JP5477345B2 - Imaging apparatus, focusing method, and program - Google Patents

Description

  The present invention relates to an imaging apparatus, an in-focus method, and a program that perform an autofocus (autofocus) process using an image recognition function.

In recent years, in an autofocus (AF) process of a digital camera, an image recognition technique such as a face recognition technique has been adopted, so that an image of a human face can be focused and photographed.
Further, in the technique described in Patent Document 1 to which the above technique is applied, the position and size of the detected face area in the captured image are set while being remembered, and the face area is detected from the through image captured next time. Describes that a face area is detected at the set position and size.

JP 2008-164839 A

  However, in the technique according to Patent Document 1, when the position and size of the face area to be detected in the captured image are set, the face area to be focused is searched with priority on the set position and size. Therefore, there is a problem that the composition is fixed when taking a still image.

  An object of the present invention is to be able to set an AF evaluation area suitable for a subject.

In order to solve the above problem, an imaging apparatus according to claim 1 is provided.
A plurality of evaluation areas for calculating a focus evaluation value are set in the imaging means, a detection means for detecting an image area of a subject from an image captured by the imaging means, and an image area of the subject detected by the detection means If the image area of the subject cannot be detected by the first area setting means and the detecting means, only one evaluation area is set at a predetermined specific position on the imaging angle of view. Two area setting means, a calculation means for calculating a focus evaluation value for each of the evaluation areas set by the first area setting means or the second area setting means, and a calculation result by the calculation means. comprising a focusing means for focusing, the Te, the first area setting means, so as to encompass the image area of the detected object by said detecting means, a plurality in a position intersecting the contour portion of the image area A narrowing-down means for setting the evaluation area and selecting and narrowing down the plurality of evaluation areas set by the first area setting means based on the focus evaluation value calculated by the calculation means; Display control means for causing the image picked up by the image pickup means to be displayed as a live view image on the display means, and for displaying the evaluation area narrowed down by the narrowing means superimposed on the live view image. The focusing means is characterized in that focusing is performed based on a focus evaluation value of the evaluation area narrowed down by the narrowing-down means .

The invention according to claim 2 is the imaging apparatus according to claim 1,
Based on the plurality of focus evaluation values calculated by the calculation means and the focal length obtained from the focus evaluation values, the peak positions of the focus evaluation values of the calculated evaluation regions are within a predetermined range. The image processing apparatus further includes a specifying unit that specifies a focal length range that includes the largest amount, and the focusing unit performs focusing based on the focal length range specified by the specifying unit.

The invention according to claim 3 is the imaging apparatus according to claim 2 ,
Average distance calculating means for calculating an average of focal lengths corresponding to peak positions of a plurality of focus evaluation values within the range specified by the specifying means is further provided, and the focusing means is calculated by the average distance calculating means. It is characterized by focusing at an average focal length.

The invention according to claim 4 is the imaging apparatus according to claim 2 ,
It further comprises intermediate distance calculating means for calculating the distance of the intermediate point of the focal length range specified by the specifying means, and the focusing means is focused at the distance of the intermediate point calculated by the intermediate distance calculating means. It is characterized by.

The focusing method of the invention according to claim 5 is:
A detection step for detecting an image area of a subject from an image captured by an imaging unit of the imaging device, and a plurality of evaluation areas for calculating a focus evaluation value are set in the image area of the subject detected in the detection step When the image area of the subject cannot be detected in the first area setting step and the detection step, only one evaluation area is set at a predetermined specific position on the imaging angle of view. 2 region setting step, a calculation step for calculating a focus evaluation value for each of the evaluation regions set in the first region setting step or the second region setting step, and a calculation result in the calculation step seen including a focusing step of focusing, the based on the first area setting step, so as to encompass the image area of the detected object in the detection step, the image A plurality of the evaluation areas are set at positions intersecting with the contour portion of the area, and the plurality of evaluation areas set in the first area setting step based on the focus evaluation value calculated in the calculation step A narrowing-down step of selecting and narrowing down, and an image captured by the imaging unit is displayed as a live view image on the display means, and the evaluation area narrowed down in the narrowing-down step is displayed on the live view image A focusing control value of the evaluation area narrowed down in the narrowing-down step, and focusing .

The program of the invention described in claim 6 is:
First, a computer provided in the imaging apparatus detects a subject image region from a captured image, and sets a plurality of evaluation regions for calculating a focus evaluation value in the subject image region detected by the detection unit. A second area that sets only one evaluation area at a predetermined specific position on the imaging angle of view when the image area of the subject cannot be detected by the first area setting means or the detection means; Setting means, calculation means for calculating a focus evaluation value for each of the evaluation areas set by the first area setting means or the second area setting means,
The image area is made to function as a focusing means for focusing based on a calculation result in the calculation means, and the first area setting means includes the image area of the subject detected by the detection means. A plurality of the evaluation areas are set at positions intersecting with the contour portion of the plurality of evaluation areas, and the plurality of evaluation areas set by the first area setting means are determined based on the focus evaluation values calculated by the calculation means. A narrowing-down means for selecting and narrowing down, an image captured by the imaging device is displayed on the display means as a live view image, and the evaluation area narrowed down by the narrowing-down means is superimposed on the live view image and further functions as a display control means for displaying said focusing means is characterized Rukoto to be focused on the basis of the focus evaluation value of the evaluation region narrowed by the narrowing section.

