JP6391304B2 - Imaging apparatus, control method, and program - Google Patents

Description

  The present invention relates to an imaging apparatus that continuously images a subject by changing the lens position of a focus lens, and a control method and program thereof.

  2. Description of the Related Art Conventionally, there is an image pickup apparatus that includes a photographing lens including a focus lens and performs so-called focus bracket photographing in which a subject is continuously photographed by changing the lens position of the focus lens.

  Patent Document 1 proposes a camera that performs focus bracket shooting by automatically setting the step interval and the number of shots of the zoom lens based on the subject distance from the camera to the subject and the aperture value.

JP 2004-333924 A

  Here, in the technique described in Patent Document 1, when the aperture value is close to the open state (the depth of field is shallow), in order to acquire an image in a state of focusing on a plurality of subjects, The number of times of imaging will increase. On the other hand, the number of times that a subject can be continuously captured is limited by the capacity of a storage element such as a RAM (Random Access Memory) that temporarily records an image.

  However, since Patent Document 1 does not mention the capacities of these storage elements, the intended number of images cannot be acquired if the number of times the subject is continuously imaged by focus bracket imaging is increased. In this case, since the intended number of images cannot be acquired, it is not possible to acquire images that are in focus on a plurality of subjects.

  An object of the present invention is to acquire an image in a focused state with respect to a plurality of subjects even with a limited number of times of imaging.

In order to achieve the above object, an imaging apparatus according to the present invention includes an imaging lens including a focus lens, and obtains a plurality of images by continuously capturing images with different lens positions in the optical axis direction of the focus lens. Imaging means, detection means for detecting the subject distance in the optical axis direction of each subject to be imaged, and the number of times of imaging for continuous imaging with different lens positions in the optical axis direction of the focus lens, And setting means for setting the depth of field at the time of each imaging, the setting means, based on the subject distance detected by the detection means and the set number of imaging, the plurality of images The lens position in the optical axis direction of the focus lens and the depth of field at the time of acquiring each are set, and the imaging unit focuses on a position corresponding to the subject distance. The depth of field when allowed by imaging, and wherein the imaging means than the depth of field of imaging by focusing on a position different from the position corresponding to the object distance is set shallower To do.

  According to the present invention, even when the number of times of imaging is limited, an image in a focused state with respect to a plurality of subjects is acquired.

1 is a block diagram illustrating a configuration of a digital camera 100 that is a first embodiment of an imaging apparatus embodying the present invention. It is a flowchart explaining the focus bracket process of the digital camera 100 which is 1st Embodiment of the imaging device which implemented this invention. It is a figure explaining illustratively the relationship between the frequency | count of imaging and the depth of field in the focus bracket process of the digital camera 100 which is 1st Embodiment of the imaging device which implemented this invention. It is the figure which illustrated the relationship between the depth of field and the resolution of an image exemplarily. It is a figure explaining the relationship between the to-be-photographed object and imaging | photography conditions by the focus bracket process of the digital camera 100 which is 2nd Embodiment of the imaging device which implemented this invention. It is a flowchart explaining the focus bracket process of the digital camera 100 which is 2nd Embodiment of the imaging device which implemented this invention. It is a figure explaining the modification of the position which performs imaging in the focus bracket process of the digital camera 100 which is 2nd Embodiment of the imaging device which implemented this invention.

(First embodiment)
A basic configuration of a digital camera (hereinafter simply referred to as a camera) 100 that is an imaging apparatus according to a first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram illustrating the configuration of a camera 100 that is a first embodiment of an imaging apparatus embodying the present invention.

  The imaging lens group 101 is an imaging lens group including a zoom lens 102, a focus lens 103, an anti-vibration lens 104, and a diaphragm 105. The zoom lens 102 is an imaging lens that optically changes the angle of view by adjusting the focal length.

  The focus lens 103 is an imaging lens that adjusts the focal position. In the present embodiment, the focal position can be changed by operating the lens position of the focus lens 103 in the optical axis direction.

  The anti-vibration lens 104 is an imaging lens that corrects image blur caused by various factors such as camera shake. The diaphragm 105 is a light amount adjustment member that adjusts the amount of light incident on the image sensor 106 described later. In this embodiment, the diaphragm 105 is provided with a mechanical shutter (not shown), and the time (exposure time) for exposing the image sensor 106 to light can be controlled by controlling the driving of the shutter. it can. In the case where a plurality of imaging lenses are not provided, a configuration in which functions such as zooming, focusing, and image stabilization included in each imaging lens described above are realized by one imaging lens may be used.

  The image sensor 106 is a charge storage type image sensor made up of a solid-state image sensor such as a CCD or CMOS capable of generating an image by accumulating charges, and pixels for imaging are arranged two-dimensionally. ing. When the optical image of the subject that has passed through the imaging lens group 101 is formed on the image sensor 106, an electrical signal (image data) corresponding to the optical image of the subject is output.

  The image processing unit 107 is an image processing unit that acquires pixel luminance values (luminance information) of a subject based on pixel interpolation processing, color conversion processing, and image data output from the image sensor 106. The image processing unit 107 is provided with an AFE (Analog Front End) (not shown), which can adjust the gain amount for the image data, correct the aberration of the lens, and perform sampling. In addition, image data input / output to / from the image processing unit 107 is appropriately converted into digital image data.

  The memory 108 is a storage means that can be electrically erased and stored, and is, for example, an EEPROM represented by a flash memory or the like. The memory 108 stores various data used in the present embodiment. For example, a program executed in the camera 100, operation constants, various exposure conditions, calculation formulas used for processing in the camera 100, and the like are stored in the memory 108 in advance. The program executed in the camera 100 is a program for instructing an operation similar to the flow shown in FIG. Further, the memory 108 has a recording area for image data constituted by a recording element such as a RAM (Random Access Memory). The RAM has a storage capacity capable of recording a predetermined number of still images, a moving image of predetermined time, and audio data, and can record the acquired digital image data.

