JP2008306765A - Image pickup device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image pickup device which allows a user to select a readout mode for a photoelectric conversion element suitable for face detection process based on the condition of an object. <P>SOLUTION: If a face region cannot be detected from an image generated from image signals output in a first readout mode, it is switched to a second readout mode that allows to obtain the image signals with higher resolution than the first readout mode. Then, the detection of the face region is performed against the image generated from the image signals output in the second readout mode. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an imaging technique.

  As a technique for determining the exposure of a conventional digital camera, there is multi-division photometry in which the in-screen photometry range is divided into a plurality of blocks and the exposure is determined from the photometry results of each block. There are also center-weighted metering that focuses on the center of the screen and spot metering that measures only an arbitrary range in the center of the screen. However, in these photometry methods, it has not always been possible to properly expose a person.

  In view of this, there has been disclosed a technique that eliminates this problem, detects the position / range of a person on the screen, and brings a photometric frame to the person so that the person is properly exposed (see Patent Document 1). In addition, Non-Patent Documents 1 to 3 are listed as face detection techniques used therein.

Non-Patent Document 1 discloses a technique for converting a color image into a mosaic image and extracting a face region by focusing on a skin color region. Non-Patent Document 2 discloses a technique for extracting a head region of a front person using geometric shape features relating to each part constituting the head of a front person image such as hair, eyes, and mouth. ing. Non-Patent Document 3 discloses a technique for extracting a front person using an edge of a person image generated by a subtle movement of a person between frames in the case of a moving image.
JP 2003-107555 A The Journal of the Institute of Television Engineers of Japan, Vol.49, No.6, pp.787-797 (1995), "Proposal of a modified HSV vote color system effective for face area extraction" IEICE Vol.74-D-II, No.11, pp.1625-1627 (1991), "Method for Extracting Facial Regions from Still-Grade Scene Images" Image Lab 1991-11 (1991), "Face Area Detection for Videophones and Its Effect"

  When reading charges from the CCD of a digital camera, there are multiple readout modes, such as an all-pixel readout mode, a thinning readout mode, and an addition readout mode, and a readout mode in which appropriate face detection processing cannot be performed depending on the situation of the subject. Is also present.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an imaging apparatus that selects a reading mode suitable for face detection processing in accordance with the state of a subject.

  In order to achieve the object of the present invention, for example, an imaging apparatus of the present invention comprises the following arrangement.

That is, output means for reading out the charges accumulated in the plurality of photoelectric conversion elements and outputting an image signal;
Face detection means for detecting a human face area in an image generated from the image signal,
The output means is a first readout mode for outputting an image signal having a first resolution from the plurality of photoelectric conversion elements, and a second readout for outputting an image signal having a second resolution higher than the first resolution. Perform the operation to output the image signal according to the readout mode of one of the modes,
When the detection of the face area is failed for the image generated by the face detection unit from the image signal output after the output unit switches to the first reading mode, the output unit switches from the first reading mode to the first reading mode. The face detection unit detects the face region of an image generated from the image signal output from the output unit in the second readout mode.

  In order to achieve the object of the present invention, for example, an imaging apparatus of the present invention comprises the following arrangement.

That is, output means for reading out the charges accumulated in the plurality of photoelectric conversion elements and outputting an image signal;
Face detection means for detecting a human face area in an image generated from the image signal,
The output means is a first readout mode for outputting an image signal having a first resolution from the plurality of photoelectric conversion elements, and a second readout for outputting an image signal having a second resolution higher than the first resolution. Perform the operation to output the image signal according to the readout mode of one of the modes,
If the size of the face area detected for the image generated by the face detection unit from the image signal output after the output unit switches to the first reading mode is less than a threshold, the output unit The reading mode is switched from the reading mode to the second reading mode, and the face detection means detects the face area for an image generated from the image signal output from the output means in the second reading mode. And

  With the configuration of the present invention, it is possible to select a reading mode suitable for face detection processing according to the state of the subject.

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

[First Embodiment]
In this embodiment, a case where a digital camera is used as an imaging device will be described. FIG. 1 is a block diagram showing a functional configuration of the digital camera according to the present embodiment.

  The operation unit 101 includes switches and buttons that are operated by an operator of the digital camera to input various instructions to the digital camera. The operation unit 101 also includes a shutter switch. When the shutter switch is half-pressed, the signal SW1 is notified from the operation unit 101 to the control unit 102. When the shutter switch is fully pressed, the signal SW2 is notified from the operation unit 101 to the control unit 102.

  Further, the operation unit 101 includes a dial member for selecting a shooting mode. The shooting mode includes a portrait mode in which shooting is performed with an emphasis on a stationary person, and a fully automatic mode in which shooting is performed with an optimal balance as a whole in consideration of the entire subject. In addition, there are also sports modes that focus on moving main subjects, landscape modes that capture a distant object, etc. Selected.

