JP2006145629A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging apparatus capable of improving user's convenience. <P>SOLUTION: The digital camera 2 is provided with a face detection circuit 55 for detecting person's face in image data and a distance calculation circuit 56 for calculating a distance up to the face. A lens motor 30 is driven by a CPU 33 via a motor driver 34 on the basis of the calculation result by the distance calculation circuit 56, and the focusing operation of the imaging lens 10 is performed so as to focus on the face detected by the face detection circuit 55. With the half-depression of a release button 12, the face 60a focused by the imaging lens 10 is displayed in an LCD 17 by an LCD driver 44 while surrounding the face by a frame 61 so that the face can be distinguished from other parts. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an imaging apparatus capable of selecting a portrait shooting mode in which a main subject is focused and shot.

As an image pickup apparatus, a digital camera that converts an object image picked up by a solid-state image pickup device such as a CCD into digital image data and records it in a built-in memory or a memory card has been widely used. Some of such digital cameras can perform portrait photography in which a main subject such as a person's face is photographed in focus (see Patent Document 1).
JP-A-11-266388

  By the way, in a general digital camera, the focus adjustment is automatically performed so that the imaging lens is focused on the center of the shooting angle of view at the time of the shooting preparation process when the release button is pressed halfway. For this reason, when performing portrait photography, if the main subject is not in the center of the focused field of view, the main subject may be out of focus.

  To prevent inconveniences such as the above, an expert who is used to operating the digital camera performs framing so that the main subject is located at the center of the shooting angle of view, and presses the release button halfway to adjust the focus once. After performing the above, framing is performed again to obtain a desired shooting angle of view. However, for beginners who are unfamiliar with the operation of digital cameras, such work is complicated and difficult to understand.

  SUMMARY An advantage of some aspects of the invention is that it provides an imaging apparatus capable of improving user convenience.

  In order to achieve the above object, the present invention provides an image pickup means for picking up a subject image transmitted through an image pickup lens and outputting image data, an automatic focus adjustment means for automatically adjusting the focus of the image pickup lens, and an image. In the imaging apparatus, comprising: an image display means for displaying; and a display control means for controlling display of the image by the image display means, wherein a portrait photographing mode for photographing with focusing on a main subject can be selected. A face detecting means for detecting the face of the person and a distance calculating means for calculating the distance to the face. Under the portrait photographing mode, the automatic focus adjusting means is based on the calculation result of the distance calculating means. In addition, the focus adjustment is performed so that the face detected by the face detection means is in focus, and the display control means is focused at least by the automatic focus adjustment means And wherein the display so as to distinguish it from other portions.

  When a plurality of faces are detected by the face detection means, it is preferable to provide an operation means for selecting a face to be focused by the automatic focus adjustment means. In this case, it is preferable that the display control means display the face selected by the operation means so that the face is shifted in the order of distance.

  In addition, when the face is not detected by the face detection unit, the automatic focus adjustment unit preferably performs the focus adjustment so that the center of the photographing field angle is in focus.

  And a strobe irradiating means for irradiating the subject with strobe light; and a strobe control means for controlling the amount of light emitted from the strobe light. Under the portrait photographing mode, the strobe control means calculates the distance calculating means. From the results, it is preferable to perform the control so that the light emission amount is decreased when the distance to the face is short, and is increased when the distance to the face is large.

  According to the imaging apparatus of the present invention, portrait photography is provided in which face detection means for detecting the face of a person in image data and distance calculation means for calculating the distance to the face are provided, and the main subject is focused and photographed. Under the mode, the automatic focus adjustment unit performs focus adjustment so that the face detected by the face detection unit is in focus based on the calculation result of the distance calculation unit, and the display control unit includes at least the automatic focus adjustment unit. Since the face focused on is displayed so as to be distinguished from other parts, even a beginner unfamiliar with the operation can easily focus on the person's face without troublesome work. Therefore, user convenience can be improved.

  1 and 2, a lens barrel 11 for holding an imaging lens 10 is incorporated in the front surface of a digital camera 2 to which the present invention is applied. A release button 12, a power switch 13, and a mode dial 14 are provided on the top surface of the digital camera 2, and a memory card slot into which a memory card 49 (see FIG. 3) is detachably loaded is covered on the side surface. A lid 15 is provided.

