JP5404238B2 - Imaging device - Google Patents

Description

  The present invention relates to an imaging apparatus having a tracking function.

  In order to perform appropriate focus control on a moving subject, an imaging device having a tracking function for tracking a subject in a moving image has been proposed. Such an imaging apparatus first stores image data of a subject to be tracked as reference data, and continuously extracts a region having the highest correlation with the reference data from a moving image, thereby realizing a tracking function. Yes. Then, an evaluation value for focus adjustment (hereinafter referred to as AF evaluation value) is obtained from the image data of the area extracted by the tracking function, and the subject to be tracked is controlled by performing focus control using the evaluation value. It is possible to continue focusing on the.

  As a method for determining the reference data, a method in which the user sets a subject to be tracked on a tracking frame provided in the center of the screen and uses image data in the tracking region surrounded by the tracking frame as reference data. There is. Alternatively, a method for allowing the user to specify only the position of the tracking area, automatically determining the size of the tracking area necessary for the imaging device to execute the tracking function, and using the image data of the tracking area after the determination as reference data There is.

  As the latter method, for example, in order to determine the size of the tracking area, there is a method using the variance obtained from the image data of the subject. Specifically, a tracking area is set around the position designated by the user, and the variance of the luminance signal and the color difference signal is obtained from the image data of the tracking area and compared with a threshold value. If each variance does not exceed the threshold value, the size of the tracking area is enlarged. If each variance exceeds the threshold value, the image data of the tracking area at that time is stored as reference data (see Patent Document 1). reference).

JP 2009-1111716 A

  Here, by using an electronic zoom process that can obtain an effect similar to the optical zoom process using a zoom lens by cutting out a partial area of the image data, the size of the tracking area is automatically set as described above. If set to, the focus control accuracy may be affected.

  This is because if the apparent size of the tracking area is made equal, the number of pixels constituting the image data of the tracking area when the electronic zoom process is used is reduced compared to the number of pixels when the electronic zoom process is not used. Due to being. In other words, even when the apparent size of the tracking area is the same, the number of pixels in the tracking area when the electronic zoom process is not used has reached the number necessary for obtaining the AF evaluation value, but the electronic zoom process is used. In some cases, the required number may not be reached. For this reason, there is a possibility that the accuracy of focus control when the electronic zoom process is used may be lower than when the electronic zoom process is not used.

  An object of the present invention is to solve the above-described problems, and even when electronic zoom processing is used, it is possible to suppress a decrease in focus control accuracy as compared to a case where electronic zoom processing is not used, and tracking. The present invention provides an image pickup apparatus that can simultaneously set the size of an area.

In order to solve the above problem, an imaging apparatus according to claim 1, an imaging device, a display unit that displays an image using image data generated by the imaging device, and an image displayed on the display unit. The tracking unit is set with reference to the position on the image specified by the operation unit, and the image data included in the tracking region ensures tracking accuracy. Control means for determining whether or not a condition for satisfying the condition is satisfied, focus control means for performing focus control on the subject in the tracking area, and changing an enlargement ratio of an image displayed by the display means in accordance with a zoom magnification having an electronic zoom means for the focus control means determines the evaluation value from the image data in the region of the same position as the tracking area, there is performed a focus control using the evaluation value, the tracking Set to a large area of the image data for obtaining the evaluation value as the frequency increases, the control unit, when the image data included in the tracking area is determined not to satisfy the condition of the tracking area The size of the display unit with respect to the screen is enlarged, and the minimum size of the tracking area with respect to the screen of the display unit is changed according to the zoom magnification in the electronic zoom unit.

  Even when the electronic zoom process is used, the present invention suppresses a decrease in focus control accuracy compared to a case where the electronic zoom process is not used, and automatically sets the size of the tracking area. It is possible to provide an imaging device that can achieve both of these.

