JP2013225020A - Electronic camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve focusing performance.SOLUTION: An image sensor 16 outputs raw image data indicating a scene captured on an imaging surface. A CPU 26 adjusts a subject distance to a desired distance on the basis of the output raw image data, and, based on the size of the face image of a person shown on the same raw image data, calculates the distance to the face of the person. The CPU 26 adjusts the depth of a field to a depth of field corresponding to a difference between the two distances calculated or adjusted by the manner described above.

Description

  The present invention relates to an electronic camera, and more particularly to an electronic camera that adjusts imaging conditions based on an optical image generated on an imaging surface.

  An example of this type of camera is disclosed in Patent Document 1. According to this background art, the AF means performs focus control based on a signal from a predetermined AF area in the image data. The extraction unit extracts a feature part from the image data. The face identifying means identifies a person's face from the characteristic parts extracted by the extracting means. The discriminating unit discriminates whether or not the size of the face identified by the face discriminating unit is a predetermined value or more. The setting means sets the AF area according to the determination result of the determination means.

JP 2004-317699 A

  However, the background art does not consider individual differences in face size, and an error may occur when the subject distance is determined from the identified face size. For example, when the subject distance is determined by paying attention to the child's face, an error may occur due to the reference of the average adult face size and subject distance, and the focusing performance may be reduced.

  Therefore, a main object of the present invention is to provide an electronic camera that can improve focusing performance.

  An electronic camera according to the present invention (10: reference numeral corresponding to the embodiment; the same applies hereinafter) includes an imaging unit (16) for outputting an image representing a scene captured on an imaging plane, and a first unit for adjusting a subject distance to a desired distance. 1 adjusting means (S17 to S19, S27 to S31), calculating means for calculating the distance to the subject corresponding to the specific subject image based on the size of the specific subject image appearing in the image output from the imaging means (S67, S121) ~ S123, S127), and second adjusting means (S125, S129, S131, adjusting the depth of field to a depth corresponding to the difference between the distance calculated by the calculating means and the distance adjusted by the first adjusting means) S37, S41).

  Preferably, the calculating means is a distance estimating means (S121 to S123) for estimating the longest distance and the shortest distance to the specific subject based on the size of the specific subject image, and the longest distance and the shortest distance estimated by the distance estimating means. Of these, distance selection means (S127) for selecting one of the distances having a large difference from the subject distance is included.

  Preferably, the first adjustment unit adjusts the subject distance based on a high-frequency component of a desired subject image that appears in the image output from the imaging unit.

  Preferably, the first adjustment unit adjusts the subject distance based on a high-frequency component in a region where the specific subject image appears in the image output from the imaging unit.

  Preferably, the first adjustment unit performs a process of adjusting the subject distance based on the high-frequency component of the predetermined region in the image output from the imaging unit in association with the imaging preparation operation.

  Preferably, a focus lens (12) provided in front of the imaging surface is further provided, and the first adjustment unit adjusts the interval between the focus lens and the imaging surface to an interval corresponding to a desired distance.

  The focus control program according to the present invention adjusts the subject distance to a desired distance in the processor (26) of the electronic camera (10) including the imaging means (16) that outputs an image representing the scene captured on the imaging plane. First adjustment step (S17 to S19, S27 to S31), a calculation step for calculating the distance to the subject corresponding to the specific subject image based on the size of the specific subject image appearing in the image output from the imaging means (S67, S121 to S123, S127) and a second adjustment step (S125, S129, S131) for adjusting the depth of field to a depth corresponding to the difference between the distance calculated by the calculation step and the distance adjusted by the first adjustment step. , S37, S41).

  A focus control method according to the present invention is a focus control method executed by an electronic camera (10) provided with an imaging means (16) that outputs an image representing a scene captured on an imaging surface, wherein a subject distance is desired A first adjustment step (S17 to S19, S27 to S31) for adjusting the distance to the distance to the subject, the distance to the subject corresponding to the specific subject image is calculated based on the size of the specific subject image appearing in the image output from the imaging means A calculation step (S67, S121 to S123, S127) and a second adjustment step of adjusting the depth of field to a depth corresponding to the difference between the distance calculated by the calculation step and the distance adjusted by the first adjustment step ( S125, S129, S131, S37, S41).