  Further, the memory 108 is also used as an image display memory (video memory), a work area of each part of the camera 100, and a recording buffer of the recording memory 111 described later.

  The display unit 109 is configured by a TFT LCD (Thin Film Transistor Driven Liquid Crystal Display) or the like, and is a display unit that displays image data converted into analog image data for display. In the present embodiment, by sequentially displaying the image data on the display unit 109, it is possible to perform live view display of image data obtained by imaging the subject. Note that a configuration in which live view display is performed using an electronic viewfinder (not shown) may be used.

  The compression / decompression processing unit 110 is a processing unit that compresses / decompresses image data recorded in the memory 108 according to an image format. The recording memory 111 is a non-volatile recording medium such as a memory card or a hard disk capable of recording image data compressed and expanded by the compression / decompression processing unit 110. In the present embodiment, a recording memory 111 that can be inserted into and removed from the camera 100 is used. However, an optical disk such as a DVD-RW disk or a magnetic disk such as a hard disk may be used. . Further, the recording memory 111 may be built in the camera 100 in advance.

  The aperture driving unit 112 is a driving unit that drives the aperture 105 and a shutter (not shown) based on the set aperture value and exposure time. The aperture value and the exposure time are set by the system control unit 120 described later based on the subject luminance information (luminance value) acquired by the image processing unit 107. That is, automatic exposure (AE) control in the present embodiment is performed by driving the diaphragm 105 and the shutter by the diaphragm driving unit 112 in accordance with an instruction from the system control unit 120. Note that the AE control is also performed by adjusting the gain amount in the image processing unit 107.

  The anti-vibration lens driving unit 113 is a drive control unit that calculates the amount of shake applied to the camera 100 based on information from the angular velocity sensor 130 and the gyro sensor 131 and drives the anti-vibration lens 104 so as to cancel the shake. Note that the calculation of the amount of shake applied to the camera 100 may be calculated by the system control unit 120.

  The focus lens driving unit 114 is a lens driving unit that drives the focus lens 103. In the present embodiment, the focus lens driving unit 114 controls driving of the focus lens 103 based on an evaluation value (contrast evaluation value) for focus detection acquired by a contrast evaluation value acquiring unit 121 described later. By driving the focus lens 103 by the focus lens driving unit 114, the subject can be continuously imaged by changing the lens position of the focus lens 103. That is, focus bracket shooting described later can be performed. Note that the driving control of the focus lens 103 may be performed in combination with phase control or other types of focus control.

  The zoom lens driving unit 115 is a driving unit that drives the zoom lens 102 in accordance with a zoom operation instruction from the user.

  The operation unit 116 is an input device group including operation members such as switches, buttons, and dials for the user to perform various instructions and settings for the camera 100. The operation unit 116 includes a release switch 117 and a menu operation button 118. including.

  When the release switch 117 is in the SW1 state (for example, half-pressed state) by a user operation, preparations before imaging such as photometric calculation, exposure control, and focus control are instructed. In addition, when the release switch 117 is in the SW2 state (for example, fully pressed state), the main imaging of the subject is instructed.

  By operating the menu operation button (mode setting means) 118, the user can set an imaging mode and an operation mode when imaging a subject, an image quality and a size of an image acquired by imaging the subject, and the like. In addition, the user can set the number of times of imaging of the subject when performing the focus bracket shooting by operating the menu operation button 118.

  Note that, as the imaging mode described above, another mode of the focus bracket mode in which focus bracket shooting is performed can be set. As the operation mode of the camera 100, a normal mode (first mode), a power saving mode (second mode) that consumes less power than the normal mode, and the like can be set.

  For example, in the normal mode, the state of the camera 100 is changed to the standby state when no operation is detected for about 1 minute from the state where the power is turned on, whereas in the power saving mode, the state is changed from the state where the power is turned on. When no operation for 10 seconds is detected, the standby state is changed. In the power saving mode, the load caused by the internal processing of the camera 100 is always set to be smaller than that in the normal mode.

  The system control unit (CPU) 120 is a control unit that comprehensively controls the overall operation of the camera 100. The CPU 120 can control the entire camera 100 by instructing each unit of the camera 100 to perform an operation in accordance with a user operation instruction. Note that the CPU 120 can execute a program stored in the memory 108 and control the operation and processing of the camera 100 according to the processing of the program. For example, a program for performing control of the image sensor 106, exposure control, focus control, zoom control, and the like is executed.

  Further, the CPU 120 includes a feature detection unit 122, a contrast evaluation value acquisition unit 121, a subject detection unit 123, a focus bracket control unit 124, and a synthesis unit 125. The details will be described below.

  A contrast evaluation value acquisition unit (evaluation value acquisition means) 121 is an acquisition unit for acquiring an evaluation value for focus detection (hereinafter referred to as a contrast evaluation value) based on image contrast information. Specifically, the contrast evaluation value acquisition unit 121 acquires image data at predetermined intervals while driving the focus lens 103, and acquires information on the transition of the contrast evaluation value in one screen based on the acquired image. To do.

  The feature detection unit 122 divides the acquired image into a plurality of blocks, and extracts feature amounts related to a face and a person for each block. Then, the feature detection unit 122 determines an area where the difference between the extracted feature quantity and the face and human body detection feature quantity stored in advance in the memory 108 exceeds a certain threshold as an area where a person exists. If this determination is repeated while changing the combinations of the size, arrangement, and arrangement angle of the divided blocks, a person included in one screen can be detected.

  In addition to the person detection described above, the feature detection unit 122 can also detect a subject other than a person using the color information luminance information of the image, the contrast evaluation value acquired in advance, or the like. The feature detection unit 122 can also calculate the movement amount and movement speed of the subject by calculating the motion vector of the detected subject.

