JP2017038174A - Imaging device, control method and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress reduction of visibility in a predetermined range when a subject is imaged to obtain a moving picture.SOLUTION: An imaging device having imaging means includes: brightness value acquiring means for obtaining a brightness value for each of plural regions corresponding to an image to be acquired by using the imaging means; exposure control means for changing exposure based on the acquired brightness value; selection means for selecting a predetermined range in an image to be acquired by using the imaging means; detection means for detecting the rate of an area in which the brightness value obtained by the brightness value acquiring means is changed, out of the areas corresponding to the predetermined range; and judging means for judging whether the rate is equal to a predetermined value or more. In a case of obtaining a moving picture, when it is determined that the rate is equal to a predetermined value or more, the exposure control means changes the exposure set at the time of the determination, and when it is determined that the rate is not equal to the predetermined value or more, the exposure control means does not change the exposure set at the time of the determination.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an imaging apparatus that captures a moving image by imaging a subject, a control method thereof, and a program.

  2. Description of the Related Art Conventionally, it is known to give a presentation by projecting a document (image) using a display device such as a projector or a monitor. As an imaging apparatus that records the contents of a presentation by imaging a projected document, Patent Document 1 proposes an imaging apparatus that can set a presentation shooting mode for shooting a projected document.

  Here, when imaging the displayed material and recording the contents of the presentation, it is desirable to control the exposure amount at the time of imaging (exposure control) so that the content of the material becomes easy to see.

  Therefore, Patent Document 2 proposes an exposure control apparatus that can change the size of the photometric area in accordance with the size of the subject. By applying the technique of Patent Literature 2 to the imaging device described in Patent Literature 1, the size of the photometric area can be set in accordance with the size of the projected material. The exposure control can be executed based only on the brightness of the image.

JP 2007-195029 A Japanese Patent Laid-Open No. 1-120179

  Here, when a subject such as a person passes in front of the displayed material during the presentation, only the brightness of a part of the entire material changes. Therefore, in the imaging apparatus described in Patent Document 1 to which the technique of Patent Document 2 is applied, when a part in which the brightness is changed as described above is included in the photometry area, the exposure is performed according to the change in the brightness. Control will be executed. In this case, since the brightness of the entire document also changes, the content of the document becomes unclear in accordance with the change in brightness in the moving image to be acquired, and the visibility of the document decreases.

  That is, when acquiring a moving image, even if exposure control is performed based on the brightness of a predetermined range such as the above-described material in the imaging range, the brightness of a part of the predetermined range changes. Accordingly, the visibility of the portion corresponding to the predetermined range is lowered. Even in such a case, it is desirable to suppress a decrease in visibility in a predetermined range.

  An object of the present invention is to suppress a reduction in visibility in a predetermined range when a subject is imaged to acquire a moving image.

  An imaging device of the present invention that achieves the above object is an imaging device including an imaging unit, and each of the plurality of regions obtained by dividing an image acquired using the imaging unit corresponds to each of the plurality of regions. A predetermined range is selected in an image acquired using the imaging unit, a luminance value acquiring unit that acquires a luminance value, an exposure control unit that controls exposure based on the luminance value acquired by the luminance value acquiring unit Detecting a ratio of a region in which the luminance value acquired by the luminance value acquisition unit is changing among a region corresponding to the predetermined range selected by the selection unit among the plurality of regions. Detecting means for determining whether the ratio detected by the detecting means is equal to or greater than a predetermined value, and the exposure control means acquires a moving image using the imaging means. When the front When the determination means determines that the ratio is greater than or equal to a predetermined value, the exposure set at the time of the determination by the determination means is changed, and the determination means determines that the ratio is not greater than or equal to the predetermined value Furthermore, the exposure set at the time of the determination by the determination means is not changed.

  ADVANTAGE OF THE INVENTION According to this invention, when imaging a to-be-photographed object and acquiring a moving image, it can suppress that the visibility of a predetermined range falls.

1 is a block diagram illustrating a configuration of a digital camera 1 that is a first embodiment of an imaging apparatus embodying the present invention. It is a figure explaining the selection method of the data range which concerns on the digital camera 1 which concerns on 1st Embodiment of this invention exemplarily. It is a flowchart explaining the exposure tracking process which concerns on embodiment of this invention, Comprising: The process during acquisition of a moving image is shown. It is the figure which illustrated the some block which concerns on 1st Embodiment of this invention exemplarily. It is a figure explaining the selection method of the data range which concerns on the digital camera 1 which concerns on 2nd Embodiment of this invention exemplarily. It is a figure explaining the determination method of the 2nd exposure which concerns on 2nd Embodiment of this invention, Comprising: The horizontal axis shows the luminance change rate (alpha), and the vertical axis | shaft has shown the exposure change rate.

