JP2014123069A - Image capturing device and control method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce effect of focusing on background when obtaining an in-focus position for each subregion.SOLUTION: An image capturing device obtains a first in-focus position for each ranging subregion included in a first ranging region comprising a plurality of predefined ranging subregions (S208, S209), sets a part of the first ranging region as a second ranging region to obtain a second in-focus position for each ranging subregion included in the second ranging region (S212), and corrects the first in-focus positions using the second in-focus positions (S213). The first and second in-focus positions are focus lens positions corresponding to peaks of an evaluation value, which is obtained based on the evaluation value, representing a focusing condition, derived at a plurality of focusing lens positions while driving a focusing lens in first and second predefined scanning ranges, where the second scanning range is narrower than the first scanning range.

Description

  The present invention relates to an imaging apparatus and a control method thereof, and more particularly to a focus detection technique in the imaging apparatus.

  Conventionally, there is a technique for performing image processing based on a distance calculated for each partial region within an imaging range (see, for example, Patent Document 1). In addition, there is a focus bracket technique in which shooting is performed by moving the focus lens position so that different subjects are sequentially focused based on the distance of each partial region (see, for example, Patent Document 2).

JP 2006-311505 A JP 2010-286752 A

  However, if there are multiple subjects within a partial area at different distances, for example, both the infinity side and the near side, and the subject on the near side is affected by the subject at the infinity side, it is suitable for that area. There has been a problem of so-called background loss, in which the in-focus position cannot be obtained correctly.

  The present invention has been made in view of the above problems, and an object of the present invention is to reduce the influence of background loss when obtaining the in-focus position for each partial area.

  In order to achieve the above object, the imaging apparatus of the present invention includes a setting unit configured to set a part of a first ranging area including a plurality of predetermined ranging areas as a second ranging area, A first process for acquiring a first focus position for each distance measurement area included in the first distance measurement area, and a second focus position for each distance measurement area included in the second distance measurement area. Acquisition means for performing the second processing for acquiring the first focusing position, and correction means for correcting the first focusing position using the second focusing position, wherein the first focusing position is: A focus lens position that is obtained based on an evaluation value indicating a focus state obtained at a plurality of focus lens positions while driving the focus lens within a predetermined first scan range and at which the evaluation value reaches a peak. , The second in-focus position moves the focus lens to the first position. While driving a narrow second scanning range than the can range determined based on the evaluation value obtained by the plurality of focus lens positions, characterized in that it is a focus lens position where the evaluation value becomes a peak.

  According to the present invention, it is possible to reduce the influence of background loss when obtaining the in-focus position for each partial region.

1 is a block diagram illustrating a configuration of an imaging apparatus according to an embodiment of the present invention. The flowchart which shows the main routine at the time of the imaging in embodiment. The flowchart of the peak position information production | generation determination process in embodiment. The flowchart of the fitting scan process in embodiment. The flowchart of the peak position information synthetic | combination process in embodiment. 6 is a flowchart of representative peak position setting processing for each subject area in the embodiment. The figure for demonstrating the ranging area in embodiment. The figure which shows an example of the acquisition result of the peak position in an embodiment, and an example of a synthetic result. The figure which shows the method of determining the area which selects the peak position in embodiment. The figure which shows the ranging area corresponding to the to-be-photographed object area in embodiment. The figure for demonstrating the omission of the background in embodiment.

  The best mode for carrying out the present invention will be described below in detail with reference to the accompanying drawings.

(Block diagram of imaging device)
FIG. 1 is a block diagram illustrating a configuration of an electronic camera that is an imaging apparatus according to an embodiment of the present invention. In FIG. 1, reflected light from a subject that has entered through a photographing lens 101 including a zoom mechanism and a diaphragm / shutter 102 that controls the amount of light is imaged on an image sensor 107 by a focus lens 104. The image sensor 107 receives the imaged light, converts it into an electrical signal, and outputs it to the A / D converter 108. The A / D converter 108 includes a CDS circuit that removes output noise from the electrical signal output from the image sensor 107, a non-linear amplifier circuit that is performed before A / D conversion, and an A / D converter circuit that performs A / D conversion. The image signal converted into a digital signal is output to the image processing unit 109.

