JP6347703B2 - Imaging apparatus and control method - Google Patents

Description

  The present invention relates to an imaging apparatus, and more particularly to face detection for detecting the face of a subject.

  2. Description of the Related Art Conventionally, there has been known an imaging apparatus that performs photometry and face detection by acquiring an image signal with a photometric sensor before shooting and processing the image signal.

  In such an imaging apparatus, face detection can be performed based on an image signal acquired by a photometric sensor, and automatic focus control (AF control) can be performed using the detection result (Patent Document 1).

JP 2008-262001 A

  However, with the conventional techniques disclosed in the above-mentioned patent documents, even if a person exists, AF control cannot be performed properly unless the face of the person can be detected based on the image signal acquired by the photometric sensor.

  Accordingly, an object of the present invention is to enable face detection with high accuracy.

  In order to achieve the above object, an imaging unit according to the present invention, a setting unit for setting a gain for an image signal obtained by imaging with the imaging unit, and an image to which the gain set by the setting unit is applied A face detection unit for detecting a face of the subject based on the signal; and a focus detection unit. The setting unit captures an image with the imaging unit based on the focus detection information obtained by the focus detection unit. A gain for the image signal obtained is set.

  According to the present invention, face detection can be performed with high accuracy.

1 is a configuration diagram of a camera system according to an embodiment of the present invention. It is a figure which shows an example of AF frame arrangement | positioning of a display element. It is a figure which shows the photometry method according to the state of the camera. It is a figure which shows the process of APU112 in face detection AF mode. It is a figure which shows the timing of the process of each CPU in face detection AF mode. FIG. 6 is a diagram in which a photometric area and an AF frame are superimposed on a photometric image. It is a figure which shows the process of APU112 in the face detection AF mode of 1st Embodiment. It is a figure which shows SW1 photometry transfer parting out focus focusing photometry process of 1st Embodiment. It is a figure which shows the timing of the process of each CPU in the face detection AF mode of 1st Embodiment. It is a figure which shows SW1 photometry transfer parting out focus focusing photometry process of 1st Embodiment. It is a figure which shows the re-face detection process of 1st Embodiment. It is a figure which shows the timing of the process of each CPU in the face detection AF mode of 1st Embodiment. It is a figure which shows the process of APU112 in the face detection AF mode of 2nd Embodiment. It is a figure which shows SW1 photometry interruption part-of-focus focusing photometry processing of 2nd Embodiment. It is a figure which shows the timing of the process of each CPU in the face detection AF mode of 2nd Embodiment. It is a figure which shows SW1 photometry interruption part-of-focus focusing photometry processing of 2nd Embodiment. It is a figure which shows the timing of the process of each CPU in the face detection AF mode of 2nd Embodiment. It is a figure which shows the process of APU112 in the face detection AF mode of 3rd Embodiment. It is a figure which shows SW1 photometric division | segmentation interruption parting focus photometry process of 3rd Embodiment. It is a figure which shows the timing of the process of each CPU in the face detection AF mode of 3rd Embodiment. It is a figure which shows the process of AF frame reselection calculation of 4th Embodiment. It is a figure which shows the timing of the process of each CPU in the face detection AF mode of 4th Embodiment.

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

  FIG. 1 is a diagram illustrating a configuration of a camera system according to an embodiment of the present invention. The camera system shown in FIG. 1 includes a camera 100 and a lens unit 200 that is detachably attached to the camera 100. First, the configuration within the camera 100 and the lens unit 200 will be described.

  A microcomputer CPU (hereinafter, camera microcomputer) 101 is a control unit that controls each unit of the camera 100.

  The memory 102 is a memory such as a RAM or a ROM connected to the camera microcomputer 101.

  The image sensor 103 is an image sensor such as a CCD or CMOS including an infrared cut filter, a low-pass filter, and the like, and an image of a subject is formed by the lens unit 200 at the time of photographing.

  The shutter 104 is closed during non-shooting to shield the image sensor 103, and is opened during shooting to guide the light beam to the image sensor 103.

  The half mirror 105 reflects a part of the light incident from the lens unit 200 when not photographing, and forms an image on the focus plate 106.

  The display element 107 is a display element for displaying an AF frame such as a PN liquid crystal, and indicates to the user which position in the imaging area is in focus when looking through the optical viewfinder.

  FIG. 2 shows an example of the arrangement of AF frames displayed on the display element 107. In the PN liquid crystal, the liquid crystal in the AF frame selected by the instruction from the camera microcomputer 101 is diffused and the AF frame is displayed. A plurality of photometric areas are indicated by dotted lines.

  The photometric sensor 108 is an image sensor such as a CCD or COMS, and is used not only for photometry but also for face detection and subject tracking.

  The pentaprism 109 guides the subject image on the focusing screen 106 to the photometric sensor 108 and the optical viewfinder.