It is the block diagram which showed the structure of the system of the digital camera which can apply this invention. It is a flowchart which shows operation | movement of a digital camera when imaging | photography mode is set. It is a flowchart for demonstrating a zoom process. It is the figure which modeled the storage state of the image data used when calculating | requiring AF evaluation value. It is a flowchart for demonstrating AF evaluation value determination processing. It is a figure for demonstrating the size of the tracking area | region on the image of 1 frame. It is a flowchart for demonstrating a tracking area size setting process.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram showing a system configuration of an imaging apparatus to which the present invention can be applied. In this embodiment, a digital camera will be described as an example. However, the present invention can be applied to a digital video camera.

  In FIG. 1, reference numeral 101 denotes a control unit that controls the entire imaging apparatus, and executes each process described below according to a program stored in a program storage memory (not shown). In addition, the control unit 101 stores image data of a subject to be tracked as reference data, and realizes a tracking function by continuously extracting a region having the highest correlation with the reference data from a moving image. it can. Reference numeral 102 denotes a photographing optical member composed of a plurality of lenses including a focus lens and a zoom lens. A lens actuator 103 adjusts the position of the focus lens and zoom lens on the optical axis of the photographing optical member 102. Reference numeral 104 denotes a driver for performing communication between the control unit 101 and the lens actuator 103.

  Reference numeral 105 denotes an image sensor that receives a subject image transmitted through the photographing optical member 102 and performs photoelectric conversion to generate image data of an analog signal. A CCD (Charge Coupled Device) image sensor or a CMOS (Complementary Metal Oxide Semiconductor) image sensor is applied as the imaging device. Reference numeral 106 denotes an AFE (analog front end circuit) that performs sampling, gain adjustment, A / D conversion, and the like on the image data of the analog signal output from the image sensor 105 and outputs the image data as digital signal image data.

  An image processing unit 107 performs various types of image processing on the digital signal image data output from the AFE 106 and outputs image data including processed luminance signals and color difference signals. For example, various image processing includes white balance processing, chromatic aberration correction processing, color blur suppression processing, distortion aberration correction processing, edge enhancement processing, noise reduction processing, and the like. Further, the image processing unit 107 performs a filtering process for removing unnecessary high frequency components on the image data output from the AFE 106 in order to generate an AF evaluation value used for focus control, and the image data obtained as a result is internally stored. Accumulate in the storage unit 108.

  Reference numeral 108 temporarily stores image data that has been subjected to image processing by the image processing unit 107, image data for display used by the display device 1011 or a zoom position for optical zoom processing or electronic zoom processing. Is an internal storage unit. Reference numeral 109 denotes an external storage unit for storing image data obtained by actual photographing in a storage medium detachable from the digital camera.

  A display unit 110 resizes the image data output from the image processing unit 107 so as to have the size of the display image data, and displays an image using the display image data. The display unit 110 not only displays a still image obtained by actual shooting, but also displays a moving image generated by the image sensor 105 in real time, so that the user can observe the state of the subject. Also, a tracking frame representing the tracking area is displayed superimposed on the moving image. Reference numeral 111 denotes an operation member that converts an instruction by an input from a user who operates the digital camera into an electric signal and transmits the electric signal to the control unit 101. The operation member 111 includes a menu button, a zoom button, a release button, a mode switching dial, a cross button, a touch panel, and the like.

  The digital camera shown in FIG. 1 is set to either a playback mode for playing back a captured image or a shooting mode for shooting when the power is turned on. The user can freely switch between the reproduction mode and the photographing mode by using the operation member 111.

  FIG. 2 is a flowchart showing the operation of the digital camera when the shooting mode is set. When the power of the digital camera is turned on and the shooting mode is set, the image sensor 105 generates a moving image, and the display unit 110 displays a subject image in real time using the generated moving image data.

  In step S <b> 201, the control unit 101 determines whether an instruction for ending the shooting mode is input from the operation member 111. The instruction to end the shooting mode is an operation for turning off the power or an operation for switching to the reproduction mode. If there is an instruction to end the shooting mode, the control unit 101 ends the flowchart, and otherwise proceeds to step S202.

  In step S202, the control unit 101 determines whether the zoom button included in the operation member 111 has been operated. If the zoom button has been operated, the process proceeds to step S203, and if not, the process proceeds to step S204.

  In step S203, the control unit 101 performs zoom processing described later, and returns to step S201.

