JP2015004922A - Focus adjustment device and imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely focus on a subject even when a main subject is a subject other than a person.SOLUTION: A focus adjustment device according to the present invention comprises: an imaging optical system that takes in subject light; a generation part that generates a first image having a subject included; a setting part that performs a template matching second images consecutively acquired on the basis of the subject light to be taken in by the imaging optical system, using the first image and thereby sets an area to be cut out from the second images, respectively as a target area; a compression part that performs a compression process to each of images of the target areas cut out from the second images; and a control part that controls a focus position in the imaging optical system on the basis of a change in a volume of data on the image of the target area subjected to the compression process.

Description

  The present invention relates to a focus adjustment device and an imaging device.

  When performing high-speed continuous shooting using a digital camera equipped with phase difference detection method or contrast detection method autofocus (AF) control, it is difficult to perform the above AF control between each shooting. In general, the focus is fixed (see Patent Document 1). Therefore, it has been devised to perform focus control in high-speed continuous shooting based on a change in the data amount of image data itself obtained by individual shooting in high-speed continuous shooting.

JP 2006-201282 A

  For example, when the change in the amount of image data is used for focus control in high-speed continuous shooting, if the amount of image data obtained is constant, the main subject is in focus even if the main subject is not in focus. It is determined that it is correct. Therefore, it has been devised to use a change in the amount of image data obtained by cutting out a predetermined range including a focus detection position and a main subject used at the time of photographing. However, when an object other than a person is used as the main subject, the object that is the main subject is not necessarily recognized as the main subject. Therefore, when the main subject is an object other than a person, the object However, there is a problem that it is difficult to focus on.

  It is an object of the present invention to provide a focus adjustment device and an imaging device that can reliably focus on an object other than a person, even if the main subject is an object other than a person.

  The focus adjustment apparatus of the present invention is continuously acquired based on an imaging optical system that captures subject light, a generation unit that generates a first image including the subject, and subject light captured by the imaging optical system. By performing template matching using the first image on the second image, a setting unit that sets a region to be cut out from each of the second images as a target region, and cut out from the second image A compression unit that performs compression processing on each of the images in the target area; and a control unit that controls a focus position in the imaging optical system based on a change in the data amount of the compressed image of the target area. , Provided.

  In addition, the imaging apparatus of the present invention is capable of continuously outputting an image based on captured subject light, and the focus position of the imaging optical system based on the image output from the imaging element. The focus adjusting device described above is controlled.

  According to the present invention, even when the main subject is an object other than a person, the object can be reliably focused.

It is a functional block diagram which shows the structure of the digital camera of this invention. (A) The figure which shows the comparison object area | region set when the size of a face area is smaller than the magnitude | size of one division area, and a face area is settled in one division area, (b) The magnitude | size of a face area The figure which shows the comparison object area | region set when it is smaller than the size of one division area, and a face area straddles several division areas, (c) When the size of a face area is larger than the magnitude | size of one division area It is a figure which shows the comparison object area | region set to. (A) The figure which shows the comparison object area | region set when the largest face area is selected among several face areas, (b) The face area superimposed on AF area was selected among several face areas It is a figure which shows the comparison object area | region set in the case. It is a figure which shows the area | region of the main subject specified from the image which imaged the race vehicle to drive, and contrast information. (A) The figure which shows the comparison object area | region set when there is one AF area which focuses, and this AF area is settled in one division area, (a) There is one AF area which focuses, Also, it is a diagram showing a comparison target area that is set when the AF area extends over a plurality of divided areas. (A) The figure which shows the comparison object area | region set when the some AF area which focuses is contained in one division area, (b) The case where the some AF area which focuses is straddling the several division area which adjoins FIG. 4C is a diagram showing a comparison target area set in (c), and FIG. 4C is a diagram showing a comparison target area set when a plurality of in-focus AF areas fit in each of divided areas. It is a flowchart which shows the flow of a series of processes in high-speed continuous shooting. It is a flowchart which shows the flow of a series of processes in high-speed continuous shooting. It is a flowchart which shows the flow of a series of processes in high-speed continuous shooting.

  Hereinafter, a digital camera 10 will be described as an example of an embodiment of the present invention. The digital camera 10 of the present invention can perform continuous shooting in which a plurality of still images are acquired by continuously performing a plurality of imaging processes in addition to shooting that acquires a still image by a single imaging process. . This continuous shooting can be performed at a high speed, such as 30 frames / second, 50 frames / second, and 60 frames / second. Hereinafter, high-speed continuous shooting will be referred to as high-speed continuous shooting.

  As shown in FIG. 1, the digital camera 10 includes an imaging optical system 15, a quick return mirror 16, a mechanical shutter 17, an image sensor 18, an analog front end (AFE) circuit 19, a timing generator (TG) 20, and a lens driving mechanism 21. , Shutter drive mechanism 22, buffer memory 25, image processing circuit 26, compression / expansion circuit 27, display control circuit 28, display device 29, connection I / F 30, CPU 40, nonvolatile memory 41, work memory 42, focus detection unit 43, a release button 44, an operation unit 45, and the like. The AFE circuit 19, the buffer memory 25, the image processing circuit 26, the compression / decompression circuit 27, the display control circuit 28, the connection I / F 30, and the CPU 40 are electrically connected via a bus 46.

  The imaging optical system 15 forms an object scene light beam and forms an object scene image near the imaging surface of the image sensor 18. In FIG. 1, the imaging optical system 15 is described as a single lens, but actually, the imaging optical system 15 includes a plurality of lenses including a focusing lens. The focusing lens is moved in the optical axis direction via the lens driving mechanism 21. Focus control is executed by moving the focusing lens in the optical axis direction.

  The imaging optical system 15 includes a diaphragm (not shown). The diaphragm diameter is adjusted according to the Av value set by the CPU 40. This Av value may be a value input by the user or a value calculated by automatic exposure calculation.

  The quick return mirror 16 is disposed on the optical path of the field light beam between the imaging optical system 15 and the imaging element 18. The quick return mirror 16 is switched between a mirror-down state and a mirror-up state. When the quick return mirror 16 is in the mirror-down state, the subject light flux is guided by the quick return mirror 16 to the focus detection unit 43 and a photometry unit (not shown). On the other hand, when the quick return mirror 16 is in the mirror-up state, the subject light flux is guided to the image sensor 18 by the quick return mirror 16.