  According to the present invention, an AF evaluation area suitable for a subject can be set.

It is a block diagram which shows schematic structure of the imaging device of one Embodiment to which this invention is applied. 12 is a flowchart illustrating an example of an operation related to an imaging process performed by the imaging apparatus. 3 is a flowchart showing a continuation of the imaging process of FIG. 2. FIG. 3 is a diagram schematically illustrating an example of a correspondence relationship between an AF evaluation value and a focus lens address according to the imaging process of FIG. 2. It is a figure which shows typically an example of the image which concerns on the imaging process of FIG. It is a figure which shows typically an example of the image which concerns on the imaging process of FIG. It is a figure which shows typically an example of the image which concerns on the imaging process of FIG.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. However, the scope of the invention is not limited to the illustrated examples.
FIG. 1 is a block diagram illustrating a schematic configuration of an imaging apparatus 100 according to an embodiment to which the present invention is applied.

As shown in FIG. 1, the imaging apparatus 100 according to the present embodiment includes a focus lens 1, a lens driving unit 2, an electronic imaging unit 3, a unit circuit 4, an imaging control unit 5, an image generation unit 6, and an AF. A processing unit 7, an image processing unit 8, a display unit 9, an image recording unit 10, an operation input unit 11, a buffer memory 12, a program memory 13, a central control unit 14 and the like are provided.
The lens driving unit 2, the imaging control unit 5, the image generation unit 6, the AF processing unit 7, the image processing unit 8, the display unit 9, the image recording unit 10, the buffer memory 12, the program memory 13, and the central control unit 14 are They are connected via a bus line 15.

  The lens driving unit 2 drives the focus lens 1 in the optical axis direction. Specifically, the lens driving unit 2 includes a driving source such as a focus motor and a driver that drives the driving source in accordance with a control signal from the central control unit 14 (none of which is shown).

  The electronic imaging unit 3 is disposed on the optical axis of the focus lens 1. The electronic imaging unit 3 is composed of, for example, an image sensor such as a charge coupled device (CCD) or a complementary metal-oxide semiconductor (CMOS), and an optical image that has passed through various lenses such as the focus lens 1 is a two-dimensional image. Convert to signal.

The unit circuit 4 receives an analog imaging signal corresponding to the optical image of the subject output from the electronic imaging unit 3, receives a CDS that holds the input imaging signal, and a gain adjustment amplifier (AGC) that amplifies the imaging signal. ), An A / D converter (ADC) for converting the amplified imaging signal into a digital imaging signal, and the like.
Then, the unit circuit 4 transmits a digital imaging signal to the image generation unit 6.

  The imaging control unit 5 performs control to drive the electronic imaging unit 3 and the unit circuit 4 at a timing according to the frame rate set by the central control unit 14. Specifically, the imaging control unit 5 includes a TG (Timing Generator), a driver for driving the electronic imaging unit 3, and the like (both not shown), and controls the operation timing of the driver and the unit circuit 4 via the TG. . That is, when the central control unit 14 sets the shutter speed according to the program diagram read from the program memory 13, the TG of the imaging control unit 5 outputs the charge accumulation time corresponding to the shutter speed to the driver as a shutter pulse, The electronic image pickup unit 3 is operated according to the drive pulse signal from the driver to control the charge accumulation time (exposure time).

  The focus lens 1, the electronic imaging unit 3, the unit circuit 4, and the imaging control unit 5 configured in this way constitute imaging means for imaging a subject.

  The image generation unit 6 performs processing such as γ correction processing and white balance processing on the image data sent from the unit circuit 4 and generates a luminance color difference signal (YUV data). Then, the image generation unit 6 outputs the generated image data of the luminance / color difference signal to the AF processing unit 7 and the image processing unit 8.

The AF processing unit 7 includes an image recognition unit 7a that performs image recognition of the captured image G based on image data of the captured image G (see FIG. 5A and the like).
For example, each time image data is sent from the image generation unit 6, the image recognition unit 7 a performs a reduction process with a predetermined magnification on the image data in both the horizontal direction (horizontal) and the vertical direction (vertical). Further, analysis result image data (for example, horizontal × vertical: 40 × 30 pixels; FIG. 5B) showing the result of analyzing the low-resolution image data using a predetermined image recognition technique is obtained. ) See) Sequentially generate L. Then, the image recognition unit 7a uses the predetermined image recognition technique for the analysis result image data L to identify the subject S to be focused and extracts the image area A.
The image recognition process may be performed by extracting the outline of the pixel set of the subject S using various information of the image such as color, brightness, contrast, and high-frequency component information, for example. This may be performed by extracting the outline by specifying and comparing with the feature information of the subject S.
Here, the image recognition unit 7 a constitutes a detection unit that detects the image area A of the subject S from the captured image G.