  In step S204, the control unit 101 determines whether or not the release button included in the operation member 111 has been operated. If it has been operated, the process proceeds to step S205, and if not, the process proceeds to step S206.

  In step S205, the control unit 101 performs still image shooting processing. When the release button included in the operation member 111 is half-pressed, the focus position and exposure value for the actual photographing are obtained from the AF evaluation value and luminance value obtained from the image data at that time, and the release button is fully pressed. Then, the actual shooting of the still image is performed with the focus position and the exposure value. The still image obtained by the main shooting is displayed on the display unit 110 immediately after the main shooting and can be confirmed by the user. When this photographing process is completed, the process returns to step S201.

  In step S206, the control unit 101 determines whether or not the position of the tracking area has been designated by the user using a dial, a cross button, or a touch panel included in the operation member 111. If designated, the process proceeds to step S207. . If not specified, the process returns to step S201.

  In step S207, the control unit 101 performs tracking area size determination processing described later, and proceeds to step S208.

  In step S208, the control unit 101 performs AF evaluation value determination processing described later, and returns to step S201.

  Next, the zoom process in step S203 will be described. In the present embodiment, if the zoom lens does not reach the telephoto end, the zoom process is performed by an optical zoom process that drives the zoom lens. When the focus lens reaches the telephoto end and is instructed to further increase the zoom magnification, electronic zoom processing is performed to realize a zoom magnification that cannot be covered only by driving the zoom lens.

  The electronic zoom processing is to increase the apparent zoom magnification by cutting out a part of the image data generated by the image sensor 105 and displaying it by changing the enlargement ratio. Since a partial area of the image data is cut out, the number of pixels that generate the displayed image data is reduced as compared with the case where the electronic zoom process is not performed. Since the number of pixels included in the image data is reduced in this way in the electronic zoom process, the optical zoom process is performed for the zoom magnification that can be achieved by the optical zoom process, and the electronic zoom process is performed only for the zoom magnification that cannot be achieved by the optical zoom process alone. Assumed to be performed.

  FIG. 3 is a flowchart for explaining the zoom processing in step S203 of FIG.

  In step S <b> 301, the control unit 101 performs initialization necessary for zoom processing on the driver 104 and the internal storage unit 108.

  In step S302, the control unit 101 receives an input corresponding to the zoom operation from the zoom button of the operation member 111, and determines whether or not the zoom operation is being performed. If it is determined that the zoom operation has not been performed, this flowchart is terminated. If the zoom operation has been performed, the process proceeds to step S303.

  In step S303, the control unit 101 determines whether zoom control is possible. Whether or not zoom control is possible is determined by checking the position of the focus lens driven by the lens actuator 103 via the driver 104 and the electronic zoom that is defined in advance and stored in the internal storage unit 108. Judgment is made from both control limits of the process. Increase the zoom magnification when you are instructed to decrease the zoom magnification when the zoom lens is at the wide-angle end, or when the zoom lens has reached the telephoto end and the electronic zoom processing has also reached its limit. When instructed to do so, it is determined that zoom control is impossible. If it is determined that zoom control is possible, the control unit 101 proceeds to step S304. If it is determined that zoom control is not possible, the control unit 101 ends this flowchart.

  In step S304, the control unit 101 determines whether or not the current zoom state is an electronic zoom range. Specifically, if the zoom lens is in a zoom state that has not reached the telephoto end, it is determined that it is not in the electronic zoom range. If the zoom lens has reached the telephoto end and a zoom state in which a part of the image data is cut out by electronic zoom processing, it is determined to be the electronic zoom range. However, when the zoom lens has reached the telephoto end and is in a zoom state in which a part of the image data is not cut out by the electronic zoom process, the determination differs depending on the content of the zoom magnification instruction. If it is instructed to increase the zoom magnification in this state, it is determined to be in the electronic zoom range, and if it is also instructed to decrease the zoom magnification in this state, it is determined not to be in the electronic zoom range.

The control unit 101 proceeds to step S305 if it is determined that it is in the electronic zoom range, and proceeds to step S306 if it is determined that it is not in the electronic zoom range.
In step S <b> 305, the control unit 101 determines a range for cutting out image data in accordance with a zoom magnification instruction, and performs electronic zoom processing. At this time, the zoom position in the current electronic zoom process is stored at an arbitrary address in the internal storage unit 108. Then, the process returns to step S302.

