JP2006145964A - Photographing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photographing apparatus capable of obtaining the maximum proper contrast in accordance with a variety of object brightness and various photographing scenes. <P>SOLUTION: Low-pass and high-pass AF filters for extracting a prescribed frequency area signal from an image signal obtained by a CCD 10_41 are arranged in an AF detection circuit 10_51, and the characteristics of respective AF filters are switched in accordance with the object field brightness detected by an AE detection circuit 10_50, and a focus lens 10_1a<SB>2</SB>is driven to a focal position based on an AF evaluation value from the switched AF filter. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a photographing apparatus that forms a subject image on an image sensor with a photographing optical system and generates and records an image signal representing the subject with the image sensor.

  As a photographing apparatus as described above, a digital camera that forms a subject image on an image sensor with a photographing lens, generates an image signal representing the subject with the image sensor, and records the image signal on an IC memory card is widely used. In such a digital camera, an automatic focus adjustment device (hereinafter referred to as an AF device) for adjusting the focus position of the taking lens and automatically focusing the subject image on the image pickup surface of the image pickup device is mounted. Digital cameras are known. As an AF device, a contrast detection method is generally used in which the sharpness of a subject image is detected and the focus is adjusted so that the contrast representing the sharpness is maximized. For example, in this contrast detection method, a high-frequency component representing contrast is extracted from a luminance signal in a focus area provided substantially at the center of the imaging screen by an AF filter such as a high-pass filter or a band-pass filter, and the contrast based on the extracted high-frequency component. This is a method of obtaining an automatic focus by moving the photographing lens so that the contrast evaluation value calculated from the signal is maximized.

As a device adopting such a contrast detection method, the first AF filter extracts the high frequency components of the image signal, the second AF filter extracts the frequency components of the image signal above the middle frequency, and these A technique for focusing on the maximum contrast point based on the extracted frequency component has been proposed (see Patent Document 1).
JP-A-6-245126

  Even when the same subject is photographed in a digital camera equipped with an AF device, the contrast is high in a bright place, so that an image signal representing the subject contains a lot of high-frequency components. On the other hand, since the contrast is low in a dark place, the image signal representing the subject contains many low-frequency components. Here, in the technique proposed in Patent Document 1 described above, a signal in the high frequency region is extracted by the first AF filter in a bright place, and a signal in the low frequency region is extracted by the second AF filter in a dark place. Thus, focus control is performed to focus on the maximum contrast point. However, it is difficult to obtain an appropriate maximum contrast point according to various brightness of a subject and various shooting scenes by performing focus control uniquely in this way.

  In view of the above circumstances, an object of the present invention is to provide an imaging apparatus capable of obtaining an appropriate maximum contrast point according to various brightnesses of subjects and various imaging scenes.

The first imaging apparatus of the imaging apparatus of the present invention that achieves the above object is an imaging that forms an image of a subject on an image sensor by an imaging optical system and generates and records an image signal representing the object by the image sensor. In the device
A focus adjustment unit that has a filter that extracts a signal in a predetermined frequency region from the image signal obtained by the imaging device, and that focuses on the maximum contrast point by contrast detection based on the signal that has passed through the filter;
A photometric means for measuring the field luminance,
The focus adjustment unit further includes a filter control unit that switches the characteristics of the filter in accordance with the field luminance measured by the photometry unit.

  The first photographing apparatus of the present invention switches the characteristics of a filter that extracts a signal in a predetermined frequency region from an image signal obtained by an image sensor in accordance with the field luminance measured by the photometric means. Therefore, for example, as shown in the embodiment, by setting a parameter corresponding to an AE (Auto Exposure) value representing the field luminance in the filter, the filter characteristic can be switched to the AE value. Accordingly, an appropriate maximum contrast point can be obtained according to various brightnesses of the subject. Further, for example, in the case of shooting in a dark place, even if it is difficult to focus the subject image on the imaging surface of the image sensor due to the conventional low contrast, in the present invention, the subject image is captured on the imaging surface of the image sensor. Can be focused quickly.