In FIGS. 5B, 6B, and 7B, the analysis result image data is binarized and an image area A represented by white without dots is represented. An image area A that corresponds to the subject S and is represented by black with dots corresponds to a portion other than the subject S.
In addition, the subject S does not necessarily have to be independent as one subject, and a plurality of subjects may overlap in the front-rear direction, or a plurality of subjects may be separated in the left-right or up-down direction. It may be.

The AF processing unit 7 includes an area determination unit 7b that performs a determination process based on the size of the image area A of the subject S.
As a first determination unit, the region determination unit 7b determines whether the size of the image region A of the subject S detected by the image recognition unit 7a is larger than the preset minimum size of each AF evaluation region P. judge. The minimum dimension of the AF evaluation area P is, for example, a minimum horizontal width of 6 pixels and a minimum vertical with respect to the analysis result image data L which is image data of low resolution (for example, horizontal × vertical: 40 × 30 pixels). The width is set to 4 pixels.
Here, the area determination unit 7b constitutes first determination means for determining whether or not the size of the image area A of the subject S is larger than the minimum dimension that can be set as the AF evaluation area P.

In addition, the AF processing unit 7 includes an area setting unit 7 c that sets an AF evaluation area P that is an evaluation area of the focus state of the focus lens 1.
The area setting unit 7c sets an AF evaluation area P (see FIG. 5A and the like) in which the AF evaluation value is calculated by the evaluation value calculation unit 7d in connection with the evaluation of the focus state of the focus lens 1 in the captured image G. To do. That is, the area detection unit changes the set number of AF evaluation areas P according to the size of the image area A of the subject S (for example, the smallest rectangular frame surrounding the image area A of the subject S), and the AF evaluation area Set P. Specifically, the area setting unit 7c determines that the area determination unit 7b determines that the size of the image area A of the subject S is larger than the minimum dimension of the AF evaluation area P. 9; see FIG. 4A). At this time, the area setting unit 7c includes a plurality of AF evaluation areas P at positions that overlap with the image area A of the subject S or positions that intersect the contour portion of the image area A of the subject S so as to include the image area A of the subject S. Set each of. On the other hand, when the area determination unit 7b determines that the size of the image area A of the subject S is equal to or smaller than the minimum dimension of the AF evaluation area P, the area setting unit 7c sets one AF evaluation area P.
In addition, when the subject S is not detected by the image recognition unit 7a, the region setting unit 7c switches the distance measurement method to “spot AF” and sets the AF evaluation region at the approximate center of the angle of view.
Here, the area setting unit 7c sets a plurality of AF evaluation areas P in which AF evaluation values should be calculated as evaluation areas for the focusing state of the imaging unit in the image area A of the subject S detected by the image recognition unit 7a. It constitutes an area setting means.

  The area setting unit 7c may set a plurality of AF evaluation areas P when the ratio of the size of the image area A of the subject S to the captured image G is a predetermined ratio (for example, 50%) or more. That is, the area determination unit 7b as the second determination unit determines whether or not the ratio of the size of the image area A of the subject S to the captured image G is equal to or greater than a predetermined ratio (for example, 50%). As a result, when it is determined that the ratio of the size of the image area A of the subject S to the captured image G is a predetermined ratio (for example, 50%) or more, the area setting unit 7c sets a plurality of AF evaluation areas P. To do.

In addition, the AF processing unit 7 includes an evaluation value calculation unit 7 d that calculates an AF evaluation value related to the evaluation of the focus state of the focus lens 1.
The evaluation value calculation unit 7d uses the analysis result image data L generated by the image recognition unit 7a based on the image data of each AF evaluation region P set by the region setting unit 7c. An AF evaluation value (see FIG. 4B) indicating the level of contrast is calculated. Specifically, when the focus lens 1 is moved in the optical axis direction by the lens driving unit 2 in the automatic focusing process, the evaluation value calculation unit 7d defines a plurality of ( For example, an AF evaluation value is calculated for each of a plurality of AF evaluation areas P at ranging positions corresponding to a predetermined number (for example, 20 to 30) of addresses among 0 to 100 focus lens addresses.
In FIG. 4B, for example, when nine AF evaluation areas P are set, the focus lens address for the AF evaluation values of the AF evaluation areas P1 to P9 calculated by the evaluation value calculation unit 7d. Are shown in association with each other.
Here, the evaluation value calculation unit 7d constitutes a calculation unit that calculates an AF evaluation value (focus evaluation value) for each of the plurality of AF evaluation regions P set by the region setting unit 7c.