  The control unit 102 controls the operation of each unit shown in the figure, and controls each unit in response to an instruction from the operation unit 101.

  The CCD unit 103 receives light incident through the lens 108a and the exposure mechanism 109a, and outputs charges corresponding to the light amount. For example, the CCD unit 103 has the configuration shown in FIG. FIG. 3 is a diagram illustrating a configuration example of the CCD unit 103. In the figure, reference numeral 301 denotes a photoelectric conversion element that converts incident light into signal charge having a charge amount corresponding to the amount of light, and has a plurality (multiple pixels) as shown in the figure. Reference numeral 302 denotes a vertical CCD that vertically transfers signal charges read from each photoelectric conversion element 301. A horizontal CCD 303 horizontally transfers signal charges for one row transferred from the vertical CCD 302.

  The CCD unit 103 has a plurality of reading modes when reading charges from each photoelectric conversion element. As an example of the reading mode, for example, as shown in FIG. 3, all photoelectric conversion elements are divided into two fields (first field and second field). Then, charges are read from all the photoelectric conversion elements in each field, but the timing is shifted in each field. This is referred to as “all pixel readout mode”.

  Also, as shown in FIG. 4, a thinning-out readout mode for reading out charges from photoelectric conversion elements only in any specified row and column, and as shown in FIG. 5, addition readout for adding and reading out signal charges from a plurality of photoelectric conversion elements There are modes. In addition, there is a horizontal addition reading mode in which the horizontal addition is performed for reading.

  Returning to FIG. 1, the A / D conversion unit 104 performs sampling, gain adjustment, A / D conversion, and the like on the analog image signal output from the CCD unit 103, and outputs it as a digital image signal.

  The image processing unit 105 performs various types of image processing on the digital image signal output from the A / D conversion unit 104, and outputs a processed digital image signal. For example, a digital image signal received from the A / D conversion unit 104 is converted into a YUV image signal and output.

  The face detection unit 106 detects a human face region from the image indicated by the digital image signal received from the image processing unit 105, and notifies the control unit 102 of information related to this region. Upon receiving such information, the control unit 102 instructs the AF processing unit 108 to position the distance measurement frame in the human face area in the image, and appropriately sets the exposure of the human face area in the image. The AE processing unit 109 is instructed to correct it. Thereby, the AF processing unit 108 controls the position of the lens 108a and the like, and the AE processing unit 109 controls the exposure mechanism 109a.

  Further, when the control unit 102 determines that the flash is necessary, the control unit 102 instructs the EF processing unit 110 to turn on the flash. When receiving the flash-on instruction, the EF processing unit 110 controls the flash unit 111, and the flash unit 111 emits light.

  The EVF display unit 107 is configured by a small liquid crystal screen or the like, and displays an image according to the image data processed by the image processing unit 105.

  The format conversion unit 112 converts the format of the digital image signal (image data) output from the image processing unit 105 into a format such as JPEG, and outputs the converted format to the image recording unit 113. The image recording unit 113 performs processing for recording the image data subjected to format conversion received from the format conversion unit 112 in a memory (not shown) in the digital camera, an external memory inserted in the digital camera, or the like.

  The external connection unit 114 functions as an interface for connecting the digital camera to an external device such as a PC (personal computer) or a printer.

  Next, the operation of this digital camera when imaging using this digital camera will be described. FIG. 2 is a flowchart of processing performed by the digital camera when imaging is performed.

  First, when the operator of the digital camera turns on a power switch included in the operation unit 101, the control unit 102 detects this and supplies power to each unit constituting the digital camera (step S201). . When power is supplied to each part of the digital camera, the shutter is opened, so that light enters the CCD part 103 through the lens 108a and the exposure mechanism 109a. Accordingly, electric charges corresponding to the amount of incident light accumulate in the photoelectric conversion element 301 constituting the CCD unit 103.

  Therefore, the charges accumulated in the respective photoelectric conversion elements 301 are read out by the vertical CCD 302 and the horizontal CCD 303 and output as analog image signals to the A / D conversion unit 104 (step S203). The charge is read by high-speed reading such as thinning-out reading and addition reading.

  The A / D conversion unit 104 performs sampling, gain adjustment, A / D conversion, and the like on the analog image signal output from the CCD unit 103, and outputs the digital image signal (step S204).

  Next, the image processing unit 105 performs various types of image processing on the digital image signal output from the A / D conversion unit 104, and outputs a processed digital image signal (step S205).

  Next, the face detection unit 106 detects a human face region from the image indicated by the digital image signal received from the image processing unit 105, and information on the region (face information, such as the position and size of the detected region). ) Is notified to the control unit 102 (step S206).

  Further, since the image processing unit 105 outputs the processed image data to the EVF display unit 107, the EVF display unit 107 displays an image according to the processed image data (step S207).