(First embodiment)
Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

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

  The imaging lens 100 includes a zoom lens, a focus lens, a shift lens, and the like, and is an imaging lens group that guides an optical image (light beam) of a subject to a sensor 102 described later. In FIG. 1, a plurality of lens groups constituting the imaging lens 100 are illustrated as one lens for explanation.

  The diaphragm 101 is a light amount adjusting member that adjusts the amount of light that passes through the imaging lens 100 and enters the camera 1. The aperture drive motor 106 is a drive motor for changing the aperture opening degree of the aperture 101. The aperture control unit 107 is an aperture control unit that controls the driving of the aperture drive motor 106. The aperture control unit 107 can adjust the aperture opening degree of the aperture 101 by driving the aperture drive motor 106 in accordance with an aperture value instructed from an exposure control unit 115 described later.

  The sensor 102 is a charge storage type solid-state imaging device, and is an imaging unit that generates analog image data by photoelectrically converting (imaging) a light beam incident through the imaging lens 100. The sensor 102 employs a CMOS image sensor in which color filters are arranged in a so-called Bayer array, but may be configured to employ a CCD image sensor.

  The shutter control unit 108 is a shutter control unit that controls the accumulation time of the sensor 102. In the present embodiment, a so-called electronic shutter system is employed in which the shutter control unit 108 controls charge reset, transfer, readout timing, and the like accumulated by the sensor 102 in accordance with an accumulation time instructed from an exposure control unit 115 described later.

  An AFE (Analog Front End) 103 is an analog gain adjusting unit that adjusts an analog gain amount of analog image data output from the sensor 102. The AFE 103 is also a correction unit that corrects aberrations of the imaging lens 100 and defects of the sensor 102.

  Analog image data output from the AFE 103 is converted into digital image data by an A / D converter (not shown), and then input to a DFE (Digital Front End) 104. The DFE 104 is a digital gain adjusting unit that adjusts the digital gain amount of the digital image data.

  The gain control unit 109 is a gain control unit that controls each gain amount set by the AFE 103 and the DFE 104 according to a gain amount (for example, ISO sensitivity) instructed from an exposure control unit 115 described later.

  A DSP (Digital Signal Processor) 105 is a video signal processing unit, and performs various processes on the digital image data output from the DFE 104. The processing performed by the DSP 105 on the digital image data includes image processing such as WB adjustment processing and gradation processing.

  The digital image data subjected to the various processes described above by the DSP 105 is recorded in the main memory 116 and a recording medium (not shown) that can be attached to and detached from the camera 1. The digital image data that has been subjected to the various processes described above by the DSP 105 is converted into analog image data for display by a D / A converter (not shown), and then displayed on a monitor 117 as display means.

  In this embodiment, as a mode (imaging mode) for capturing an image of a subject, it is suitable for capturing a moving image by capturing a material (image) projected using an image device such as an external monitor or a screen. Mode (hereinafter referred to as presentation mode) can be set. Specifically, when the presentation mode is set, exposure control suitable for imaging the projected material is executed as compared with the case where another imaging mode is set. Details of this will be described later in the description of the exposure tracking process.

  The luminance value acquisition unit 110 divides digital image data (hereinafter simply referred to as an image) acquired based on an input signal from the sensor 102 into a plurality of regions (blocks), and acquires a luminance value of each block. Value acquisition means. In the present embodiment, the luminance value acquisition unit 110 divides an image with the number of divisions as illustrated in FIG.

  In the present embodiment, the image acquired by the sensor 102 is divided into a plurality of regions and the luminance value is acquired. However, the present invention is not limited to this. As the luminance value acquisition unit 110 of the present embodiment, an imaging range (imaging screen) corresponding to an image acquired using the sensor 102 is divided into a plurality of blocks, and a luminance value can be acquired for each of the plurality of blocks. Any configuration may be used. For example, a so-called photometric sensor different from the sensor 102 is provided inside the camera 1. Then, the luminance knowledge acquisition unit 110 divides the image data acquired by the photometric sensor into a plurality of blocks and acquires the luminance value of each block corresponding to the imaging range of the sensor 102. Also good.

  The luminance value recording unit 111 is a luminance value recording unit that records the luminance value acquired by the luminance value acquisition unit 110. The luminance value recording unit (recording unit) 111 is an area corresponding to a material range when a material range (predetermined range) corresponding to the material in the acquired image is selected by the material selection unit 113 described later. Record the luminance value of (block). Details of this will be described later in the description of the exposure tracking process.

  The evaluation value generation unit 112 is an evaluation value generation unit that applies the exposure value weighting data set in advance to the luminance value acquired by the luminance value acquisition unit 110 and generates an evaluation value for exposure control. . As a method for calculating the evaluation value, an evaluation value is calculated based on a method using various weight data stored in advance such as a center weight or a spot weight, or a brightness value of a material range selected by a material selection unit 113 described later. There is a way to generate.