  A finder eyepiece window 16, a liquid crystal display (LCD) 17, and an operation unit 18 that constitute an electronic viewfinder are provided on the back surface of the digital camera 2. The LCD 17 displays captured images, so-called through images, and various menu screens. The operation unit 18 is a zoom operation button 19 for changing the zoom lens of the imaging lens 10 to the wide side or the tele side, or a menu button 20 that is operated when a menu screen is displayed on the LCD 17 or when a selection content is determined. , And a cross key 21 that is operated when the cursor is moved in the menu screen or when selecting a face to be focused in a portrait shooting mode to be described later.

  In the digital camera 2, a still image shooting mode for shooting a still image, a moving image shooting mode for shooting a movie, a playback mode for displaying the shot image on the LCD 17, and a setting mode for performing various settings can be selected. Switching between these modes is performed by rotating the mode dial 14. In the moving image shooting mode, surrounding sound is recorded through a microphone (not shown) along with shooting of a moving image.

  In addition, the digital camera 2 can perform portrait photography in which a main subject is photographed in focus. This portrait shooting mode is set to be feasible by operating the operation unit 18 in the still image shooting mode.

  The release button 12 is a two-stage push switch. After the framing of the subject by the LCD 17, when the release button 12 is lightly pressed (half-pressed), various shooting preparation processes such as automatic exposure adjustment (AE) and automatic focus adjustment (AF) are performed. In this state, when the release button 12 is pressed once more (fully pressed), the imaging signal for one screen subjected to the imaging preparation process is converted into image data, and then image processing and compression processing described later are performed. Recorded in the memory card 49.

  In FIG. 3 showing the electrical configuration of the digital camera 2, a lens motor 30 is connected to the imaging lens 10. An iris motor 32 is connected to the diaphragm 31. These motors 30 and 32 are stepping motors, are controlled in operation by drive pulses transmitted from motor drivers 34 and 35 connected to the CPU 33, and perform photographing preparation processing in response to half-pressing of the release button 12.

  The lens motor 30 moves the zoom lens of the imaging lens 10 to the wide side or the tele side in conjunction with the operation of the zoom operation button 19. Further, the focus lens of the imaging lens 10 is moved in accordance with the subject distance and zoom lens zooming, and the focus adjustment is performed so that the shooting conditions are optimized. The iris motor 32 operates the diaphragm 31 to perform exposure adjustment.

  Behind the imaging lens 10 is a CCD 36 that captures a subject image that has passed through the imaging lens 10. A timing generator (TG) 37 controlled by the CPU 33 is connected to the CCD 36, and the shutter speed of the electronic shutter is determined by a timing signal (clock pulse) input from the TG 37.

  The imaging signal output from the CCD 36 is input to a correlated double sampling circuit (CDS) 38, and is output as R, G, B image data that accurately corresponds to the accumulated charge amount of each cell of the CCD 36. The image data output from the CDS 38 is amplified by an amplifier (AMP) 39 and converted into digital image data by an A / D converter (A / D) 40.

  The image input controller 41 is connected to the CPU 33 via the bus 42, and controls the CCD 36, CDS 38, AMP 39, and A / D 40 in accordance with a control command from the CPU 33. The image data output from the A / D 40 is temporarily stored in the SDRAM 43 and displayed on the LCD 17 as a through image via the LCD driver 44.

  The image signal processing circuit 45 reads the image data from the SDRAM 43, performs various image processing such as gradation conversion, white balance correction, and γ correction processing, and stores the image data in the SDRAM 43 again. The YC conversion processing circuit 46 reads out the image data subjected to various processes by the image signal processing circuit 45 from the SDRAM 43, and converts it into a luminance signal Y and color difference signals Cr and Cb. The compression / decompression processing circuit 47 performs image compression on the converted image data in a predetermined compression format (for example, JPEG format). The compressed image data is recorded on the memory card 49 via the media controller 48.

  In addition to the release button 12 and the operation unit 18 described above, an EEPROM 50 is connected to the CPU 33. The EEPROM 50 stores various control programs and setting information. The CPU 33 reads these pieces of information from the EEPROM 50 to the SDRAM 43, which is a working memory, and executes various processes.