In addition, the AF processing unit 7 includes a range specifying unit 7e that specifies a range in which AF evaluation values are concentrated when a plurality of AF evaluation values are aligned according to the distance measurement position of the focus lens 1.
Specifically, the range specifying unit 7e first arranges the AF evaluation values of the plurality of AF evaluation areas P according to the focus lens address (ranging position), and within the evaluation value search range set to a predetermined range. Are searched for the positions where the peak positions of the AF evaluation values are most frequently included. For example, in FIG. 4B, the peak position of the AF evaluation values in the AF evaluation areas P1 to P4, P6, P7, and P9 other than the AF evaluation areas P5 and P8 is around 40 in the focus lens address. The range in which the addresses are concentrated is specified as the evaluation value concentration range R.
In FIG. 4B, the AF evaluation values of each AF evaluation area P are aligned in association with the distance measurement position of the focus lens 1, but may be aligned according to the focal distance of the focus lens 1.
Here, the range specifying unit 7e determines the peak position of the AF evaluation value in each AF evaluation region based on the plurality of AF evaluation values calculated by the evaluation value calculating unit 7d and the focal length obtained from the AF evaluation value. A specifying means for specifying a focal length range (evaluation value concentration range R) that is included most in a predetermined range is configured.

Further, the AF processing unit 7 includes a distance calculation unit 7f that calculates a focal length at which the imaging unit can be focused.
The distance calculation unit 7f acquires the distance measurement positions of the focus lens 1 corresponding to the peak positions of the plurality of AF evaluation values within the evaluation value concentration range R specified by the range specification part 7e, and uses these distance measurement positions. The average of the converted focal lengths (average focal length) is calculated. For example, in FIG. 4B, the distance calculation unit 7f includes the AF evaluation values of the AF evaluation areas P1 to P4, P6, P7, and P9 existing in the evaluation value concentration range R specified by the range specifying unit 7e. The average focal length is specified by calculating the average of the focal lengths corresponding to the peak positions.
Here, the distance calculation unit 7f constitutes an average distance calculation unit that calculates the average of the focal lengths corresponding to the peak positions of the plurality of AF evaluation values within the evaluation value concentration range R specified by the range specifying unit 7e. Yes.

Note that the distance calculation unit (calculation means) 7f replaces the average of the focal lengths of the plurality of AF evaluation areas P with the largest number of AF evaluation areas P among the plurality of AF evaluation areas P within the evaluation value concentration range R. The focus lens address that can be focused on may be calculated as the focal length. That is, the distance calculation unit 7f may calculate, as the focal length, a focus lens address that can include the most AF evaluation region P images within the depth of field within the evaluation value concentration range R.
In addition, the distance calculation unit 7f may calculate the intermediate position of the evaluation value concentration range R as the intermediate distance calculation means to obtain the focal distance.

  The image processing unit 8 includes an encoding unit (not shown) that compresses and encodes image data (YUV data) generated by the image generation unit 6 using a predetermined encoding method (for example, JPEG method), and image recording. The image processing apparatus includes a decoding unit (not shown) that decodes the encoded image data read from the unit 10 using a decoding method corresponding to the encoding method.

The display unit 9 converts the YUV data for one frame stored in the buffer memory 12 into a video signal, and then displays it as a live view image on the display screen. Specifically, the display unit 9 sequentially displays a live view image based on a plurality of image frames generated by imaging a subject, or displays a REC view image captured as a main captured image.
At the time of image reproduction, the display unit 9 displays an image based on the image data read from the image recording unit 10 and decoded by the image processing unit 8.

  Further, as a display unit, the display unit 9 is associated with the AF evaluation region P at the focal length that is in focus when the shutter button 11a of the operation input unit 11 is half-pressed during display of the live view image. An AF frame (in-focus area frame) W is displayed (see FIGS. 5C, 6C, and 7C).

  The image recording unit 10 is configured by, for example, a nonvolatile memory (flash memory). The image recording unit 10 also includes still image data and moving image data that have been compressed and encoded by a coding unit (not shown) of the image processing unit 8 using a predetermined coding method (for example, JPEG method, MPEG method, etc.). Record.

  The operation input unit 11 is for performing a predetermined operation of the imaging apparatus 100. Specifically, the operation input unit 11 is related to a subject shooting instruction, a shutter button 11a that can be half-pressed and fully pressed, a selection determination button (not shown) related to a selection instruction such as an imaging mode or a function, and a zoom amount. A zoom button (not shown) associated with the adjustment instruction is provided, and a predetermined operation signal is output to the central control unit 14 in accordance with the operation of these buttons.

  The buffer memory 12 is a buffer for temporarily storing image data and the like, and is also used as a working memory for the central control unit 14.

  The program memory 13 stores various programs and data related to the functions of the imaging apparatus 100. The program memory 13 also has a combination of an aperture value (F) and a shutter speed corresponding to an appropriate exposure value (EV) at each shooting such as still image shooting, continuous shooting, and live view image shooting. Program AE data constituting the program diagram shown and an EV value table are also stored.