  The subject detection unit 123 is a distance detection unit that detects information related to the distance to the subject (hereinafter referred to as subject distance) based on the contrast evaluation value acquired by the contrast evaluation value acquisition unit 121. At this time, in addition to the contrast evaluation value, information related to the subject distance may be detected using information related to the subject detected by the feature detection unit 122.

  In addition, the subject detection unit 123 calculates a region (hereinafter referred to as a subject region) where focus bracket shooting is performed based on the information on the subject distance calculated previously and the information on the subject detected by the feature detection unit 122. In the present embodiment, in order to acquire an image focused on the entire subject area, focus bracket shooting is performed in accordance with the subject distance.

  In the present embodiment, information on the distance from the image sensor 106 to the subject is the subject distance, but the present invention is not limited to this. For example, the configuration may be such that information on the distance from the imaging lens group 101 to the subject is the subject distance. In addition, the subject distance may be detected by a known method other than the method described above, such as a phase difference method using a distance measuring sensor.

  The focus bracket control unit 124 sets the number of times the subject is imaged by one continuous imaging in the focus bracket imaging based on the amount of image data to be acquired and the capacity of the memory 108. Details of the method for setting the number of times of imaging will be described later.

  In addition, the focus bracket control unit 124 sets shooting conditions for performing focus bracket shooting based on information such as a contrast evaluation value, a subject distance (or subject region), and the number of times of imaging. Details of the method for setting the shooting conditions will be described later.

  In this embodiment, by driving the focus lens 103, the diaphragm 105, and the shutter based on the set information regarding the number of times of imaging and the imaging conditions, it is possible to acquire images in a focused state with respect to a plurality of subjects. .

  The synthesizing unit 125 is a synthesizing unit that synthesizes a plurality of acquired images and generates image data (hereinafter, referred to as an omnifocal image) in a state where the whole area of the subject area is focused. Specifically, the composition unit 125 reads a plurality of images acquired by the focus bracket process from the memory 108. Next, the synthesizing unit 125 compares the contrast evaluation values of the images acquired by the contrast evaluation value acquiring unit 121, and extracts the clearest pixel portion for each pixel of each image. Then, an omnifocal image is generated by combining the pixel portions of the extracted images. A series of processing from detection of the subject distance to acquisition of the omnifocal image described above is referred to as focus bracket processing in the present embodiment. The above is the basic configuration of the camera 100.

  Hereinafter, the details of the above-described focus bracket process will be described with reference to FIG. FIG. 2 is a flowchart illustrating the focus bracket process of the camera 100 that is the first embodiment of the imaging apparatus embodying the present invention. In the present embodiment, a case where the focus bracket mode is set in advance by the user operating the menu operation button 118 will be described. In addition, information acquired in each step described below is appropriately recorded in the memory 108 and read out from the memory 108.

  When the release switch 117 is set to the SW1 state by the user, the focus bracketing process is started, and the CPU 120 acquires a through image using the image sensor 106. The through image is temporarily recorded in the memory 108 after the image processing unit 107 performs the various processes described above.

  Further, the image processing unit 107 performs a photometric calculation based on the through image, and acquires a luminance value (luminance information) of the through image. In the present embodiment, the obtained through image (for one screen) is divided into a plurality of blocks, and an average luminance value is calculated for each of these blocks. Then, the average luminance value of all the blocks is integrated to calculate a representative luminance value, and the representative luminance value is used as the luminance value of the subject for subsequent processing. Note that the photometric calculation method is not limited to this, and the luminance value may be calculated by another known method.

  In step S101, the contrast evaluation value acquisition unit 121 acquires the contrast evaluation value in one screen based on the through image. Further, the feature detection unit 122 detects a subject existing in one screen based on the through image.

  When only a person is an imaging target for focus bracket shooting, the feature detection unit 122 identifies a person area in one screen and performs focus bracket shooting based on the person area.

  Next, in step S102, the subject detection unit 123 detects information related to the subject distance based on the previously acquired contrast evaluation value. In step S <b> 103, the subject detection unit 123 sets a subject region based on information on the subject distance and information on the subject detected by the feature detection unit 122.

  Next, in step S <b> 104, the focus bracket control unit (first setting unit) 124 sets the number of times of imaging based on information on the amount of acquired image data and the capacity of the memory 108.

  Here, the details of the method of setting the number of times of imaging will be described. In general, there is a limit to the number of images that can be temporarily stored in the buffer memory of the memory (storage means) 108 in accordance with the amount of data of the image to be acquired (for example, size and image quality). For example, it is assumed that the capacity of the RAM of the memory 108 which is the buffer memory of this embodiment is 1 megabyte (1024 bytes) and the amount of data to be acquired is about 220 kilobytes. In this case, the number of times that continuous imaging can be performed once in the focus bracket process (hereinafter referred to as the number of imaging possible) is 4 (1024 ÷ 220≈4.4 when the RAM capacity is divided by the data capacity per image). 65)

  Therefore, the focus bracket (data amount detection means) control unit 124 detects information regarding the data amount of the acquired image and the capacity of the RAM of the memory 108. Then, the focus bracket control unit (calculation unit) 124 calculates the number of images that can be captured based on the detected information regarding the data amount of the acquired image and the capacity of the RAM of the memory 108.

  In the present embodiment, the focus bracket control unit 124 sets the number of times that is less than or equal to the number of times that imaging is possible as the number of consecutive imaging times in the focus bracket process. In the following description, it is assumed that the number of images that can be captured is four and the number of imaging is set to four.

  Note that the information regarding the data amount of the image is detected by the focus bracket control unit (calculation unit) 124 based on the size of the image to be acquired (number of recording pixels) and the image quality. For example, when the image quality to be acquired is set to a higher image quality (fine image quality) than the normal image quality (exemplarily referred to as normal image quality), the data amount of the image increases.