  The mechanical shutter 17 is disposed on the optical path of the field light beam between the quick return mirror 16 and the image sensor 18. The mechanical shutter 17 is opened and closed by a shutter drive mechanism 22 that has received a drive signal from the TG 20.

  The image sensor 18 is composed of a CCD image sensor, a CMOS image sensor, or the like. The image sensor 18 accumulates signals and reads signals in accordance with the drive signal supplied from the TG 20.

  The TG 20 outputs a drive signal to the image sensor 18 and the shutter drive mechanism 22 in response to an instruction from the CPU 40. Further, the TG 20 supplies a synchronization signal to the AFE circuit 19 and the CPU 40. Here, the TG 20 controls the exposure time per frame by a combination of the pattern of the drive signal supplied to the image sensor 18 and the pattern of the drive signal supplied to the mechanical shutter 17. The exposure time is set to a value corresponding to the Tv value designated by the CPU 40. Here, the Tv value may be a value input by the user or a value calculated by automatic exposure calculation. Here, when high-speed continuous shooting is performed, drive control (signal accumulation and signal readout) of the image sensor 18 is performed while the mechanical shutter 17 is kept open. In this case, the exposure time is controlled only by the drive signal supplied to the image sensor 18. That is, when high-speed continuous shooting is performed, the electronic shutter is used instead of the mechanical shutter 17.

  The AFE circuit 19 includes a CDS circuit, a gain circuit, an A / D conversion circuit, and the like. The CDS circuit removes the noise component of the analog signal output from the image sensor 18 by correlated double sampling. The gain circuit amplifies the analog signal from which noise has been removed. The A / D conversion circuit converts the amplified analog signal into a digital signal.

  Here, the signal amplification factor (gain) used when the signal is amplified by the gain circuit is a value based on the Sv value from the CPU 40. This Sv value is a sensitivity at the time of photographing (ISO sensitivity), and this Sv value may be a value designated by the user or a value calculated by automatic exposure calculation.

  The focus detection unit 43 generates a defocus signal of the imaging optical system 15 for the imaging element 18 by dividing the pupil of the field light beam guided from the quick return mirror 16 in the mirror-down state and then reintegrating it. Consists of a phase difference detection type focus detection unit. Here, the defocus signal of the imaging optical system 15 is generated in each of a plurality of AF areas arranged in a plurality with respect to the imaging range.

  In the buffer memory 25, the digital signal output from the AFE circuit 19 is written. In the buffer memory 25, the digital signal output from the AFE circuit 19 is written, and other digital signals transferred from the image processing circuit 26 are written. Here, the buffer memory 25 can store digital signals for a plurality of frames.

  The image processing circuit 26 includes a white balance processing circuit, a pixel interpolation circuit, a matrix processing circuit, a non-linear transformation (γ correction) processing circuit, an edge enhancement processing circuit, and the like. For the digital signal read from the buffer memory 25, Processing such as white balance, pixel interpolation, matrix, non-linear transformation (γ correction) and contour enhancement is performed.

  The image processing circuit 26 includes a template generation unit 47 and a trimming unit 48. The template generation unit 47 specifies an area including the main subject using contrast information obtained from image data captured during AF processing. After this specification, the template generation unit 47 generates an image composed of the specified area as a template image. Note that, when generating the template image, the contrast information of the image data captured at the time of AF processing is used. However, in addition to the contrast information, the color information in the image data is used to specify the region including the subject. Is also possible.

  The trimming unit 48 trims an area corresponding to a comparison target area described later from each of the image data obtained by the high-speed continuous shooting. Note that image data (target image data) generated by the trimming process is stored in the buffer memory 25.

  The compression / decompression circuit 27 performs compression processing on the image data that has undergone image processing and the target image data. The compressed image data is written into the storage medium 50 via the connection I / F 30. Here, examples of the storage medium 50 include a memory card including a nonvolatile memory, an optical disk, and a magnetic disk. Further, the compression / decompression circuit 27 performs decompression processing on the compressed image data read from the storage medium 50. The display control circuit 28 converts the input image data into a predetermined signal for display and displays it on the display device 29.

  The CPU 40 controls each unit using the work memory 42 as a temporary storage work area according to a control program stored in the nonvolatile memory 41. In the CPU 40, the functions of the face detection unit 51, the region setting unit 52, the data comparison unit 53, and the focus control unit 54 become effective during high-speed continuous shooting.

  The face detection unit 51 detects the face of a person included in the image. As the process for detecting the face, for example, a skin color area included in the image is detected, and a process for determining whether the face is a feature from the feature amount included in the skin color area, or a plurality of face shape templates. For example, a process for detecting a face region from the correlation between the template and the image is prepared. When a face is detected, the face detection unit 51 obtains position information of a rectangular area including the detected face. Here, the position information of the face area is address data indicating the position coordinates of the four corner vertices of the face area.

  The region setting unit 52 sets a region (comparison target region) to be used when comparing the data amount executed by the data comparison unit 53. The area setting unit 52 divides the image obtained by the first imaging process into a total of m × n areas of vertical m and horizontal n. Data relating to this area division is stored in the work memory 42, for example. Hereinafter, an area obtained by dividing an image will be described as a divided area. When a face is detected in the face detection processing by the face detection unit 51, a divided area including the detected face area is set as a comparison target area among a plurality of divided areas set in the image. On the other hand, when a face is not detected in the face detection process by the face detection unit 51, the region setting unit 52 executes the following process depending on whether a template image is generated. For example, when a template image is generated, the region setting unit 52 performs template matching using the template image and an image acquired by high-speed continuous shooting. Then, the region setting unit 52 sets a rectangular region including a region that matches the template image by template matching as a comparison target region. On the other hand, when the template image is not generated, the area setting unit 52 sets a divided area including the AF area used in the focus control in the first imaging process as the comparison target area. Then, after setting the comparison target region by any of the methods described above, the region setting unit 52 obtains position information of the comparison target region. The position information of the comparison target region is output to the image processing circuit 26. The trimming unit 48 of the image processing circuit 26 performs a trimming process on each image data obtained by the high-speed continuous shooting based on the position information of the comparison target region. By this trimming process, target image data is generated.