  The image processing unit 109 performs predetermined image processing such as gamma conversion on the image signal output from the A / D conversion unit 108, and the format conversion unit 110 converts the image signal into a format suitable for recording and display, and incorporates the image signal. Stored in the memory 111. The built-in memory 111 is a high-speed memory such as a random access memory, for example, and is hereinafter referred to as “DRAM”. The DRAM 111 is used as a high-speed buffer as temporary image storage means or as a working memory for image compression / decompression. The image recording unit 112 includes a recording medium such as a memory card and an interface thereof, and images and the like are recorded via the DRAM 111. In addition to displaying images, the image display unit 115 displays operations for assisting operation, displays camera status, displays a shooting screen and a distance measurement area during shooting, and displays an image display memory 114 (hereinafter referred to as “VRAM”). The display is performed via.

  The operation unit 116 is for operating the camera from the outside, and includes, for example, the following switches. That is, there are a menu switch for performing various settings such as a shooting function of the image pickup apparatus and a setting at the time of image reproduction, a zoom lever for instructing a zoom operation of the photographing lens 101, an operation mode switching switch between a shooting mode and a playback mode, and the like. The shooting mode switch 117 is used to select a shooting mode such as a macro mode, a distant view mode, and a sports mode. In this embodiment, the AF scan range, the AF operation, and the like are changed according to the shooting mode selected by the user. The The camera further includes a main switch 118 for powering on the system, a switch 119 (hereinafter referred to as “SW1”) for performing shooting preparation operations such as AF and AE, and shooting after the operation of SW1. Imaging switch 120 (hereinafter referred to as “SW2”).

  The system control unit 113 controls the entire system such as a shooting sequence. The system control unit 113 also performs a process of detecting a subject from the image data processed by the image processing unit 109 (subject detection unit). The AE processing unit 103 performs photometric processing on the image processed image signal output from the image processing unit 109, obtains an AE evaluation for exposure control, and controls the shutter speed, aperture, and sensitivity to perform exposure. To control. When the image sensor 107 has an electronic shutter function, the reset and readout timing of the image sensor 107 are also controlled. The AF processing unit 106 calculates an AF evaluation value from the contrast of the image, obtains an in-focus position based on the calculated AF evaluation value (focus detection), and drives the motor 105 to drive the focus lens 104. The higher the AF evaluation value, the stronger the contrast and the closer to the in-focus state, and the lower the AF evaluation value, the weaker the contrast and the farther from the in-focus state.

  The angular velocity sensor unit 121 detects camera movement due to camera shake or panning, and the moving object detection unit 122 detects a moving object from the captured video output signal.

(Operation of imaging device)
Next, the operation in the embodiment of the imaging apparatus having the above configuration will be described along the flowchart of FIG. FIG. 2 is a flowchart showing a main routine during imaging. First, in S201, it is determined whether or not SW1 (119) has been pressed. If it is determined that SW1 (119) is not pressed, the process returns to S201, and the determination of SW1 (119) is repeated.

  If it is determined that SW1 (119) has been pressed, the process proceeds to S202 to determine whether to acquire a peak position for each distance measurement area. The peak position refers to the focus lens position where the AF evaluation value is maximized, that is, the focus lens position where each distance measurement area is in focus (the focus position of each distance measurement area).

(Peak position acquisition judgment for each ranging area)
Here, the peak position acquisition determination process for each distance measurement area performed in S202 will be described with reference to FIG. In order to acquire the peak position for each distance measurement area, the focus lens 104 is driven in the entire region from the infinity to the nearest (first scan range) in order to acquire distance information of all subjects in the screen ( Scanning) and may take a long time. Therefore, unnecessary scanning is avoided by determining whether or not the conditions are suitable for performing a scan for acquiring a peak position for each distance measurement area.