  Upon receiving the face information, the control unit 102 instructs the AF processing unit 108 to position the distance measurement frame in the human face area in the image, and exposes the human face area in the image. The AE processing unit 109 is instructed to correct appropriately (step S208). Thereby, the AF processing unit 108 controls the position of the lens 108a and the like, and the AE processing unit 109 controls the exposure mechanism 109a.

  Then, the control unit 102 returns the process to step S203 via step S209 and repeats the subsequent processes unless receiving a signal of SW1 from the shutter switch (that is, notification of half-pressing of the shutter switch). .

  On the other hand, when the control unit 102 receives a notification of the signal SW1 from the shutter switch, the process proceeds to step S210 via step S209, and the process of capturing the first image based on the exposure and focus at this time is performed. This is performed (step S210). That is, when the control unit 102 detects the notification of the signal SW1, the image data output from the image processing unit 105 is temporarily stored as a first image in a memory (not shown). Thereby, a 1st image can be imaged.

  Next, the control unit 102 uses the face information to instruct the AF processing unit 108 to position the distance measurement frame in the human face area in the first image, and in the first image, The AE processing unit 109 is instructed to appropriately correct the exposure of the face area (step S211). Thereby, the AF processing unit 108 controls the position of the lens 108a and the like, and the AE processing unit 109 controls the exposure mechanism 109a.

  Then, the control unit 102 returns the process to step S210 via step S213 and repeats the subsequent processes unless receiving a signal of SW2 from the shutter switch (that is, notification of full pressing of the shutter switch). .

  On the other hand, when the control unit 102 receives notification of the signal SW2 from the shutter switch, the process proceeds to step S214 via step S213 to determine whether or not the flash is to be emitted (step S214). Whether or not the flash is to be emitted may be determined in advance by using the operation unit 101, and may be determined by reading the setting data, or may be determined automatically by detecting the surrounding darkness. You may make it do.

  As a result of this determination, when flash emission is performed, the process proceeds to step S215, and the control unit 102 controls the EF processing unit 110 to cause the flash unit 111 to perform pre-emission, calculate the emission amount, and set the EF frame. Processing such as weighting is performed (step S215). Then, the flash unit 111 is caused to emit light with the light emission amount determined by the processing in step S215 (step S216). Then, an image is taken.

  That is, the light emitted from the external environment (including the human face) emitted by flash light enters the CCD unit 103 through the lens 108a and the exposure mechanism 109a, and thus enters the photoelectric conversion element 301 constituting the CCD unit 103. Charges corresponding to the amount of light emitted accumulate. Therefore, the vertical CCD 302 and the horizontal CCD 303 read out the electric charge accumulated in each photoelectric conversion element 301 and output it as an analog image signal to the A / D conversion unit 104 (step S219). The readout of charges is performed by the all-pixel readout.

  The A / D conversion unit 104 performs sampling, gain adjustment, A / D conversion, and the like on the analog image signal output from the CCD unit 103, and outputs the digital image signal (step S220).

  Next, the image processing unit 105 performs various types of image processing on the digital image signal output from the A / D conversion unit 104, and outputs a processed digital image signal (step S221).

  The format conversion unit 112 converts the format of the digital image signal (image data) output from the image processing unit 105 into a format such as JPEG, and outputs it to the image recording unit 113 (step S222). The image recording unit 113 performs a process of recording the format-converted image data in a predetermined memory (step S223).

  Through the processing described above, when an image including a human face is captured, the AE and AF processes are performed so that the distance measurement frame is positioned in the face area and the exposure of the face area is appropriately corrected. Can be performed in the previous stage of shooting.

  Next, with respect to the processing performed until the control unit 102 detects the signal SW1, that is, the processing from step S203 to step S208, three examples will be given below, and each example will be described.

<Processing Example 1>
FIG. 6 is a flowchart of the processing of the processing example 1. First, the charges accumulated in the photoelectric conversion elements 301 are read out by the vertical CCD 302 and the horizontal CCD 303 by high-speed reading such as thinning-out reading and addition reading, and are output as analog image signals to the A / D conversion unit 104 (step S602). ).

  The A / D conversion unit 104 performs sampling, gain adjustment, A / D conversion, and the like on the analog image signal output from the CCD unit 103, and outputs the digital image signal (step S603).

  Next, the image processing unit 105 performs various types of image processing on the digital image signal output from the A / D conversion unit 104, and outputs a processed digital image signal (step S604).

  Here, it is possible to set in advance whether or not to perform face detection using the operation unit 101. However, if it is set not to perform face detection (face detection off), the process proceeds to step S605. Then, the process proceeds to step S609. Then, since the image processing unit 105 outputs the processed image data to the EVF display unit 107, the EVF display unit 107 displays an image according to the processed image data (step S609). Then, the control unit 102 performs photometry on the entire image, sets a default photometry range frame to the image, and performs range finding using an area within the frame (step S613). In the following, including this step, when the control unit 102 performs photometry and distance measurement, the AF processing unit 108 is instructed with the distance measurement result, and the AE processing unit 109 is instructed with the photometry result.