  The external control program according to the present invention includes an imaging means (16) for outputting an image representing a scene captured on the imaging surface, and a processor (26) for executing processing according to the internal control program stored in the memory (44). A first control step (S17 to S19, S27 to S31) for adjusting a subject distance to a desired distance, and an identification program appearing in an image output from an imaging means, which is an external control program supplied to the electronic camera (10) A calculation step (S67, S121 to S123, S127) for calculating the distance to the subject corresponding to the specific subject image based on the size of the subject image, and the first adjustment step and the distance calculated by the depth of field calculation step An external control program for causing the processor to execute a second adjustment step (S125, S129, S131, S37, S41) for adjusting the depth corresponding to the difference from the distance adjusted by the system in cooperation with the internal control program It is a non.

  An electronic camera (10) according to the present invention includes an image pickup means (16) for outputting an image representing a scene captured on an image pickup surface, a fetch means (60) for fetching an external control program, and an external control program fetched by the fetch means And an internal camera that executes processing according to the internal control program stored in the memory (44). The external control program includes a first adjustment step (S17 to S19, S19 to S19, for adjusting the subject distance to a desired distance). S27 to S31), a calculation step (S67, S121 to S123, S127) for calculating a distance to the subject corresponding to the specific subject image based on the size of the specific subject image that appears in the image output from the imaging means, A second adjustment step (S125, S129, S131, S) for adjusting the depth of field to a depth corresponding to the difference between the distance calculated in the calculation step and the distance adjusted in the first adjustment step. 37, S41) corresponds to a program that executes in cooperation with the internal control program.

  According to the present invention, the distance to the specific subject is calculated based on the size of the specific subject image. The depth of field is adjusted to a depth corresponding to the difference between the calculated distance and the subject distance adjusted by the first adjusting means. This ensures high sharpness for both the subject existing at the subject distance and the specific subject. Thus, the focusing performance is improved.

  The above object, other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

It is a block diagram which shows the basic composition of one Example of this invention. It is a block diagram which shows the structure of one Example of this invention. FIG. 3 is an illustrative view showing one example of a mapping state of an SDRAM applied to the embodiment in FIG. 2; It is an illustration figure which shows an example of the allocation state of the evaluation area in an imaging surface. It is an illustration figure which shows an example of the face detection frame used in a face detection process. It is an illustration figure which shows an example of a structure of the face dictionary referred in a face detection process. It is an illustration figure which shows a part of face detection process. FIG. 3 is an illustrative view showing one example of a configuration of a register referred to in the embodiment in FIG. 2; FIG. 10 is an illustrative view showing one example of a configuration of another register referred to in the embodiment in FIG. 2; It is an illustration figure which shows a part of depth-of-field calculation process. It is an illustration figure which shows an example of the image displayed on the LCD monitor. It is an illustration figure which shows another part of depth-of-field calculation processing. It is an illustration figure which shows another example of the image displayed on the LCD monitor. (A) is an illustrative view showing another example of an image displayed on the LCD monitor, and (B) is an illustrative view showing still another example of the image displayed on the LCD monitor. It is a flowchart which shows a part of operation | movement of CPU applied to the FIG. 2 Example. It is a flowchart which shows a part of other operation | movement of CPU applied to the FIG. 2 Example. FIG. 11 is a flowchart showing still another portion of behavior of the CPU applied to the embodiment in FIG. 2; FIG. 10 is a flowchart showing yet another portion of behavior of the CPU applied to the embodiment in FIG. 2; It is a flowchart which shows a part of other operation | movement of CPU applied to the FIG. 2 Example. FIG. 11 is a flowchart showing still another portion of behavior of the CPU applied to the embodiment in FIG. 2; FIG. 10 is a flowchart showing yet another portion of behavior of the CPU applied to the embodiment in FIG. 2; It is a block diagram which shows the structure of the other Example of this invention.

Embodiments of the present invention will be described below with reference to the drawings.
[Basic configuration]

  Referring to FIG. 1, the electronic camera of this embodiment is basically configured as follows. The imaging unit 1 outputs an image representing a scene captured on the imaging surface. The first adjusting means 2 adjusts the subject distance to a desired distance. The calculation unit 3 calculates the distance to the subject corresponding to the specific subject image based on the size of the specific subject image that appears in the image output from the imaging unit 1. The second adjusting unit 4 adjusts the depth of field to a depth corresponding to the difference between the distance calculated by the calculating unit 3 and the distance adjusted by the first adjusting unit 2.