  First, in S301, it is determined whether or not the detected subject is outside the plurality of arranged ranging areas. In this embodiment, for example, with respect to an image 701 as shown in FIG. 7A, ranging areas are arranged in 9 rows and 7 columns as shown in FIG. 7B. The distance measurement areas arranged in 9 rows and 7 columns are collectively referred to as a distance measurement area 801 (first distance measurement area).

  When the detected subject is outside the distance measuring area 801, the distance to the subject cannot be measured, and it is not necessary to acquire the peak position for each distance measuring region. Therefore, if it is determined that the subject is outside the distance measurement area 801 (YES in S301), it is determined in S306 that the peak position for each distance measurement area is not acquired, and the process is completed.

  If it is determined that the detected subject is within the distance measuring area 801 (NO in S301), it is determined whether the subject detected in S302 is moving. If the subject is moving (YES in S302), the distance cannot be measured correctly, and the peak position for each distance measurement area cannot be acquired. Therefore, the peak position for each distance measurement area is not acquired in S306. To complete the process.

  If it is determined that the subject is not moving (NO in S302), it is determined in S303 whether the photographic scene has low illuminance. When the shooting scene is low illuminance, it is necessary to apply a gain to keep the brightness appropriate. However, if the gain exceeds a predetermined value, the distance cannot be measured correctly, so the peak position for each distance measurement area can be acquired. Can not. Therefore, when it is determined that the shooting scene has low illuminance (YES in S303), it is determined in S306 that the peak position for each distance measurement area is not acquired, and the process is completed.

  If it is determined that the shooting scene is not low illuminance (NO in S303), it is determined in S304 whether the shooting scene is a point light source. The point light source is a scene in which the light source is a small point, and in such a scene, distance measurement cannot be performed correctly, and the peak position for each distance measurement area cannot be obtained. Therefore, when it is determined that the shooting scene is a point light source (YES in S304), it is determined in S306 that the peak position for each distance measurement area is not acquired, and the process is completed.

  If it is determined that the shooting scene is not a point light source (NO in S304), it is determined in S305 that a peak position for each distance measurement area is acquired, and the process is completed.

  As a result of the processing of S202 described above, if it is determined in S203 that the peak position for each distance measurement area is not acquired, the process proceeds to S204, and AF evaluation is performed without acquiring the peak position for each distance measurement area while moving the focus lens 104. Perform a scan to get the value. Here, for example, the AF evaluation value is acquired based on an image signal obtained from a predetermined area such as an area near the center of the screen or the entire screen. And based on the acquired AF evaluation value, it moves to a focus position in S205. The in-focus position is a peak position at which it is determined that the entire image should be focused. For example, the in-focus position is the nearest peak position among the peak positions obtained based on the AF evaluation value. To do.

  Next, in S206, it is determined whether or not SW2 (120) has been pressed. When it is determined that SW2 (120) is not pressed, the process returns to S206 and the determination of SW2 (120) is repeated. If it is determined that SW2 (120) is pressed, shooting is performed in S207. Here, for example, bracket shooting may be performed in which exposure conditions, color effect filters, and the like are changed to continuously capture images.

  On the other hand, if it is determined in S203 that the peak position for each ranging area is acquired, the process proceeds to S208. In S208, in order to acquire the peak position for each distance measurement area, a plurality of distance measurement areas are arranged in the screen, and the peak position acquisition scan for each distance measurement area (hereinafter simply referred to as “peak position acquisition scan”). ) To obtain an AF evaluation value for each area. As described above, the distance measurement areas are arranged in 9 rows and 7 columns as shown in FIG. 7B, for example. However, the present invention is not limited to this, and the distance within the screen. If it is understood, other arrangements may be used.