  The focus detection circuit 110 performs focus detection by guiding a part of the light incident from the lens unit 200 and passing through the half mirror 105 to the AF sensor in the focus detection circuit 110 by the AF mirror 111. The focus detection information that is the result of focus detection is not particularly limited as long as it is information corresponding to the AF method, such as phase difference information used in phase difference detection AF or evaluation value information used in contrast AF. .

  A CPU (hereinafter referred to as APU) 112 is a CPU for image processing / calculation of the photometric sensor 108, and is used for face detection processing, subject tracking processing, and photometric processing based on the image signal acquired by the photometric sensor 108 here. Perform various calculations. Further, a gain for an image signal obtained by imaging with the photometric sensor 108 is set, or the set gain is applied to the image signal.

  The memory 113 is a memory such as a RAM or a ROM connected to the APU 112.

  In the above camera system, a CPU dedicated to the photometric sensor such as the APU 112 is prepared, but the processing may be performed by the camera microcomputer 101 or the like.

  A CPU (hereinafter referred to as LPU) 201 is a CPU in the lens unit, and sends lens information, distance information to the subject, and the like to the camera microcomputer 101. The LPU 201 drives the lens in the lens unit 200 in response to a request from the camera microcomputer 101.

  This is the end of the description of the configuration diagram of the camera system shown in FIG.

  Next, a photometric method according to the state of the camera 100 will be described with reference to FIG.

  First, when the photometry is started from the state where the camera 100 is not performing photometry, the first photometry is performed. This first photometry is a photometry method for measuring the brightness state in a short time from the state in which the brightness of the subject is not known, for example, when the camera 100 is activated or after the lens is replaced. Since the first and second times of the first photometry are performed quickly, accumulation S and readout S that do not use all the pixels that can be received by the photometry sensor 108 are performed. Based on these two photometric results, the third time of photometry calculates the storage parameters during storage, and storage A and readout A are performed using all pixels that can be received by the photometric sensor 108. The image signals obtained by the storage A and the readout A are characterized by using sufficient pixels to perform face detection, and are necessary for face detection such as SW1 metering, close-out focusing metering, and final focusing metering described later. The same method is used for photometry. The description of the algorithm of the photometric calculation processing is omitted, but the photometric value as shown in FIG. 2 is divided into a predetermined number of block areas, and the photometric value is calculated for each block, thereby reducing the overall brightness. An operation that can be measured. In this calculation, after measuring the brightness, the storage parameters such as the storage time, the gain, and the reading mode are determined so that the brightness of the image signal to be acquired next becomes appropriate.

  Next, the first metering is completed, and the metering that is started when a photographing button (not shown in FIG. 1) is pressed is referred to as SW1 metering. In this SW1 photometry, the photometric value of each photometric area is calculated by photometric calculation from the image signal obtained by the storage A and readout A described above. Further, the SW1 photometry operates differently from the storage A and the readout A in order to obtain various information related to future photographing, in addition to simply calculating a photometric value. In the present embodiment, flicker information is acquired from the image signal obtained by the accumulation F and readout F in order to determine the so-called flicker blinking cycle, such as a fluorescent lamp that periodically blinks based on the cycle of the alternating current. It is assumed that flicker detection calculation is performed. The accumulation F, readout F, and flicker detection calculation are not related to the features of the present invention and will not be described in detail. For example, during the accumulation F period, a plurality of pieces acquired with an accumulation time shorter than the flicker blinking period are used. The flicker blinking cycle and the like are measured by comparing the signal levels of the image signals.

  Next, in a mode in which focus control is performed so as to preferentially focus on a face detected by face detection (hereinafter referred to as face detection AF mode), this is performed for face detection immediately before focusing. Abandon the metering and set it as in-focus metering. This close-up focus metering is a photometry performed when the camera microcomputer 101 determines that the lens is focused once more, and a person's face is present in the imaging region based on the image signal obtained by the storage A and readout A described above. After performing face detection calculation to determine whether or not, photometry calculation is performed. The face detection AF mode may be set automatically by the camera microcomputer 101 based on the image signal acquired from the photometric sensor 108 or may be set according to the operation of the operation unit (not shown) by the user. Good.

  Next, photometry performed when the final focus is achieved is referred to as final focus photometry. In this final focus metering, the brightness of the final subject after focusing is measured by performing a photometry calculation based on the image signal obtained by the storage A and readout A described above.

  This is the end of the description of the types of photometry relating to the embodiment of the present invention shown in FIG.

  Next, processing of the APU 112 in the face detection AF mode according to the embodiment of the present invention will be described using the flowchart of FIG.

  First, in step S401, it is determined whether there is a first photometry request from the camera microcomputer 101. If there is not, step S401 is repeated, and if there is, the first photometric process in step S402 is performed. For the first photometry process, the process described with reference to FIG. 3 is performed. Next, the process proceeds to step S403.

  In step S403, it is determined whether there is a SW1 photometry request from the camera microcomputer 101. If there is not, step S403 is repeated, and if there is, SW1 photometry processing in step S404 is performed. For the SW1 photometry process, the process described with reference to FIG. 3 is performed. Next, the process proceeds to step S405.