The central control unit 14 is a one-chip microcomputer that controls each unit of the imaging apparatus 100.
The central control unit 14 controls each unit of the imaging apparatus 100 based on the operation signal output from the operation input unit 11 and input. Specifically, when an imaging signal output according to a predetermined operation of the shutter button 11a of the operation input unit 11 is input, the central control unit 14 performs electronic control using a TG according to a predetermined program stored in the program memory 13. A process of taking a still image by controlling the drive timing of the imaging unit 3 and the unit circuit 4 is executed. One frame of YUV data stored in the buffer memory 12 by shooting this still image is compressed and encoded by the image processing unit 8 by the JPEG method or the like, and recorded as still image data in the image recording unit 10. .

Further, the central control unit 14 sends a predetermined control signal to the lens so that the focal length of the focus lens 1 becomes the focal length within the evaluation value concentration range R specified by the range specifying unit 7e in the automatic focusing process. It outputs to the drive part 2 and drives a focus motor to adjust the focus position of the focus lens 1. Specifically, the central control unit 14 outputs a predetermined control signal to the lens driving unit 2 based on the average focal length calculated by the distance calculation unit 7f from a plurality of focal lengths in the evaluation value concentration range R. By driving the focus motor, the focal length of the focus lens 1 is adjusted to be the average focal length.
Here, the central control unit 14, the focus lens 1, and the lens driving unit 2 constitute focusing means for focusing based on the calculation result by the evaluation value calculation unit 7d.

Next, imaging processing according to the focusing method performed by the imaging apparatus 100 will be described with reference to FIGS.
2 and 3 are flowcharts illustrating an example of an operation related to the imaging process.
The imaging process is a process of capturing a still image or a moving image under the control of the central control unit 14, and a plurality of images displayed on the menu screen based on a predetermined operation of the selection determination button of the operation input unit 11 by the user. This is executed when an imaging mode is selected from the imaging modes.

As shown in FIG. 2, first, the central control unit 14 displays a live view image on the display screen of the display unit 9 based on a plurality of image frames generated by imaging a subject (step S1).
Subsequently, the central control unit 14 determines whether or not the user has pressed the shutter button 11a of the operation input unit 11 halfway (step S2).
Here, if it is determined that the shutter button 11a is half-pressed (step S2; YES), the image recognition unit 7a of the AF processing unit 7 includes a plurality of image frames ( Every time the image data according to FIG. 5A and the like is sent from the image generation unit 6 to the AF processing unit 7, a process of detecting the image area A of the subject S from the image data is performed (step S3). . Specifically, the image recognition unit 7a of the AF processing unit 7 performs a reduction process at a predetermined magnification on each image data sent from the image generation unit 6 and performs analysis result image data L (for example, horizontal × vertical). : 40 × 30 pixels), the subject S (see FIG. 5B) to be focused is specified and extracted from the analysis result image data L using a predetermined image recognition technique.

Next, the AF processing unit 7 determines whether or not the subject S is detected based on the detection result of the subject S by the image recognition unit 7a (step S4). When it is determined that the subject S has been detected (step S4; YES), the area determination unit 7b of the AF processing unit 7 sets the size of the image region A of the subject S detected by the image recognition unit 7a in advance. It is determined whether or not it is larger than the minimum dimension of each AF evaluation area P that has been set (step S5).
If it is determined that the size of the image area A of the subject S is larger than the minimum size of the AF evaluation area P (step S5; YES), the area setting unit 7c of the AF processing unit 7 A plurality of AF evaluation areas P (for example, nine; see FIG. 4A) at positions that overlap with the image area A of the subject S or positions that intersect the contour portion of the image area A of the subject S so as to include A. Each is set (step S6).

As shown in FIG. 3, the evaluation value calculation unit 7d of the AF processing unit 7 determines the level of contrast of the image based on the image data of the AF evaluation region P set by the region setting unit 7c for the analysis result image data L. An AF evaluation value is calculated (step S7). Specifically, the evaluation value calculation unit 7d is a predetermined number (for example, 20 to 30) of a plurality of (for example, 0 to 100) focus lens addresses that define the position of the focus lens 1 in the optical axis direction. An AF evaluation value is calculated for each of the plurality of AF evaluation areas P at the distance measurement position corresponding to the address.
Next, the range specifying unit 7e arranges the AF evaluation values of the plurality of AF evaluation areas P according to the focus lens address (ranging position), and searches for and specifies a range that includes the most peak positions of the AF evaluation values. (Step S8). For example, in FIG. 4B, the range specifying unit 7e evaluates the range where the focus lens address where the peak positions of the AF evaluation values of the AF evaluation areas P1 to P4, P6, P7, and P9 exist is around 40. It is specified as the concentration range R. Thereafter, the central control unit 14 superimposes an AF frame W (see FIG. 5C, etc.) corresponding to the edge portion of the AF evaluation area P within the evaluation value concentration range R on the subject S of the live view image, thereby displaying the display unit. 9 is displayed.