  On the other hand, if it is set to perform face detection (face detection ON), the process proceeds to step S606 via step S605. Then, the face detection unit 106 detects a human face region from the image indicated by the digital image signal received from the image processing unit 105, and information (face information) related to this region, such as the position and size of the detected region. Is notified to the control unit 102 (step S606).

  If face detection fails (face information cannot be obtained), the process proceeds to step S609 via step S607. On the other hand, if there is a face in the image and face detection is successful (face information is obtained), the process proceeds to step S608 via step S607. Since the image processing unit 105 outputs the processed image data to the EVF display unit 107, the EVF display unit 107 displays an image according to the processed image data (step S608).

  Next, the control unit 102 determines whether photometry and distance measurement are performed using only the face area or using the face area and the entire image (step S610).

  For example, if the photographing mode is set to the portrait mode or the sport mode by the dial member of the operation unit 101, the photometry and the distance measurement are performed using only the face area. This is because the photographer's intention to shoot with emphasis on the person is estimated and the background image is more likely to be out of focus compared to the person. On the other hand, if the fully automatic mode is set, it is possible to obtain a safer image by considering not only the person but also the background exposure and focus state. To do.

  As another example, if the zoom lens included in the lens 108a is on the telephoto side from the predetermined position, photometry and distance measurement are performed using only the face area. This is because the photographer's intention to shoot with an emphasis on the enlarged person is estimated. On the contrary, if the zoom lens is not present on the telephoto side from the predetermined position, photometry and distance measurement are performed using the face area and the entire image. This is because the photographer's intention to photograph the background together with the person is estimated. If it is determined that photometry and distance measurement are to be performed using only the face area as a result of the determination, the process proceeds to step S611. Then, the control unit 102 instructs the AF processing unit 108 to position the range-finding frame in the human face area in the image and corrects the exposure of the human face area in the image appropriately. The processing unit 109 is instructed (step S611).

  On the other hand, if it is determined that photometry and distance measurement are to be performed using the face area and the entire image, the process proceeds to step S612.

  If the size of the human face area is larger than the predetermined value and exists in the predetermined area in the center of the screen, the face is considered to be the main subject and distance measurement is performed on this face area. Do. If a plurality of face regions satisfy this condition, distance measurement is performed for all of the plurality of face regions. However, if none of the human face regions satisfies the above conditions, the human face is considered not to be the main subject, and distance measurement is performed on a subject existing at a close distance. In the photometry, the weight of the area regarded as the main subject is set to be heavier than that of the other areas, and the evaluation photometry is performed using the photometric value of the entire screen.

<Processing example 2>
FIG. 7 is a flowchart of the process 2. First, the operator of this digital camera can select and set the read mode of charges from the photoelectric conversion element 301 using the operation unit 101 in advance. Here, it is possible to select and set one of the high-speed reading mode by the thinning-out reading, the addition reading, etc., and the all-pixel reading mode. Therefore, first, the control unit 102 checks which setting is made (step S700). As a result, if the high-speed reading mode is set, the process proceeds to step S701.

  Then, the charges accumulated in the respective photoelectric conversion elements 301 are read out by high-speed reading by the vertical CCD 302 and the horizontal CCD 303, and are output as analog image signals to the A / D conversion unit 104 (step S701).

  The A / D conversion unit 104 performs sampling, gain adjustment, A / D conversion, and the like on the analog image signal output from the CCD unit 103, and outputs the digital image signal (step S703).

  Next, the image processing unit 105 performs various types of image processing on the digital image signal output from the A / D conversion unit 104, and outputs a processed digital image signal (step S704).

  Here, it is possible to set in advance whether or not to perform face detection using the operation unit 101. However, if it is set not to perform face detection (face detection off), the process proceeds to step S705. Then, the process proceeds to step S713. Then, since the image processing unit 105 outputs the processed image data to the EVF display unit 107, the EVF display unit 107 displays an image according to the processed image data (step S713). Then, the control unit 102 performs photometry on the entire image, sets a default photometry range frame to this image, and performs range finding using an area within the frame (step S714).

  On the other hand, if it is set to perform face detection (face detection ON), the process proceeds to step S706 via step S705. Then, the face detection unit 106 detects a human face region from the image indicated by the digital image signal received from the image processing unit 105, and information (face information) related to this region, such as the position and size of the detected region. Is notified to the control unit 102 (step S706).

  If face detection fails (face information cannot be obtained), the process proceeds to step S708 via step S707 to determine whether to switch the reading mode (step S708). In this embodiment, when face detection fails, it is set in advance whether to use the high-speed reading mode or the all-pixel reading mode.

  As a result, if the all-pixel readout mode is set, the process proceeds to step S702. If the high-speed readout mode is set (when the mode is not switched), the process proceeds to step S713.

  On the other hand, when there is a face in the image and the face is detected successfully (face information is obtained), the process proceeds to step S709 via step S707. Then, since the image processing unit 105 outputs the processed image data to the EVF display unit 107, the EVF display unit 107 displays an image according to the processed image data (step S709).