  The data comparison unit 53 compares the data amounts of the target image data subjected to the compression process. In general, when the same scene is photographed twice in succession, if the individual photographing is in focus, the data amounts of the two image data obtained by the respective photographings are approximated. However, when the first shot is in focus and the second shot is not in focus, the image obtained by the first shot is an image with high sharpness, and the image obtained by the second shot is The image is low in sharpness. Here, the data amount of an image with high sharpness tends to be larger than the data amount of an image with low sharpness. The comparison target area is an area including a face area of a person, an area of a subject other than a person, or an in-focus AF area. Therefore, by comparing the data amounts of the target image data that has been subjected to compression processing, it is possible to perform focus control so that a region to be noticed is focused and other regions are not focused.

  The focus control unit 54 performs focus control during shooting. For example, focus control in the first imaging process in high-speed continuous shooting is focus control using the detection result in the focus detection unit 43. Further, the second and subsequent focus control in high-speed continuous shooting is focus control based on the comparison result by the data comparison unit 53. Note that the second and subsequent focus control is feedback control using the relationship between the sharpness in the target image data obtained by trimming the comparison target region and the data amount of the target image data.

Next, setting of the comparison target area will be described. First, the area setting unit 52 divides an image obtained by the first imaging process into m × n divided areas. FIG. 2 shows a case where the image P obtained by the first imaging process is divided into ₂₄ areas A _{1 to} A ₂₄ in total of 4 vertically and 6 horizontally.

  Then, the comparison target area is set according to the following procedure. First, when a face is detected by the face detection unit 51, the region setting unit 52 determines whether the detected face is single (one) or plural (two or more). For example, when one face is detected from the image P, the area setting unit 52 determines whether or not the detected face area (face area) is smaller than one divided area. When it is determined that the face area is smaller than the divided area, the area setting unit 52 determines whether the detected face area falls within any of the plurality of divided areas or straddles the plurality of divided areas.

As shown in FIG. 2A, when the detected face area FR ₁ is smaller than one divided area and the face area FR ₁ fits in the divided area A ₁₇ , the area setting unit 52 sets the divided area A _17. Is set as the comparison target area.

As shown in FIG. 2B, even if the detected face area FR ₂ is smaller than one divided area, the face area FR ₂ is divided into a plurality of divided areas A ₁₀ , A ₁₁ , A ₁₆ , A There are times when it straddles ₁₇ . In such a case, the area setting unit 52 sets the divided areas A ₁₀ , A ₁₁ , A ₁₆ , and A ₁₇ as comparison target areas. FIG. 2B illustrates a case where the face area FR ₂ extends over a plurality of divided areas A ₁₀ , A ₁₁ , A ₁₆ , A ₁₇ , but the face area is adjacent in the vertical direction or the horizontal direction 2. When straddling two divided regions, two divided regions straddling the face region are set as comparison target regions.

As shown in FIG. 2C, when the face area FR ₃ is larger than one divided area, the face area FR ₃ straddles a plurality of divided areas. In such a case, the area setting unit 52 The divided areas A ₁₀ , A ₁₁ , A ₁₂ , A ₁₆ , A ₁₇ , A ₁₈ , A ₂₂ , A ₂₃ , and A ₂₄ that the face area FR ₃ straddles are set as comparison target areas. Note that the comparison target area is set in the same manner when the detected face area extends over other divided areas.

Next, when there are a plurality of faces detected by the face detection unit 51, the area setting unit 52 first has a face area larger than one divided area among the face areas based on the detected plurality of faces. It is determined whether or not. FIG. 3A shows a case where three face regions FR ₄ , FR ₅ , FR ₆ are detected. When the face area FR ₆ is the largest face area among the face areas FR ₄ , FR ₅ , and FR ₆ , the area setting unit 52 selects the face area FR ₆ . Then, the area setting unit 52 sets the divided areas A ₁₆ , A ₁₇ , A ₂₂ , A ₂₃ that the selected face area FR ₆ spans as comparison target areas.

As shown in FIG. 3B, all of the detected three face regions FR ₇ , FR ₈ , FR ₉ may be smaller than one divided region. In such a case, the area setting unit 52 determines whether there is a face area to be superimposed on any of the AF areas based on the position of the face area and the position of the AF area. If there is a face area to be superimposed on any of the AF areas, the area dividing unit 52 selects the face area, and sets a divided area in which the selected face area fits or a divided area that spans the face area as a comparison target area. To do. In FIG. 3B, since the face area FR ₈ is superimposed on the AF area, the area setting unit 52 selects the face area FR ₈ . Then, the area setting unit 52 sets the divided regions A ₉ the face area FR ₈ falls as a comparison target area. If none of the detected face areas is superimposed on the AF area, the divided area where the largest face area is located among the detected face areas may be set as the comparison target area, or the focused AF is performed. A divided region including an area may be set as a comparison target region.

  On the other hand, when a face is not detected by the face detection unit 51 and a template image is generated, a comparison target region is set by the following method. The AF process when executing high-speed continuous shooting is executed in response to a half-press operation of the release button 44. Therefore, the template generation unit 47 acquires the contrast information from the image data obtained during the AF process, and then generates a template image using the acquired contrast information. As shown in FIG. 4, for example, consider a case where high-speed continuous shooting is performed on a running race vehicle. In this case, it is common to shoot with the focus on the helmet worn by the driver. Therefore, the contrast near the helmet is higher than in other areas. Therefore, the template generation unit 47 generates template image data using a rectangular region 60 including a helmet with high contrast.

  Therefore, the region setting unit 52 performs template matching using the template image data on the image data obtained by each imaging process in the high-speed continuous shooting, and sets a region corresponding to the template image data as a comparison target region. .

  Furthermore, there is a case where no face is detected by the face detection unit 51 and a template image is not generated. In this case, the region setting unit 52 sets one of the plurality of divided regions as a comparison target region based on the result of focus control executed when high-speed continuous shooting is started. In the first imaging process described above, focus control using a defocus signal for each AF area obtained by the focus detection unit 43 is executed. The area setting unit 52 sets a comparison target area using an AF area in focus among these AF areas.

As shown in FIG. 5 (a), if the AF area _{B 1} is a AF area in focus, the AF area _{B 1} represents is within a divided region _{A 10.} Therefore, the area setting unit 52 sets the divided regions _{A 10} to AF area _{B 1} is fit for comparison region.