  In step S405, it is determined whether or not there is a parting focus request from the camera microcomputer 101. If not, the process returns to step S403. If there is, the parting focus photometry process in step S406 is performed. As for the close-out focusing metering process, the process described with reference to FIG. 3 is performed. Next, the process proceeds to step S407.

  In step S407, it is determined whether there is a final focus metering request from the camera microcomputer 101. If so, step S407 is repeated. If there is, the final focus metering process in step S408 is performed. For the final focus metering process, the process described with reference to FIG. 3 is performed, and this flowchart is terminated. Next, the processing timing of each CPU until the final focusing in the face detection AF mode will be described using the timing chart of FIG.

  First, in order to perform the first photometry, the camera microcomputer 101 issues a first photometry request to the APU 112. At that time, the camera microcomputer 101 sends focus information 1 to the APU 112. Focus information refers to how much the subject corresponding to the AF frame is in focus (correctness of the focus position of the lens with respect to the subject corresponding to the AF frame) when the camera microcomputer 101 detects the focus. It is the information being expressed. The focus information is calculated by the camera microcomputer 101 based on the lens information sent from the LPU 201 to the camera microcomputer 101 and the focus detection information obtained by the focus detection circuit 110. The detailed content of the focus information and the calculation method thereof are not particularly limited, but in the present embodiment, the higher the number, the more focused (the higher the degree of focus), and 0 to 10 points. It shall be expressed.

  Focus information 1 at the time of the first photometry is information when the focus position of the lens is indefinite, for example, when the camera 100 is activated, and when the camera microcomputer 101 starts focus detection. Therefore, in this embodiment, it is assumed that the focus information of all AF frames is 0 point.

  While the APU 112 performs the first photometry, the camera microcomputer 101 performs focus detection 1 and requests the LPU 201 for lens drive 1 according to the detection result.

  An image captured by the APU 112 at the time of the first photometry represents an image (photometric image) based on the image signal obtained by the photometric sensor 108 indicated by the photometric image focus information 1 and the focus information 1. As described with reference to FIG. 3, the storage parameter of the storage A is set so that the brightness of the subject is measured in a short time in the first time and the second time, and the brightness of the image signal acquired in the third time is appropriate. However, there is a case where the brightness of the image signal acquired at the third time is not appropriate. As such an example, the present embodiment shows an example in which a person is extremely backlit.

  After the APU 112 transmits the first photometry result to the camera microcomputer 101, the camera microcomputer 101 next makes a SW1 photometry request. At that time, the camera microcomputer 101 sends focus information 2 to the APU 112. The focus information 2 at the time of SW1 metering is a higher score than the focus information 1 from the results of the focus detection 1 and the lens drive 1 at the first metering. In the present embodiment, it is assumed that Focus 5 which is an AF frame near the face of a person has 5 points, and Focus 4 which is an AF frame near the torso has 6 points. In FIG. 5, it is expressed that the focus information 2 is sent at the same time when the camera microcomputer 101 issues the SW1 photometry request to the APU 112, but the timing for sending the focus information 2 is not limited to the timing shown in FIG. . For example, when the lens driving time is short, the focus detection and the lens driving may be performed finely. When the lens driving is long, the number of points at that time when the SW1 photometry request is issued from the total driving time. The camera microcomputer 101 may calculate whether or not.

  Next, the APU 112 that has received the SW1 photometry request from the camera microcomputer 101 performs accumulation A1. As described with reference to FIG. 3, the accumulation parameter set in the accumulation A <b> 1 is the one calculated in the first photometry. The accumulation parameters include accumulation time, gain, accumulation method, and the like. In this embodiment, a gain determination method using a photometric image and focus information will be described with reference to FIG.

  FIG. 6 is a diagram in which the photometric area and AF frame described in FIG. 1 are superimposed on the photometric image. In addition, it represents focus information when the photometry image is taken. In the example of FIG. 6, the focus information has 5 points for the AF frame Focus5 and 6 points for the Focus4, so the focus is starting to focus near the Focus4 and 5, and in the photometric image, the focus is slightly focused near the Focus4 and 5 You can see that the image was taken. On the other hand, since the number of points of the other AF frames is 0, it is clear that the image is not in focus at all, and an image that is not in focus in Focus 1, 2, and 3 is captured in the photometric image. The photometry area near the AF frame that is in focus (focus level is a predetermined value or more) is set as the Ef area, and the photometry area near the AF frame that is out of focus (the focus level is less than the predetermined value) is the Ea area. To do. In addition, the photometric result in the Ef region is Ef, and the photometric result in the Ea region is Ea. Here, by performing Ef−Ea, the difference in brightness between the Ef region and the Ea region can be calculated. That is, the difference in brightness between an image in the vicinity of focus and an image in the vicinity of out of focus can be found. The calculation method of Ef and Ea is not particularly limited. For example, let Ef be the photometric value obtained by averaging the photometric values of the photometric areas included in the Ef region, and Ea be the photometric value obtained by averaging the photometric values of the photometric regions included in the Ea region. In addition, the weighted addition value, the maximum value, the mode value, and the like of the photometric values in each photometric area may be used as the representative photometric values Ef and Ea. Here, if the bright value is a large number and the dark value is a small number, when Ef−Ea is negative, it can be determined that the in-focus area is dark, so it can be determined that the light is backlit. Therefore, at the next photometry, it is determined to increase the gain as an accumulation parameter so that the focus 4 and the vicinity of Focus 5 have appropriate brightness.