  Next, the control unit 102 determines whether to perform photometry and distance measurement using only the face area or using the face area and the entire image (step S710).

  This is determined by the dial member of the operation unit 101 as in the processing example 1. If the shooting mode is set to portrait mode or sport mode, metering and ranging are performed using only the face area. If fully automatic mode is set, metering and ranging are performed on the face area and the image. Use the whole.

  As a result of this determination, if it is determined that photometry and distance measurement are to be performed using only the face area, the process proceeds to step S711. Then, the control unit 102 instructs the AF processing unit 108 to position the range-finding frame in the human face area in the image and corrects the exposure of the human face area in the image appropriately. The processing unit 109 is instructed (step S711).

  On the other hand, if it is determined that photometry and distance measurement are to be performed using the face area and the entire image, the process proceeds to step S712.

  If the size of the human face area is larger than the predetermined value and exists in the predetermined area in the center of the screen, the face is considered to be the main subject and distance measurement is performed on this face area. Do. If a plurality of face regions satisfy this condition, distance measurement is performed for all of the plurality of face regions. However, if none of the human face regions satisfies the above conditions, the human face is considered not to be the main subject, and distance measurement is performed on a subject existing at a close distance. In the photometry, the weight of the area regarded as the main subject is set to be heavier than that of the other areas, and the evaluation photometry is performed using the photometric value of the entire screen.

  On the other hand, if it is determined in step S700 or step S708 that the all-pixel readout mode is set, the process proceeds to step S702.

  Then, the charges accumulated in the respective photoelectric conversion elements 301 are read out by reading out all the pixels by the vertical CCD 302 and the horizontal CCD 303, and output to the A / D conversion unit 104 as an analog image signal (step S702).

  The A / D conversion unit 104 performs sampling, gain adjustment, A / D conversion, and the like on the analog image signal output from the CCD unit 103, and outputs it as a digital image signal (step S715).

  Next, the image processing unit 105 performs various types of image processing on the digital image signal output from the A / D conversion unit 104, and outputs a processed digital image signal (step S716).

  If it is set not to perform face detection (face detection off), the process proceeds to step S724 via step S717. Then, the image processing unit 105 outputs the processed image data to the EVF display unit 107, so that the EVF display unit 107 displays an image according to the processed image data (step S724). Then, the control unit 102 performs photometry on the entire image, sets a default photometry range frame to this image, and performs range finding using an area within the frame (step S725).

  On the other hand, if it is set to perform face detection (face detection ON), the process proceeds to step S718 via step S717. Then, the face detection unit 106 detects a human face region from the image indicated by the digital image signal received from the image processing unit 105, and information (face information) related to this region, such as the position and size of the detected region. Is notified to the control unit 102 (step S718).

  If face detection has failed (face information has not been obtained), the process proceeds to step S724 via step S719. On the other hand, when there is a face in the image and the face is detected successfully (face information is obtained), the process proceeds to step S720 via step S719. Since the image processing unit 105 outputs the processed image data to the EVF display unit 107, the EVF display unit 107 displays an image according to the processed image data (step S720).

  Next, the control unit 102 determines whether to perform photometry and distance measurement using only the face area or using the face area and the entire image (step S721).

  This is determined by the dial member of the operation unit 101 as in the processing example 1. If the shooting mode is set to portrait mode or sport mode, metering and ranging are performed using only the face area. If fully automatic mode is set, metering and ranging are performed on the face area and the image. Use the whole.

  If it is determined that photometry and distance measurement are to be performed using only the face area as a result of this determination, the process proceeds to step S722. Then, the control unit 102 instructs the AF processing unit 108 to position the range-finding frame in the human face area in the image and corrects the exposure of the human face area in the image appropriately. The processing unit 109 is instructed (step S722).

  On the other hand, if it is determined that photometry and distance measurement are to be performed using the face area and the entire image, the process proceeds to step S723.

  If the size of the human face area is larger than the predetermined value and exists in the predetermined area in the center of the screen, the face is considered to be the main subject and distance measurement is performed on this face area. Do. If a plurality of face regions satisfy this condition, distance measurement is performed for all of the plurality of face regions. However, if none of the human face regions satisfies the above conditions, the human face is considered not to be the main subject, and distance measurement is performed on a subject existing at a close distance. In the photometry, the weight of the area regarded as the main subject is set to be heavier than that of the other areas, and the evaluation photometry is performed using the photometric value of the entire screen.