  In addition, when the size of an image to be acquired is set to a size (exemplarily referred to as a large size) larger than a normal size (exemplarily referred to as a middle size), the data amount of the image increases.

  As described above, in the present embodiment, the data amount of the image is detected based on the image quality and size of the image described above. The information related to the data amount of the image may be detected based on the parameters other than the image size and image quality described above.

  Further, in the present embodiment, the number of images that can be captured is set as the number of images that can be captured in the focus bracket process, but at least a number that is less than or equal to the number of images that can be captured may be set.

  Hereinafter, the aperture value at the time of focus bracket shooting will be described with reference to FIG. FIG. 3 is a diagram for exemplarily explaining the relationship between the number of times of imaging and the depth of field in the focus bracket process of the camera 100 which is the first embodiment of the imaging apparatus embodying the present invention. Note that even with the same aperture value, since the depth of field changes according to the subject distance, the horizontal axis in FIG. 3 indicates the subject distance converted to logarithm.

  FIG. 3A exemplarily illustrates the relationship between the contrast evaluation value and the subject distance when the subject 1, the person 2, and the tree are present in the screen (within the angle of view) as the subject to be imaged. FIG. Each subject distance exists at a position where the person 1 is about 0.5 m, a person 2 is about 3 m, and a tree is about 50 m. The subject distance L1 is the person who is the closest subject from the camera 100. 1 shows the subject distance. L2 indicates the object distance of the tree that is the object farthest from the camera 100.

  In the present embodiment, the area from the person 1 to the tree is set as the subject area D described above. Then, focus bracket shooting is performed by changing the lens position of the focus lens 103 so that the entire area of the subject region D is in focus, and an omnifocal image is generated by combining the acquired images.

  Here, when focus bracket shooting is performed in accordance with the subject area D, the aperture value is set based on the previously set number of times of imaging and the subject area D. The details will be described below with reference to FIG. FIG. 4 exemplarily illustrates the relationship between the depth of field and the resolution of the image. FIG. 4A illustrates a case where F10 is set as the aperture value on the small aperture side. FIG. 4B shows a case where F3.5 is set as the aperture value on the open side. Furthermore, in FIG. 4, the focal point 310 of the focus lens and the surface 311 on which the image sensor is located are present at the same positions in FIGS. 4 (a) and 4 (b), and FIGS. 4 (a) and 4 (b). The right figure shows an example of an image acquired at each aperture value.

  Generally, when a subject is imaged with an aperture value on the open side set, an image with a shallow depth of field and a high resolution is acquired. Also, when the subject is imaged with the aperture value on the small aperture side set, an image with a deep depth of field and a low resolution is acquired.

  For example, as shown in FIG. 4, both the aperture value F10 and the aperture value F3.5 are focused on the subject because the circle of confusion (312a, 312b) is smaller than the allowable circle of confusion 313 of the image sensor. A state image 317 can be acquired.

  As shown in FIGS. 4A and 4B, the aperture value F10 has a greater depth of focus than the aperture value F3.5 at the same subject distance (316a> 316b). Since the depth of field is obtained by converting the focal depth to the subject side, the aperture value F10 is deeper than the aperture value F3.5 at the same subject distance. Therefore, in the case of the aperture value F10, it is possible to focus on a wider range with one imaging than in the case of the aperture value F3.5.

  In this case, since the depth of field of the image that can be acquired by one imaging is deep on the subject side, the aperture value F10 is the aperture value F3.5 when performing the focus bracket photographing on the same subject region. As a result, the number of imaging can be reduced.

  However, in the case of the aperture value F10, the aperture diameter of the aperture 105 is smaller than in the case of the aperture value F3.5, so that the resolution of the acquired image is lowered due to the influence of the light diffraction phenomenon (FIG. 4 ( (Refer to the right figure of a) and (b)). In this case, the quality of the omnifocal image generated by combining the acquired images is deteriorated. That is, when focus bracket shooting is performed on the same subject area, an image with a higher aperture value F3.5 than the aperture value F10 can be acquired.

  For example, when a relatively wide aperture value and a small number of imaging are set, depending on the size of the subject area, it may not be possible to acquire an image that is focused on the entire subject area with the set number of imaging times. is there. In this case, it is not possible to generate an omnifocal image that is focused on the entire subject area.

  Therefore, in this embodiment, by setting the aperture value according to the information regarding the subject distance of the subject to be imaged and the number of times of imaging, the quality of the acquired image is reduced even if the number of times of imaging is limited. In this way, an image focused on a plurality of subjects is acquired.

  Returning to FIG. 2, in step S <b> 105, the focus bracket control unit (second setting unit) 124 calculates an aperture value F in the focus bracket process based on the previously set number of times of imaging. First, assuming that the number of images to be obtained is n and the subject area is D, the depth of field K is calculated using Equation (1):

It is sufficient if the condition is satisfied.

Depth of field K is calculated using equation (2) where Kf is the depth of front and Kr is the depth of field behind.
K = Kf + Kr (2)
Should be satisfied. The forward depth of field Kf and the backward depth of field Kr are expressed by using equations (3) to (4), where δ is the allowable circle of confusion, L is the subject distance, and f is the focal length of the focus lens 103.

Can be calculated as Then, the aperture value F is calculated by substituting the equations (3) and (4) into the equation (2).

  In the case of the same aperture value, the closer to the camera 100, the shallower the depth of field, so the subject distance L used in equations (3) to (4) corresponds to the subject closest to the camera 100. . In the present embodiment, a subject distance L1 corresponding to the person 1 illustrated in FIG. With this configuration, the smallest aperture value that can be set based on the set number of times of imaging and the subject area D can be calculated.

  For example, the subject distance, the subject area, and the luminance value are the same, and the number of times of imaging is 20 times (second number), 10 times (first number), 5 times (third number) in descending order. The number of times is assumed to be set respectively. In this case, according to the above formulas (1) to (4), when the number of times of imaging is 10 (first number), the aperture set when the number of times of imaging is 20 (second number). An aperture value on the smaller aperture side than the value is set. Further, when the number of times of imaging is 10 (first number), the aperture value on the open side is set more than when the number of times of imaging is 5 times (third number).