Subsequently, the distance calculation unit 7f acquires the ranging positions of the focus lens 1 corresponding to the peak positions of the plurality of AF evaluation values within the evaluation value concentration range R specified by the range specifying unit 7e, and performs these measurement. The average focal length (average focal length) converted from the distance position is calculated (step S9). For example, in FIG. 4B, the distance calculation unit 7f calculates the average focal length corresponding to the peak positions of the AF evaluation values in the AF evaluation areas P1 to P4, P6, P7, and P9.
Next, the central control unit 14 outputs a predetermined control signal to the lens driving unit 2 to drive the focus motor based on the average focal length calculated by the distance calculation unit 7f, thereby driving the focus of the focus lens 1. A focusing process is performed to adjust the distance to the average focal length (step S10).

  As shown in FIG. 2, when it is determined in step S5 that the size of the image area A of the subject S is equal to or smaller than the minimum dimension of the AF evaluation area P (step S5; NO), the area setting unit 7c Then, one AF evaluation area P with the minimum dimension is set so that the center coordinates of the AF evaluation area P with the minimum dimension overlap the center coordinates of the image area A (step S11). Thereafter, the central control unit 14 causes the display unit 9 to display the AF frame W corresponding to the edge portion of the AF evaluation area P on the subject S of the live view image.

As shown in FIG. 3, the evaluation value calculation unit 7d is based on the image data of the AF evaluation region P set by the region setting unit 7c for the analysis result image data L (for example, horizontal × vertical: 40 × 30 pixels). After performing the process of calculating the AF evaluation value indicating the level of contrast of the image, the central control unit 14 measures the distance of the focus lens 1 corresponding to the peak position of the AF evaluation value calculated by the evaluation value calculation unit 7d. Based on the position, a predetermined control signal is output to the lens driving unit 2 to drive the focus motor, thereby performing a focusing process for adjusting the focus position of the focus lens 1 (step S12).
As shown in FIG. 2, when it is determined in step S4 that the subject S is not detected (step S4; NO), the area setting unit 7c sets the distance measuring method to “spot AF”. After switching and setting the AF evaluation area P at approximately the center of the angle of view (step S13), the central control unit 14 shifts the processing to step S12 and performs the subsequent processing.

As shown in FIG. 3, after the focusing process in step S10 or step S12, the central control unit 14 determines whether or not the shutter button 11a of the operation input unit 11 has been fully pressed by the user (step S14). .
If it is determined that the shutter button 11a has been fully pressed (step S14; YES), the central control unit 14 instructs the imaging control unit 5 to set exposure conditions (shutter speed, aperture, amplification factor, etc.), white balance, and the like. Are adjusted so that an optical image of a subject (see FIG. 5C and the like) is picked up by the electronic image pickup unit 3 under predetermined conditions. Thereafter, the central control unit 14 performs predetermined encoding on the YUV data of the still image (or moving image) generated through the unit circuit 4 and the image generation unit 6 by the encoding unit (not shown) of the image processing unit 8. After being compressed and encoded by a method (for example, JPEG method, MPEG method, etc.), it is recorded in the image recording unit 10 (step S15).

On the other hand, if it is determined in step S14 that the shutter button 11a has not been fully pressed (step S14; NO), the central control unit 14 determines whether or not the half-press operation of the shutter button 11a has been released. (Step S16).
If it is determined that the half-pressing operation of the shutter button 11a has not been released (step S16; NO), the central control unit 14 shifts the process to step S14, and the shutter button 11a is fully pressed. Until the process is repeated, the subsequent processing is repeated. On the other hand, if it is determined that the half-press operation of the shutter button 11a has been released (step S16; YES), the central control unit 14 shifts the process to step S1 and starts the process from the beginning of the imaging process.

As described above, according to the imaging apparatus 100 of the present embodiment, a plurality of AF evaluation areas P are set based on the image area A of the subject S, and based on the set image data of the plurality of AF evaluation areas P. Since the AF evaluation value of each AF evaluation area P is calculated, the AF evaluation area P can be set for the image area A of the subject S regardless of the composition. When these AF evaluation values are aligned according to the focal length of the focus lens 1, an evaluation value concentration range R in which the AF evaluation values are concentrated is specified, and the focal length within the evaluation value concentration range R is specified. Since the focus lens 1 is focused, for example, even if the subject S has a low contrast, such as a night view (see FIG. 5) or a large subject (see FIGS. 6 and 7), a plurality of AF evaluation regions corresponding to the subject S are used. P can be set, and among these AF evaluation areas P, the AF evaluation area P having the peak position of the AF evaluation value within the evaluation value concentration range R is validated, and the focal length within the evaluation value concentration range R is set. The focus lens 1 can be focused.
Therefore, it is possible to focus on the subject S regardless of the composition, so that it is not necessary to focus on a high-contrast portion in advance and then refocus the low-contrast portion within the angle of view by touching the camera. The focus adjustment of the imaging apparatus 100 can be performed appropriately and simply.