  However, when the calculation described with reference to FIG. 6 is performed from the photometric image focus information 1 of FIG. 5, the focus information is all 0 points, so the Ef region cannot be determined. Therefore, it is not possible to determine the gain of the storage parameter that brightens the in-focus portion at the next photometry.

  Therefore, the photometry image obtained by the storage A1 and reading performed when the SW1 photometry request is received is a photometry image as shown in photometry image focus information 2 in FIG. 5, that is, a photometry image in which the subject portion remains dark. The Ef region and the Ea region are determined from the focus information 2 when the photometric image is obtained, and Ef−Ea is calculated based on the image signal corresponding to the photometric image. Thereby, the gain of the storage parameter for the next photometry is determined. Thereafter, the processing described in FIG. 3 is performed.

  On the other hand, the camera microcomputer 101 performs focus detection 2 and performs lens driving 2 to determine whether or not the final focusing can be achieved by part-time focusing, that is, one more lens driving. If the lens drive 2 is long and exceeds the time when the SW1 photometry is completed, the camera microcomputer 101 can request the APU 112 to close the focus without time lag. However, when the lens driving 2 as shown in FIG. 5 is short, the close-out focusing request is waited until the SW1 photometry is finished, and a time lag occurs as shown by the thick black line.

  When the SW1 photometry is completed at the APU 112, the camera microcomputer 101 issues a close-up focusing photometry request. At that time, the camera microcomputer 101 sends focus information 3 to the APU 112. Focus information 3 at the time of close-up focus metering is higher than the focus information 2 from the results of focus detection 2 and lens drive 2 at the time of SW1 metering.

  The APU 112 that has received the parting focus metering request from the camera microcomputer 101 performs accumulation A2. The storage parameter set in this storage A2 is a gain determined from Ef-Ea of the SW1 photometry described above. As a photometric image obtained by accumulation A2 and reading performed when a close-out focusing photometry request is received, a photometric image as shown in photometric image focus information 3 in FIG. 5, that is, a photometric image with a bright subject is photographed. . As described with reference to FIG. 3, in parting focus metering, face detection calculation is performed based on the image signal acquired by the photometric sensor 108. Although details of the algorithm of the face detection calculation will not be described in detail here, use of an image signal obtained with an appropriate exposure when determining a face from the image signal improves the face detection accuracy. This is because feature points such as eyes, nose and mouth are judged from the image signal, and if the feature points are too dark, the shape cannot be judged.

  The APU 112 sends the result of the face detection calculation to the camera microcomputer 101, and thereafter performs the processing described in FIG. Upon receiving the face detection calculation result, the camera microcomputer 101 performs AF frame reselection calculation from the focus information 3 and the face detection calculation result at the time of close-up focusing, and performs lens drive Ex again. In this example, Focus 4 has the highest score of 9 for Focus 4, but lens drive Ex is performed so as to focus on Focus 5 based on the face detection result. At that time, the camera microcomputer 101 issues a final focus metering request to the APU 112, and thereafter performs the processing described with reference to FIG.

  This is the end of the description of the processing timing of each CPU until the final focusing in the face detection AF mode according to the embodiment of the present invention shown in FIG.

(First embodiment)
As described above, when each CPU process until the final focusing in the face detection AF mode is performed, a time lag occurs when the lens drive 2 is short. Therefore, in the present embodiment, the processing of each CPU until the final focusing in the face detection AF mode is performed so as to reduce the time lag that occurs when the lens drive 2 is short.

  FIG. 7 is a flowchart for the processing of the APU 112 in the face detection AF mode of the present embodiment.

  First, in step S701, it is determined whether there is a first photometry request from the camera microcomputer 101. If there is not, step S701 is repeated, and if there is, the first photometric process in step S702 is performed. For the first photometry process, the process described with reference to FIG. 3 is performed. Next, the process proceeds to step S703.

  In step S703, SW1 photometry change-off part-time focusing photometry processing, which is a feature of the present embodiment, is performed. The SW1 photometry transfer part-off focusing photometry processing will be described later with reference to FIGS. Next, the process proceeds to step S704.

  In step S704, it is determined whether there is a final focus metering request from the camera microcomputer 101. If so, step S704 is repeated, and if there is, the final focus metering process in step S705 is performed. For the final focus metering process, the process described with reference to FIG. 3 is performed, and this flowchart is terminated.