  In step S106, the focus bracket control unit 124 sets a lens position (hereinafter referred to as a focus position) Pn of the focus lens 103 in the focus bracket process based on the previously calculated number of times of imaging and information on the subject area D. .

  In the present embodiment, since the smallest aperture value that can be set according to the previously set number of imaging is set, the focus position Pn is based on the depth of field according to the aperture value and the subject distance. Can be determined.

  Specifically, the focus bracket control unit 124 determines a position at which the entire area of the subject area D can be covered within the range of the depth of field of the plurality of acquired images based on the previously calculated aperture value and the number of imaging. Set as Pn. That is, the focus position Pn is set so that the subject is included within at least one depth of field of the plurality of images.

  For example, as illustrated in FIG. 3B, in the focus bracketing process in which imaging is performed four times, the person 1, any one of the depths of field when the imaging is performed four times with the set aperture value, The focus positions P1 to P4 are set so that the person 2 and the tree are included. FIG. 3B is a diagram for exemplarily explaining the focus position Pn corresponding to the subject region D in FIG.

  Returning to FIG. 2, in step S <b> 107, the CPU 120 drives the aperture 105 via the aperture drive unit 112 based on the previously calculated aperture value F. In step S108, the CPU 120 determines whether the release switch 117 is in the SW2 state. The process of step S117 is repeated until the release switch 117 is in the SW2 state.

  Next, in step S109, the focus bracket control unit 124 sequentially captures the subject based on the previously set focus position, and records the acquired images in the memory 108, respectively.

  Next, in step S110, the synthesizing unit (synthesizing unit) 125 reads the plurality of images acquired previously from the memory 108, and extracts the clearest pixel portion in pixel units of the plurality of images. The synthesizing unit 125 generates an omnifocal image in which a plurality of subjects are focused from a plurality of pieces of image data by synthesizing the pixel portions of the extracted images, and the omnifocal image is stored in the memory 108. Record and finish the focus bracketing process. The generated omnifocal image may be displayed on the display unit 109 for review.

  As described above, the camera 100 according to the present embodiment sets the aperture value used in the focus bracket process based on the subject distance and the number of times of imaging. Therefore, the camera 100 is focused on the subject included in the subject area with the set number of times of imaging. An image of the state can be acquired.

  At this time, since the number of times of imaging is set according to the data amount of the image to be acquired and the capacity of the memory 108, an aperture value as small as possible can be set among aperture values that can be set by one continuous imaging. With this configuration, the camera 100 according to the present embodiment acquires a plurality of images that can generate an omnifocal image focused on the entire area of the subject region while suppressing deterioration in quality by one continuous imaging. be able to. Therefore, the camera 100 according to the present embodiment can acquire images in focus on a plurality of subjects even with a limited number of imaging times.

  In the present embodiment, the number of times that the focus bracketing process can be performed is set based on the amount of image data to be acquired and the capacity of the memory 108, but is not limited thereto. For example, the configuration may be such that the number of possible imaging is set based on the set operation mode. In this case, when the operation mode of the camera 100 is the power saving mode, the number of images that can be imaged is smaller than when the operation mode of the camera 100 is the normal mode.

  In the present embodiment, the omnifocal image is acquired by the combining unit 125 provided in the camera 100, but the configuration is not limited thereto. For example, the camera 100 is configured to acquire a plurality of images for generating an omnifocal image and to combine the plurality of images with an apparatus (not shown) provided outside the camera 100. Also good.

  Further, in the present embodiment, the case where the focus bracket photographing is performed in order to generate the omnifocal image has been described, but the present invention is not limited to this. For example, the configuration may be such that focus bracket shooting is performed without the purpose of generating an omnifocal image.

  In the present embodiment, the aperture value used for the focus bracket process is calculated based on the above-described equations (1) to (4). However, the present invention is not limited to this. For example, a configuration may be adopted in which table data that can calculate the aperture value based on the number of times that the image can be captured and the subject distance area is stored in the memory 108 in advance, and the aperture value is calculated based on the table data. In addition, the aperture value can be calculated by any method as long as the aperture value calculation method can generate an omnifocal image that is focused on the entire area of the subject area based on information on the number of times of imaging and the subject distance. It may be calculated.

(Second Embodiment)
In the above-described embodiment, a case has been described in which a subject area is calculated based on the subject distance, and a plurality of images that are in focus on the entire subject area are acquired. In this embodiment, when the distance between subjects to be imaged is large, a digital camera (hereinafter simply referred to as “aperture value”) that changes the aperture value when capturing an area where the subject exists and when capturing an area where the subject does not exist is described. The camera 100 will be described with reference to FIGS.

  In addition, about the structure of the camera 100, the thing similar to 1st Embodiment mentioned above is abbreviate | omitted, and only a different structure from 1st Embodiment mentioned above is demonstrated. Further, it is assumed that a program for instructing an operation similar to the flow shown in FIG.

  The contrast evaluation value acquisition unit 121 of the present embodiment determines whether or not the contrast evaluation value is greater than a predetermined threshold value after acquiring information on the transition of the contrast evaluation value in one screen. .

  Then, the subject detection unit 123 determines that the subject exists at a position where the contrast evaluation value is determined to be larger than the threshold value in one screen. Thereafter, the subject detection unit (distance detection means) 123 detects information related to the subject distance based on the detected subject. Note that the feature detection unit 122 may detect the feature of the subject and detect the subject to be imaged based on the detection result.