The distance to the specific subject is calculated based on the size of the specific subject image. The depth of field is adjusted to a depth corresponding to the difference between the calculated distance and the subject distance adjusted by the first adjusting means 2. This ensures high sharpness for both the subject existing at the subject distance and the specific subject. Thus, the focusing performance is improved.
[Example]

  Referring to FIG. 2, the digital camera 10 of this embodiment includes a focus lens 12 and an aperture unit 14 driven by drivers 18a and 18b, respectively. The optical image of the scene that has passed through these members is irradiated onto the imaging surface of the image sensor 16 and subjected to photoelectric conversion. As a result, a charge representing the scene is generated.

  When the power is turned on, the CPU 26 instructs the driver 18c to repeat the exposure operation and the charge readout operation under the imaging task in order to execute the moving image capturing process. In response to a vertical synchronization signal Vsync periodically generated from an SG (Signal Generator) (not shown), the driver 18c exposes the imaging surface and reads out the charges generated on the imaging surface in a raster scanning manner. From the image sensor 16, raw image data based on the read charges is periodically output. The CPU 26 also arranges the focus lens 12 at the pan focus position that is the initial setting position.

  The preprocessing circuit 20 performs processing such as digital clamping, pixel defect correction, and gain control on the raw image data output from the image sensor 16. The raw image data subjected to these processes is written into the raw image area 32a (see FIG. 3) of the SDRAM 32 through the memory control circuit 30.

  The post-processing circuit 34 reads the raw image data stored in the raw image area 32a through the memory control circuit 30, and performs color separation processing, white balance adjustment processing, and YUV conversion processing on the read raw image data. The post-processing circuit 34 further performs display zoom processing and search zoom processing in parallel on the image data in the YUV format. As a result, display image data and search image data conforming to the YUV format are individually created. The display image data is written into the display image area 32b (see FIG. 3) of the SDRAM 32 by the memory control circuit 30. The search image data is written into the search image area 32c (see FIG. 3) of the SDRAM 32 by the memory control circuit 30.

  The LCD driver 36 repeatedly reads the display image data stored in the display image area 32b through the memory control circuit 30, and drives the LCD monitor 38 based on the read image data. As a result, a real-time moving image (through image) representing the scene is displayed on the LCD monitor 38.

  Referring to FIG. 4, an evaluation area EVA is assigned to the center of the imaging surface. The evaluation area EVA is divided into 16 in each of the horizontal direction and the vertical direction, and 256 divided areas form the evaluation area EVA. In addition to the above-described processing, the preprocessing circuit 20 shown in FIG. 2 executes simple RGB conversion processing that simply converts raw image data into RGB data.

  The AE evaluation circuit 22 integrates RGB data belonging to the evaluation area EVA among the RGB data generated by the preprocessing circuit 20 every time the vertical synchronization signal Vsync is generated. As a result, 256 integral values, that is, 256 AE evaluation values, are output from the AE evaluation circuit 22 in response to the vertical synchronization signal Vsync. The AF evaluation circuit 24 integrates the high-frequency components of the RGB data belonging to the evaluation area EVA among the RGB data generated by the preprocessing circuit 20 every time the vertical synchronization signal Vsync is generated. As a result, 256 integral values, that is, 256 AF evaluation values, are output from the AF evaluation circuit 24 in response to the vertical synchronization signal Vsync. Processing based on the AE evaluation value and the AF evaluation value obtained in this way will be described later.

  Under the face detection task executed in parallel with the imaging task, the CPU 26 initializes the flag FLGfc to “0”. Next, the CPU 26 executes face detection processing each time the vertical synchronization signal Vsync is generated in order to search for a human face image from the search image data stored in the search image area 32c.

  In the face detection process, a face detection frame FD whose size is adjusted in the manner shown in FIG. 5 and a face dictionary DC containing five dictionary images (= face images with different orientations) shown in FIG. 6 are used. The face dictionary DC is stored in the flash memory 44.

  In the face detection process, first, the entire evaluation area EVA is set as a search area. Further, in order to define a variable range of the size of the face detection frame FD, the maximum size FSZmax is set to “200”, and the minimum size FSZmin is set to “20”.

  The face detection frame FD is moved by a predetermined amount in a raster scanning manner from the start position (upper left position) to the end position (lower right position) of the face search area (see FIG. 7). The size of the face detection frame FD is reduced by “5” from “FSZmax” to “FSZmin” every time the face detection frame FD reaches the end position.