  FIG. 8 is a flowchart of the SW1 photometry transfer part-off focusing photometry processing in the present embodiment.

  First, in step S801, it is determined whether there is a SW1 photometry request from the camera microcomputer 101. If not, step S801 is repeated, and if there is, the storage A process is performed in step S802. For the accumulation A process, the process described with reference to FIG. 3 is performed. Next, the process proceeds to step S803.

  Next, in step S803, it is determined whether or not there is a parting focus request from the camera microcomputer 101. If not, the process proceeds to step S804, and if present, the process proceeds to step S810.

  In step S804, it is determined whether or not the storage A in step S802 has been completed. If it is determined that the accumulation has been completed, the process proceeds to step S805. If it is not determined that the accumulation has been completed, the process returns to step S803. Next, steps S805 to S809 perform a series of processes related to SW1 photometry. This series of SW1 photometry processing has already been described with reference to FIG.

  In step S810, it is determined whether or not the storage A in step S802 has been completed. If it is determined that the accumulation has been completed, the process proceeds to step S811, and if it is not determined that the accumulation has been completed, step S810 is repeated.

  Next, Steps S811 to S814 perform a series of processes related to parting focus photometry. Since this series of parting focus metering has already been described with reference to FIG. 3, the description thereof is omitted.

  This is the end of the description of the SW1 photometry transfer part-off focusing photometry processing in the present embodiment.

  Next, the processing timing of each CPU until the final focusing in the face detection AF mode will be described using the timing chart of FIG.

  The process from the first metering to the SW1 metering request is performed in the same manner as the timing chart of FIG. Next, after performing the focus detection 2, the camera microcomputer 101 requests the APU 112 for a close-up focusing request.

  In FIG. 5, the camera microcomputer 101 does not issue a parting focus request or waits until the SW1 photometry is completed. On the other hand, in FIG. 9, the APU 112 performs accumulation A1 as SW1 photometry, but upon receiving a close-up focus request from the camera microcomputer 101, the APU 112 changes over to the process as focus-focus photometry. More specifically, the APU 112 performs face detection calculation based on the image signal corresponding to the photometric image of the photometric image focus information 1 obtained from accumulation A and readout as SW1 photometry. As described above, the use of an image signal obtained with appropriate exposure increases the accuracy of face detection. Therefore, in the photometric image of the photometric image focus information 2, the focus time can be shortened when face detection is possible. There are benefits.

  The APU 112 sends the result of the face detection calculation to the camera microcomputer 101, and thereafter performs the processing described in FIG. 3 and FIG.

  This is the end of the description of the processing timing of each CPU until the final focusing in the face detection AF mode when face detection is possible with the photometric image of the photometric image focus information 2.

  FIG. 10 is a flowchart of the SW1 photometry change-over close-out focus metering process when a face cannot be detected in the photometry image of the photometry image focus information 2.

  The processing from step S1001 to step S1012 performs the same processing as the processing from step S801 to step S812 in FIG.

  In step S1013, a re-face detection process is performed. The detailed processing flow will be described with reference to FIG. 11. As described above, in the photometric image of the photometric image focus information 2, the brightness of the face is low and the face detection accuracy may be low. When it is not found, a process for performing face detection again is performed.

  Next, the process proceeds to steps S1014 and S1015. In steps S1014 and S1015, processing similar to the processing in steps S813 and S814 in FIG. 8 is performed, and this flowchart is ended.

  FIG. 11 is a flowchart of the reface detection process in FIG.

  In step S1101, it is determined whether face detection has been performed. If it is determined that a face has been detected, the process ends. If no face is detected, the process proceeds to step S1102.

  In step S1102, photometric calculation processing is performed, and the gain of the next accumulation parameter is determined from Ef and Ea described above.

  In step S1103, accumulation A processing is performed. In this accumulation A, accumulation is performed using the accumulation parameter determined in S1102, and the process proceeds to step S1104.

  In step S1104, it is determined whether or not the accumulation is completed. If it is not completed, step S1104 is repeated. If it is determined that it has been completed, the reading process of step S1105 is performed.

  In step S1106, face detection calculation processing is performed and the process ends.

  In this flowchart, when a face cannot be detected, an additional accumulation is described. However, a plurality of accumulations may be performed. At this time, if the gain of the storage parameter determined in step S1102 is the same as the previous one, the image obtained by the storage A process is the same photometric image, and therefore, the repetition is repeated by changing the gain value. You may decide not to.

  Furthermore, the number of repetitions may be changed by an operation unit (not shown in FIG. 1) according to information such as a shooting mode set by the user, for example, a person shooting mode or a landscape mode.

  Next, the timing of processing of each CPU until the final focusing in the face detection AF mode when face detection is impossible in the photometric image of the photometric image focus information 2 will be described using the timing chart of FIG. .