As shown in FIG. 5B, when the AF area B ₂ extending over the divided areas A ₉ , A ₁₀ , A ₁₅ , A ₁₆ is an in-focus AF area, the area setting unit 52 includes the divided areas A ₉ , A ₁₀ , A ₁₅ , and A ₁₆ are set as comparison target areas.

For example, during shooting, a plurality of AF areas may be in-focus AF areas. In such a case, the area setting unit 52 determines whether or not each of the focused AF areas fits in one divided area. FIG. 6A shows a case where a plurality of in-focus AF areas fit within a single divided area, and the in-focus AF area is shown in a solid color. In this case, the area setting unit 52 sets the divided area A ₁₀ that is the AF area in focus falls as a comparison target area.

On the other hand, when there are a plurality of in-focus AF areas and each AF area fits in a plurality of divided areas, the area setting unit 52 sets all the divided areas including the in-focus AF areas as comparison target areas. . In the case of FIG. 6B, the AF area indicated by filling is an in-focus AF area. In this case, the area setting unit 52 sets the divided areas A ₉ , A ₁₀ , A ₁₅ , and A ₁₆ where the focused AF area is located as the comparison target area.

As shown in FIG. 6C, the focused AF areas may not be located close to each other but may be located discretely. In such a case, the area setting unit 52 sets the divided area A ₈ and the divided areas A ₁₀ and A ₁₁ including the focused AF area as the comparison target areas.

  Hereinafter, the flow of processing when performing high-speed continuous shooting will be described with reference to the flowcharts of FIGS.

  Step S101 is processing for determining whether or not the release button has been pressed halfway. Although details are omitted, the release button 44 is provided with a detection switch for detecting the half-pressing operation and the full-pressing operation. When the release button 44 is half-pressed, a detection switch that detects the half-press operation is turned on, and a signal (hereinafter, half-press signal) is output to the CPU 40. In response to the input of the half-press signal, the CPU 40 sets the result of the determination process in step S101 to Yes. In this case, the process proceeds to step S102.

  On the other hand, when the release button 44 is not half-pressed, the half-press signal is not input to the CPU 40. In this case, the CPU 40 sets the result of the determination process in step S101 to No. That is, the determination process of step S101 is repeatedly executed until the determination result of step S101 is Yes.

  Step S102 is processing for executing AE processing and AF processing. The CPU 40 executes AE processing based on a signal output from a photometry device (not shown). When the CPU 40 executes the AE process, a combination of the Tv value, the Av value, and the Sv value is determined. In addition, the CPU 40 executes AF processing based on the defocus signal output from the focus detection unit 43.

  Step S103 is processing for generating template image data. The CPU 40 uses the contrast information of the image data obtained at the time of the AF processing, and specifies a region with high contrast as a region to be a main subject. Then, the image processing circuit 26 generates image data based on the identified region as the main subject as template image data.

  Step S104 is processing for determining whether or not the half-press operation of the release button has been released. As described above, when the release button 44 is half-pressed, a half-press signal is input to the CPU 40. Further, when the half-press operation of the release button 44 is released, the output of the half-press signal to the CPU 40 is stopped. That is, in this step S104, the CPU 40 determines whether or not the half-press operation of the release button 44 has been released depending on whether or not the output of the half-press signal of the release button 44 has been stopped.

  For example, when the output of the half-press signal is continued, the CPU 40 determines that the half-press operation of the release button 44 has not been released. In this case, the result of the determination process in step S104 is No, and the process proceeds to step S105. On the other hand, when the output of the half-press signal is stopped, the CPU 40 determines that the half-press operation of the release button 44 has been released. In this case, the result of the determination process in step S104 is Yes, and the process returns to step S101.

  Step S105 is processing for determining whether or not the release button has been fully pressed. When the release button 44 is fully pressed, a detection switch for detecting the full press operation is turned on, and a signal (full press signal) is output to the CPU 40. In response to the input of the full press signal, the CPU 40 sets the result of the determination process in step S104 to Yes. In this case, the process proceeds to step S106. On the other hand, when the full press signal is not input, the CPU 40 sets the result of the determination process in step S105 to No. In this case, the process returns to step S104.

  Step S106 is an imaging process (first time). The CPU 40 designates the Tv value, Av value, and Sv value determined in step S102 to the lens driving mechanism 21, the TG 20, and the AFE circuit 19. At the same time, the CPU 40 switches the quick return mirror 16 to the mirror-up state. Then, the CPU 40 outputs an imaging start signal to the TG 20. Thereby, an imaging process is performed.

By performing this imaging process, an image signal is output from the imaging element 18. This image signal is stored in the buffer memory 25 via the AFE circuit 19. The image processing circuit 26 reads the image signal stored in the buffer memory 25. The image processing circuit 26 performs image processing such as white balance adjustment, color interpolation, gradation conversion, and color conversion on the read image signal. Thus, the image data P ₁ is generated. The compression / decompression circuit 27 duplicates (copies) image-processed image data on the buffer memory 25. Then, performs compression process on the image data P ₁ duplicating. Then, the compressed image data P ₁ is stored in the buffer memory 25.

Step S107 is a process of storing data amount of the image data _{P 1} and the image data _{P 1.} The CPU 40 reads the compressed image data P ₁ stored in the buffer memory 25 and stores it in the storage medium 50. At the same time, the CPU 40 writes the data amount of the compressed image data P _{1 in} the work memory 42.

Step S108 is face detection processing. CPU40 reads out the image data _{P 1} to which image processing has been applied from the buffer memory 25, executes the face detection process. When a face is detected by this face detection process, the CPU 40 extracts a rectangular area including the detected face as a face area.

  Step S109 is processing for determining whether or not a face has been detected. If a face is detected in the face detection process in step S108, the CPU 40 sets the result of the determination process in step S109 to Yes. In this case, the process proceeds to step S110. On the other hand, when a face is not detected in the face detection process in step S108, the CPU 40 sets the result of the determination process in step S109 to No. In this case, the process proceeds to step S111.