  The material selection unit 113 is a selection unit that selects the above-described material range. Specifically, when the image acquired using the sensor 102 is displayed on the monitor 117, the material selection unit 113 is instructed by a manual operation of the user and has a predetermined range of the monitor 117 displaying the image ( Data range) can be selected. Details of this will be described later in the description of the selection method of the material range.

  The material range storage unit 114 is a designated position storage unit that stores the position of the material range selected by the material selection unit 113. Specifically, the material range storage unit 114 of the present embodiment stores a block corresponding to the material range selected by the material selection unit 113 in association with a position in the image (in the imaging range).

  The exposure control unit 115 is an exposure control unit that controls (sets) each exposure parameter corresponding to the evaluation value based on the evaluation value generated by the evaluation value generation unit 112 described above. Specifically, the exposure control unit 115 controls the aperture control unit 107, the shutter control unit 108, and the gain control unit 109 to change the exposure parameters such as the aperture value, the accumulation time, and the gain amount, thereby generating the first. An exposure amount corresponding to the evaluated value can be set.

  In the present embodiment, the exposure control unit 115 performs exposure control based on the brightness value of the material range selected by the material selection unit 113 so that the exposure is suitable for the brightness of the material range. Further, the exposure control unit 115 can perform control so as not to change the exposure suitable for the brightness of the selected material range until a predetermined condition is satisfied. Details of this will be described later in the description of the exposure tracking process.

  The main memory 116 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 main memory 116 stores various data related to the operation of the camera 1, for example, constants for operations executed by the camera 1, various exposure conditions, calculation formulas, and the like.

  The monitor 117 is a display unit that employs a capacitive touch panel, and can display analog image data converted by the DSP 105. When the imaging mode of the camera 1 is set to the presentation mode, the user selects a position on the image displayed on the monitor 117 so that the range specified by the touch operation is changed to the material selection unit 113. Is selected as the material range. Details of this will be described later in the description of the selection method of the material range.

  The bus 118 is a common path provided inside the camera 1. The bus 118 is connected to the DSP 105, the brightness value recording unit 111, the evaluation value generation unit 112, the material range storage unit 114, the exposure control unit 115, the main memory 116, and a CPU 119 described later. The CPU 119 is a control unit that comprehensively controls the operation of the camera 1. The above is the basic configuration of the camera 1.

(Imaging operation of the digital camera 1)
Hereinafter, the basic imaging operation of the subject by the camera 1 will be described. When the release switch (not shown) is set to the SW1 state (for example, half-pressed) by the user, the CPU 119 controls the driving of the imaging lens 100 via a lens control unit (not shown) to perform AF (Auto Focus). Execute the process.

  Next, the exposure control unit 115 reads information on the default exposure stored in the main memory 116, and sets the default exposure via each control unit. The exposure control unit 115 captures an image of the subject by controlling the driving of the sensor 102.

  Next, the luminance value acquisition unit 110 divides the image acquired using the sensor 102 side into a plurality of blocks, and acquires the luminance value of the subject for each of the plurality of blocks. Then, the evaluation value generating unit 112 generates an evaluation value for exposure control based on the preset weighting data for exposure control and the previously acquired luminance value.

  Next, the exposure control unit 115 sets the exposure amount based on the previously generated evaluation value in accordance with the release switch being set to the SW2 state (for example, fully pressed) by the user, and performs the main imaging of the subject. The exposure amount is set by appropriately controlling the aperture value, accumulation time, and gain amount by the exposure control unit 115 based on a program diagram stored in the main memory 116 in advance.

  Then, various processes are performed on the image acquired by imaging, and the image is recorded in the main memory 116 and displayed on the monitor 117. The camera 1 can reproduce and acquire a moving image by executing the above-described operation for each predetermined frame rate. The above is the basic imaging operation according to the present embodiment, and the operation when the imaging mode is set to the normal mode. When the imaging mode is set to the presentation mode and the document range is selected, the exposure follow-up process described later is executed, so that exposure control for each frame is not executed.

(Selection method of material range)
Hereinafter, with reference to FIG. 2, the selection method of the material range which concerns on the camera 1 of this embodiment is demonstrated. FIG. 2 is a diagram for exemplarily explaining a method for selecting a material range according to the camera 1 according to the first embodiment of the present invention. In FIG. 2, each subject is not shown for explanation.

  As shown in FIG. 2, the material selection unit 113 of the present embodiment selects (sets) a range designated by the user as the material range 202 in the imaging range 201 displayed on the so-called touch panel type monitor 117.

  Specifically, when a plurality of positions (designated positions) 203 of the imaging range 201 are designated by the user, the material selection unit 113 selects (sets) a rectangular range connecting the plurality of designated positions as the material range 202. To do. In the present embodiment, when the user designates two points on the imaging range 201, a material range having a size corresponding to the designated two points can be selected (set).

  Note that the selection method of the material range is not limited to this. For example, a frame indicating the document range may be displayed in advance in the imaging range, and the size of the frame indicating the document range may be manually changed by the user to select the document range 202. .