  The bus 42 detects an exposure amount, that is, whether the shutter speed of the electronic shutter and the aperture value of the aperture 31 are appropriate for shooting, and detects whether the white balance is appropriate for shooting. 51, an AF detection circuit 52 that detects whether the focus adjustment of the imaging lens 10 is appropriate for shooting, a strobe control circuit 54 that controls the operation of the strobe device 53, a face detection circuit 55, and a distance calculation circuit 56 Is connected.

  The AE / AWB and AF detection circuits 51 and 52 sequentially transmit detection results to the CPU 33 via the bus 42 when the release button 12 is half-pressed. The CPU 33 controls the operations of the imaging lens 10, the diaphragm 31, and the CCD 36 based on the detection results transmitted from these detection circuits 51 and 52.

  Under the normal shooting mode, the AF detection circuit 52 uses the luminance signal Y and the contour signal derived from the image data to calculate a focus evaluation value that indicates whether or not the subject is in focus, and calculates the calculated focus. Whether or not the focus adjustment at the center of the shooting angle of view is appropriate is detected based on the evaluation value.

  The strobe device 53 has an automatic flash mode that automatically fires a flash when the subject brightness is low, a forced flash mode that fires a strobe regardless of the subject brightness, a flash prohibit mode that prohibits strobe flash, and a red-eye reduction mode that reduces red-eye effects. These are selectable by operating the operation unit 18.

  The strobe control circuit 54 controls the amount of strobe light emitted from the strobe device 53 according to the calculation result of a distance calculation circuit 56 described later in the portrait photographing mode. That is, the light emission amount of the strobe light is controlled so that the light emission amount is decreased when the distance to the face is short, and conversely, the light emission amount is increased when the distance to the face is long. Note that, for example, a plurality of threshold values are provided for the calculation result of the distance calculation circuit 56, and the light emission amount is changed stepwise by comparing the magnitude relationship between the threshold value and the calculation result.

  The face detection circuit 55 detects the face of a person in the image data under the portrait shooting mode. For example, the face detection circuit 55 extracts the skin color portion of the image from the gradation color of each pixel represented by the image data, and when the area of the skin color portion is equal to or larger than a preset threshold value, The skin color part is detected as a human face. Alternatively, the face of a person is detected by extracting specific portions of the face such as eyes and mouth using a known pattern recognition technique. The face detection circuit 55 transmits the detection result to the CPU 33 and the distance calculation circuit 56.

  The distance calculation circuit 56 calculates the distance to the face based on the detection result of the face detection circuit 55 and the focal length of the imaging lens 10. Specifically, for example, as described in Japanese Patent Application Laid-Open No. 2003-75717, the distance to the face with respect to the area of the skin color portion detected by the face detection circuit 55 is determined for each focal length of the imaging lens 10 by the EEPROM 50. Is stored in advance as a data table, and the distance to the face is obtained by referring to this data table. The distance calculation circuit 56 transmits the calculation result to the CPU 33 and the strobe control circuit 54.

  The CPU 33 drives the lens motor 30 via the motor driver 34 based on the calculation result of the distance calculation circuit 56 and adjusts the focus of the imaging lens 10 so that the face selected with the cross key 21 is in focus. . When the human face is not detected by the face detection circuit 55, the CPU 33 performs focus adjustment so that the center of the shooting angle of view is in focus as in the normal shooting mode.

  As shown in FIG. 4, when the release button 12 is half-pressed, the LCD driver 44 surrounds the face 60a focused on the imaging lens 10 with a frame 61 so as to distinguish it from other parts and displays it on the LCD 17. Let As described above, the frame 61 can be shifted to the face 60b or 60c of another person detected by the face detection circuit 55 by operating the cross key 21 of the operation unit 18.

  The LCD driver 44 controls the display on the LCD 17 so that the frame 61 is shifted in the order of the distance of the person. In other words, taking FIG. 4 as an example, first, a frame 61 is displayed on the face 60b of the person whose distance is the closest (the area of the face is the largest), and according to the operation of the cross key 21, the person of an intermediate distance is displayed. The frames 61 are displayed in the order of the face 60a, and finally the face 60c of the person who is the farthest (smallest face area). Note that the display position of the frame 61 is determined based on the coordinates of the detected portion of the face with respect to the shooting angle of view when the face detection circuit 55 detects a human face.