In addition, the average of the focal lengths corresponding to the peak positions of the plurality of AF evaluation values within the evaluation value concentration range R is calculated, and the focus lens 1 is focused at the average focal length. Among the plurality of AF evaluation areas P, it is possible to increase the number of AF evaluation areas P that are in focus in terms of phenomenon.
That is, for example, as shown in FIG. 4B, of the nine AF evaluation areas P, the seven AF evaluation areas P in which the peak position of the AF evaluation value is within the evaluation value concentration range R are average focus. Strictly speaking, if the focus lens 1 is focused at a distance, there may be a portion where the image is out of focus and the image is blurred. However, the focus is phenomenologically with respect to more images in the AF evaluation area P. The focus adjustment can be easily performed even on the subject S having a low contrast by setting it to a substantially matched state.

  Further, when the shutter button 11a of the operation input unit 11 is pressed halfway during the live view image display, the AF frame W is displayed in association with the AF evaluation area P at the focal length for focusing the focus lens 1. Therefore, a plurality of AF frames W corresponding to an effective AF evaluation area P having a peak position of the AF evaluation value within the evaluation value concentration range R can be displayed, and the user is substantially focused on the phenomenon. It is possible to notify the location that is in the state. Therefore, even when the subject S having a low contrast is photographed, the user can recognize a place where the subject S is in focus.

  Further, the AF evaluation area P can be set by changing the number of AF evaluation areas P set according to the size of the image area A of the subject S. Specifically, when the size of the image area A of the subject S is larger than the minimum size of the AF evaluation area P, a plurality of AF evaluation areas P are set, while the size of the image area A of the subject S is AF evaluation. If the area P is equal to or smaller than the minimum dimension, one AF evaluation area P can be set. That is, by changing the number of AF evaluation areas P to be set according to the size of the image area A of the subject S, it is possible to deal with the subject S of any size, and the focus adjustment of the focus lens 1 is further improved. It can be done properly.

  Further, when a plurality of AF evaluation areas P are set, the position so as to include the image area A of the subject S, that is, the position that overlaps the image area A of the subject S or the outline portion of the image area A of the subject S. Since each of the plurality of AF evaluation areas P is set to the evaluation value calculation unit, even if the subject S itself has a low contrast, there is a contrast difference at least at the boundary between the subject S and the other portions. A more appropriate AF evaluation value can be calculated by 7d, and the focus adjustment of the focus lens 1 can be performed more appropriately.

The present invention is not limited to the above-described embodiment, and various improvements and design changes may be made without departing from the spirit of the present invention.
For example, the evaluation value concentration range R set in advance as a predetermined range is exemplified as the range in which the AF evaluation values calculated by the evaluation value calculation unit 7d are concentrated. However, the present invention is not limited to this. Of the AF evaluation values of a plurality of AF evaluation areas P, a range in which AF evaluation values of a predetermined ratio (for example, 5 to 7 ratio) are included may be set as a range in which AF evaluation values are concentrated.

  In the above embodiment, the detection of the subject S in the imaging process is performed when the shutter button 11a of the operation input unit 11 is half-pressed. Regardless, it may be executed while the live view image is being displayed.

  Furthermore, in specifying the image area A of the subject S, the analysis result image data L is generated from the image data sent from the image generation unit 6 and is performed using the image data L. There is no need to generate the analysis result image data L, and the image data itself sent from the image generation unit 6 may be used.

  Moreover, although the central control unit 14 and the lens driving unit 2 are illustrated as focusing means, the present invention is not limited to this, and a driving mechanism (not shown) that moves the electronic imaging unit 3 in the optical axis direction is provided. The drive mechanism may be driven under the control of the central control unit 14.

  Further, the configuration of the imaging apparatus 100 is merely an example illustrated in the above embodiment, and is not limited thereto. The imaging device 100 includes at least an imaging unit, a detection unit, a region setting unit, a calculation unit, and a focusing unit. Any change can be made as appropriate.

In addition, in the above embodiment, the AF processing unit 7 and the lens driving unit 2 drive the functions as the detection unit, the region setting unit, the calculation unit, and the focusing unit under the control of the central control unit 14. However, the present invention is not limited to this, and may be realized by executing a predetermined program or the like by the central control unit 14.
That is, a program including a detection processing routine, an area setting processing routine, a calculation processing routine, and a focusing control processing routine is stored in the program memory 13 that stores the program. Then, the CPU of the central control unit 14 may function as a detection unit that detects the image area A of the subject S from the captured image G captured by the imaging unit by the detection processing routine. Further, the CPU of the central control unit 14 in the area setting process routine, the evaluation area (AF evaluation area P) in which the focus evaluation value (AF evaluation value) is calculated in the image area A of the subject S detected in the detection process routine. ) May be made to function as an area setting means for setting a plurality. In addition, the CPU of the central control unit 14 may function as a calculation unit that calculates a focus evaluation value (AF evaluation value) for each of the plurality of evaluation areas set by the area setting process routine by the calculation process routine. . Further, the CPU of the central control unit 14 may function as a focusing unit that focuses the imaging unit based on the calculation result of the calculation processing routine by the focusing control processing routine.