  In addition, a frame indicating the material range is displayed in advance on the monitor 117 so as to be superimposed on the acquired image, and the user changes the angle of view at the time of imaging so that the material displayed outside is accommodated in this frame (imaging). The material range 202 may be selected by moving the position). That is, a configuration may be adopted in which each region corresponding to a preset region among the plurality of regions described above is selected as the material range 202.

  Alternatively, the user may designate an arbitrary position on the monitor 117 and select a plurality of blocks adjacent to the block including the designated position through the material range 202.

  As described above, the method for selecting a material range in the present embodiment may be any method as long as it is caused by a user's manual operation. In addition to the touch operation on the monitor 117, the material range may be selected by operating an operation unit (not shown). The above is the method for selecting a material range according to the present embodiment.

(Exposure tracking process)
Hereinafter, with reference to FIG. 3, exposure follow-up processing for the camera 1 of the present embodiment will be described. In the following description, it is assumed that the imaging mode of the camera 1 is set to the presentation mode and a moving image is acquired.

  When the imaging mode of the camera 1 is set to the presentation mode, as shown in FIG. 2, the material range 202 selected by the material selecting unit 113 is a material displayed on an external display device or a screen. There is a high possibility. In this case, there is a high possibility that the material range 202 selected by the material selection unit 113 is a main subject that the user intends to image.

  Therefore, even when the subject passes between the position where the material is projected and the camera 1 or when the animation effect is activated in a part of the material range, the brightness of the entire material as the main subject is obtained. It is desirable that the content of the material is clear.

  In addition, when an externally projected material is captured and recorded as a moving image, the material is switched as the presentation progresses. Therefore, when the luminance value of the material portion (image corresponding to the material) changes according to the switching of the material, it is desirable to execute exposure control based on the changed luminance value according to the luminance change.

  However, when acquiring a moving image, it is also important not to degrade the quality of the moving image. For example, if the exposure is frequently changed in accordance with the luminance change of the entire document, so-called hunting in which the brightness of the moving image changes frequently occurs. Therefore, in the case where an externally projected material is imaged and recorded as a moving image, it is desirable not to perform exposure control unnecessarily when the luminance changes to such an extent that the content of the material is not blurred.

  To summarize the above, when capturing images recorded on the outside and recording them as moving images, the brightness changes so that the content of the materials (images corresponding to the materials) is unclear. It is desirable to perform the exposure control only when this occurs.

  Therefore, the camera 1 of the present embodiment sets the exposure based on the luminance value of the document range in response to the selection of the document range by the user, and until it is determined that the luminance value of the entire document range has changed. This is addressed by not changing the exposure. Hereinafter, with reference to FIG. 3, an exposure control process (exposure tracking process) when the presentation mode is set will be described in detail.

  FIG. 3 is a flowchart for explaining exposure tracking processing during acquisition of a moving image according to the embodiment of the present invention. When the exposure tracking process is started in response to the selection of the document range by the user, the luminance value acquisition unit 110 divides the image acquired using the sensor 102 into a plurality of blocks in step S301, Get the brightness value of the block. In step S301, the luminance value recording unit 111 records the acquired information on the luminance value of each block in the main memory 116 in association with the information on the position of each block.

  FIG. 4 is a diagram illustratively showing a plurality of blocks according to the first embodiment of the present invention, and the shade of the color of each block represents the luminance value of each block. In FIG. 4, the block whose color is closer to white has a larger luminance value (brighter), and the block whose color is closer to black has a lower luminance value (darker). In this embodiment, as shown in FIG. 4, the acquired image is divided into a plurality of blocks. The luminance value of each block is recorded in a state associated with a serial number with the block corresponding to the upper left corner as the origin.

  Next, in step S <b> 302, the exposure control unit 115 reads information related to the position of the previously selected material range from the material range storage unit 114. The exposure control unit 115 performs exposure control based on the average luminance value (representative luminance value) of the luminance values of the blocks corresponding to the material range. The exposure changed by the exposure control is referred to as a first exposure.

  In the present embodiment, in this embodiment, a block included (overlapped) in the material range selected by the user is a block corresponding to the material range. In other words, among the blocks obtained by dividing the image, blocks that are superimposed on the material range selected by the user and blocks that are included in the material range are blocks corresponding to the material range. Therefore, in this embodiment, as shown in FIG. 4, a total of 25 blocks, 12 to 16, 21 to 25, 30 to 34, 39 to 43, and 48 to 52, are designated by the user. Is a block corresponding to the material range selected by. Hereinafter, in order to simplify the description, blocks corresponding to the material range selected by the user are collectively referred to simply as a material range.

  Next, in step S303, the CPU 119 determines whether a predetermined number of frames have elapsed since the frame in which the process of step S301 was executed. If the CPU 119 determines that a predetermined number of frames have elapsed, the luminance value acquisition unit 110 acquires and records the luminance value again in step S304.