  FIG. 5 is a diagram for exemplarily explaining the relationship between the subject to be imaged by the focus bracket process of the camera 100 which is the second embodiment of the imaging apparatus embodying the present invention and the imaging condition, and the direction away from the camera 100. The case where the persons 1 and 2 exist in order is described. In FIG. 5, a subject distance L3 is a subject distance corresponding to the person 3, and a subject distance L4 indicates a subject distance corresponding to the person 4. In the following description, it is assumed that the detected number of possible images is 3 and the distance between the subjects of the person 3 and the person 4 is sufficiently long.

  As shown in FIG. 5, when the person 3 and the person 4 are sufficiently separated from each other, if the area from the person 3 to the person 4 is imaged with the same aperture value, the area where the subject does not exist is captured. And wasteful imaging is performed. In particular, when the number of detected subjects is large or the number of images that can be captured is small, it is desirable to suppress the useless imaging as much as possible and acquire an image focused on the subject.

  Therefore, in this embodiment, when there are a plurality of subjects in one screen and the distance between the subjects is sufficiently large, the aperture value of the region where the subject does not exist is set as the aperture value of the region where the subject exists. Set to a smaller aperture than the aperture value.

  For example, as illustrated in FIG. 5, the aperture value for imaging an area between the person 3 and the person 4 where no subject exists is larger than the aperture value for the age at which the person 3 and the person 4 are imaged. Set the small aperture. With this configuration, it is possible to suppress the number of times of imaging compared to the first embodiment described above. The details will be described below with reference to FIG.

  FIG. 6 is a flowchart for explaining the focus bracketing process of the camera 100 which is the second embodiment of the imaging apparatus embodying the present invention. In the present embodiment, a case where the focus bracket mode is set in advance by the user operating the menu operation button 118 will be described. In addition, information acquired in each step described below is appropriately recorded in the memory 108 and read out from the memory 108.

  When the user sets the release switch 117 to the SW1 state, the focus bracketing process is started, the CPU 120 acquires and records a through image using the image sensor 106, and the image processing unit 107 detects the brightness value (brightness of the through image). Information).

  In step S201, the contrast evaluation value acquisition unit (evaluation value acquisition means) 121 acquires a contrast evaluation value in one screen based on the through image. Further, the feature detection unit 122 detects a subject existing in one screen based on the through image.

  Next, in step S <b> 202, the subject detection unit (distance information detection unit) 123 detects information related to the subject distance according to the contrast evaluation value acquired previously and the detection result from the feature detection unit 122.

  Next, in step S <b> 203, the focus bracket control unit (calculation unit) 124 calculates the number of possible images Nmax based on the data amount of the acquired image and information on the capacity of the memory 108. Since the method for detecting the number of possible imaging Nmax is the same as in the first embodiment described above, the description thereof is omitted.

  Next, in step S204, the subject detection unit 123 determines that there is a subject to be imaged at a position where the acquired contrast evaluation value is larger than a preset threshold value. Based on this determination, the subject detection unit (subject detection means) 123 detects the number M of subjects present in one screen.

  Hereinafter, the details will be described for the case where the number of possible images Nmax is detected three times in step S203 and the number of subjects M is two in step S204. As described above, in this embodiment, in order to suppress wasteful imaging, the aperture at the time of focus bracket shooting is divided into an area determined to have a subject in one screen and an area determined to have no subject in one screen. Change the value.

  At this time, in order to suppress useless imaging, it is desirable to acquire an image in a state where the entire area of the area is in focus with a single imaging in a region between subjects where no subject exists. In other words, it is desirable to perform focus bracket shooting in which an image is taken once for each of the region where the subject exists (first region) and the region between the subjects (second region).

  However, when the number of possible images Nmax is small or the number of subjects M is large, focus bracket photographing may not be performed with the number of times described above. Therefore, in the present embodiment, whether or not the first area and the second area can be imaged once each is determined based on the possible number of times Nmax and the number of subjects M in steps S205 to S205. The determination is made at S206.

  Returning to FIG. 6, in step S <b> 205, the focus bracket control unit 124 determines whether or not the previously obtained number of possible images Nmax is smaller than the number of subjects M.

  If it is determined that the number of possible images Nmax is equal to or greater than the number of subjects M (YES in step S205), the process proceeds to step S206. In step S206, the focus bracket control unit 124 determines whether or not the number Nmax of images that can be captured is equal to or greater than the number obtained by subtracting 1 from the number obtained by doubling the number M of subjects (the number 2M−1).

  When it is determined that the number of possible images Nmax is equal to or greater than the number of 2M−1 (YES in step S206), the first region and the second region can be imaged once each. You can set the number of times. In this case, the number of times of imaging is provisionally determined to be 2M-1 or less, and the process proceeds to step S207.

  Next, in step S207, the focus bracket control unit (second setting unit) 124 sets an aperture value (first aperture value) Fa for imaging the first region. At this time, the first aperture value Fa is set to the most open aperture value among the settable aperture values.

  Next, in step S208, the focus bracket control unit 124 is included in the depth of field when the subject detected with the first aperture value Fa previously set is captured in the region where the subject to be imaged exists. Judge no area. Note that the area where the subject to be imaged is the area between the subject closest to the camera 100 and the subject closest to the infinity among the detected subjects. In step S209, the focus bracket control unit 124 sets an aperture value (second aperture value) Fb for imaging the second area.

  As described above, in this embodiment, since there is no subject to be imaged in the second area, the influence is small even if the resolution of the acquired image is reduced. In other words, when imaging the second area, setting the aperture value on the small aperture side and imaging the subject has little effect. Therefore, the second aperture value Fb covers at least a range not included in the depth of field corresponding to the first aperture value Fa when the subject is imaged with the first aperture value Fa. Should be set.

  Therefore, in a situation where the number of times of imaging is at least 2M−1, ha, the aperture value on the open side as much as possible is set as the first aperture value Fa, and the subject is captured when the subject is imaged with the first aperture value Fa. The second aperture value Fb is set so as to cover an area not included in the depth of field.