  In step S306, the control unit 101 instructs the lens actuator 103 to drive the zoom lens according to the zoom magnification instruction, and performs optical zoom processing. At this time, the zoom position in the current optical zoom process is stored at an arbitrary address in the internal storage unit 108. Then, the process returns to step S302.

  As described above, the optical zoom process and the electronic zoom process are switched according to the zoom magnification.

  Next, the AF evaluation value determination process in step S208 will be described. FIG. 4 is a diagram schematically illustrating a storage state of image data stored in the internal storage unit 108 and used when obtaining an AF evaluation value.

  Reference numeral 401 in FIG. 4A indicates image data when electronic zoom processing is not performed, and reference numeral 403 indicates an example of the tracking area set in the image data 401. Reference numeral 411 in FIG. 4B shows image data in a state where the electronic zoom processing is not performed. By performing the electronic zoom process, a part of the image data 411 surrounded by a dotted line (here, corresponding to four fifths of the image data 411) is cut out as the image data 412. Reference numeral 413 denotes an example of the tracking area set in the image data 412. The image data 412 is enlarged to the same size as the image data 401 and displayed on the display unit 110. On the image displayed on the display unit 110, the apparent size of the tracking area 403 and the tracking area 413 are equal. .

  FIG. 4C shows the storage state of the image data in the tracking area 403 used when obtaining the AF evaluation value, and FIG. 4D shows the image of the tracking area 413 used when obtaining the AF evaluation value. This indicates the data storage state.

  The small area 421, the middle area 422, and the large area 423 in FIG. 4C indicate the sizes that can be taken by the tracking area 403. The small area 421 has 6 rows and 6 columns, and the middle area 422 has 8 rows and 8 columns. The region 423 is composed of pixels of 10 rows and 10 columns. This tracking area is merely an example, and may be a tracking area having a different number of pixels or different shapes. Reference numeral 424 denotes a maximum value storage area for storing the maximum value of pixels in each row of the tracking area 403, and stores the same number of pixel values as the number of lines in the tracking area 403. That is, the maximum value storage area stores six values when the size of the tracking area 403 is equal to the small area 421, eight values when equal to the middle area 422, and ten values when equal to the large area 423. Is stored.

  The small region 431, the middle region 432, and the large region 433 in FIG. 4D are tracked so that the relative size ratios of the small region 421, the middle region 422, and the large region 423 in FIG. The area 413 is classified into three sizes. However, when the apparent size of the tracking area 413 is the same as that of the tracking area 403, the number of pixels included in the area is smaller than that of the tracking area 403. Further, when the zoom magnification of the electronic zoom process changes, the number of pixels included in each of the small area 431, the middle area 432, and the large area 433 also changes. In the example of FIG. 4B, the small region 431 is a pixel of 5 rows and 5 columns, the middle region 432 is a pixel of 7 rows and 7 columns, and the large region 433 is a pixel of 8 rows and 8 columns. Reference numeral 434 denotes a maximum value storage area for storing the maximum value of pixels in each row of the tracking area 413, and stores the same number of pixel values as the number of lines in the tracking area 413.

  FIG. 5 is a flowchart for explaining the AF evaluation value determination processing in step S208 of FIG. Here, a case where electronic zoom processing is not performed will be described as an example. When the electronic zoom processing is performed, in the description of FIG. 5 below, the tracking area 403 may be replaced with the tracking area 413 and the maximum value storage area 424 may be replaced with the maximum value storage area 434.

  In step S501, the control unit 101 resets the value stored in the maximum value storage area 424, and sets the reference position in the tracking area 403 to the left end of the uppermost stage. The control unit 101 sequentially moves the reference position from the top left end of the tracking area 403 and reads out all the pixel values included in the tracking area 403.

  In step S502, the control unit 101 compares the pixel value at the reference position in the tracking area 403 with the value in the maximum value storage area 424 corresponding to the row at the reference position. As a result of the comparison, if the pixel value at the reference position of the tracking area 403 is larger, the control unit 101 proceeds to step S503, otherwise proceeds to step S504.