  A part of the search image data belonging to the face detection frame FD is read from the search image area 32 c through the memory control circuit 30. The feature amount of the read search image data is collated with the feature amount of each of the five dictionary images stored in the face dictionary DC. If a matching degree exceeding the threshold TH is obtained, it is considered that a face image has been detected. The current position and size of the face detection frame FD and the dictionary number of the collation source are registered in the face detection register RGSTdt shown in FIG. 8 as face information.

  When a plurality of pieces of face information are registered in the face detection register RGSTdt after the face detection process is completed, the area indicated by the face information whose position is closest to the center of the imaging surface is a strict AF process and depth of field calculation described later. It is a target area for processing. When single face information is registered in the face detection register RGSTdt, an area indicated by the face information is a target area for the strict AF process and the depth of field calculation process.

  The position and size of the face information set as the processing target area are registered in the processing target register RGSTex shown in FIG. Further, the CPU 26 sets a flag FLGfc to “1” in order to announce that the person's face image has been found.

  When face information is not registered in the face detection register RGSTdt after the face detection process is completed, that is, when no face image is found, the CPU 26 sets a flag FLGfc to indicate that no face image has been found. Is set to “0”.

  When the shutter button 28sh is in the non-operating state, the CPU 26 executes a simple AE process based on the output from the AE evaluation circuit 22 under the imaging task, and calculates an appropriate EV value. The simple AE process is executed in parallel with the moving image capturing process, and the aperture amount and the exposure time that define the calculated appropriate EV value are set in the drivers 18b and 18c, respectively. As a result, the brightness of the through image is appropriately adjusted.

  When the shutter button 28sh is half-pressed, the CPU 26 executes a strict AE process based on the 256 AE evaluation values output from the AE evaluation circuit 22 under the imaging task. The aperture amount and the exposure time that define the optimum EV value calculated by the strict AE process are set in the drivers 18b and 18c, respectively. As a result, the brightness of the through image is adjusted strictly.

  When the flag FLGfc indicates “1”, under the imaging task, the CPU 26 executes a strict AF process focusing on the area indicated by the face information registered in the processing target register RGSTex. The CPU 26 extracts an AF evaluation value corresponding to the position and size stored in the processing target register RGSTex from the 256 AF evaluation values output from the AF evaluation circuit 24. The focus lens 12 is arranged at a focal point focusing on the area indicated by the face information registered in the processing target register RGSTex, and the sharpness of the area in the through image is improved.

  When the flag FLGfc indicates “1”, under the imaging task, the CPU 26 executes a depth-of-field calculation process for the face registered in the processing target register RGSTex.

  In the depth of field calculation process, first, the maximum distance Lmax and the minimum distance Lmin from the size registered in the processing target register RGSTex to the discovered face estimated in consideration of individual differences in face size. Is calculated. Further, the distance (= AF distance) Laf to the subject included in the target area of the strict AF process is detected based on the position of the focus lens 12 arranged by executing the strict AF process.

  The absolute value of the difference between the maximum distance Lmax and the AF distance Laf calculated in this way is compared with the absolute value of the difference between the minimum distance Lmin and the AF distance Laf, and the larger value is doubled to increase the object field. The depth Dhb is calculated.

  The CPU 26 instructs the driver 18b to adjust the aperture unit 14 based on the depth of field Dhb calculated by the depth of field calculation process. As a result, the depth of field is changed to the calculated depth Dhb.

  As a result of the strict AF process, when an obstacle composed of a grid-like wire mesh or the like is present closer to the person related to the detected face image, the obstacle may be focused. According to the example shown in FIG. 10, the fence FC constituted by a latticed wire net is present on the near side from the person HB, and the focus lens 12 is arranged based on the position Paf1 of the fence FC as a result of the strict AF processing. . In this case, the AF distance Laf indicates the distance between the focus lens 12 and the fence FC.

In this case, since the absolute value of the difference between the maximum distance Lmax and the AF distance Laf is larger than the absolute value of the difference between the minimum distance Lmin and the AF distance Laf, the depth of field Dhb is obtained by the following equation (1). be able to.
[Equation 1]
Dhb = | Lmax−Laf | × 2

  Since the depth of field is changed based on the value calculated in this way, the face of the person HB is included in the in-focus range even when the strict AF process is executed with reference to the fence FC. . Therefore, the through image displayed on the LCD monitor 38 is focused on both the fence FC and the face of the person HB (see FIG. 11).