  From the first time metering to the parting focus metering request is performed in the same manner as the timing chart of FIG. In FIG. 9, face detection is performed from the photometric image of the photometric image focus information 2, and as a result, the face detection information is sent to the camera microcomputer 101. In FIG. 11, when it is determined that the face is not found from the result of the face detection, the accumulation A2 is performed once again. The accumulation parameter set in this accumulation A2 is accumulated with the gain determined from Ef-Ea of the SW1 photometry described above. The photometric image obtained by this accumulation A2 and reading is a photometric image in which the subject portion is bright as shown in the photometric image focus information 3 of FIG. This increases the possibility that a face that could not be detected in the photometric image of the photometric image focus information 2 can be detected, and sends face detection information to the camera microcomputer 101. There may be a time lag, but there is a merit that face detection can be performed with higher accuracy.

  Thereafter, the processing described in FIGS. 3 and 5 is performed.

  This is the end of the description of the processing timing of each CPU until the final focusing in the face detection AF mode when face detection is impossible in the photometric image of the photometric image focus information 2.

  As described above, in the present embodiment, face detection can be performed with high accuracy while reducing the time lag that occurs when the lens drive 2 is short.

(Second Embodiment)
The second embodiment of the present invention will be described below.

  FIG. 13 is a flowchart for the processing of the APU 112 in the face detection AF mode according to this embodiment.

  First, in step 1301, it is determined whether or not there is a first photometry request from the camera microcomputer 101. If there is not, step S1301 is repeated, and if there is, the first photometric process in step S1302 is performed. For the first photometry process, the process described with reference to FIG. 3 is performed. Next, the process proceeds to step S1303.

  In step S1303, SW1 photometry interruption part-off focusing photometry processing, which is a feature of the present embodiment, is performed. The SW1 metering interruption part-of-focus focusing metering process will be described later with reference to FIGS. Next, the process proceeds to step S1304.

  In step S1304, it is determined whether there is a final focus metering request from the camera microcomputer 101. If yes, step S1304 is repeated. If there is, the final focus metering process in step S1305 is performed. For the final focus metering process, the process described with reference to FIG. 3 is performed, and this flowchart is terminated.

  FIG. 14 is a flowchart of the SW1 photometry interruption part-off focusing photometry processing in the present embodiment.

  The processing from step S1401 to step S1409 is the same as the processing from step S801 to step S809 in FIG.

  In step S1410, a process for interrupting the storage A process started in step S1402 in response to the SW1 photometry request from the camera microcomputer 101 is performed. Although details of the interruption process will not be described, a process of interrupting the accumulation of the photometric sensor 108 and making the accumulation resumable from the beginning is performed.

  Next, in step S1411, accumulation A processing corresponding to the parting focus metering request is performed from the beginning, and thereafter, steps S1412 to S1416 perform the same processing as steps S810 to S814 in FIG. To do.

  Next, the processing timing of each CPU until the final focusing in the face detection AF mode will be described using the timing chart of FIG.

  The process from the first metering to the SW1 metering request is performed in the same manner as the timing chart of FIG.

  Next, after performing the focus detection 2, the camera microcomputer 101 requests the APU 112 for a close-up focusing request.

  In FIG. 9, the APU 112 is a timing chart for switching from SW1 photometry to a close-out focusing request. On the other hand, in FIG. 15, the APU 112 performs accumulation A1 as SW1 metering. However, upon receiving a close-up focusing request from the camera microcomputer 101, the APU 112 interrupts the storage A1 process, and again performs the close-up focus metering from the beginning. Accumulation A2 is performed.

  Due to this interruption processing, the gain of the storage parameter in the storage A2 cannot be determined, so that the photometric image of the read photometric image focus information 3 is taken with the subject portion being dark. The photometric image of the photometric image focus information 3 has an advantage that the focusing time can be shortened when face detection is possible.

  The APU 112 sends the result of the face detection calculation to the camera microcomputer 101, and thereafter performs the processing described in FIG. 3 and FIG.

  This is the end of the description of the processing timing of each CPU until the final focusing in the face detection AF mode when face detection is possible with the photometric image of the photometric image focus information 3.

  FIG. 16 is a flowchart of the SW1 metering interruption part-of-focus focusing metering process when a face cannot be detected in the metering image of the metering image focus information 3.

  The processing from step S1601 to step S1614 performs the same processing as the processing from step S1401 to step S1414 in FIG.

  In step S1615, a re-face detection process is performed. Although the detailed processing flow has been described with reference to FIG. 11, in the photometric image of the photometric image focus information 3, processing for performing face detection again when the brightness near the face is low and a face cannot be found is performed.

  Next, the process proceeds to step S1616 and step S1617. Steps S1616 and S1617 are the same as the processes in steps S1415 and S1416 of FIG.

  Next, the timing of processing of each microcomputer until the final focusing in the face detection AF mode when a face cannot be detected in the photometric image of the photometric image focus information 3 will be described using the timing chart of FIG.