Step S110 is processing for setting a face area as a comparison target area. First, CPU 40 divides the image based on the image data P ₁ of the image processed into a plurality of divided regions. For example, when one of the face from the image data P ₁ has been detected, CPU 40 compares the magnitude of the size and divided areas of the face area. When the size of the face area is equal to or smaller than the size of one divided area, the CPU 40 determines whether the face area fits in one divided area or straddles a plurality of divided areas. When the face area fits in one divided area, the CPU 40 sets the divided area in which the face area fits as a comparison target area. On the other hand, when the face region extends over a plurality of divided regions, the CPU 40 sets the divided region over which the face region extends as a comparison target region. When the size of the face area exceeds the size of one divided area, the CPU 40 sets a plurality of divided areas across the face area as comparison target areas.

  Next, when a plurality of faces are detected, the CPU 40 determines whether there is a face area that exceeds the size of one divided area among the plurality of detected face areas. When there is a face area that exceeds the size of one divided area, the CPU 40 sets a divided area that the face area spans as a comparison target area. On the other hand, when all of the detected plurality of face areas are smaller than the size of one divided area, the CPU 40 sets the divided area where the face area superimposed on the AF area is located as the comparison target area. . Here, the divided area where the face area superimposed on the AF area is located is a divided area where the face area superimposed on the AF area fits, or a divided area straddling the face area superimposed on the AF area. After setting the comparison target area, the CPU 40 acquires the position information of the divided area set as the comparison target area and writes it in the work memory 42.

Determination processing in step S109 is executed, if the result of the determination processing becomes No, when the face of a person from the image data P ₁ is not detected in other words, the process proceeds to step S111.

  Step S111 is processing for determining whether template image data is generated. When template image data is generated in the process of step S103 described above, the CPU 40 sets the result of the determination process of step S111 to Yes. In this case, the process proceeds to step S112. On the other hand, when the template image data is not generated in the process of step S103, the CPU 40 sets the result of the determination process of step S111 to No. In this case, the process proceeds to step S113.

Step S112 is processing for setting a comparison target region using template matching. CPU40 executes the template image data, the template matching processing using the image data P ₁ obtained by the first imaging process. Then, CPU 40, of the image based on the image data P _1, sets a rectangular area that matches the image based on the template image data as a comparison target area. The CPU 40 acquires the position information of the set comparison target area and writes it in the work memory 42.

  If the result of the determination process in step S111 is No, in other words, if template image data has not been generated, the process proceeds to step S113.

  Step S113 is processing for setting a comparison target area based on the AF area. The CPU 40 identifies an AF area in focus among the AF areas. Then, the CPU 40 sets a divided area where the identified AF area is located or a divided area where the AF area is straddled as a comparison target area. After setting the comparison target area, the CPU 40 acquires the position information of the divided area set in the comparison target area and writes it in the work memory 42.

  The comparison target area is set by performing any one of the processes in step S110, step S112, and step S113 described above. After setting the comparison target area, the process proceeds to step S114.

Step S114 is a trimming process on the image data P ₁ using the position information of the comparison regions. The image processing circuit 26 reads the image processed image data P ₁ stored in the buffer memory 25. Then, the image processing circuit 26 uses the position information of the comparison regions set, trimming processing on the image data P _1. By performing this trimming process, target image data P ₁ ′ based on the comparison target region is generated. The generated target image data P ₁ ′ is stored in the buffer memory 25.

Step S115 is a process of storing the data amounts of the target image data P ₁ ′ and the target image data P ₁ ′ subjected to the trimming process. The compression / decompression circuit 27 reads the target image data P ₁ ′ stored in the buffer memory 25. Then, the compression / decompression circuit 27 performs a compression process on the read target image data P ₁ ′. The target image data P ₁ ′ subjected to this compression processing is stored in the buffer memory 25. At the same time, the CPU 40 stores the data amount of the target image data P ₁ ′ subjected to the compression process in the work memory 42.

  Step S116 is processing for determining whether or not the operation of the release button has been released. As described above, when the release button 44 is operated, a signal (half-press signal, full-press signal) based on the operation of the release button 44 is input to the CPU 40. In this step S116, it is determined whether or not the operation of the release button 44 has been released depending on whether or not the output of the signal based on the operation of the release button 44 has been stopped.

  For example, if the output of the signal based on the operation of the release button 44 is continued, the CPU 40 determines that the operation of the release button 44 has not been released. In this case, the result of the determination process in step S116 is No, and the process proceeds to step S117. On the other hand, when the output of the signal based on the operation of the release button 44 is stopped, the CPU 40 determines that the operation of the release button 44 has been released. In this case, the result of the determination process in step S116 is Yes. In this case, the processing related to high-speed continuous shooting ends.

Step S117 is an imaging process (second time). This second imaging process is an imaging process in which the position of the focusing lens constituting the imaging optical system 15 is fixed. When the second imaging process is executed, the image signal output from the imaging device 18 is stored in the buffer memory 25 via the AFE circuit 19. The image processing circuit 26 reads the image signal stored in the buffer memory 25 and performs image processing such as white balance adjustment, color interpolation, gradation conversion, and color conversion. Thus, the image data P ₂ is generated. The compression / decompression circuit 27 duplicates (copies) the image processed image data P ₂ stored in the buffer memory 25 onto the buffer memory 25. Then, it performs compression process on the image data P ₂ duplicating. Then, the compressed image data P ₂ is stored in the buffer memory 25.

Step S118 is a process of storing data amount of the image data _{P 2} and the image data _{P 2.} The CPU 40 reads the compressed image data P ₂ stored in the buffer memory 25 and stores it in the storage medium 50. At the same time, the CPU 40 writes the data amount of the compressed image data P _{2 in} the work memory 42.

  Step S119 is a process of determining whether or not a comparison target area is set using template matching. When the comparison target area is set using template matching, the CPU 40 sets the result of the determination process in step S119 to Yes. In this case, the process proceeds to step S120. On the other hand, when the comparison target area is not set using template matching, in other words, when the comparison target area is set based on the detected face or AF area, the CPU 40 determines the result of the determination process in step S119. No. In this case, the process proceeds to step S121.

Step S120 is a process of determining whether or not there is a location in the image data P ₂ that matches the target image data P ₁ ′. The image processing circuit 26 reads out target image data P ₁ ′ and image data P ₂ . After reading out these image data, the image processing circuit 26 performs template matching using these image data. If there is a location that matches the target image data P ₁ ′ in the image data P ₂ by template matching, the image processing circuit 26 sets the result of the determination process in step S 120 to Yes. In this case, the process proceeds to step S121. On the other hand, when the image data P ₂ does not have a portion where the target image data P ₁ ′ matches, the image processing circuit 26 sets the result of the determination process in step S120 to No. In this case, the process proceeds to step S124.