DESCRIPTION OF SYMBOLS 100 Imaging device 1 Focus lens 2 Lens drive part 3 Electronic imaging part 7 AF process part 7a Image recognition part 7b Area determination part 7c Area setting part 7d Evaluation value calculation part 7e Range specification part 7f Distance calculation part 11 Operation input part 11a Shutter button 14 Central control unit

Claims (6)

Imaging means;
Detecting means for detecting an image area of a subject from an image captured by the imaging means;
First area setting means for setting a plurality of evaluation areas in which a focus evaluation value is to be calculated in the image area of the subject detected by the detection means;
A second area setting means for setting only one evaluation area at a predetermined specific position on the imaging angle of view when an image area of a subject cannot be detected by the detection means;
Calculation means for calculating a focus evaluation value for each of the evaluation areas set by the first area setting means or the second area setting means;
Focusing means for focusing based on the calculation result by the calculating means;
Equipped with a,
The first area setting means sets a plurality of the evaluation areas at positions intersecting with a contour portion of the image area so as to include the image area of the subject detected by the detection means,
Based on the focus evaluation value calculated by the calculation means, a narrowing means for selecting and narrowing down the plurality of evaluation areas set by the first area setting means;
Displaying means for causing the image picked up by the image pick-up means to be displayed as a live view image on the display means, and for displaying the evaluation area narrowed down by the narrowing means superimposed on the live view image. ,
The imaging apparatus characterized in that the focusing means focuses based on a focus evaluation value of the evaluation region narrowed down by the narrowing means . Based on the plurality of focus evaluation values calculated by the calculation means and the focal length obtained from the focus evaluation values, the peak positions of the focus evaluation values of the calculated evaluation regions are within a predetermined range. Further comprising a specifying means for specifying the focal length range including the most,
The imaging apparatus according to claim 1, wherein the focusing unit performs focusing based on a focal length range specified by the specifying unit. Average distance calculating means for calculating an average of focal lengths corresponding to peak positions of a plurality of focus evaluation values within the range specified by the specifying means;
The imaging apparatus according to claim 2 , wherein the focusing unit focuses at the average focal length calculated by the average distance calculating unit. An intermediate distance calculating means for calculating the distance of the intermediate point of the focal length range specified by the specifying means;
The imaging apparatus according to claim 2 , wherein the focusing unit focuses at a distance of the intermediate point calculated by the intermediate distance calculating unit. A detection step of detecting an image region of a subject from an image captured by an imaging unit of the imaging device;
A first area setting step for setting a plurality of evaluation areas in which a focus evaluation value is to be calculated in the image area of the subject detected in the detection step;
A second area setting step for setting only one evaluation area at a predetermined position on the imaging angle of view when an image area of the subject cannot be detected in the detection step;
A calculation step for calculating a focus evaluation value for each of the evaluation regions set in the first region setting step or the second region setting step;
A focusing step for focusing based on the calculation result in the calculation step;
Only including,
In the first area setting step, a plurality of the evaluation areas are set at positions intersecting with a contour portion of the image area so as to include the image area of the subject detected in the detection step,
Based on the focus evaluation value calculated in the calculation step, a narrowing step for selecting and narrowing down the plurality of evaluation regions set in the first region setting step;
A display control step for causing the image picked up by the image pickup unit to be displayed as a live view image on a display unit, and for displaying the evaluation region narrowed down in the narrowing down step on the live view image. ,
The focusing method is characterized in that focusing is performed based on a focus evaluation value of the evaluation area narrowed down in the narrowing down step . A computer provided in the imaging apparatus;
Detecting means for detecting an image area of a subject from an image to be captured;
First area setting means for setting a plurality of evaluation areas in which a focus evaluation value is to be calculated in the image area of the subject detected by the detection means;
A second region setting unit configured to set only one evaluation region at a predetermined specific position on the imaging angle of view when the detection unit cannot detect the image region of the subject;
Calculating means for calculating a focus evaluation value for each of the evaluation areas set by the first area setting means or the second area setting means;
Focusing means for focusing based on the calculation result in the calculating means;
To function as,
The first area setting means sets a plurality of the evaluation areas at positions intersecting with a contour portion of the image area so as to include the image area of the subject detected by the detection means,
Based on the focus evaluation value calculated by the calculation means, a narrowing-down means for selecting and narrowing down the plurality of evaluation areas set by the first area setting means,
The image picked up by the image pickup device is displayed as a live view image on the display means, and further functions as a display control means for displaying the evaluation area narrowed down by the narrowing means superimposed on the live view image. ,
It said focusing means, program characterized Rukoto to be focused on the basis of the focus evaluation value of the evaluation region narrowed by the narrowing section.

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