  In the present embodiment, the predetermined number of frames described above is one frame. In other words, the luminance value is obtained by measuring light based on the acquired image for each frame when the moving image is acquired (when the subject is imaged). The predetermined number of frames is not limited to one frame, and may be configured to be set to a number other than one frame.

  Next, in steps S305 to S306, the CPU 119 compares the luminance value before a predetermined frame with the luminance value of the currently processed frame, and the luminance value changes for the block corresponding to the data range. Detect the block percentage. The details will be specifically described below.

  In step S305, the CPU 119 compares the luminance value before the predetermined frame acquired in step S301 with the current luminance value acquired in step S304, and calculates a luminance value change amount (luminance change amount) H. Then, the CPU (detection means) 119 detects a block (luminance change block) in which the acquired change amount H exceeds a preset threshold value K.

For example, in the block with the first serial number (the upper left corner in FIG. 4) among the plurality of blocks, when the previous luminance value is Y1a and the current luminance value is Y1b, the luminance change amount H is expressed by equation (1). As shown in (2),
When Y1a <Y1b Y1b ÷ Y1a = H (1)
When Y1a> Y1b Y1a ÷ Y1b = H (2)
It becomes. That is, in this embodiment, the change rate between the previous brightness value and the current brightness value is set as the brightness change amount H. By executing this process for each of a plurality of blocks, the luminance change amount H of each block is obtained.

  As the threshold value K described above, any threshold value K may be set as long as the amount of change in luminance H is smaller than the threshold value K so that the exposure is appropriate for the material range. For example, the threshold value K may be set based on the dynamic range of the sensor 102 or the like. The appropriate exposure for the material range is an exposure that makes the content of the material (image corresponding to the material) clear as the brightness of the material range.

  Next, in step S306, the CPU (detection means) 119 detects the proportion of blocks in which the luminance value changes in the region (block) corresponding to the previously selected material range. Specifically, in step S306, the CPU 119 detects a ratio (luminance change ratio) α in which a luminance change block is included among the blocks included in the material range. In this embodiment, the ratio of the luminance change block is detected among all the blocks included in the data range. However, the ratio of the luminance change block to a predetermined number of blocks or more included in the data range is detected. The structure to do may be sufficient.

In the present embodiment, the number of luminance change blocks occupying the number of blocks corresponding to the material range is the above-described luminance change ratio α. When the number of blocks corresponding to the document range is A1, and the number of the luminance change blocks among them is P1, the luminance change ratio α is as shown in Equation (3):
α = (P1 / A1) × 10 (3)
It becomes.

  Next, in step S307, the CPU (determination unit) 119 determines whether or not the previously calculated luminance change rate α is equal to or greater than a predetermined value Th1. In the present embodiment, the predetermined value Th1 = 2.7. That is, in step S307, the CPU 119 determines whether 27% or more of the blocks corresponding to the material range are luminance change blocks.

  In the present embodiment, the above-described predetermined value Th1 is set to 2.7. However, for example, the predetermined value Th1 may be set to other values such as the predetermined value Th1 = 5. The predetermined value Th1 of the present embodiment may be a value that can at least determine whether or not the luminance of the entire material has changed.

  If it is determined that the luminance change rate α is not equal to or greater than the predetermined value (NO in step S307), the process proceeds to step S309 without changing the current exposure (first exposure) set at the time of the determination. That is, even if the luminance of the subject changes, the process proceeds to step S309 without changing the exposure.

  If it is determined that the luminance change rate α is equal to or greater than the predetermined value (YES in step S307), the exposure control unit 115 changes the current exposure based on the representative luminance value of the document range in step S308. Perform exposure control. The exposure changed by the exposure control is referred to as a second exposure.

  Next, in step S309, the CPU 119 determines whether or not the material range has been changed by the user based on the information acquired from the material selection unit 113. If the CPU 119 determines that the material range has not been changed (NO in step S309), the process returns to step S303 to repeat the exposure tracking process for the current material range.

  If the CPU 119 determines that the document range has been changed (YES in step S309), the exposure tracking process currently being processed is terminated, and a new exposure tracking process is started based on the changed document range. To do. That is, the brightness value of each block is acquired and recorded according to the change of the material range, the exposure is set based on the brightness value, and a new exposure tracking process is started. The above is the exposure tracking process of this embodiment.

  As described above, the camera 1 of the present embodiment is configured to change whether to change the exposure based on the material range selected by the user according to the ratio of the luminance change block in the material range. The camera 1 changes the exposure based on the brightness value of the document range that is set when the user selects the document range only when the luminance change ratio is equal to or greater than the predetermined value Th1, otherwise, The exposure is not changed.

  With this configuration, the camera 1 according to the present embodiment can suppress the brightness of the entire material range from being unclear in the content of the material when imaging the material projected outside. Further, the camera 1 of the present embodiment can change the exposure set in accordance with the material range only when the luminance value of the entire material changes to a value that makes the content of the material unclear. That is, the camera 1 according to the present embodiment captures a material projected outside and records it as a moving image, and when a luminance change that causes the content of the material to be unclear occurs, Exposure control can be performed based on the brightness of the entire document. Therefore, the camera 1 of the present embodiment can suppress a reduction in the visibility of a predetermined range when capturing a moving image by capturing a subject.