  From the first metering to the parting focus metering request is performed in the same manner as the timing chart of FIG. In FIG. 15, face detection is performed from the photometric image of the photometric image focus information 3 and the resulting face detection information is sent to the camera microcomputer 101. In FIG. 17, when it is determined that the face is not found based on the result of the face detection, the accumulation A3 is performed once again. The accumulation parameter set in this accumulation A3 is accumulated with the gain determined from Ef-Ea of the SW1 photometry described above. The photometric image obtained by this accumulation A3 and reading is a photometric image in which the subject portion is bright as shown in the photometric image 2 focus information 3 of FIG. This increases the possibility of detecting a face that could not be detected in the photometric image of the photometric image focus information 3, and sends face detection information to the camera microcomputer 101. Although there is a possibility that the in-focus time will be longer, there is an advantage that face detection can be performed with higher accuracy. Thereafter, the processing described in FIGS. 3 and 5 is performed.

  This is the end of the description of the processing timing of each CPU until the final focusing in the face detection AF mode when a face cannot be detected in the photometric image of the photometric image focus information 3.

  As described above, in the present embodiment, it is possible to perform focus control with high accuracy using the detection result of face detection while reducing the time lag that occurs when the lens drive 2 is short.

(Third embodiment)
The third embodiment of the present invention will be described below.

  FIG. 18 is a flowchart for the processing of the APU 112 in the face detection AF mode according to this embodiment.

  First, in step S1801, it is determined whether there is a first photometry request from the camera microcomputer 101. If there is not, step S1801 is repeated, and if there is, the first photometric process in step S1802 is performed. For the first photometry process, the process described with reference to FIG. 3 is performed. Next, the process proceeds to step S1803.

  In step S1803, the SW1 metering break interruption part-off focusing photometry process, which is a feature of the present embodiment, is performed. The SW1 metering break interruption close-out focus metering process will be described later with reference to FIG. Next, the process proceeds to step S1804.

  In step S1804, it is determined whether there is a final focus metering request from the camera microcomputer 101. If yes, step S1804 is repeated. If there is, the final focus metering process in step S1805 is performed. For the final focus metering process, the process described with reference to FIG. 3 is performed, and this flowchart is terminated.

  FIG. 19 is a flowchart of the SW1 metering break interruption close-out focus metering process in the present embodiment.

  The processing from step S1901 to step S1909 is the same as the processing from step S801 to step S809 in FIG.

  In step S1910, it is determined whether or not the accumulation A process started in step S1902 has been completed by more than half. In the present embodiment, it is determined whether or not half or more has been completed by measuring the accumulation time using a timer included in the camera microcomputer 101.

  If it is determined that more than half have been completed, the process advances to step S1911.

  In step S1911, it is determined whether or not the process of accumulation A started in step S1902 is completed. If not completed, step S1911 is repeated. If it is determined that the process has been completed, the process advances to step S1912. In step S1912, a reading process is performed, and the process proceeds to step S1913. In step S1913, photometric calculation processing is performed based on the image signal corresponding to the photometric image, and the gain of the next storage parameter is determined from Ef and Ea described above.

  In step S1914, close-out focus metering is performed and the process ends.

  On the other hand, if it is not determined in step S1910 that the accumulation process has been completed by more than half, the process proceeds to step S1915. In step S1915, the SW1 photometry interruption part-of-focus focusing photometry processing described in the second embodiment is performed and the process ends.

  Next, the processing timing of each CPU until the final focusing in the face detection AF mode will be described using the timing chart of FIG.

  The process from the first metering to the SW1 metering request is performed in the same manner as the timing chart of FIG.

  Next, the camera microcomputer 101 performs the lens drive 2 after performing the focus detection 2. However, if the lens drive time is long, the timing at which it is possible to determine that the close-up focus metering can be performed is extended, and therefore the accumulation A1 is also progressing. . The APU 112 that has received a parting focus metering request from the state where the accumulation A1 has progressed more than half, performs reading and photometry calculations without interrupting the accumulation A1, and performs accumulation measurement parameters for the next metering using Ef-Ea. The process up to determining the gain is performed.

  The photometric image obtained by the accumulation A2 and reading performed using the gain of the accumulation parameter is a photometric image in which the subject portion is bright as shown in the photometric image focus information 3 of FIG. This increases the possibility that a face that could not be detected in the photometric image of the photometric image focus information 2 can be detected, and sends face detection information to the camera microcomputer 101. Although the time lag becomes longer from the parting focus metering request indicated by the thick black line in FIG. 20 to the accumulation A2, there is an advantage that face detection can be performed more accurately.

  Thereafter, the processing described in FIGS. 3 and 5 is performed.

  As described above, in this embodiment, face detection can be performed with high accuracy.

(Fourth embodiment)
The fourth embodiment of the present invention will be described below.

  In the first to third embodiments, in the AF frame reselection calculation process, the camera microcomputer 101 performs lens drive Ex from the face detection information and focus information from the APU 112, and if there is a face in the face detection information, it is as close to the face as possible. The AF frame is selected.