Note that in step S701, an example in which the read mode of charge from the photoelectric conversion element 301 is selected and set in advance using the operation unit 101 is described, but the present invention is not limited to this.
For example, when the processing example 2 is in the first order, the high-speed reading mode is set in step S701. If the control unit 102 does not receive the signal SW1 and the processing example 2 enters the second or later order, the charge reading mode is determined according to the face detection result in the immediately preceding steps S706 and S718. Select and set. Specifically, if the size of the human face area obtained in the immediately preceding steps S706 and S718 is equal to or greater than a predetermined value, it is determined that face detection is easy. In step S701, the high-speed reading mode is set. Set. If the size of the human face area obtained in the immediately preceding steps S706 and S718 is less than a predetermined value, it is determined that face detection is difficult, and in step S701, an all-pixel readout mode is set. Even when face detection fails in the immediately preceding steps S706 and S718, it is determined that face detection is difficult, and in step S701, an all-pixel readout mode is set.

  In this way, a configuration may be adopted in which the charge reading mode is automatically selected and set.

<Processing example 3>
FIG. 10 is a flowchart of the process 3. First, the charges accumulated in the photoelectric conversion elements 301 are read by the vertical CCD 302 and the horizontal CCD 303 by high-speed reading such as thinning-out reading and addition reading, and are output to the A / D conversion unit 104 as analog image signals (step S1102). ). Here, the reading in step S1102 is referred to as a first high-speed reading.

  The A / D conversion unit 104 performs sampling, gain adjustment, A / D conversion, and the like on the analog image signal output from the CCD unit 103, and outputs the digital image signal (step S1103).

  Next, the image processing unit 105 performs various types of image processing on the digital image signal output from the A / D conversion unit 104, and outputs a processed digital image signal (step S1104).

  Then, the face detection unit 106 detects a human face region from the image indicated by the digital image signal received from the image processing unit 105, and information (face information) related to this region, such as the position and size of the detected region. Is notified to the control unit 102 (step S1105).

  If face detection fails (face information is not obtained), the process proceeds to step S1110 via step S1106. Then, the charges accumulated in the respective photoelectric conversion elements 301 are read out by the vertical CCD 302 and the horizontal CCD 303 by the second high-speed reading, which is a high-speed reading method different from the first high-speed reading (step S1110). That is, it is considered that the face could not be detected in detail from the image read by the first high-speed reading. Therefore, in order to obtain an image having a higher resolution than the image read by the first high-speed reading, the first high-speed reading is read by the second high-speed reading mode which is a mode in which the thinning rate and the addition rate are changed. . And it outputs to the A / D conversion part 104 as an analog image signal (step S1110).

  The A / D conversion unit 104 performs sampling, gain adjustment, A / D conversion, and the like on the analog image signal output from the CCD unit 103, and outputs the result as a digital image signal (step S1111).

  Next, the image processing unit 105 performs various types of image processing on the digital image signal output from the A / D conversion unit 104, and outputs a processed digital image signal (step S1112).

  Then, the face detection unit 106 detects a human face region from the image indicated by the digital image signal received from the image processing unit 105, and information (face information) related to this region, such as the position and size of the detected region. Is notified to the control unit 102 (step S1113).

  If face detection fails (face information cannot be obtained), the process proceeds to step S1118 via step S1114. Then, the control unit 102 performs photometry on the entire image, sets a default photometry range frame to this image, and performs range finding using an area within the frame (step S1118).

  On the other hand, if there is a face in the image and face detection is successful (face information is obtained), the process proceeds to step S1115 via step S1114.

  On the other hand, if the face is detected in the image by the face detection process in step S1105 and the face is successfully detected (face information is obtained), the process proceeds to step S1108 via step S1106. Then, it is checked whether or not the size of the detected face area is equal to or larger than a predetermined size (for example, one tenth or more of the entire image area) (step S1108). As a result of this check, if the detected face area size is equal to or smaller than the predetermined size, the process proceeds to step S1110. On the other hand, if the detected face area size is greater than or equal to the predetermined size, the process advances to step S1109. Next, an average value of luminance values of each pixel in the face area is obtained, and it is checked whether or not the obtained average luminance value is equal to or greater than a predetermined value (step S1109).

  As a result, if the average luminance value is less than or equal to the predetermined value, the process proceeds to step S1110. On the other hand, if the average luminance value is greater than or equal to the predetermined value, the process proceeds to step S1115, and the control unit 102 performs photometry and distance measurement using only the face area, or uses the face area and the entire image. (Step S1115).

  This is determined by the dial member of the operation unit 101 as in the processing example 1. If the shooting mode is set to portrait mode or sport mode, metering and ranging are performed using only the face area. If fully automatic mode is set, metering and ranging are performed on the face area and the image. Use the whole.

  As a result of the determination, if it is determined that photometry and distance measurement are performed using only the face area, the process proceeds to step S1116. Then, the control unit 102 instructs the AF processing unit 108 to position the range-finding frame in the human face area in the image and corrects the exposure of the human face area in the image appropriately. The processing unit 109 is instructed (step S1116).

  On the other hand, if it is determined that photometry and distance measurement are to be performed using the face area and the entire image, the process proceeds to step S1117.