  For example, when it is determined that the luminance change rate α is not greater than or equal to a predetermined value, a new exposure is calculated, and this exposure is not applied in exposure control, so that the luminance change rate α is greater than or equal to a predetermined value. It may be configured such that the exposure set at the time of the determination is not changed.

  Further, for example, as described above, when the block designated by the user and a plurality of blocks adjacent to the block are set as the document range, the current exposure is specified by the user according to the selection of the document range. The configuration may be such that the exposure is changed based on the luminance value of the block.

(Second Embodiment)
In the present embodiment, a method for selecting a material range without manual operation by the user and an exposure tracking process based on the material range selected based on the method will be described with reference to FIGS. 5 and 6. The basic configuration and imaging operation of the digital camera (hereinafter simply referred to as a camera) 1 are substantially the same as those in the first embodiment described above, and a description thereof will be omitted.

  FIG. 5 is a diagram illustrating an example of a method for selecting a material range according to the camera 1 according to the second embodiment of the present invention. In FIG. 5, each subject is not shown for the sake of explanation.

  As illustrated in FIG. 5, the camera 1 according to the present embodiment predetermines a range 502 surrounded by a thick line in the imaging range 501, and the material selection unit 113 sets a block corresponding to the range 502 as a material range. Select (set).

  Therefore, the camera 1 of the present embodiment can select the material range in the acquired image (or imaging range) without manual operation by the user. Then, the exposure follow-up process of the first embodiment described above is executed based on the luminance value of this material range. For example, exposure control weighting data in which the weighting degree of the range 502 is increased is stored in the main memory 116 in advance. When the imaging mode of the camera 1 is set to the presentation mode, an evaluation value is calculated based on the weighted data and the luminance value of the block corresponding to the range 502, and exposure control is performed based on the evaluation value. Run.

  In the present embodiment, the data range is a block corresponding to the range 502 including approximately 40% of the blocks including the center of the imaging range 501. That is, when the entire imaging range is divided into a total of 63 blocks as shown in FIG. 5, a total of 25 of 12-16, 21-25, 30-34, 39-43, 48-52. Select the block as the material range. This is because it is assumed that when the material is imaged, the material is positioned substantially in the center of the imaging range 501 and the size of the material relative to the entire imaging range 501 is relatively large.

  The range 502 is not limited to that described above. The above-described range 502 may be any range as long as it is appropriate as the position where the material is located and the size of the material in the imaging range 501 when imaging the material projected outside. .

  Here, as a method different from the above-described configuration, a configuration in which blocks that can be determined as having substantially the same luminance value and color in the imaging range are selected as the data range. As this configuration, the luminance value of the block located at the approximate center among the blocks corresponding to the predetermined range including the block located at the approximate center of the imaging range, such as the block No. 32 shown in FIG. A block in which the difference falls within a predetermined range may be selected as the material range. Note that the reference for determining the difference in luminance value is not limited to the block located in the approximate center of the imaging range, and may be based on a block corresponding to a position preset by the user before the start of imaging. Good.

  The above is the method for selecting a material range according to the present embodiment. As described above, according to the selection method of the material range in the present embodiment, the material range can be selected without a manual operation by the user.

  Here, unlike the case where the user manually selects the material range as in the first embodiment described above, the material range selected in the present embodiment is different from the range where the material is actually located in the image. There is a case. In this case, even if the exposure is changed based on the representative luminance value of the selected document range, the exposure may become bright enough to make the contents of the document unclear.

  Therefore, in the exposure follow-up process of the present embodiment, the reliability of exposure control is improved by determining the second exposure based on the magnitude of the luminance change rate α. The details will be described below with reference to FIG.

  FIG. 6 is a diagram for exemplarily explaining the second exposure determination method according to the second embodiment of the present invention, where the horizontal axis indicates the luminance change rate α and the vertical axis indicates the exposure change rate. The exposure follow-up process of the present embodiment is substantially the same as that of the first embodiment described above except for the above-described step S308, and thus the description thereof is omitted.

  Here, the exposure change ratio is a ratio related to a difference between an exposure (target exposure) based on the representative luminance value of the document range after the luminance change and an exposure (second exposure) that is actually changed (set).

  As shown in FIG. 6, the camera 1 of the present embodiment has an exposure change rate of 100% when the luminance change rate α = 10. That is, when it is determined that the blocks (25 in total) selected as the range (data range) 502 illustrated in FIG. 5 are luminance change blocks, the exposure change ratio becomes 100%. Further, when the luminance change rate α = 2.7, the exposure change rate is 5%. That is, when it is determined that approximately 9 blocks among the blocks (25 in total) selected as the range (data range) 502 illustrated in FIG. 5 are luminance change blocks, the exposure change ratio is 5%. become.