Step S121 is a trimming process on image data _{P 2.} When the divided area including the face area is set as the comparison target area, or when the divided area including the focused AF area is set as the comparison target area, the image processing circuit 26 compares the comparison area. based on the position information of the divided area set as a target area, it executes the trimming process on the image data P _2. In this case, the position of the comparison target area is fixed.

On the other hand, if template matching is performed and the image data P ₂ has a portion that matches the target image data P ₁ ′, the matching portion becomes the comparison target region. Accordingly, the image processing circuit 26 based on the position information of the comparison regions obtained by template matching, executes the trimming process on the image data P _2. By performing this trimming process, target image data P ₂ ′ is generated. The generated target image data P ₂ ′ is stored in the buffer memory 25. In this case, since the position of the subject included in the template image may have changed (the subject has moved), in this case, the comparison target region is not necessarily fixed.

Step S122 is a process of storing the data amounts of the target image data P ₂ ′ and the target image data P ₂ ′. The compression / decompression circuit 27 reads the target image data P ₂ ′ stored in the buffer memory 25. Then, the compression / decompression circuit 27 performs a compression process on the read target image data P ₂ ′. The target image data P ₂ ′ subjected to this compression processing is stored in the buffer memory 25. At the same time, the CPU 40 stores the data amount of the compressed target image data P ₂ ′ in the work memory 42.

Step S123 is a process of calculating a change amount of the data amount between the target image data P ₁ ′ and the target image data P ₂ ′. CPU40 reads the data of the target image data P ₁ stored in the work memory 42 _'and the target image data P _2', respectively, from the data amount of the target image data, obtains the data amount of the variation delta _12. Specifically, CPU 40 subtracts the data amount of the _'target image data P ₁ from the data _of' target image data P _2, obtains the data amount of the variation delta _12.

If the determination process in Step S120 described above is No, that is, if there is no portion that matches the target image data P ₁ ′ in the image data P ₂ even after performing template matching, the process proceeds to Step S124.

Step S124 is a process of calculating the data amount of variation between the image data P ₁ and the image data P _2. CPU40 reads data amount of the image data P ₁ and the image data P ₂ stored in the work memory 42, respectively, from the data amount of the image data, obtains the data amount of the variation delta _12.

Step S125 is processing for determining whether or not the amount of change in the data amount exceeds the reference range. If step S123 or the data amount of change amount delta ₁₂ determined in step S124 exceeds the reference range, CPU 40 is the result of the determination process of step S125 and Yes, the process proceeds to step S126. On the other hand, if the data amount of change amount delta ₁₂ determined in step S123 or step S124 is equal to or less than the reference range, CPU 40 is the result of the determination processing in step S125 and No, the process proceeds to step S129.

  That is, when the result of the determination process in step S125 is No, it can be estimated that the change amount of the data amount is included in the error range. Therefore, the position of the focusing lens is fixed to the position of the focusing lens in the second imaging process. The reference range is preferably a range obtained in advance by experiments, statistics, and the like.

Step S126 is processing for determining whether or not the amount of change in the data amount has decreased. If step S123 and data amount of change amount delta ₁₂ obtained in step S124 is a negative value, it is determined that the CPU40, the amount of change in the data amount has been reduced. In this case, the CPU 40 sets the result of the determination process in step S126 to Yes. In this case, the process proceeds to step S127. On the other hand, if the amount of change delta ₁₂ data amount is a positive value, it is determined that the CPU40, the amount of change in the data amount is increased. In this case, the CPU 40 sets the result of the determination process in step S126 to No, and proceeds to step S129.

  Step S127 is processing for calculating the amount of movement of the focusing lens. The CPU 40 calculates the moving amount of the focusing lens using the data amount change obtained in step S123 or step S124. In calculating the amount of movement of the focusing lens, characteristics unique to the imaging optical system 15 such as the focal length are taken into consideration.

  Step S128 is processing to move the focusing lens. The CPU 40 moves the focusing lens via the lens driving mechanism 21 based on the movement amount obtained in step S127. At this time, the moving direction of the focusing lens is set in advance in either the closest end direction or the infinite end direction.

  For example, the data amount of image data obtained by shooting is larger than that of image data that is not focused. That is, when the change amount of the data amount is a negative value, the image data obtained by the second imaging process is focused on the main subject compared to the image data obtained by the first imaging process. It can be estimated that the image data is not. On the other hand, when the change amount of the data amount is a positive value, the image data obtained by the second imaging process is focused on the main subject more than the image data obtained by the first imaging process. It can be estimated to be data. Therefore, when the amount of change in the data amount becomes a negative value, as described above, control is performed to move the focusing lens so as to focus on the main subject.

  Step S129 is processing to determine whether or not the operation of the release button has been released. If the output of the signal based on the operation of the release button 44 is continued, the CPU 40 determines that the operation of the release button 44 has not been released. In this case, the result of the determination process in step S129 is No, and the process proceeds to step S130. That is, the third and subsequent imaging processes are executed.

  On the other hand, when the output of the signal based on the operation of the release button 44 is stopped, the CPU 40 determines that the operation of the release button 44 has been released. In this case, the determination in step S129 is Yes. In this case, the processing related to high-speed continuous shooting ends.

  Hereinafter, the third and subsequent imaging processes will be described. Since the same process is executed after the third and subsequent imaging processes are performed, in FIG. 9, the description is made using the symbol n (n ≧ 3).

Step S130 is the third imaging process. By this imaging process, the image signal output from the image sensor 18 is stored in the buffer memory 25 via the AFE circuit 19. The image processing circuit 26 reads an image signal stored in the buffer memory 25 and performs image processing such as white balance adjustment, color interpolation, gradation conversion, and color conversion. Thus, the image data P ₃ is generated. The compression / decompression circuit 27 copies (copies) the image processed image data P ₃ stored in the buffer memory 25 onto the buffer memory 25. Then, it performs compression process on the image data P ₃ duplicating. Then, the compressed image data P ₃ is stored in the buffer memory 25.

