of the captured image satisfies a predetermined condition. . In this case, the setting unit 77 determines whether or not the luminance of the peripheral region Rp is equal to or less than the fourth threshold value. When the high brightness area Rh is detected, the setting unit 77 determines the magnitude of the fourth threshold value using the brightness of the partial area R excluding the high brightness area Rh from the peripheral area Rp.

  Note that the fourth threshold value is a value determined in the same manner as the second threshold value and the third threshold value. That is, the fourth threshold is the resolution in the peripheral region Rp when the shift lens 151 is driven in the second driving range B and the resolution in the peripheral region Rp is reduced to 70% or less of the resolution in the vicinity of the central portion of the captured image. This is a value corresponding to the brightness at which the degradation of the image quality due to the degradation of the image becomes invisible to the user. It is assumed that the fourth threshold is determined in advance based on experiments or the like.

  When the brightness of the peripheral area Rp is less than the fourth threshold, that is, when the background is sufficiently dark, the setting unit 77 cannot visually recognize a decrease in image quality even if the resolution is reduced in the peripheral area Rp. Estimated. In addition, when the luminance value of the peripheral region Rp is equal to or higher than the fourth threshold, that is, when the background is not so dark, the setting unit 77 can visually recognize a decrease in image quality due to a decrease in resolution in the peripheral region Rp. Presume that there is.

  The setting unit 77 sets the drive range of the shift lens 151 to the second drive range B when the brightness of the peripheral region Rp is determined to be less than the fourth threshold value. The setting unit 77 sets the driving range of the shift lens 151 to the first driving range A when the luminance of the peripheral region Rp is determined to be equal to or higher than the fourth threshold value. When the region detection unit 75 determines that the main subject region Rs exists in the peripheral region Rp, the setting unit 77 sets the drive range of the shift lens 151 to the first value regardless of the luminance value of the peripheral region Rp. Set to 1 drive range A.

  In the digital camera 1 of the modified example described above, in the flowchart shown in FIG. 7, the brightness of the peripheral region Rp is detected using the result of the normal division photometry in step S107, and the peripheral region Rp is detected in step S108. It is determined whether the luminance is equal to or higher than a fourth threshold value. If the luminance of the peripheral region Rp is equal to or higher than the fourth threshold value, the process proceeds to step S109 to set the first drive range A, and if the luminance of the peripheral region Rp is less than the fourth threshold value, the process proceeds to step S110 to perform the second drive. A range B may be set.

(3) Instead of detecting the main subject based on pre-emission, the main subject may be detected by image processing. In this case, the image processing unit 71 performs, for example, a known face detection process on the image data generated using the image signal output from the image sensor 6. That is, the image processing unit 71 detects a skin color area (face image data) included in the image data. When the face image data is detected, the region detection unit 75 sets the partial region R corresponding to the face image data as the main subject region Rs.

(4) The exposure control unit 74 determines the appropriate exposure based on the brightness detected by the pre-emission split photometry instead of determining the appropriate exposure based on the brightness detected by the normal split photometry. Also good.
(5) There may be a case where the flash device 19 does not emit light during the main photographing. For example, by increasing the imaging sensitivity of the imaging device 6, the setting unit 77 can set the driving range of the shift lens 151 to the first driving range A even when the subject in the peripheral region Rp is photographed brightly. Good.

(6) Instead of performing the image blur correction by driving the shift lens 151, the image blur correction may be performed by driving the imaging device 6. In this case, the digital camera 1 includes an actuator for driving the image sensor 6 within the drive range shown in FIG. 3 and a position detection sensor for detecting the position of the image sensor 6 on the drive range. Furthermore, the digital camera 1 may correct the image blur by driving the shift lens 151 and the image sensor 6 of the blur correction device 15 in a plane orthogonal to the optical axis of the photographing lens 2.

  In addition, the present invention is not limited to the above-described embodiment as long as the characteristics of the present invention are not impaired, and other forms conceivable within the scope of the technical idea of the present invention are also within the scope of the present invention. included. The embodiments and modifications used in the description may be configured by appropriately combining them.