The second photographing apparatus of the present invention that achieves the above object forms a subject image on the image sensor by the photographing optical system, and generates and records an image signal representing the subject by the image sensor. In the shooting device
A focus adjustment unit that has a filter that extracts a signal in a predetermined frequency region from the image signal obtained by the imaging device, and that focuses on the maximum contrast point by contrast detection based on the signal that has passed through the filter;
With a scene setting operator to select the shooting scene,
The focus adjustment unit may further include a filter control unit that switches the characteristics of the filter in accordance with the shooting scene set by the scene setting operator.

  The second image capturing apparatus of the present invention switches the characteristics of a filter that extracts a signal in a predetermined frequency region from an image signal obtained by an image sensor in accordance with a shooting scene set by a scene setting operator. Therefore, as shown in an embodiment described later, by setting a parameter corresponding to the shooting scene of the night view, sports, landscape, and person selected with the mode dial which is a scene setting operator, to the shooting scene. Switch to the appropriate filter characteristics. Therefore, an appropriate maximum contrast point can be obtained according to various shooting scenes. In this way, for example, when shooting a landscape, it is often the case that a far object is photographed, and these distant objects appear small, and as a result, the image signal contains a lot of high frequency components. A clear image can be obtained by setting the parameters for use.

  According to the photographing apparatus of the present invention, an appropriate maximum contrast point can be obtained according to various brightness of a subject and various photographing scenes.

  Embodiments of the present invention will be described below.

  FIG. 1 is an external perspective view of a digital camera, which is an embodiment of a first photographing apparatus according to the present invention, as seen from diagonally above the front.

  A zoom lens barrel 10_1 having a photographing lens 10_1a, which is an optical zoom lens, is provided at the center of the front surface of the digital camera 10 shown in FIG. In addition, on the front upper portion of the digital camera 10, a flash light emitting device 10_2 that emits flash light in synchronization with photographing and a light amount of the flash light are detected in order to control the light amount of the flash light from the flash light emitting device 10_2. A flash light control sensor 10_3 and an optical viewfinder objective window 10_4 are provided.

  Further, on the left side of the front surface of the digital camera 10, a slide-type power switch 10_5 is turned on when a battery built in the digital camera 10 is charged, when image data is transmitted, or when a self-timer is activated. Illumination lamp 10_6 that blinks is provided.

  Further, on the upper surface of the digital camera 10, a shutter button 10_7 and a microphone 10_8 for picking up sound are provided.

  Further, on the right side surface of the digital camera 10 shown in FIG. 1, a speaker 10_9, a USB terminal 10_10 to which a USB cable used when transmitting photographed image data to a personal computer or the like is connected, and an external power supply terminal 10_11.

  FIG. 2 is an external perspective view of the digital camera shown in FIG.

  An optical viewfinder eyepiece window 10_22, a viewfinder lamp 10_23 that is turned on when shooting preparation is completed or flashes during shooting, a still image mode, a playback mode, and a moving image shooting are provided on the upper back of the digital camera 10 shown in FIG. And a mode switch 10_24 for switching modes. Further, on the right side of the mode switch 10_24, a macro button 10_25, a zoom button 10_26, and a flash button 10_27 are provided.

  The macro button 10_25 is a button for switching whether or not to perform macro shooting. When the macro button 10_25 is pressed once, the macro shooting mode is set, and when pressed again, the macro shooting mode is canceled.

  The zoom button 10_26 is a button that zooms up to the telephoto side (tele side) by pressing down and zooms down to the wide angle side (wide side) by pressing down. The zoom button 10_26 is a button for selecting various menus displayed on the liquid crystal monitor 10_28 described later by simply pressing the zoom button 10_26.

  The flash button 10_27 is a button for repeatedly switching the flash state every time it is pressed, such as auto flash → red-eye reduction flash → forced flash → flash prohibition → slow sync → auto flash.

  In addition, a liquid crystal monitor 10_28, a MENU / OK button 10_29, a BACK button 10_30, a DISP button 10_31, and a photo mode button 10_32 are provided at the center of the back of the digital camera 10.

  The liquid crystal monitor 28 displays an image composed of image data generated by capturing subject light with the digital camera 10, information at various settings, and the like.

  The MENU / OK button 10_29 is a button for displaying various menus at the time of shooting and playback and determining the menu selected by the zoom button 10_26.