  If the size of the human face area is larger than the predetermined value and exists in the predetermined area in the center of the screen, the face is considered to be the main subject and distance measurement is performed on this face area. Do. If a plurality of face regions satisfy this condition, distance measurement is performed for all of the plurality of face regions. However, if none of the human face regions satisfies the above conditions, the human face is considered not to be the main subject, and distance measurement is performed on a subject existing at a close distance. In the photometry, the weight of the area regarded as the main subject is set to be heavier than that of the other areas, and the evaluation photometry is performed using the photometric value of the entire screen.

  As described above, according to the present embodiment, since face detection is always performed before the shutter switch is half-pressed, the face detection processing time within the photographing time can be shortened.

[Second Embodiment]
FIG. 8 is a block diagram showing a functional configuration of the digital camera according to the present embodiment. In the figure, the same parts as those in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.

  The second image processing unit 812 performs various kinds of image processing on the digital image signal output from the A / D conversion unit 104, and outputs a processed digital image signal. For example, a digital image signal received from the A / D conversion unit 104 is converted into a YUV image signal and output.

  The first image processing unit 805 performs image processing that is simpler than the image processing performed by the second image processing unit 812 on the digital image signal output from the A / D conversion unit 104, and obtains an image of the image processing result. Data is sent to the face detection unit 106. That is, since the first image processing unit 805 performs only image processing necessary for face detection, the first image processing unit 805 is simpler than the image processing performed by the second image processing unit 812.

  The face detection unit 106 detects a human face region from the image indicated by the digital image signal received from the first image processing unit 805, and notifies the control unit 102 of information related to this region. That is, the second embodiment is the same as the first embodiment except that the supply source of the image data to be face-detected is different.

  Next, the operation of this digital camera when imaging using this digital camera will be described. FIG. 9 is a flowchart of processing performed by the digital camera when imaging is performed.

  First, when the operator of the digital camera turns on a power switch included in the operation unit 101, the control unit 102 detects this and supplies power to each unit constituting the digital camera (step S901). . When power is supplied to each part of the digital camera, the shutter is opened, so that light enters the CCD part 103 through the lens 108a and the exposure mechanism 109a. Accordingly, electric charges corresponding to the amount of incident light accumulate in the photoelectric conversion element 301 constituting the CCD unit 103.

  Therefore, the charges accumulated in the photoelectric conversion elements 301 are read out by the vertical CCD 302 and the horizontal CCD 303, and are output as analog image signals to the A / D conversion unit 104 (step S903). The charge is read by high-speed reading such as thinning-out reading and addition reading.

  The A / D conversion unit 104 performs sampling, gain adjustment, A / D conversion, and the like on the analog image signal output from the CCD unit 103 and outputs it as a digital image signal (step S904).

  Next, the first image processing unit 805 performs simpler image processing on the digital image signal output from the A / D conversion unit 104 than that performed by the second image processing unit 812, and performs a processed digital image. A signal is output (step S905).

  Next, the face detection unit 106 detects a human face region from the image indicated by the digital image signal received from the first image processing unit 805, and includes information related to this region, such as the position and size of the detected region ( (Face information) is notified to the control unit 102 (step S906).

  Further, since the first image processing unit 805 outputs the processed image data to the EVF display unit 107, the EVF display unit 107 displays an image according to the processed image data (step S907).

  Upon receiving the face information, the control unit 102 instructs the AF processing unit 108 to position the distance measurement frame in the human face area in the image, and exposes the human face area in the image. The AE processing unit 109 is instructed to correct appropriately (step S908). Thereby, the AF processing unit 108 controls the position of the lens 108a and the like, and the AE processing unit 109 controls the exposure mechanism 109a.

  Then, the control unit 102 returns the process to step S903 via step S909 and repeats the subsequent processes unless receiving a signal of SW1 from the shutter switch (that is, notification of half-pressing of the shutter switch). .

  On the other hand, when the control unit 102 receives a notification of the signal SW1 from the shutter switch, the process proceeds to step S910 via step S909, and the process of capturing the first image based on the exposure and focus at this time is performed. This is performed (step S910). That is, when the control unit 102 detects the notification of the signal SW1, the image data output from the first image processing unit 805 is temporarily stored as a first image in a memory (not shown). Thereby, a 1st image can be imaged.

  Next, the control unit 102 uses the face information to instruct the AF processing unit 108 to position the distance measurement frame in the human face area in the first image, and in the first image, The AE processing unit 109 is instructed to appropriately correct the exposure of the face area (step S911). Thereby, the AF processing unit 108 controls the position of the lens 108a and the like, and the AE processing unit 109 controls the exposure mechanism 109a.

  Then, the control unit 102 returns the process to step S910 via step S913, and repeats the subsequent processes, unless receiving notification of the signal SW2 from the shutter switch (that is, notification of full pressing of the shutter switch). .