6 ... Image sensor, 7 ... Control circuit,
71 ... Image processing unit, 74 ... Exposure control unit,
75... Region detection unit, 77.
78 ... Shake correction control unit, 15 ... Shake correction device,
151: Shift lens, 153: Actuator,
19 ... Flash device

Claims (8)

A blur correction unit that includes at least one of a blur correction optical system and an image sensor that are displaced in a plane that intersects the optical axis of the imaging optical system, and that corrects blur of an image of a subject on the imaging surface of the image sensor;
Drive means for driving the blur correction optical system or the image sensor in one drive range of a first drive range and a second drive range wider than the first drive range;
Divided photometry means for dividing the subject into a plurality of areas and detecting luminance for each of the plurality of areas;
Based on the brightness detected by the split photometry means, the brightness at the time of shooting in the second area, which is the peripheral area of the first area including the center of the shooting screen, is lower than the predetermined brightness on the shooting screen. When estimating, the driving range is set to the second driving range, and when estimating that the brightness of the second area at the time of shooting is higher than a predetermined brightness, the driving range is set to the first driving range. A digital camera comprising a setting means for setting to a digital camera. The digital camera according to claim 1, wherein
Main subject detection means for detecting a main subject among the subjects;
Exposure condition setting means for setting an exposure condition for photographing the main subject with an appropriate exposure amount based on the luminance detected by the split photometry means;
The setting unit includes an exposure amount predicting unit that predicts an exposure amount at the time of photographing the second region based on the luminance and the exposure condition detected by the divided photometry unit,
The setting unit estimates that the brightness of the second region is lower than the predetermined brightness when the exposure amount of the second region predicted by the exposure amount prediction unit is lower than a first threshold value. A featured digital camera. The digital camera according to claim 1, wherein
A main subject detecting means for detecting a main subject among the subjects;
The setting means includes brightness calculation means for calculating the brightness of the main subject and the brightness of the second area based on the brightness detected by the split photometry means,
The setting means estimates that the brightness of the second area is lower than the predetermined brightness when the difference between the brightness of the main subject and the brightness of the second area is higher than a second threshold value. A digital camera. The digital camera according to claim 1, wherein
The setting means includes luminance calculation means for calculating the luminance of the second region based on the luminance detected by the divided photometry means,
The digital camera is characterized in that the setting means estimates that the brightness of the second area is lower than the predetermined brightness when the brightness of the second area is lower than a third threshold. The digital camera according to any one of claims 1 to 4,
Position detecting means for detecting a region occupied by a main subject on the captured image as a main subject region;
Determination means for determining whether or not the main subject region overlaps the second region;
The digital camera according to claim 1, wherein when the determination unit determines that the main subject region and the second region overlap, the setting unit sets the drive range to the first drive range. The digital camera according to any one of claims 1 to 4,
A light emitting means for emitting irradiation light toward the subject;
The digital camera according to claim 1, wherein the divided photometry unit detects the luminance of the subject for each of the plurality of regions based on the reflected light from the subject irradiated by the light emitting unit. The digital camera according to claim 6, wherein
A luminance included in a predetermined luminance range among the luminances of the plurality of areas detected by the divided photometry unit according to the light emission of the light emitting unit is set as a reference luminance, and a value lower than the set reference luminance by a predetermined value Further comprising a threshold value determining means for determining as the fourth threshold value,
If the setting means determines that there is a partial area whose luminance detected by the divided photometry means is higher than a fourth threshold among the plurality of partial areas included in the second area, It is estimated that the brightness of a 2nd area | region is higher than predetermined brightness, The digital camera characterized by the above-mentioned. The digital camera according to any one of claims 1 to 7,
Based on the luminance detected by the split photometry means, further comprising a high luminance area detecting means for detecting an area occupied by a high luminance subject having a luminance higher than a fifth threshold in the second area as a high luminance area;
When the high-brightness area is detected by the high-brightness area detection unit, the setting unit determines the second area based on the luminance of the area obtained by removing the high-brightness area from the divided area of the divided photometry unit. It is estimated whether or not the brightness of the camera is lower than the predetermined brightness.

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