  When the exposure change ratio is 100%, the same exposure as the target exposure is set as the second exposure. When the exposure change ratio is 5%, the exposure of about 5% of the difference between the target exposure and the exposure before the luminance change (first exposure) is set as the second exposure. That is, as the exposure change ratio increases, the difference between the actually set second exposure and the target exposure decreases, and when the exposure change ratio reaches 100%, the second exposure matches the target exposure.

  As described above, since the exposure change ratio is determined based on the magnitude of the luminance change ratio α, the second exposure can be changed based on the magnitude of the luminance change ratio α. For example, when the luminance change rate α is the first value, the second exposure can be made larger than when the luminance change rate is the second value smaller than the first value.

  That is, when the number of luminance change blocks occupying the material range is large, it is considered that there is a high probability that the entire material has a luminance change, so the change in the second exposure relative to the first exposure is increased. On the other hand, when the number of luminance change blocks occupying the material range is small, it is considered that the probability that the luminance change of the entire material has occurred is low, so the change in the second exposure with respect to the first exposure is reduced. . With this configuration, it is possible to improve the degree of reliability of exposure control when capturing images of materials projected outside.

  With the configuration described above, the camera 1 according to the present embodiment, when capturing an image of a subject in the presentation mode, does not involve manual operation by the user, and the brightness of the entire document is in a state where the content of the document is unclear. This can be suppressed. In addition, the camera 1 of the present embodiment has an exposure set in accordance with the document range only when the brightness value of the entire document changes to a value that makes the content of the document unclear without manual operation by the user. Can be changed. Furthermore, the camera 1 of this embodiment can determine the exposure corresponding to the luminance value after the change based on the probability that the luminance change of the entire document has occurred.

  Therefore, the camera 1 of the present embodiment can suppress a reduction in the visibility of a predetermined range when capturing a moving image by capturing a subject. Further, the camera 1 of the present embodiment can improve the reliability of exposure control in the presentation mode.

As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these, A various deformation | transformation and change are possible within the range of the summary. For example, in the above-described embodiment, the luminance change amount H is calculated based on the change ratio between the previous luminance value and the current luminance value, but the absolute value of the difference between the previous luminance value and the current luminance value is calculated. Alternatively, the configuration may be such that the luminance change amount H is set. Specifically, as shown in equation (4),
| Y1b−Y1a | = H (4)
And Then, among the plurality of blocks, a block in which the luminance change amount H of each block calculated based on the above equation (4) exceeds the threshold value K is defined as a luminance change block.

  In the embodiment described above, the luminance change ratio α is the ratio of the number of luminance change blocks to the number of blocks corresponding to the data range, but is not limited thereto. For example, the CPU (detection means) 119 is configured such that the ratio of the size (area) of the luminance change block to the size (area) of the block corresponding to the material range is the luminance change ratio α. Also good. In this case, it is desirable to change the predetermined value Th1 described above to a value related to the size of each block.

  In the above-described embodiment, the exposure control unit 115 performs the exposure control based on the evaluation value generated by the evaluation value generation unit 112. However, the present invention is not limited to this. For example, the configuration may be such that the exposure control unit 115 executes the exposure control based on the luminance value of each block acquired by the luminance value acquisition unit 110 without providing the evaluation value generation unit 112.

  In the above-described embodiment, each control unit, the luminance value acquisition unit 110, the evaluation value generation unit 112, the CPU 119, and the like operate in cooperation with each other to control each operation of the camera 1. However, the present invention is not limited to this.

  For example, a configuration may be adopted in which a program according to the flow illustrated in FIG. 3 is stored in the main memory 116 in advance, and the operation of the camera is controlled by the CPU 119 or the like executing the program. .

  In addition, the structure which newly provides the camera control part which controls operation | movement of the camera 1 collectively may be sufficient. In this case, the camera control may be configured so that the CPU is provided therein and the camera control unit executes a program according to the flow illustrated in FIG.

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

  In addition, the present invention supplies a program that realizes one or more functions of the above-described embodiment to a system or apparatus via a network or a storage medium, and one or more processors in a computer of the system or apparatus read the program. It can also be realized by executing processing. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

DESCRIPTION OF SYMBOLS 1 Digital camera 102 Sensor 110 Luminance value acquisition part 111 Brightness value recording part 113 Position designation part 115 Exposure control part

Claims (16)