  On the other hand, when the control unit 102 receives notification of the signal SW2 from the shutter switch, the process proceeds to step S914 via step S913, and it is determined whether or not the flash is emitted (step S914). Whether or not the flash is to be emitted may be determined in advance by using the operation unit 101, and may be determined by reading the setting data, or may be determined automatically by detecting the surrounding darkness. You may make it do.

  As a result of this determination, when the flash is emitted, the process proceeds to step S915, and the control unit 102 controls the EF processing unit 110 to cause the flash unit 111 to perform pre-emission, calculate the emission amount, and set the EF frame. Processing such as weighting is performed (step S915). Then, the flash unit 111 is caused to emit light with the light emission amount determined by the processing in step S915 (step S916). Then, an image is taken.

  That is, the light emitted from the external environment (including the human face) emitted by flash light enters the CCD unit 103 through the lens 108a and the exposure mechanism 109a, and thus enters the photoelectric conversion element 301 constituting the CCD unit 103. Charges corresponding to the amount of light emitted accumulate. Accordingly, the vertical CCD 302 and the horizontal CCD 303 read out the electric charge accumulated in each photoelectric conversion element 301 and output it as an analog image signal to the A / D conversion unit 104 (step S919). The readout of charges is performed by the all-pixel readout.

  The A / D conversion unit 104 performs sampling, gain adjustment, A / D conversion, and the like on the analog image signal output from the CCD unit 103, and outputs it as a digital image signal (step S920).

  Next, the second image processing unit 812 performs various kinds of image processing on the digital image signal output from the A / D conversion unit 104, and outputs a processed digital image signal (step S921).

  The format conversion unit 112 converts the format of the digital image signal (image data) output from the second image processing unit 812 into a format such as JPEG, and outputs it to the image recording unit 113 (step S922). The image recording unit 113 performs processing for recording the format-converted image data in a predetermined memory (step S923).

[Other Embodiments]
Needless to say, the object of the present invention can be achieved as follows. That is, a recording medium (or storage medium) that records a program code of software that implements the functions of the above-described embodiments is supplied to a system or apparatus. Then, the computer (or CPU or MPU) of the system or apparatus reads and executes the program code stored in the recording medium. In this case, the program code itself read from the recording medium realizes the functions of the above-described embodiment, and the recording medium on which the program code is recorded constitutes the present invention.

  Further, by executing the program code read by the computer, an operating system (OS) or the like running on the computer performs part or all of the actual processing based on the instruction of the program code. Needless to say, the process includes the case where the functions of the above-described embodiments are realized.

  Furthermore, it is assumed that the program code read from the recording medium is written in a memory provided in a function expansion card inserted into the computer or a function expansion unit connected to the computer. After that, based on the instruction of the program code, the CPU included in the function expansion card or function expansion unit performs part or all of the actual processing, and the function of the above-described embodiment is realized by the processing. Needless to say.

  When the present invention is applied to the recording medium, program code corresponding to the flowchart described above is stored in the recording medium.

It is a block diagram which shows the function structure of the digital camera which concerns on the 1st Embodiment of this invention. 6 is a flowchart of processing performed by the digital camera when imaging is performed. 2 is a diagram illustrating a configuration example of a CCD unit 103. FIG. It is a figure explaining the thinning-out reading mode. It is a figure explaining addition reading mode. 10 is a flowchart of processing of Processing Example 1; 12 is a flowchart of processing of Processing Example 2; It is a block diagram which shows the function structure of the digital camera which concerns on the 2nd Embodiment of this invention. 6 is a flowchart of processing performed by the digital camera when imaging is performed. 10 is a flowchart of processing of Processing Example 3;

Claims (2)

Output means for reading out the charges accumulated in the plurality of photoelectric conversion elements and outputting an image signal;
Face detection means for detecting a human face area in an image generated from the image signal,
The output means is a first readout mode for outputting an image signal having a first resolution from the plurality of photoelectric conversion elements, and a second readout for outputting an image signal having a second resolution higher than the first resolution. Perform the operation to output the image signal according to the readout mode of one of the modes,
When the detection of the face area is failed for the image generated by the face detection unit from the image signal output after the output unit switches to the first reading mode, the output unit starts from the first reading mode. 2. The imaging apparatus according to claim 1, wherein the face detection unit detects the face area of an image generated from an image signal output from the output unit in the second readout mode. Output means for reading out the charges accumulated in the plurality of photoelectric conversion elements and outputting an image signal;
Face detection means for detecting a human face area in an image generated from the image signal,
The output means is a first readout mode for outputting an image signal having a first resolution from the plurality of photoelectric conversion elements, and a second readout for outputting an image signal having a second resolution higher than the first resolution. Perform the operation to output the image signal according to the readout mode of one of the modes,
If the size of the face area detected for the image generated by the face detection unit from the image signal output after the output unit switches to the first reading mode is less than a threshold, the output unit The reading mode is switched from the reading mode to the second reading mode, and the face detection means detects the face area for an image generated from the image signal output from the output means in the second reading mode. An imaging device.

Images