  In step S503, the control unit 101 updates the value of the maximum value storage area 424 corresponding to the row of the reference position to the pixel value of the reference position of the tracking area 403, and proceeds to step S504. Initially, since the value in the maximum value storage area 424 is reset, the uppermost pixel value at the uppermost stage in the tracking area 403 is stored in the uppermost maximum value storage area 424.

  In step S504, the control unit 101 determines whether all pixel values in the same row have been referred to. If the pixel values have been referred to, the process proceeds to step S506.

  In step S505, the control unit 101 moves the reference position to the adjacent right pixel, and returns to step S502.

  In step S506, the control unit 101 determines whether the pixel values of all rows have been referred to. If there is a row that has not been referred to yet, the control unit 101 proceeds to step S507. If all the rows have been referenced, the control unit 101 proceeds to step S508. .

  In step S507, the control unit 101 moves the reference position to the leftmost pixel in the adjacent lower row, and returns to step S502.

  By performing the processing in this manner, the control unit 101 performs processing for storing the maximum pixel value in each row of the tracking area 403 in the maximum value storage area 424 corresponding to that line for all the rows in the tracking area 403. Do.

  In step S508, the control unit 101 calculates an AF evaluation value using the pixel value stored in the maximum value storage area 424, and ends this flowchart. Specifically, the AF evaluation value is calculated by adding all the maximum values of each row included in the maximum value storage area 424, and setting the AF evaluation value so that the larger the added value is, the larger the value is. . This is because the pixel value obtained from the region increases as the focus is adjusted.

  Here, when determining the AF evaluation value, as the number of rows of pixels included in the tracking areas 403 and 413 increases, the random noise component included in the maximum value storage areas 424 and 434 can be suppressed by addition. . In other words, the smaller the number of rows of pixels included in the tracking areas 403 and 413, the higher the ratio of random noise components in the addition result even if the values in the maximum value storage areas 424 and 434 are added. As a result, the accuracy of the AF evaluation value also decreases.

  Therefore, the control unit 101 changes the minimum size of the tracking area that can be set according to the zoom magnification in order to secure the number of rows of pixels included in the tracking area. Specifically, when the zoom magnification of the electronic zoom process is higher than the threshold, setting the size of the tracking area 413 to the small area 431 is prohibited, and only one of the middle area 432 and the large area 433 is set. It can be so. The AF evaluation value determination process described with reference to FIGS. 4 and 5 is an example, and the AF evaluation value may be obtained by another known method. As long as the number of pixels that refer to the pixel value increases, random noise can be suppressed as long as the AF evaluation value is obtained by another method. is there.

  FIG. 6 is a diagram for explaining one frame image of the moving image displayed on the display unit 110 and the size of the tracking area on the one frame image. 6A to 6C, reference numeral 601 denotes an image displayed on the display unit 110, and reference numerals 611, 612, and 613 denote tracking areas set on the image 601. 6D, reference numeral 602 denotes an image displayed on the display unit 110 when reference data necessary for executing the tracking function cannot be obtained at a position designated by the user as will be described later. It is.

  FIG. 7 is a flowchart for explaining the tracking area size setting process in step S207 of FIG.

  In step S <b> 701, the center position of the tracking area is set at a position instructed by the user using the operation member 111. When the user performs an operation to instruct the position of the tracking area, a temporary tracking frame is displayed on the display unit 110 so as to be superimposed on the moving image, and the user moves the tracking frame by operating the operation member. The operation member 111 includes, for example, a dial and a cross button, and the tracking frame can be moved to an arbitrary position on the image by the user's operation. Alternatively, the operation member 111 includes a touch panel configured integrally with the display unit 110, and the user touches an arbitrary position on the screen of the display unit 110 to move the tracking frame to that position. It may be. Further, instead of the tracking frame, a cross mark or a cursor may be displayed on the display unit 110 to allow the user to specify an arbitrary position. In the present embodiment, the control unit 101 moves the tracking frame to a position designated by the user, and sets the center position of the tracking frame as the center position of the tracking area.