  When the shutter button 28 sh is in a non-operating state, if an AF target area designation operation is performed by an operator's touch operation on the LCD monitor 38, the touch position is detected by the touch sensor 50, and the detection result is given to the CPU 26.

  Next, the CPU 26 executes a strict AF process focusing on an area corresponding to the touch position. The CPU 26 extracts an AF evaluation value corresponding to the touch position from 256 AF evaluation values output from the AF evaluation circuit 24. The focus lens 12 is disposed at a focal point focusing on the area corresponding to the touch position, and the sharpness of the area in the through image is improved.

  When the strict AF process is executed by the AF area specifying operation, the strict AF process is not executed after the strict AE process is executed when the shutter button 28sh is half-pressed. However, when the flag FLGfc indicates “1”, under the imaging task, the CPU 26 executes the depth-of-field calculation process for the face registered in the processing target register RGSTex in the same manner as described above. The CPU 26 instructs the driver 18b to adjust the aperture unit 14 based on the depth of field Dhb calculated by the depth of field calculation process. As a result, the depth of field is changed to the calculated depth Dhb as described above.

  When the strict AF process is performed by the AF area specifying operation, there is a possibility that an object other than a person is focused according to the operation of the operator. According to the example shown in FIG. 12, when the operator designates the monument ST displayed on the LCD monitor 38, the focus lens 12 is arranged based on the position Paf2 of the monument ST as a result of the strict AF process. In this case, the AF distance Laf indicates the distance between the focus lens 12 and the monument ST.

In this case, since the absolute value of the difference between the minimum distance Lmin and the AF distance Laf is larger than the absolute value of the difference between the maximum distance Lmax and the AF distance Laf, the depth of field Dhb is obtained by the following equation (2). be able to.
[Equation 2]
Dhb = | Lmin−Laf | × 2

  Since the depth of field is changed based on the value calculated in this manner, the face of the person HB is included in the in-focus range even when the strict AF process is executed based on the stone monument ST. . Therefore, the through image displayed on the LCD monitor 38 is focused on both the monument ST and the face of the person HB (see FIG. 13).

  When the shutter button 28sh is pressed halfway without performing the AF area designation operation, if the flag FLGfc indicates “0” after the above-described strict AE processing is executed, that is, if the face of the person is not found, the imaging task Below, CPU26 performs the strict AF process which paid its attention to the screen center. As a result, the sharpness of the screen center in the through image is improved.

  Thereafter, when the operator moves the digital camera 10 while the shutter button 28sh is half-pressed, if a face image of a person is found due to the change in the orientation of the imaging surface, the value indicated by the flag FLGfc is It is updated from “0” to “1”. In this case, under the imaging task, the CPU 26 executes the depth-of-field calculation processing for the face registered in the processing target register RGSTex in the same manner as described above. As a result, the depth of field is changed to the calculated depth Dhb as described above.

  Referring to FIG. 14A, when the shutter button 28sh is pressed halfway when the flower FW lifted by both hands of the person HB is present in the center of the screen, the face image of the person HB immediately after the completion of the strict AE process Is not found, a strict AF process focusing on the center of the screen is executed.

  Thereafter, when the face image of the person is captured on the imaging surface as shown in FIG. 14B by changing the orientation of the imaging surface while the half-pressed state of the shutter button 28sh is maintained, the subject image of the face image is captured. The depth of field calculation process is executed, and the depth of field is changed to the calculated depth Dhb.

  In this case, even when the strict AF process is executed based on the flower FW, the face of the person HB is included in the focus range. Accordingly, the through image displayed on the LCD monitor 38 is focused on both the flower FW and the face of the person HB.

  When the shutter button 28sh is fully pressed, the CPU 26 executes a still image capturing process and a recording process under the imaging task. The raw image data of one frame at the time when the shutter button 28sh is fully pressed is captured into the still image area 32d (see FIG. 3) of the SDRAM 32 by the still image capturing process. In addition, one still image file is created on the recording medium 42 by the recording process. The captured raw image data is recorded in a newly created still image file by a recording process.

  The CPU 26 executes a plurality of tasks including the imaging task shown in FIGS. 15 to 17 and the face detection task shown in FIG. 18 in parallel. Note that control programs corresponding to these tasks are stored in the flash memory 44.

  Referring to FIG. 15, in step S1, “0” is initially set to flag FLGfc. In step S3, a face detection task is activated, and in step S5, a moving image capturing process is started. As a result, a through image representing a scene is displayed on the LCD monitor 38.