  Next, in S209, based on the AF evaluation value obtained in S208, the peak position for each distance measurement area (the focus position of each distance measurement area) is acquired. Hereinafter, the peak position for each distance measurement area obtained here is referred to as “first peak position information” (first in-focus position), and an example thereof is shown in FIG. The processes of S208 and S209 described above correspond to the first process. Note that “x” in FIG. 8A cannot be used when the subject cannot be measured correctly because the subject contrast is low or the subject has moved from the ranging area during scanning. Indicates the distance measurement result. In this way, it is determined whether or not the distance measurement result can be used, and the usable distance measurement result is used.

  Next, in S210, a peak position to be focused, that is, a focus position is selected from the first peak position information. Here, a method for determining the in-focus position will be described.

  When a subject is detected, a subject frame 1201 is displayed on the screen as shown in FIG. The subject frame 1201 indicates an area determined as a subject. An area indicated by a distance measurement area 1202 (second distance measurement area) relating to the subject area is set as an area for selecting a peak position. On the other hand, when no subject is detected, a predetermined area 1301 (second distance measurement area) in the center of the screen is set as an area for selecting a peak position, as shown in FIG. 9B.

  Then, it is determined whether or not there is an adjacent distance measurement area having a peak position within a predetermined depth in the selected area. A distance measurement area that satisfies this condition is set as an adjacent distance measurement area. If there is an adjacent ranging area, an adjacent ranging area having the nearest peak position is selected from each adjacent ranging area, and the peak position is selected as the in-focus position. If there is no adjacent distance measurement area, the closest peak position in the selected area is set as the in-focus position.

  Next, in S211, it is determined using the first peak position information whether there is no distance difference in the scene being imaged, that is, whether the subject is distributed within a predetermined distance range. In the distance distribution determination in the present embodiment, the first peak position information is compared, and if the difference is small, it is determined that the subject is distributed within a predetermined distance range. In this distance distribution determination, other methods may be used as long as it can be determined whether or not the subject is within a predetermined distance range.

  If it is determined that the subject is distributed within the predetermined distance range, the process proceeds to S205 and the above-described processing is performed. In S205, the focus lens 104 is moved to the in-focus position obtained in S210. If it is determined in S211 that the subject is not within the predetermined distance range, an alignment scan process is performed in S212.

(Adjusting scan)
Here, the alignment scan process (second process) performed in S212 will be described with reference to the flowchart of FIG. First, in step S401, it is determined whether a subject is detected and whether the detected subject is a face. If it is determined that the subject is a face, the size of the subject can be detected. In step S402, the distance measurement area is reset according to the size of the subject in order to suppress background loss. In the present embodiment, resetting is performed when the subject is a face. However, the distance measurement area may be reset for any subject as long as the size of the subject can be detected.

  Here, background loss will be described with reference to FIG. In FIG. 11A, reference numeral 1501 denotes an AF evaluation value of a subject on the infinity side, 1502 denotes an AF evaluation value of another subject closer to the subject, and 1503 acquires an AF evaluation value in a peak position acquisition scan. Position.

  Since the peak position acquisition scan described above scans a wide range from the infinity side to the close side, the focus lens 104 is moved at a high speed. For this reason, the point interval for acquiring the AF evaluation value is wide, and the peak position is obtained from the AF evaluation values on both the infinity side and the close side, so even if there is a subject on the close side, to be influenced. This phenomenon is called background loss.

  Next, in S403, a scan parameter including a speed at which the focus lens 104 is moved during scanning and the number of points from which an AF evaluation value is acquired is set. The speed at which the focus lens 104 is moved in the alignment scan is set to a speed slower than the speed at the time of peak position acquisition scan.

  Note that if the subject size is known and the ranging area is set so that background loss does not occur, background loss does not occur, so the scan parameters differ from those when the subject size is unknown. It may be allowed.

  In step S404, the scan range of the focus lens 104 is set. The scan range is set around the in-focus position determined in S210 of FIG. Since a focus position is selected as the in-focus position, if the scan is performed around this position, the peak position of the target subject can be correctly captured. As a result, the AF evaluation value can be acquired in a narrow range (second scan range) as indicated by 1504 in FIG. 11B, and is not affected by the subject on the infinity side. It is possible to calculate the peak position of the subject.