Step S131 is a process of storing data amount of the image data _{P 3} and the image data _{P 3.} The CPU 40 reads the compressed image data P ₃ stored in the buffer memory 25 and stores it in the storage medium 50. At the same time, the CPU 40 writes the data amount of the compressed image data P _{3 in} the work memory 42.

  Step S132 is a process of determining whether or not a comparison target area is set using template matching. When the comparison handling area is set using template matching, the CPU 40 sets the result of the determination process in step S132 to Yes. In this case, the process proceeds to step S133. On the other hand, when the comparison target area is not set using template matching, in other words, when the comparison target area is set based on the detected face or AF area, the CPU 40 determines the result of the determination process in step S132. No. In this case, the process proceeds to step S134.

Step S133 is a process of determining whether or not there is a location in the image data P ₃ that matches the target image data P ₁ ′. The image processing circuit 26 reads the target image data P ₁ ′ and the image data P ₃ . After reading out these image data, the image processing circuit 26 performs template matching using these image data. If there is a location that matches the target image data P ₁ ′ in the image data P ₃ by template matching, the image processing circuit 26 sets the result of the determination process in step S 133 to Yes. In this case, the process proceeds to step S134. On the other hand, when the image data P ₃ does not have a portion that matches the image data P ₁ ′, the image processing circuit 26 sets the result of the determination process in step S133 to No. In this case, the process proceeds to step S137.

Step S134 is a trimming process on image data _{P 3.} When the divided area including the face area is set as the comparison target area, or when the divided area including the focused AF area is set as the comparison target area, the image processing circuit 26 compares the comparison area. based on the position information of the divided area set as a target area, it executes the trimming process on the image data P _3. In this case, the position of the comparison target area is fixed.

On the other hand, if template matching is performed and the image data P ₃ has a location that matches the target image data P ₁ ′, the matching location becomes the comparison target region. Accordingly, the image processing circuit 26 based on the position information of the comparison regions obtained by template matching, executes the trimming process on the image data P _3. By performing this trimming process, target image data P ₃ ′ is generated. The generated target image data P ₃ ′ is stored in the buffer memory 25. In this case, since the position of the subject included in the template image may have changed (the subject has moved), in this case, the comparison target region is not necessarily fixed.

Step S135 is a process of storing the data amounts of the target image data P ₃ ′ and the target image data P ₃ ′ subjected to the trimming process. The compression / decompression circuit 27 reads the target image data P ₃ ′ stored in the buffer memory 25. Then, the compression / decompression circuit 27 performs a compression process on the read target image data P ₃ ′. The target image data P ₃ ′ subjected to this compression processing is stored in the buffer memory 25. At the same time, the CPU 40 stores the data amount of the target image data P ₃ ′ subjected to the compression process in the work memory 42.

Step S136 is a process of calculating the amount of change in the data amount of the target image data P ₁ ′, the target image data P ₂ ′, and the target image data P ₃ ′. The CPU 40 reads out the data amounts of the target image data P ₁ ′, target image data P ₂ ′, and target image data P ₃ ′ stored in the work memory 42, respectively. Then, the CPU 40 obtains data amount changes Δ ₁₃ and Δ ₂₃ . Specifically, CPU 40 obtains a change amount delta ₁₃ data amount by subtracting the data amount of the _'target image data P ₁ from the data _of' target image data P _3, the data amount of the target image data P _{3 '} subtracting the data amount of the target image data P _{2 'from} obtaining the change amount delta ₂₃ data amount.

On the other hand, if the determination processing in step S133 described above is No, ie, if they fit a target image data P _{1 'in} the image data P ₃ even if the template matching, the process proceeds to step S137.

Step S137 is a process of calculating the amount of change in the data amount of the image data P ₁ , the image data P _2, and the image data P ₃ . The CPU 40 reads the data amounts of the image data P ₁ , the image data P _2, and the image data P ₃ stored in the work memory, and obtains the change amount of the data amount from the data amounts of these image data. Specifically, CPU 40 obtains a change amount delta ₁₃ data amount by subtracting the data amount of the image data P ₁ from the data amount of the image data P _3, the data amount of the image data P ₃ of the image data P ₂ obtaining a variation delta ₂₃ data amount by subtracting the amount of data.

Step S138 is processing for determining whether or not the amount of change in the data amount exceeds the reference range. CPU40, among the calculated data amount of change amount in step S136 or step S137, determines whether the change amount delta ₂₃ of the data amount exceeds a reference range. For example, if the data amount of the change amount delta ₂₃ exceeds the reference range, CPU 40 is the result of the determination process of step S138 and Yes, the process proceeds to step S139. On the other hand, if the change amount delta ₂₃ amount of data reference range or less, CPU 40 is the result of the determination processing in step S138 and No, the process proceeds to step S145. In this case, the position of the focusing lens remains fixed.

Step S139 is processing for determining whether or not the amount of change in data amount has decreased. CPU40 are variations of delta ₁₃ of the obtained data amount, determines whether or not reduced with respect to the data amount of variation delta _23. For example, when the change amount delta ₁₃ data amount is less variation delta ₂₃ amount of data, CPU 40 is a Yes result in decision process in step S139. In this case, the process proceeds to step S140. On the other hand, when the data amount change amount Δ ₁₃ exceeds the data amount change amount Δ ₂₃ , the CPU 40 sets the result of the determination processing in step S 139 to No. In this case, the process proceeds to step S143.

  Step S140 is a process for determining whether or not the lens is fixed in the previous imaging process. For example, in the second imaging process, when the position of the focusing lens is fixed, the result of the determination process in step S140 is Yes. In this case, the process proceeds to step S145. On the other hand, when the position of the focusing lens is moved in the second imaging process, the result of the determination process in step S140 is No. In this case, the process proceeds to step S141.

Step S141 is processing for calculating the amount of movement of the focusing lens. CPU40 calculates the movement amount of the focusing lens by using the amount of change delta ₂₃ data.

  Step S142 is a process of moving the focusing lens in the same direction. The CPU 40 moves the focusing lens through the lens driving mechanism 21 in the same direction as the moving direction of the focusing lens in step S128. Note that the amount of movement of the focusing lens at this time is the amount of movement obtained in step S141.

  If it is determined in step S139 that the change amount of the data amount has not decreased, the process proceeds to step S143.

Step S143 is processing for calculating the amount of movement of the focusing lens. CPU40 calculates the movement amount of the focusing lens by using the amount of change delta ₂₃ data.