  In the present embodiment, a tracking area having a predetermined small size, medium size, or large size is selected as the tracking area. These small, medium, and large tracking areas are set so that the ratio of the size to the image displayed on the display unit 110 is constant regardless of the zoom magnification.

  In step S702, the control unit 101 reads the zoom position stored in the internal storage unit 108, and determines whether or not electronic zoom processing is being performed. If the electronic zoom process is being performed, the control unit 101 proceeds to step S703, and if not, the process proceeds to step S705.

  In step S703, the control unit 101 determines whether or not the zoom magnification is greater than or equal to a threshold. If the zoom magnification is greater than or equal to the threshold, the process proceeds to step S704, and if less than the threshold, the process proceeds to step S705.

  In step S704, the control unit 101 sets a medium-size tracking area as the initial size of the tracking area. If it demonstrates using FIG. 6, the tracking area | region 612 of medium size in FIG.6 (b) will be set centering on the position designated by the user.

  In step S705, the control unit 101 sets a small-sized tracking area as the initial size of the tracking area. Similarly, with reference to FIG. 6, the tracking area 611 having a small size in FIG. 6A is set around the position designated by the user.

  As described above, the control unit 101 sets the tracking area 611 having a small size both when the optical zoom process is performed and when the electronic zoom process is performed as long as the zoom magnification is less than the threshold value. To do. Since the ratio of the size of the small-size tracking area 611 to the image 601 displayed on the display unit 110 is set to be constant regardless of the zoom magnification, the tracking area increases as the zoom magnification in the electronic zoom processing increases. The number of pixels included in 611 decreases. For this reason, when the zoom magnification is equal to or greater than the threshold, the number of pixels included in the tracking area 611 does not reach the number necessary to ensure the accuracy of the AF evaluation value in the AF evaluation value determination process in step S208. Therefore, when the zoom magnification becomes equal to or larger than the threshold value, the control unit 101 sets a tracking area 612 having a medium size that can secure the number of pixels necessary for ensuring the accuracy of the AF evaluation value as the initial size of the tracking area. Like to do.

  In step S706, the control unit 101 determines whether the image data in the tracking area satisfies a predetermined condition. Specifically, the difference between the maximum luminance and the minimum luminance obtained from the pixels in the tracking area is obtained, and if this difference is greater than or equal to the reference value, the process proceeds to step S707, and if less than the reference value, the process proceeds to step S708.

  In step S707, the control unit 101 causes the internal storage unit 108 to store, as reference data, image data configured with pixel values included in the tracking area. If the reference data can be obtained, this flowchart is terminated, and the process proceeds to the AF evaluation value determination process in step S208 of FIG.

  The determination in step S706 is performed if a luminance difference equal to or greater than the reference value is obtained from the pixels in the tracking area, even if pattern matching using the luminance value is performed, another subject is erroneously extracted. This is because it is considered that there is a low possibility that it will occur. For example, in the examples shown in FIGS. 6A and 6B, the small size tracking area 611 and the medium size tracking area 612 include only the windshield of the vehicle, and the luminance difference in the tracking area Has not reached the reference value. When tracking is performed with pattern matching using luminance values in this state, the luminance values in the windshield are similar, so even if the position of the car is stopped, the tracking area does not protrude from the windshield. It is unstable and unstable. In contrast, in the example shown in FIG. 6C, the large tracking area 611 includes not only the windshield, but also the boundary between the windshield and the background, and the boundary between the windshield and the car roof. The luminance difference is larger than the reference value. Even if tracking is performed by pattern matching using luminance values, an area in which these boundary portions are included in the same positional relationship will be extracted, so even if the position of the car slides, the tracking area is set accordingly. Can be followed.

  In step S706, the control unit 101 has obtained the difference between the maximum luminance and the minimum luminance obtained from the pixels in the tracking area, but is not limited thereto. The predetermined condition may be any condition as long as it is a condition for ensuring tracking accuracy. For example, as described in the background art, if each variance of the luminance signal and the chrominance signal is greater than or equal to a reference value from the pixel value of the tracking area, the pixel value of the tracking area at that time is stored as reference data. Also good. This is because when the pixel values of the tracking area are similar (when the variance is small), it is highly likely that the tracking area contains only a uniform subject such as the windshield described above. is there. Alternatively, if the difference between the saturation and hue values is not less than the reference value or the variance is not less than the reference value without obtaining the luminance value, the pixel value of the tracking area at that time is used as the reference. It may be stored as data.