  Next, in S405, an alignment scan is performed with the set scan parameter and scan range, and a peak position for each distance measurement area of the distance measurement area is acquired based on the obtained AF evaluation value. The peak position for each distance measurement area obtained here is hereinafter referred to as “second peak position information” (second focus position), and an example thereof is shown in FIG. In FIG. 8B, the distance could not be measured correctly because the area outside the distance measurement area, the contrast of the subject was low, the subject moved from the distance measurement area during scanning, or the subject did not exist in the scan range. “×” is written in the distance measurement area. Note that the absence of a subject in the scan range is a case where the subject is closer to the near end of the scan range or closer to the infinity side than the infinity end.

  By performing this fitting scan, it is possible to acquire the focus position suitable for the subject when the subject area is known like a face, and the influence of perspective conflict is reduced even if the subject size is unknown. The focus position can be acquired.

  When the alignment scan shown in FIG. 4 is completed, the process proceeds to S213 in FIG. 2 to synthesize the alignment scan processing result (second peak position information) in S212 and the first peak position information obtained in S209. .

(Composition of peak position information)
Here, the peak position information synthesis processing performed in S213 will be described with reference to the flowchart of FIG. First, in S501, when the first peak position information is obtained for one of the ranging areas arranged as shown in FIG. 7B, as shown in FIG. It is determined whether the peak position information of 1 can be used. For example, in FIG. 8A, a distance measurement area marked with “x” is a distance measurement area where the first peak position information cannot be used.

  An AF evaluation value may be used to determine whether the subject has moved from the distance measurement area during scanning. Also, if the subject does not move from the ranging area during scanning, the AF evaluation value has a mountain shape according to the position of the focus lens 104 and the distance to the subject, but if the subject moves, it has a mountain shape. Don't be. You may determine whether it moved using this.

  If it is determined in S501 that the first peak position information is not usable, it is next determined in S503 whether the second peak position information is usable. For example, as shown in FIG. 8B, if the same distance measurement area is “x”, the second peak position information cannot be used. If the second peak position information is usable, the second peak position information is adopted in S504, and the process proceeds to S510.

  If the second peak position information is not usable in S503, neither the first peak position information nor the second peak position information can be used. Therefore, in S505, the data of the ranging area is invalid data, and the process returns to S510. move on.

  On the other hand, if it is determined in S501 that the first peak position information is usable, it is next determined in S502 whether the second peak position information is usable. If it is determined that the second peak position information is not usable, the first peak position information is adopted in S506, and the process proceeds to S510.

  If it is determined in S502 that the second peak position information can be used, the second peak position information is focused on the closest side in comparison with the first peak position information in S507. It is determined whether or not. If the background subject is affected by the AF evaluation value of the background subject, the peak position of the subject on the near side is affected by the peak position of the subject on the infinity side, and is close to the peak position on the infinity side. It becomes. If it is closer to the numerical value, it can be determined that the distance is correctly measured using the AF evaluation value of the subject. When it is determined that the second peak position information is the peak position information that is in focus closer to the first peak position information, the second peak position information is adopted in S508, and the process proceeds to S510. Further, when it is determined that the second peak position information is the peak position information that is focused on the infinity side with respect to the first peak position information, the first peak position information is adopted in S509, and in S510 move on.

  In S510, it is determined whether information in all the ranging areas in the ranging area 801 has been checked. If all the ranging areas have been checked, the process is completed. If the check of all the ranging areas has not been completed, the process returns to S501 and the above processing is repeated for another ranging area.

  When the first peak position information is shown in FIG. 8A and the second peak position information is shown in FIG. 8B, the combining process shown in FIG. As shown in c), synthesized peak position information is obtained. That is, in each ranging area, the first peak position information and the second peak position information are compared, and the one that is not x is used. If the peak position information is different, the combined peak position information is obtained by using the peak position information indicating the closest side (902, 1002, 1102, 1103).