  Step S144 is a process of moving the focusing lens in the reverse direction. The CPU 40 moves the focusing lens through the lens driving mechanism 21 in the direction opposite to the moving direction of the focusing lens in step S128. Note that the amount of movement of the focusing lens at this time is the amount of movement obtained in step S141.

  Step S145 is processing for determining whether or not the operation of the release button has been released. If the output of the signal based on the operation of the release button 44 is continued, the CPU 40 determines that the operation of the release button 44 has not been released. In this case, the result of the determination process in step S145 is No, and the process proceeds to step S130. That is, the fourth and subsequent imaging processes are executed. On the other hand, when the output of the signal based on the operation of the release button 44 is stopped, the CPU 40 determines that the operation of the release button 44 has been released. In this case, the determination in step S145 is Yes. In this case, the processing related to high-speed continuous shooting ends.

  Thereafter, the processing from step S130 to step S145 is repeatedly executed until the release button is released.

  Thus, in the present embodiment, focus control in each imaging process is executed based on the change in the data amount when the compression process is performed on the target image data. Here, when a human face is detected, a divided area including the detected face area is set as a comparison target area. Similarly, if there is an in-focus AF area, a divided area including the in-focus AF area is set as a comparison target area. Therefore, in such a case, it is possible to appropriately perform focus control on a previously focused region such as a human face without using conventional focus control.

  In addition, when performing high-speed continuous shooting using an object other than a human face as a main subject, the object that is the main subject may not be detected even if the subject detection process described above is performed. For example, if the focused area is set as the main subject area before performing high-speed continuous shooting, and if the main subject is not detected in the subject detection, the amount of change in the data amount relative to the area is simply compared. . Therefore, it becomes impossible to obtain an image focused on the area intended by the user. However, in the present embodiment, by setting an area with high contrast as an area including the main subject from image data obtained when AF processing is performed, it is possible to obtain a feature amount in the area intended by the user. . Therefore, during high-speed continuous shooting, by performing template matching using the area intended by the user, the position of the area intended by the user can be identified in the obtained image, and image data based on the identified area By using the amount of change in the amount of data, even if the main subject is not a person or when the position of the main subject changes, focus control that focuses on the area that seems to be the main subject is appropriate. Can be done.

  In this embodiment, the area of the main subject is specified from the contrast information of the image data obtained at the time of AF processing, and a template image based on the specified area is generated. However, a user input operation has been performed in advance. It is also possible to generate a template image based on the region. It is also possible to store a plurality of template images in advance and use any of the plurality of template images.

  In the present embodiment, when a divided region including the detected face is set as a comparison target region, the position of the comparison target region is fixed. However, by performing template matching using target image data generated based on the divided region set as the comparison target region on newly acquired image data, the divided region including the detected face May be specified. That is, by performing the above-described operation, it is possible to cope with a case where the detected face position changes during high-speed continuous shooting. In this case, the face position may be located across a plurality of divided areas. Therefore, the area to be subjected to the trimming process may be an area having the same size as the comparison target area used when performing template matching, not a divided area where the face is located.

  In this embodiment, image data obtained by each imaging process is used. However, the present invention is not limited to this, and in a digital camera, face detection processing is performed using image data obtained by reducing the obtained image data. Therefore, the focus control of the present embodiment can be performed using reduced image data.

  In the present invention, the focus control in the digital camera is the phase difference detection type focus control. However, the present invention is not limited to this and may be the contrast detection type focus control.

  As a digital camera of the present invention, a digital camera having a quick return mirror is described as an example. However, the present invention is not limited to this, and a compact camera not equipped with a quick return mirror has a camera function. In addition to a mobile phone, a camera mounted on or connected to a computer may be used.

  DESCRIPTION OF SYMBOLS 10 ... Digital camera, 18 ... Image sensor, 26 ... Image processing circuit, 27 ... Compression / decompression circuit, 40 ... CPU, 41 ... Non-volatile memory, 42 ... Work memory, 47 ... Template generation part, 48 ... Trimming part, 51 ... Face detection unit, 52 ... Area setting unit, 53 ... Data comparison unit, 54 ... Focus control unit

Claims (9)

An imaging optical system that captures subject light;
A generating unit that generates a first image including a subject;
Regions cut out from each of the second images by performing template matching using the first image on the second images continuously acquired based on the subject light captured by the imaging optical system A setting unit for setting as a target area;
A compression unit that performs compression processing on each of the images of the target area cut out from the second image;
A control unit that controls a focus position in the imaging optical system based on a change in the data amount of the compressed image of the target area;
A focus adjustment device comprising: The focus adjustment apparatus according to claim 1,
The generation unit generates an image of the subject included in the third image as the first image by using at least contrast information of the third image captured before acquiring the second image. A focusing device characterized by that. The focus adjustment device according to claim 1 or 2,
A subject detection unit for detecting the subject;
The setting unit sets the target region by performing template matching using the first image when the subject detection unit cannot detect the subject when the second image is acquired. Focus adjustment device characterized by. The focus adjustment apparatus according to claim 3.
The focus adjustment apparatus, wherein the setting unit sets an area of the detected subject as the target region when the subject is detected by the subject detection unit. In the focus adjustment apparatus according to any one of claims 1 to 4,
Using a plurality of focus detection areas provided corresponding to a range for acquiring an image, and including a focus detection unit that detects a focus state of the imaging optical system;
The setting unit sets, as the target region, a region including a focus detection area that is in focus among the plurality of focus detection areas, when the first image is not generated by the generation unit. Focus adjustment device characterized. The focus adjustment apparatus according to any one of claims 1 to 5,
The focus adjustment apparatus, wherein the control unit performs initial adjustment of the focus position in accordance with an instruction from a user. The focus adjustment apparatus according to any one of claims 1 to 5,
The focus adjustment apparatus, wherein the control unit performs initial adjustment of the focus position by a phase difference detection method. The focus adjustment apparatus according to any one of claims 1 to 7,
The focus adjustment apparatus, wherein the control unit displaces the focus position when a change amount of the data amount exceeds a reference range. An image sensor capable of continuously outputting images based on captured subject light; and
The focus adjustment apparatus according to any one of claims 1 to 8, wherein a focus position of the imaging optical system is controlled based on an image output from the imaging element.
An imaging apparatus comprising:

Images