  In step S7, the focus lens 12 is placed at the pan focus position, which is the initial setting position, and in step S9, "0" is set to the flag FLGaf.

  In step S11, it is determined whether or not an AF area specifying operation has been performed by an operator's touch operation on the LCD monitor 38. If the determination result is YES, the process proceeds to step S17. If the determination result is NO, step S13 is performed. Proceed to In step 13, it is determined whether or not the shutter button 28sh has been half-pressed. If the determination result is YES, the process proceeds to step S23, whereas if the determination result is NO, the simple AE process is executed in step S15. As a result, the brightness of the through image is appropriately adjusted. When the process of step S15 is completed, the process returns to step S11.

  In step S17, an area corresponding to the touch position is determined as an AF target, and a strict AF process focusing on the determined AF target area is executed in step S19. In step S21, “1” is set to the flag FLGaf.

  In step S23, a strict AE process is executed based on the 256 AE evaluation values output from the AE evaluation circuit 22. As a result, the brightness of the through image is adjusted strictly. In step S25, it is determined whether or not “0” is set in the flag FLGaf. If the determination result is NO, the process proceeds to step S35, and if the determination result is YES, the process proceeds to step S27.

  In step S27, it is determined whether or not “1” is set in the flag FLGfc. If the determination result is YES, the process proceeds to step S33 via step S29. If the determination result is NO, the process proceeds to step S33 via step S31. Proceed to

  In step S29, an area corresponding to the position and size of the face image registered in the processing target register RGSTex is determined as an AF target, and in step S31, a predetermined area in the center of the screen is determined as an AF target. Strict AF processing focusing on the AF target determined in step S29 or S31 is executed in step S33. As a result, the sharpness of the AF target area in the through image is improved.

  In step S35, it is determined whether or not “1” is set in the flag FLGfc. If the determination result is YES, the process proceeds to step S43 through steps S37 and S39. If the determination result is NO, the process proceeds to step S41. It progresses to step S43 through a process.

  In step S37, depth-of-field calculation processing for the face registered in the processing target register RGSTex is executed, and the calculated depth of field Dhb is determined as the set depth in step S39. In step S41, the predetermined depth is determined as the set depth. In step S43, the driver 18b is commanded to adjust the aperture unit 14 based on the set depth determined in step S39 or S41. As a result, the depth of field is changed to the set depth determined in step S39 or S41.

  In step S45, it is determined whether or not the shutter button 28sh has been fully pressed. If the determination result is NO, it is determined in step S47 whether or not the half-pressed state of the shutter button 28sh has been released. If the determination result in step S47 is NO, the process returns to step S35, while if the determination result in step S47 is YES, the process returns to step S7.

  If the decision result in the step S45 is YES, a still image capturing process is executed in a step S49, and a recording process is executed in a step S51. One frame of raw image data at the time when the shutter button 28sh is fully pressed is captured in the still image area 32d of the SDRAM 32 by the still image capturing process. In addition, one still image file is created on the recording medium 42 by the recording process. The captured raw image data is recorded in a newly created still image file by a recording process. When the process of step S51 is completed, the process returns to step S7.

  Referring to FIG. 18, in step S61, “0” is set to flag FLGfc, and in step S63, the stored contents of processing target register RGSTex are cleared to be initialized. In step S65, it is repeatedly determined whether or not the vertical synchronization signal Vsync has been generated. If the determination result is updated from NO to YES, the process proceeds to step S67.

  In step S67, face detection processing is executed to search for a human face image from the search image data. In step S69, it is determined whether or not face information is stored in the face detection register RGSTdt by the process in step S67. If the determination result is YES, the process proceeds to step S73. If the determination result is NO, the process proceeds to step S71. . In step S71, “0” is set in the flag FLGfc, and then the process returns to step S65.

  In step S73, it is determined whether or not a plurality of pieces of face information are stored in the face detection register RGSTdt. If the determination result is NO, the process proceeds to step S77. If the determination result is YES, the process proceeds to step S75. Proceed to S77.

  In step S75, face information whose position stored in the face detection register RGSTdt is closest to the center of the imaging surface is determined as processing target face information. In step S77, the position and size of the face information set as processing target face information are determined. Store in the processing target register RGSTex. In step S79, the flag FLGfc is set to “1”, and then the process returns to step S65.

  The face detection process in step S67 is executed according to a subroutine shown in FIGS. Referring to FIG. 19, in step S81, the stored contents are cleared to initialize face detection register RGSTdt.