  Next, in S214, the peak position to be focused is selected using the combined peak position information. Note that the method of selecting the peak position to be focused is the same as the processing in S210. Then, using the corrected peak position information, it is determined whether or not the subject is distributed within the predetermined distance range in the same manner as the processing described in S211. If it is determined that the subject is distributed within the predetermined distance range, the process proceeds to S205 and the above-described processing is performed. In this case, in S205, the focus lens 104 is moved to the in-focus position determined in S214.

  On the other hand, if it is determined that the subject is not within the predetermined distance range, then a subject area is generated in S216. In this embodiment, the image is divided from the color information and luminance information in the screen, the region that is likely to be the subject is determined, and the difference in the combined peak position information of the ranging area corresponding to the region that is likely to be the subject is within the predetermined range. For example, the area is set as the subject area. Further, if there are a plurality of regions that are likely to be subjects, and the difference in the combined peak position information of the distance measurement regions corresponding to these regions is within a predetermined range, those distance measurement regions are set as one subject area. It should be noted that any other method may be used as long as it is possible to divide a region and set a subject area from image information, subject distance information, and the like. The area for detecting the subject may be divided by an arbitrary division method, but if it is divided so as to match the distance measurement area, the color information and luminance information of the area and the distance information of the subject can be easily obtained. Can be matched. FIG. 10 shows subject areas 1401 to 1405 as an example of the case of division so as to coincide with the distance measurement area.

  Next, in S217, a representative peak position (representative in-focus position) of each generated subject area is set. The method for setting the representative peak position will be described later with reference to FIG.

  Next, in S218, the priority order of the subject areas is set. Here, the priority order of the subject areas is the order of the subject areas to be focused at the time of focus bracket shooting, and the subject areas with higher priorities are focused first. This priority order is given priority to the subject area corresponding to the ranging area having the representative peak position as the in-focus position determined in S214, the subject area size is large, and the subject area position is the center of the image. The second and subsequent priorities are determined from a state such as close to.

  Next, in S219, it is determined whether or not SW2 (120) has been pressed. If it is determined that SW2 (120) is not pressed, the process returns to S219 and repeats the determination of SW2 (120). If it is determined that SW2 (120) has been pressed, in step S220, the focus lens 104 is sequentially moved to the position of the focus lens 104 in focus on each subject area based on the priority order determined in step S218. Perform bracket shooting processing.

  Next, in S221, based on the peak position information of each subject area, blur processing by image processing is applied, and the processing is completed. In the blur processing by image processing, the amount of blur varies depending on the difference in peak position of each subject area. For example, when the peak position difference of each subject area is larger than a predetermined value, the optical blur is large and no further blur processing is applied, but when the difference is small, the blur amount by image processing is increased.

(Representative peak position setting for each subject area)
The representative peak position setting process for each subject area performed in S217 will be described with reference to FIG. Note that the processing shown in FIG. 6 is repeated until the processing for all the subject areas generated in S216 is completed. First, in S601, it is determined whether or not the subject in the scene being shot is a face. If it is determined that the subject is a face, a subject area corresponding to the detected face is determined in S602. The subject area corresponding to the face can be determined by selecting the subject area at the position corresponding to the detected face position from the subject areas generated in S216.

  Next, in S603, the peak position of the distance measurement area reset to the face area during the fitting scan is set as the representative peak position of the corresponding subject area. Thereby, the peak position suitable for the subject area corresponding to the face can be associated.

  On the other hand, if it is determined in step S601 that the face is not a face, in step S604, a distance measurement area corresponding to the subject area is selected. The distance measurement area corresponding to the subject area is an area surrounded by a dotted line or a solid line as indicated by reference numerals 1401 to 1405 in FIG. The areas 1403, 1404, and 1405 are combined into one distance measurement area because the combined peak position information is within a predetermined range. That is, the distance measurement area 3 corresponding to the subject area is the distance measurement area 3 as a background area in which the distance measurement areas 1 and 1402 indicated by reference numeral 1401 and the distance measurement areas 2, 1403, 1404, and 1405 indicated by reference numeral 1402 are integrated.