  In step S708, the control unit 101 determines whether the tracking area is set to the maximum size (large size 613). If the tracking area is not set to the maximum size, the process proceeds to step S709. If the tracking area has already been set to the maximum size, the tracking area cannot be enlarged any further, and the process advances to step S710.

  In step S709, the control unit 101 enlarges the size of the tracking area by one step. If the set tracking area is small, the medium size is set. If the set tracking area is medium size, the large size is set, and the process returns to step S706.

  In step S710, the control unit 101 cannot acquire the reference data necessary for ensuring the accuracy of the tracking function. Therefore, the control unit 101 notifies the display unit 110 of FIG. The illustrated display is performed, and this flowchart is terminated.

  As described above, according to the present embodiment, in order to secure the number of pixels included in the tracking area, the minimum value of the ratio of the size of the tracking area to the size of the image displayed on the display unit 110 is limited according to the zoom magnification. doing.

  In the present embodiment, the small-size tracking area cannot be set only when the electronic zoom process is performed and the zoom magnification is equal to or greater than the threshold. However, the present invention is not limited to this. The number of types that can be set for the tracking area is further increased, multiple thresholds are set for the zoom ratio, and the minimum size that can be set for the tracking area is increased as the number of thresholds exceeding the zoom ratio increases. It doesn't matter. Alternatively, the size of the tracking area that can be set according to the zoom magnification is continuously changed, and the tracking according to the zoom magnification is included so that a predetermined number of pixels necessary for ensuring the accuracy of the AF evaluation value are included. The minimum size of the area may be calculated and set.

  In addition, although the tracking area and the area from which the pixel value is read in order to obtain the AF evaluation value are set equal, the present invention is not limited to this. As long as the size of the tracking area increases, the size of the area from which the pixel value is read in order to obtain the AF evaluation value increases. However, even in this case, the minimum size of the tracking area is the number of pixels necessary for ensuring the accuracy of the AF evaluation value in the area for obtaining the AF evaluation value corresponding to the minimum size. Must be configured to be included.

  Further, the present invention can be applied even to an imaging apparatus that does not include a photographing optical member for performing optical zoom processing or a lens actuator and performs zooming only by electronic zoom processing.

DESCRIPTION OF SYMBOLS 101 Control part 102 Image | photographing optical member 103 Lens actuator 104 Driver 105 Image pick-up element 106 AFE
107 Image processing unit 108 Internal storage unit 109 External storage unit 110 Display unit 111 Operation member

Claims (3)

An image sensor;
Display means for displaying an image using image data generated by the image sensor;
Operating means for causing the position of the tracking target in the image displayed on the display means to be designated;
Control means for setting a tracking area on the basis of the position on the image designated by the operation means and determining whether image data included in the tracking area satisfies a condition for ensuring tracking accuracy When,
Focus control means for performing focus control on the subject in the tracking area;
Electronic zoom means for changing an enlargement ratio of an image displayed by the display means according to a zoom magnification;
The focus control means obtains an evaluation value from image data in an area at the same position as the tracking area, performs focus control using the evaluation value, and obtains the evaluation value as the tracking area becomes larger Set the image data area of
Wherein when the image data included in the tracking area is determined not to satisfy the above condition is for enlarging the size relative to the screen of the display unit of the tracking area, the said tracking area An image pickup apparatus, wherein a minimum size of a display unit with respect to a screen is changed according to the zoom magnification of the electronic zoom unit.   The said control means memorize | stores the image data of the said tracking area | region as reference | standard data, and tracks by extracting the area | region with high correlation with the said reference | standard data from a moving image continuously. Imaging device. Before The Kijo matter, or the difference of pixel values in the tracking area is not less than the reference value, or to claim 1 or 2 the variance of pixel values in the tracking area is equal to or is more than the reference value The imaging device described.

Images