  In step S83, the entire evaluation area EVA is set as a search area. In step S85, the maximum size FSZmax is set to “200” and the minimum size FSZmin is set to “20” in order to define a variable range of the size of the face detection frame FD.

  In step S87, the size of the face detection frame FD is set to “FSZmax”, and in step S89, the face detection frame FD is arranged at the upper left position of the search area. In step S91, a part of the search image data belonging to the face detection frame FD is read from the search image area 32c, and the feature amount of the read search image data is calculated.

  In step S93, the variable N is set to “1”. In step S95, the feature amount calculated in step S91 is collated with the feature amount of the Nth dictionary image stored in the face dictionary DC. As a result of the collation, whether or not a collation degree exceeding the threshold value TH is determined in step S97. If the determination result is NO, the process proceeds to step S101, and if the determination result is YES, the process proceeds to step S99. In step S99, the current position and size of the face detection frame FD are registered in the face detection register RGSTdt as face information.

  In step S101, the variable N is incremented, and in step S103, it is determined whether or not the variable N exceeds “5”. If the determination result is NO, the process returns to step S95, while if the determination result is YES, the process proceeds to step S105.

  In step S105, it is determined whether or not the face detection frame FD has reached the lower right position of the search area. If the determination result is YES, the process proceeds to step S109. If the determination result is NO, the face detection is performed in step S107. The frame FD is moved in the raster direction by a predetermined amount, and then the process returns to step S91.

  In step S109, it is determined whether or not the size of the face detection frame FD is equal to or less than “FSZmin”. If the determination result is YES, the process returns to the upper layer routine. If the determination result is NO, the process proceeds to step S111. .

  In step S111, the size of the face detection frame FD is reduced by “5”, and in step S113, the face detection frame FD is arranged at the upper left position of the search area. When the process of step S113 is completed, the process returns to step S91.

  The depth of field calculation process (face object) in step S37 is executed according to a subroutine shown in FIG. Referring to FIG. 21, in step S121, the maximum distance Lmax to the discovered face estimated based on the size registered in the processing target register RGSTex is calculated. In step S123, the minimum distance Lmin to the discovered face estimated based on the size registered in the processing target register RGSTex is calculated.

  In step S125, the AF distance Laf is detected based on the position of the focus lens 12 arranged by executing the strict AF process in step S19 or S33.

  In step S127, it is determined whether or not the absolute value of the difference between the maximum distance Lmax and the AF distance Laf calculated in step S121 is greater than or equal to the absolute value of the difference between the minimum distance Lmin and the AF distance Laf calculated in step S123. Determine. If the determination result is YES, the process proceeds to step S129, and if the determination result is NO, the process proceeds to step S131.

  In step S129, the depth of field Dhb is calculated by multiplying the absolute value of the difference between the maximum distance Lmax and the AF distance Laf by “2”. In step S131, the absolute value of the difference between the minimum distance Lmin and the AF distance Laf is “ Multiply by 2 ″ to calculate the depth of field Dhb. When the process of step S129 or S131 is completed, the process returns to the upper hierarchy routine.

  As can be seen from the above description, the image sensor 16 outputs raw image data representing a scene captured on the imaging surface. The CPU 26 adjusts the subject distance to a desired distance based on the output raw image data (S17 to S19, S27 to S31), and the person's face based on the size of the person's face image appearing in the same raw image data. The distance to the part is calculated (S67, S121 to S123, S127). The CPU 26 also adjusts the depth of field to a depth corresponding to the difference between the two distances calculated or adjusted as described above (S125, S129, S131, S37, S41).

  As described above, the distance to the face of the person is calculated based on the size of the face image. The depth of field is adjusted to a depth corresponding to the difference between the calculated distance and the adjusted subject distance. As a result, high sharpness is ensured for both the subject existing at the subject distance and the face of the person. Thus, the focusing performance is improved.

  In this embodiment, the multitask OS and control programs corresponding to a plurality of tasks executed thereby are stored in the flash memory 44 in advance. However, a communication I / F 60 for connecting to an external server is provided in the digital camera 10 in the manner shown in FIG. 22, and some control programs are prepared as internal control programs in the flash memory 44 from the beginning, while other parts are prepared. These control programs may be acquired from an external server as an external control program. In this case, the above-described operation is realized by cooperation of the internal control program and the external control program.