  Next, in S605, a distance measurement area that is correctly measured in the distance measurement area selected in S604 is selected as a selection area. In the example shown in FIG. 10, in-focus peak position information is set for all the distance measurement areas selected as the subject areas, but appropriate information may not be obtained (indicated by “x”). Here, a ranging area from which such a ranging area is removed is set as a selection area.

  Next, the number of distance measurement areas included in the selected area, that is, the number of effective distance measurement areas having composite peak position information is determined. First, in S606, it is determined whether or not three or more effective ranging areas are included in the selected area. If it is determined that there are fewer than three, it is next determined in S607 whether the effective distance measurement area included in the selected area is zero.

  If it is determined that the effective distance measurement area is 0, in step S608, the representative peak position of the subject area is set to a predetermined fixed point (for example, an infinitely focused focus lens position). , Complete the process. The representative peak position refers to a peak position corresponding to the subject area, and refers to a focus lens position that can focus on a wide range of the subject area.

  If it is determined that the effective distance measurement area is not 0, it is next determined in step S609 whether one effective distance measurement area is present. If it is determined that there is one effective ranging area in the selected area, the combined peak position information of the ranging area is set as the representative peak position of the subject area in S610. If it is determined that there is not one effective distance measurement area, there are two effective distance measurement areas included in the selected area. Therefore, in S611, the combined peak position that is in focus on the closest side of the two areas. Information is the representative peak position.

  If it is determined in S606 that there are three or more effective ranging areas, then in S612, the composite peak position information of the ranging areas in the selected area is rearranged in the order of focus from the closest side. . Next, in S613, the synthetic peak position information that is in closest focus is set as the first comparison base data.

  Next, in S614, it is determined whether or not comparison has been performed for all the combined peak position information in the distance measurement area within the selected area. If all the comparisons have not been performed, next, one synthetic peak position on the infinity side is set as a comparison target with the comparison base data in S615. In the first comparison, one infinity side is compared to the synthetic peak position information indicated by the comparison base data. In the second and subsequent comparisons, one infinity side of the synthetic peak position information that was compared before is compared. This is the target synthetic peak position information.

  Next, in S616, the difference between the comparison base data and the composite peak position information to be compared is calculated. If it is determined that the difference is within a predetermined depth of focus, for example, the comparison base data and the combined peak position information to be compared are within one depth, then in S618, the same depth counter is incremented. The same depth counter is given to the distance measurement area of the comparison base data, and is used to determine how many distance measurement areas have the same depth as the distance measurement area.

  In step S619, it is determined whether the same depth counter assigned to the distance measurement area of the current comparison base data is the maximum as compared to other distance measurement areas in the selected area. When it is determined that the same depth counter is maximum, the combined peak position information set as the comparison base data is set as the representative peak position. By this processing, the depth at which the combined peak position information is most concentrated can be obtained. If it is determined that it is not the maximum, the process returns to S614.

  If it is determined in S616 that the difference is outside the predetermined depth, the combined peak position information of the distance measurement area to be compared is set as comparison base data in S617, and the process returns to S614. If it is determined in S614 that all the combined peak position information in the effective ranging area in the selected area has been compared, it is determined in S621 whether a representative peak position has been set. Do. If it is determined that the representative peak position is set, the process is completed.

  If it is determined that the representative peak position is not set, it means that there is no composite peak position information of the same depth between valid ranging areas in the selected area. In this case, in S622, the nearest synthetic peak position information is set as the representative peak position among the synthetic peak position information of the effective ranging area, and the processing is completed.