  However, if the focus information of the AF frame near the face is low, that is, if you are trying to focus on something other than the face, the lens drive Ex time will be long or the focus will be judged in a state where the focus is not correct. There is a possibility that.

  FIG. 21 is a flowchart for the processing of the camera microcomputer 101 for AF frame reselection calculation in the fourth embodiment.

  In step S2101, face information is analyzed from the face detection information received from the APU 112, and the process proceeds to step S2102. In step S2102, it is determined whether a face exists.

  If it is determined that no face exists, the process proceeds to step S2103. In step S2103, an AF frame having the highest score is selected from the focus information, and the process proceeds to step S2104. In step S2104, lens drive Ex is performed on the selected AF frame, and the process ends.

  On the other hand, if it is determined in step S2102 that a face exists, the process proceeds to step S2105. In step S2105, the process proceeds to step S2106 for performing processing for determining the number of focus information points near the face. If it is determined in step S2106 that the focus information score near the face is lower than an arbitrary threshold value, the process advances to step S2103. If it is determined that the value is above a certain threshold value, the process proceeds to step S2107.

  In step S2107, processing for selecting an AF frame near the face is performed, and the process proceeds to step S2104. Lens driving Ex is performed on the selected AF frame, and the process ends.

  Next, the processing timing of each CPU until the final focusing in the face detection AF mode in the fourth embodiment of the present invention will be described using the timing chart of FIG.

  The camera microcomputer 101 requests part-time focusing photometry from the APU 112 by lens driving n. At this time, the score of a large subject near Focus 5 is the highest at 8 points, and the face near Focus 3 is as low as 1 point. The APU 112 transmits the fact that there was a face as face detection information to the camera microcomputer 101 by performing face detection calculation from the photometric image of the photometric image focus information n by parting focus metering.

  The camera microcomputer 101 performs AF frame reselection calculation, and there is a face in the vicinity of Focus 3. However, since the score is low, lens drive Ex is performed so as to focus on Focus 5, and the process ends.

  As described above, in the present embodiment, when the focus control cannot be performed accurately using the detection result of the face detection, the focus control can be performed accurately by not using the detection result of the face detection. it can.

  In the above-described embodiment, the gain is determined from Ef−Ea. However, any gain may be used as long as the brightness of the Ef region becomes a level at which face detection is possible, and therefore, it may be determined based on at least Ef. For example, Ef may be compared with a predetermined value to obtain a gain that makes Ef a predetermined value.

  In addition, the processes described in the above embodiments can be combined with each other.

  In the above-described embodiment, the configuration in which the face detection process is performed based on the image signal obtained by the photometric sensor 108 has been described, but the configuration in which the face detection process is performed based on the image signal obtained by the image sensor 103 is described. Also good.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

DESCRIPTION OF SYMBOLS 100 Camera 101 Camera microcomputer 103 Image pick-up element 107 Display element 108 Photometric sensor 110 Focus detection circuit 112 APU
200 Lens unit 201 LPU

Claims (7)

Imaging means;
Setting means for setting a gain for an image signal obtained by imaging with the imaging means;
Face detection means for detecting the face of the subject based on the image signal to which the gain set by the setting means is applied;
A focus detection means,
The imaging apparatus according to claim 1, wherein the setting means sets a gain for an image signal obtained by imaging by the imaging means based on focus detection information obtained by the focus detection means.   2. The imaging according to claim 1, wherein the setting unit sets the gain based on an image signal obtained by imaging with the imaging unit and focus detection information when the imaging is performed. apparatus. Further comprising a computing means for computing a photometric value based on an image signal obtained by imaging with the imaging means;
The said setting means sets the said gain based on the representative photometric value of the area | region where the degree of focus based on the said focus detection information calculated by the said calculating means becomes more than predetermined value. The imaging device described in 1.   The setting means includes a subject based on a first image signal obtained by applying a first gain set by the setting means to an image signal obtained by performing first imaging by the imaging means by the face detection means. If the face cannot be detected, the second imaging performed after the first imaging based on the first image signal and the first focus detection information obtained when the first imaging is performed. The imaging apparatus according to claim 1, wherein a second gain is set for an image signal obtained by performing the above.   When the face detection unit cannot detect the face of the subject based on the first image signal, the face detection unit performs face detection of the subject based on the second image signal to which the second gain is applied. The imaging apparatus according to claim 4, wherein the imaging apparatus is characterized. A focus control unit that performs focus control based on a result of face detection by the face detection unit;
The focus control means, when the face of the subject can be detected based on the first image signal by the face detection means, performs focus control based on a result of the face detection. 5. The imaging device according to 5. A setting step for setting a gain for an image signal obtained by imaging with an imaging means;
A face detection step of performing face detection of the subject based on the image signal to which the gain set in the setting step is applied,
The method for controlling an imaging apparatus, wherein the setting step sets a gain for an image signal obtained by imaging with the imaging unit based on focus detection information obtained by the focus detection unit.

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