An imaging apparatus provided with imaging means,
For each of a plurality of regions obtained by dividing the image acquired using the imaging unit, a luminance value acquisition unit that acquires a luminance value corresponding to each of the plurality of regions;
Exposure control means for controlling exposure based on the brightness value acquired by the brightness value acquiring means;
Selection means for selecting a predetermined range in an image acquired using the imaging means;
Detecting means for detecting a ratio of a region in which the luminance value acquired by the luminance value acquiring unit is changed among the plurality of regions corresponding to the predetermined range selected by the selecting unit; ,
Determination means for determining whether the ratio detected by the detection means is equal to or greater than a predetermined value;
Have
The exposure control unit is set at the time of the determination by the determination unit when the determination unit determines that the ratio is equal to or greater than a predetermined value when acquiring a moving image using the imaging unit. An image pickup apparatus, wherein exposure is changed, and when the determination unit determines that the ratio is not equal to or greater than a predetermined value, the exposure set at the time of the determination by the determination unit is not changed.   The detection unit is configured to set a threshold value in which a change amount of the luminance value acquired by the luminance value acquisition unit is set in advance in a region corresponding to the predetermined range selected by the selection unit among the plurality of regions. The imaging apparatus according to claim 1, wherein a ratio of a region that has changed exceeding is detected.   The exposure control unit is set at the time of the determination by the determination unit when the determination unit determines that the ratio is equal to or greater than a predetermined value when acquiring a moving image using the imaging unit. The imaging apparatus according to claim 1, wherein the first exposure is changed to a second exposure based on a luminance value after the change.   The imaging apparatus according to claim 3, wherein the second exposure is an exposure based on a luminance value of each region corresponding to the predetermined range selected by the selection unit among the plurality of regions. .   The ratio is the number of regions in which the luminance value acquired by the luminance value acquisition unit is changing among the number of regions corresponding to the predetermined range selected by the selection unit among the plurality of regions. The imaging device according to claim 1, wherein the imaging device has a ratio of   The ratio detected by the detection means is the luminance value acquired by the luminance value acquisition means in the size of the area corresponding to the predetermined range selected by the selection means among the plurality of areas. The imaging apparatus according to claim 1, wherein the imaging apparatus is a ratio of a size of a changing area.   The exposure control unit is set at the time of the determination by the determination unit when the determination unit determines that the ratio is equal to or greater than a predetermined value when acquiring a moving image using the imaging unit. The imaging apparatus according to claim 1, wherein exposure is changed according to the ratio detected by the detection unit.   When the exposure control means acquires a moving image using the imaging means, the ratio detected by the detection means is first when the determination means determines that the ratio is greater than or equal to a predetermined value. 8. The exposure to be changed is larger when the ratio is the second value than when the ratio detected by the detection means is a second value smaller than the first value. The imaging device described in 1.   When the image acquired by the imaging unit is displayed on a display device, the selection unit sets a range specified by a user's manual operation in the image displayed on the display device as the predetermined range. The imaging device according to claim 1, wherein the imaging device is selected.   The selection means includes a region specified by a user's manual operation among the plurality of regions, and selects a plurality of regions adjacent to the region specified by the user as the predetermined range. The imaging device according to any one of claims 1 to 8.   The imaging apparatus according to any one of claims 1 to 8, wherein the selection unit selects, as the predetermined range, an area corresponding to a preset area from the plurality of areas.   The detection means is an area in which the luminance value acquired by the luminance value acquisition means changes for each predetermined frame of frames from which a moving image is acquired after the predetermined range is selected by the selection means. The image pickup apparatus according to claim 1, wherein the ratio is detected.   The detection unit compares the luminance value before the predetermined frame with the luminance value of the frame currently being processed, so that the region corresponding to the predetermined range selected by the selection unit is selected from the plurality of regions. The imaging apparatus according to claim 12, wherein a ratio of a region in which the luminance value acquired by the luminance value acquisition unit is changing is detected. The luminance value acquisition unit acquires a luminance value for each of the plurality of areas in response to the change of the predetermined range by the selection unit;
When the exposure control means acquires a moving image using the imaging means, the predetermined control after the change of the plurality of areas is changed in response to the change of the predetermined range by the selection means. The imaging apparatus according to claim 1, wherein the exposure is changed based on a luminance value of an area corresponding to the range. An imaging apparatus comprising: an imaging unit; and a luminance value acquisition unit that acquires a luminance value corresponding to each of the plurality of regions for each of a plurality of regions obtained by dividing an image acquired using the imaging unit. ,
An exposure control step of controlling exposure based on the luminance value acquired by the luminance value acquisition means;
A selection step of selecting a predetermined range in an image acquired using the imaging means;
A detection step of detecting a ratio of a region in which the luminance value acquired by the luminance value acquisition unit is changed among the plurality of regions corresponding to the predetermined range selected in the selection step. When,
A determination step of determining whether the ratio detected in the detection step is equal to or greater than a predetermined value;
Have
In the exposure control step, when a moving image is acquired using the imaging means, the determination is set when the determination is made when the determination step determines that the ratio is equal to or greater than a predetermined value. A control method for an imaging apparatus, wherein the exposure set when the determination is made is not changed when it is determined in the determination step that the ratio is not equal to or greater than a predetermined value.   A computer-readable program for causing a computer to execute the control method for an imaging apparatus according to claim 15.

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