  Next, the operation of the digital camera 2 having the above configuration will be described with reference to the flowchart of FIG. First, when shooting a subject with the digital camera 2, the power switch 13 is operated to turn on the digital camera 2, and the mode dial 14 is operated to select a still image shooting mode or a moving image shooting mode. .

  Under the photographing mode, subject light incident through the imaging lens 10 and the diaphragm 31 is photoelectrically converted by the CCD 36 and sampled by the CDS 38. The image data output from the CDS 38 is amplified by the AMP 39 and converted into digital image data by the A / D 40.

  The digitally converted image data is subjected to various types of image processing by the image signal processing circuit 45 and then sequentially stored in the SDRAM 43 via the image input controller 41 and displayed on the LCD 17 as a through image. When the release button 12 is half-pressed in this state, the exposure amount, white balance, and focus are detected by the AE / AWB detection circuit 51 and the AF detection circuit 52, and shooting preparation processing is performed based on the detection result.

  When shooting is executed by fully pressing the release button 12 after shooting preparation processing, in the still image shooting mode, the image data stored in the SDRAM 43 at that time is read to the YC conversion processing circuit 46 and the luminance signal Y And the color difference signals Cr and Cb, the compression processing is performed by the compression / decompression processing circuit 47 and recorded in the memory card 49 via the media controller 48.

  On the other hand, under the moving image shooting mode, image data is recorded at a constant frame rate (for example, 30 frames / second) until the release button 12 is fully pressed again. At the same time, ambient sounds are recorded via the microphone. The sound recorded by the microphone is recorded on the memory card 49 in association with the image data.

  In FIG. 5, when the operation unit 18 is operated and the portrait photographing mode is selected, the image data stored in the SDRAM 43 at that time is data-locked as the release button 12 is half-pressed, and the face detection circuit 55. Thus, the face of a person in the image data is detected. The detection result of the face detection circuit 55 is transmitted to the CPU 33 and the distance calculation circuit 56.

  In the distance calculation circuit 56, a data table in which the distance to the face with respect to the face area detected by the face detection circuit 55 is tabulated for each focal length of the imaging lens 10 is read from the EEPROM 50, and this data table is referred to Distance to is required. The calculation result of the distance calculation circuit 56 is transmitted to the CPU 33 and the strobe control circuit 54.

  Next, the CPU 33 drives the lens motor 30 via the motor driver 34 based on the calculation result of the distance calculation circuit 56, and the face detected by the face detection circuit 55 is focused on the face with the closest distance. As described above, the focus of the imaging lens 10 is adjusted.

  After the focus adjustment, a frame 61 is displayed on the LCD 17 so as to surround the face focused by the CPU 33 under the control of the LCD driver 44. If the face surrounded by the frame 61 is not the face of the desired person, the cross key 21 is operated to move the frame 61 to the desired face. At this time, the frame 61 is shifted by the LCD driver 44 in order from the closest distance to the face.

  When the frame 61 is shifted, the image data that has been data-locked by the SDRAM 43 until then is discarded, and the image data is again captured by the CCD 36. Then, the focus adjustment of the imaging lens 10 is performed again by the CPU 33 so that the face to which the frame 61 has been shifted is focused, and the image data stored in the SDRAM 43 when the focus adjustment is completed is data-locked. .

  On the other hand, when the face of the person is not detected by the face detection circuit 55, the CPU 33 adjusts the focus so as to focus on the central portion of the shooting angle of view as in the normal shooting mode.

  When the frame 61 is displayed on the LCD 17 and the release button 12 is fully pressed in a state where the focus adjustment of the imaging lens 10 by the CPU 33 has been completed, the image finally stored in the SDRAM 43 as in the normal shooting mode. The data is subjected to YC conversion and compression processing and recorded on the memory card 49. If the release button 12 is not fully pressed after the release button 12 is pressed halfway, a frame 61 is displayed on the LCD 17 until the predetermined time elapses. The image data that has been locked is discarded, and the through image is displayed on the LCD 17 again.