  In this embodiment, the process executed by the CPU 26 is divided into a plurality of tasks including an imaging task shown in FIGS. 15 to 17 and a face detection task shown in FIG. However, these tasks may be further divided into a plurality of small tasks, and a part of the divided plurality of small tasks may be integrated with other tasks. Further, when the transfer task is divided into a plurality of small tasks, all or part of the transfer task may be acquired from an external server.

  In this embodiment, the digital still camera has been described. However, the present invention can also be applied to a digital video camera, a mobile phone terminal, a smartphone, or the like.

DESCRIPTION OF SYMBOLS 10 ... Digital camera 12 ... Focus lens 14 ... Aperture unit 16 ... Image sensor 26 ... CPU
32 ... SDRAM
38 ... LCD monitor

Claims (10)

Imaging means for outputting an image representing a scene captured on the imaging surface;
First adjusting means for adjusting the subject distance to a desired distance;
A calculating unit that calculates a distance to a subject corresponding to the specific subject image based on a size of the specific subject image that appears in the image output from the imaging unit; and a distance in which the depth of field is calculated by the calculating unit And an electronic camera comprising second adjusting means for adjusting to a depth corresponding to the difference between the distance adjusted by the first adjusting means.   The calculating means estimates a longest distance and a shortest distance to the specific subject based on a size of the specific subject image, and the subject distance among the longest distance and the shortest distance estimated by the distance estimating means The electronic camera according to claim 1, further comprising distance selection means for selecting one of the distances having a large difference from.   The electronic camera according to claim 1, wherein the first adjustment unit adjusts the subject distance based on a high-frequency component of a desired subject image that appears in the image output from the imaging unit.   3. The electronic camera according to claim 1, wherein the first adjustment unit adjusts the subject distance based on a high-frequency component of a region where the specific subject image appears in the image output from the imaging unit.   3. The electronic device according to claim 1, wherein the first adjustment unit performs a process of adjusting the subject distance based on a high-frequency component of a predetermined region in the image output from the imaging unit in association with an imaging preparation operation. camera. A focus lens provided in front of the imaging surface;
The electronic camera according to claim 1, wherein the first adjustment unit adjusts an interval between the focus lens and the imaging surface to an interval corresponding to the desired distance. In the processor of an electronic camera provided with an imaging means for outputting an image representing a scene captured on the imaging surface,
A first adjustment step for adjusting the subject distance to a desired distance;
A calculation step of calculating a distance to a subject corresponding to the specific subject image based on a size of the specific subject image appearing in the image output from the imaging unit; and a distance in which the depth of field is calculated by the calculation step And a focus control program for executing a second adjustment step for adjusting to a depth corresponding to the difference between the distance adjusted by the first adjustment step. A focusing control method executed by an electronic camera including an imaging unit that outputs an image representing a scene captured on an imaging surface,
A first adjustment step for adjusting the subject distance to a desired distance;
A calculation step of calculating a distance to a subject corresponding to the specific subject image based on a size of the specific subject image appearing in the image output from the imaging unit; and a distance in which the depth of field is calculated by the calculation step And a second adjustment step for adjusting to a depth corresponding to the difference between the distance adjusted by the first adjustment step. An external control program supplied to an electronic camera comprising an imaging means for outputting an image representing a scene captured on an imaging surface, and a processor for executing processing according to an internal control program stored in a memory,
A first adjustment step for adjusting the subject distance to a desired distance;
A calculation step of calculating a distance to a subject corresponding to the specific subject image based on a size of the specific subject image appearing in the image output from the imaging unit; and a distance in which the depth of field is calculated by the calculation step And an external control program for causing the processor to execute a second adjustment step for adjusting the depth corresponding to the difference between the distance and the distance adjusted by the first adjustment step in cooperation with the internal control program. Imaging means for outputting an image representing a scene captured on the imaging surface;
An electronic camera comprising a capturing unit that captures an external control program, and a processor that executes processing according to the external control program captured by the capturing unit and the internal control program stored in a memory,
The external control program is
A first adjustment step for adjusting the subject distance to a desired distance;
A calculation step of calculating a distance to a subject corresponding to the specific subject image based on a size of the specific subject image appearing in the image output from the imaging unit; and a distance in which the depth of field is calculated by the calculation step And an electronic camera corresponding to a program that executes a second adjustment step for adjusting the depth corresponding to the difference between the distance adjusted by the first adjustment step in cooperation with the internal control program.

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