  At this time, when the second area is included in the depth of field corresponding to the first aperture value Fa when the subject is imaged with the first aperture value Fa, the second area is compared with the second area. There is no need to perform new imaging. Therefore, in the present embodiment, new imaging is performed with the second aperture value Fb only for the second region that is not included in the depth of field when the subject is imaged with the first aperture value Fa.

  In step S210, the focus bracket control unit (first setting unit) 124 sets the number of times of imaging according to the subject to be imaged and the second area determined in step S208. As described above, the number of times of imaging of 2M-1 times or less is set.

  Next, in step S211, the focus bracket control unit 124 sets the focus position Pn based on the information regarding the number of times of imaging, the number M of subjects, the first aperture value Fa, the second aperture value Fb, and the like calculated previously. The focus position Pn is set by setting the position of the focus position Pn based on the distance from the camera 100 and the depth of field according to the first aperture value Fa and the second aperture value Fb. be able to.

  Next, when it is determined that the number Nmax of images that can be captured is less than the number of 2M-1 (NO in step S206), the focus bracket (first setting means) control unit 124 determines the number of imaging in step S212. Set to the same number (M times) as number M.

  In the case of proceeding to step S212, since the number M of subjects is smaller than the number of possible images Nmax, it is possible to image in accordance with the first area. However, since the number Nmax that can be imaged is smaller than the number of 2M−1, it is not possible to image the second area.

  Therefore, in step S213, the focus bracket control unit (second setting means) 124 performs imaging in accordance with the first area, and the aperture value (third aperture value) Fc at that time is the first aperture value described above. An aperture value on the smaller aperture side than the value Fa is set. The method for setting the third aperture value Fc is calculated using the equations (1) to (4) of the first embodiment described above. Since the process of step S214 is the same as that of step S106 of 1st Embodiment mentioned above, description is abbreviate | omitted.

  Next, when it is determined that the number Nmax of images that can be captured is smaller than the number M of subjects (NO in step S205), in step S215, the focus bracket control unit (first setting unit) 124 Set to the same number of times as Nmax (Nmax times).

  The case where the process proceeds to step S215 is a case where the number M of subjects is equal to or greater than the number of images that can be captured. Accordingly, in step S216, the focus bracket control unit (second setting unit) 124 sets the fourth aperture value Fd so as to focus on the detected subject in Nmax times of imaging. Note that the fourth aperture value Fd is calculated using the equations (1) to (4) of the first embodiment described above. As the fourth aperture value, an aperture value on the smaller aperture side than the first aperture value Fa and the third aperture value Fc is set. Since the process of step S217 is the same as that of step S106 of 1st Embodiment mentioned above, description is abbreviate | omitted.

  Next, in step S218, the CPU 120 drives the aperture 105 via the aperture driver 112 based on the determination results in steps S205 and S206 and the previously calculated aperture values Fa to Fb. The subsequent processes in steps S219 to S221 are the same as the processes in steps S108 to S110 of the first embodiment described above, and thus the description thereof is omitted.

  If the number of times of imaging is set to 2M-1 times, the aperture 105 is driven so as to become the first aperture value Fa in step S218. Thereafter, the subject is imaged in order while driving the aperture 105 appropriately in accordance with the set focus position. With this configuration, focus bracket photography can be performed by changing the aperture value between the first region and the second region. The above is the description of the focus bracket process of the present embodiment.

  As described above, the camera 100 according to the present embodiment changes the aperture value at the time of focus bracket shooting between the area where it is determined that a subject exists and the area where it is determined that no subject exists in one screen. That is, imaging is performed once for each of a region where a subject exists and a region between subjects where no subject exists.

  In addition, even if it is impossible to capture one time for each of the region where the subject exists and the region between the subjects where the subject does not exist, if the number of subjects is less than the number of possible images, the number of subjects is set. Set as the number of imaging.

  Furthermore, if it is not possible to take an image once for each of the region where the subject exists and the region between the subjects where the subject does not exist, and if the number of subjects is equal to or greater than the number of images that can be captured, the number of possible images is captured. Set as number of times.

  With the configuration described above, the camera 100 according to the present embodiment can perform focus bracket imaging while suppressing unnecessary imaging, and thus can acquire an image focused on a subject. Therefore, the camera 100 according to the present embodiment can acquire images in focus on a plurality of subjects even with a limited number of imaging times.

  In the present embodiment, as shown in FIG. 5, the area between the subjects is imaged. However, the present invention is not limited to this. For example, as in the modification illustrated in FIG. 7, a configuration may be employed in which images other than the area where the detected subject exists are not captured. FIG. 7 is a diagram illustrating a modification of the position at which imaging is performed in the focus bracket process of the camera 100 which is the second embodiment of the imaging apparatus embodying the present invention.

  With this configuration, it is possible to further reduce the number of times the subject is imaged, so that it is possible to set a further open aperture value when performing focus bracket photography. Therefore, it is possible to generate an omnifocal image in which the resolution of the area where the subject exists is further improved.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary. For example, in the above-described embodiment, the configuration is such that the camera 100 automatically sets the number of times of imaging. However, the configuration may be such that the user uses the menu operation buttons 118 to set in advance.

  At this time, if the number of times of imaging set by the user is larger than the number of images that can be captured, imaging is performed at the number of images that can be captured. Set. In other words, when the number of times of imaging set by the user is larger than the number of times of imaging, the aperture value on the small aperture side is set as compared with the case where the number of times of imaging is smaller than the number of times of imaging.

  In the embodiment described above, the configuration is such that the control unit and the processing unit provided in the camera 100 operate in cooperation with each other to control the operation of the camera 100. However, the present invention is not limited to this. It is not something. The program according to the flow of FIG. 2 or FIG. 6 described above may be stored in the memory 108 in advance, and the CPU 120 may execute the program to control the operation of the camera 100.