  When the release button 12 is fully pressed and the flash photography by the flash device 53 is set, the flash control circuit 54 reduces the light emission amount when the distance to the face is short. Conversely, the amount of strobe light emission is controlled so as to increase when the distance to the face is far.

  As described above, the face detection circuit 55 detects the face of the person in the image data, the distance calculation circuit 56 calculates the distance to the face, and the calculation result of the distance calculation circuit 56 in the portrait shooting mode. The focus adjustment is performed so that the face detected by the face detection circuit 55 is in focus, and the focused face is surrounded by a frame 61 and displayed on the LCD 17 separately from other parts. Even for an unfamiliar beginner, perform framing so that the person's face is positioned at the center of the shooting angle of view, press the release button halfway, adjust the focus once, and then re-framing to achieve the desired shooting angle of view. It is possible to easily focus on a person's face without the troublesome task of performing.

  Furthermore, since the amount of strobe light emission is controlled according to the calculation result of the distance calculation circuit 56, the amount of light emission is not too much when the person is near and does not fly out, and the amount of light emission is small when the person is far away. It wo n’t be too black.

  In the above embodiment, only the focused face is surrounded by the frame 61 and displayed on the LCD 17. However, all the faces detected by the face detection circuit 55 are surrounded by the frame, and the frame surrounding the focused face is displayed. May be displayed with a thicker frame than other frames. Further, instead of enclosing with the frame 61, a focused face may be colored or a specific mark such as an arrow may be used.

  In the above-described embodiment, the frame 61 is displayed when the release button 12 is half-pressed. However, a separate operation button for displaying the frame 61 may be provided separately from the release button 12. Furthermore, although the digital camera 2 has been described as an example of the imaging device, the present invention is not limited to this and can be applied to other imaging devices such as a camera-equipped mobile phone.

It is a front external perspective view of a digital camera to which the present invention is applied. It is a back external view of a digital camera. It is a block diagram which shows the electric constitution of a digital camera. It is explanatory drawing which shows the display state of LCD in portrait photography mode. It is a flowchart which shows the process sequence of the digital camera under portrait photography mode.

Explanation of symbols

2 Digital Camera 10 Imaging Lens 12 Release Button 17 Liquid Crystal Display (LCD)
18 Operation unit 21 Four-way key 30 Lens motor 33 CPU
34 Motor driver 36 CCD
44 LCD Driver 49 Memory Card 53 Strobe Device 54 Strobe Control Circuit 55 Face Detection Circuit 56 Distance Calculation Circuit 61 Frame

Claims (5)

An imaging unit that captures a subject image that has passed through the imaging lens and outputs image data, an automatic focus adjustment unit that automatically adjusts the focus of the imaging lens, an image display unit that displays an image, and the image display unit Display control means for controlling the display of the image,
In an imaging device capable of selecting a portrait shooting mode in which a main subject is focused and shot,
A face detecting means for detecting a human face in the image data, and a distance calculating means for calculating a distance to the face;
Under the portrait photographing mode, the automatic focus adjustment unit performs the focus adjustment so that the face detected by the face detection unit is in focus based on the calculation result of the distance calculation unit,
The image pickup apparatus, wherein the display control means displays at least the face focused by the automatic focus adjustment means so as to be distinguished from other parts.   The imaging apparatus according to claim 1, further comprising an operation unit that selects a face to be focused by the automatic focus adjustment unit when a plurality of faces are detected by the face detection unit.   The imaging apparatus according to claim 2, wherein the display control unit displays the face selected by the operation unit so that the face is shifted in the order of distance.   The automatic focus adjustment unit performs the focus adjustment so that a center portion of a photographing field angle is focused when a face is not detected by the face detection unit. The imaging device described in 1. A strobe irradiating means for irradiating a subject with strobe light; and a strobe control means for controlling a light emission amount of the strobe light;
Under the portrait shooting mode, the strobe control means performs the control from the calculation result of the distance calculation means so that the light emission amount is decreased when the distance to the face is short, and is increased when the distance to the face is long. The imaging apparatus according to claim 1, wherein:

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