  In the example described above, the case where the comparison base data that maximizes the same depth counter is set as the representative peak position has been described, but the present invention is not limited to this. For example, a statistical value such as a median value, an average value, and a maximum value of the combined peak position information distributed within the depth at which the same depth counter is maximum may be used as the representative peak position.

  As described above, according to the present invention, it is possible to determine the representative peak position of the subject divided into regions. As a result, it is possible to perform photographing at the focus lens position suitable for the subject divided into the respective regions.

  Although the present invention has been described in detail based on preferred embodiments thereof, the present invention is not limited to these specific embodiments, and various forms within the scope of the present invention are also included in the present invention. included. A part of the above-described embodiments may be appropriately combined.

  The present invention can also be realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, or the like) of the system or apparatus reads the program. It is a process to be executed.

Claims (12)

Setting means for setting a part of a first distance measurement area composed of a plurality of predetermined distance measurement areas as a second distance measurement area;
A first process for obtaining a first focus position for each distance measurement area included in the first distance measurement area, and a second focus for each distance measurement area included in the second distance measurement area. Acquisition means for performing a second process of acquiring a position;
Correction means for correcting the first in-focus position using the second in-focus position;
The first in-focus position is obtained based on an evaluation value indicating an in-focus state obtained at a plurality of focus lens positions while driving the focus lens in a predetermined first scan range. The second focus position is obtained at a plurality of focus lens positions while driving the focus lens in a second scan range narrower than the first scan range. An imaging apparatus characterized by a focus lens position obtained based on an evaluation value, at which the evaluation value reaches a peak.   2. The imaging apparatus according to claim 1, wherein the second scan range is set around the first focus position of the first distance measurement area corresponding to the second distance measurement area. .   The imaging apparatus according to claim 1, wherein an interval between the plurality of focus lens positions in the second process is narrower than an interval in the first process.   The correction means is configured to detect the first focusing position and the second focusing position when the distance measurement areas in which both the first focusing position and the second focusing position are obtained have different values. The imaging apparatus according to any one of claims 1 to 3, wherein a closer side of the focus positions is selected and set as a focus position of the distance measurement area.   The correction means sets the obtained focus position as the focus position of the distance measurement area for the distance measurement area from which either the first focus position or the second focus position is obtained. The imaging device according to any one of claims 1 to 4, wherein It further has subject detection means for detecting a subject from the photographed image,
The setting means sets, as the second distance measurement area, a distance measurement area corresponding to the subject in the first distance measurement area when the subject is detected by the subject detection means. 6. The method according to claim 1, wherein a predetermined distance measurement area of the first distance measurement areas is set as the second distance measurement area when not detected. 7. The imaging device described in 1.   The acquisition unit determines whether or not the focus position of each ranging area can be used based on the evaluation value, and sets the usable focus positions as the first and second focus positions. The imaging apparatus according to any one of claims 1 to 6.   The imaging apparatus according to claim 7, wherein the acquisition unit determines whether or not the focus position can be used based on a shape formed by the evaluation value of each distance measurement area.   9. The imaging apparatus according to claim 1, wherein the second process is not performed when the first in-focus positions are distributed within a predetermined distance range. 10. A first processing step in which the acquisition means acquires a first in-focus position for each ranging area included in the first ranging area composed of a plurality of predetermined ranging areas;
A setting step in which a setting unit sets a part of the first ranging area as a second ranging area;
A second processing step in which the acquisition means acquires a second in-focus position for each ranging area included in the second ranging area;
A correction unit, the correction step of correcting the first focus position using the second focus position,
The first in-focus position is obtained based on an evaluation value indicating an in-focus state obtained at a plurality of focus lens positions while driving the focus lens in a predetermined first scan range. The second focus position is obtained at a plurality of focus lens positions while driving the focus lens in a second scan range narrower than the first scan range. A control method for an image pickup apparatus, characterized in that a focus lens position at which the evaluation value reaches a peak is obtained based on the evaluation value.   The program for making a computer perform each process of the control method of Claim 10.   A computer-readable storage medium storing the program according to claim 11.