  Moreover, as long as it has the function of a program, it does not ask | require the form of programs, such as an object code, the program run by an interpreter, the script data supplied to OS. The recording medium for supplying the program may be, for example, a magnetic recording medium such as a hard disk or a magnetic tape, or an optical / magneto-optical recording medium.

  In the above-described embodiment, the case where a digital camera is employed as an example of an imaging apparatus that implements the present invention has been described. However, the present invention is not limited to this. For example, the present invention can be applied to various imaging devices within the scope of the gist such as a portable device such as a digital video camera or a smartphone.

(Other embodiments)
The present invention can also be realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various recording media. Then, the computer (or CPU, MPU, etc.) of the system or apparatus reads out and executes the program.

100 Digital camera (imaging device)
101 Imaging lens group (imaging lens)
103 focus lens 114 focus lens drive unit (lens drive means)
123 Subject detection unit (distance information detection means)
124 focus bracket control unit (first and second setting means)

Claims (16)

Imaging means for acquiring a plurality of images a focus lens having an imaging lens comprising, in the image shooting continuously at different lens positions in the optical axis direction of the focusing lens,
A detecting means that detect the object distance in the optical axis direction of each object which is an imaging target,
And setting means to set the depth of field at the time of the focus lens of the imaging count for image shooting continuously at different lens positions in the optical axis direction, and each of the imaging,
Have
Before Ki設 constant means, before said detected by dangerous detecting means on the basis of the imaging count set as a subject distance, the lens position in the optical axis direction of the focus lens when acquiring each of the plurality of images The depth of field when the imaging means focuses on a position corresponding to the subject distance, and the imaging means determines a position corresponding to the subject distance. An imaging device characterized in that the depth of field is set to be shallower than the depth of field when imaging is performed by focusing on a different position . Furthermore, it has a synthesis means,
The imaging apparatus according to claim 1, wherein the synthesizing unit generates an omnifocal image by extracting and synthesizing a focused region from the plurality of images. The imaging apparatus according to claim 1, wherein the setting unit sets an aperture value when imaging the subject, and sets the depth of field by changing the aperture value. Before Ki設 constant unit, when the imaging count is a first number of the small aperture side of the aperture value the imaging count is set when a second number of more than the first number The aperture value according to claim 3 is set. Before Ki設 constant unit, when the imaging count is the first number of open side of the aperture where the imaging count is set when a third number of less than said first number The aperture value according to claim 4 is set. A data amount detecting means for detecting a data amount of an image to be acquired;
Based on the data volume of the image detected by the data amount detection unit, the calculation unit calculates a number of times that the subject can be imaged continuously at a time by changing the lens position in the optical axis direction of the focus lens. ,
Before Ki設 constant means, the imaging apparatus according the number of following the imageable number calculated by the calculation means to any one of claims 1 to 5, characterized in that to set as the number of times of imaging. The calculation means has a capacity of a storage means for storing the image data detected by the data amount detection means and the images successively taken at a time by changing the lens position in the optical axis direction of the focus lens. The imaging device according to claim 6 , wherein the number of times that the imaging can be performed is calculated based on the imaging device. As the operation mode of the imaging device, a mode setting means capable of setting a power second mode consumes less than the first mode and the first mode,
On the basis of the set operation mode by said mode setting means, a calculation means for calculating a Zoka number ability of kite a subject at different lens positions in the optical axis direction of the focus lens sequentially at a time, Have
The calculation means, when the second mode is set by the mode setting means, sets the number of imaging times smaller than when the first mode is set. The imaging device according to any one of 1 to 5 . The setting means, before one of the number of subjects Kifuku, the region from the subject existing in most near side with respect to the imaging device to an object existing in most infinity side with respect to the imaging device, the plurality of The imaging apparatus according to any one of claims 1 to 8 , wherein the depth of field is set so as to be included in a depth of field when any one of images is captured . The imaging apparatus according to claim 1, wherein the detection unit detects the number of the subjects based on the subject distance. The imaging device according to claim 10, wherein the detection unit detects the number of the subjects using an evaluation value for focus detection in the image. Before Ki設 constant means, when the imageable count is less than the number of the previous SL-be Utsushitai, either the imageable number of claims 7 to 9, characterized in that to set as the number of imaging operations the imaging apparatus according to an item or. Before Ki設 constant means, when the imageable number is pre Symbol less than the number obtained by subtracting 1 from the number obtained by doubling the number of the Utsushitai, it is focused at a position corresponding to the subject distance imaging claim the depth of field at the time of, and setting shallower than the depth of field of imaging by focusing at a different position from the position where the imaging means corresponding to the object distance 12 The imaging device described in 1. Having an evaluation value acquisition means for acquiring an evaluation value based on the contrast information of the acquired image;
Before Ki設 constant means, it said than if the evaluation value is imaging an object corresponding to the first evaluation value, the object corresponding to the second evaluation value the evaluation value is higher than the first evaluation value The imaging apparatus according to any one of claims 1 to 13 , wherein the depth of field is set shallower when imaging. A method for controlling an imaging apparatus,
An imaging step of acquiring a plurality of images including an image pickup lens, and an image shooting continuously at different lens positions in the optical axis direction of the focus lens including a focus lens,
A detection step that detect the object distance in the optical axis direction of each object which is an imaging target,
And configuration process to set the depth of field at the time of the focus lens of the imaging count for image shooting continuously at different lens positions in the optical axis direction, and each of the imaging,
Have
Before Ki設 constant step, before dangerous out based on the imaging count set as the object distance detected by the process, the lens position in the optical axis direction of the focus lens when acquiring each of the plurality of images The depth of field when the imaging step focuses on a position corresponding to the subject distance, and the imaging step determines the depth of field. An imaging device characterized in that the depth of field is set to be shallower than the depth of field when imaging is performed by focusing on a different position . A computer-readable program for causing a computer to execute the control method for an imaging apparatus according to claim 15 .