  The BACK button 10_30 is a button for returning or canceling the operation state by the MENU / OK button 10_29 or the like.

  The DISP button 10_31 is a button for switching the state of the screen displayed on the liquid crystal monitor 10_28. For example, the display of the liquid crystal monitor 10_28 is turned on / off at the time of shooting, and the character display is turned on / off at the time of reproduction. It is a button.

  The photo mode button 10_32 is a button for setting the number of pixels, sensitivity, color, number of prints, and the like.

Further, a housing lid 10_33 for housing a battery and a memory card is provided at the lower back of the digital camera 10. Further, a strap attachment portion 10_34 is also provided on the side surface portion of the digital camera 10. FIG.

The digital camera 10, a zoom lens 10_1A ₁ and the focusing lens 10_1A ₂ constituting the taking lens 10_1A described above, the image pickup device (CCD which converts the subject image focused through the imaging lens 10_1A into an analog signal 10_41).

  The digital camera 10 also includes an A / D conversion circuit 10_42 that generates an analog image signal by A / D converting an analog image signal from the CCD 10_41, and a digital image from the A / D conversion circuit 10_42. An image input controller 10_43 that transmits a signal to the bus line 10_100, and an image signal processing circuit that converts a digital image signal input via the bus line 10_100 into a YC signal represented by luminance (Y) and color (C). 10_44.

  Further, the digital camera 10 includes a compression processing circuit 10_45 that compresses a YC signal input via the bus line 10_100, and a YSC signal input via the bus line 10_100 as an NTSC (National TV Standards Committee) signal. Is provided. The NTSC signal output from the video encoder 10_46 is supplied to the liquid crystal monitor 10_34 described above, and an image is displayed on the liquid crystal monitor 10_34.

Further, the digital camera 10 includes a CPU 10_47 for controlling the entire digital camera 10, motor drivers 10_48 and 10_49 for driving the zoom lens 10_1a ₁ and the focus lens 10_1a ₂ , and the shutter button 10_8 described above. .

  Further, the digital camera 10 is provided with an AE detection circuit 10_50 (corresponding to an example of the photometric means in the present invention) that detects the field luminance based on a digital image signal.

Further, the digital camera 10 has a filter to be described later that extracts a signal in a predetermined frequency region based on a digital image signal, and focuses on the maximum contrast point by contrast detection based on a signal that has passed through the filter. An AF detection circuit 10_51 is provided. Here, the AF detection circuit 10_51, the CPU 10_47, the motor driver 10_49, and the focus lens 10_1a ₁ correspond to an example of a focus adjustment unit according to the present invention. The CPU 10_47 also serves as a filter control unit according to the present invention that switches the filter characteristics according to the subject luminance detected by the AE detection circuit 10_50.

  The digital camera 10 further includes a memory (SDRAM) 10_52 for storing digital image signals and a medium for recording the YC signal compressed by the compression processing circuit 10_45 on a recording medium 10_54 which is a portable recording medium. A controller 10_53 is provided.

  FIG. 4 is a diagram showing a configuration of the AF circuit shown in FIG.

  FIG. 4 shows the CCD 10_41, the A / D conversion circuit 10_42, and the AF circuit 10_51 described above. Here, in order to simplify the drawing, the image input controller 10_43, the bus line 10_100, and the like are not shown.

  The analog image signal from the CCD 10_41 is A / D converted into a digital image signal by the A / D conversion circuit 10_42, and passes through the image input controller 10_43, the bus line 10_100, and the image signal processing circuit 10_44 shown in FIG. , Input to the AF circuit 10_51.

  In the AF circuit 10_51, the pre-gamma processing unit 10_511 converts the brightness level represented by the input digital image signal into a level of a predetermined magnitude according to a preset input / output characteristic (gamma curve). To the AF filter 10_512 for use.

  The configuration of the low-pass AF filter 10_512 will be described later. The AF filter 10_512 is an image signal having a frequency having a low-frequency component corresponding to the field luminance value (EV value) detected by the AE detection circuit 10_50. The image signal having the frequency component corresponding to the switched characteristic is output to the high-pass AF filters 10_513 and 517.

  Although the configurations of the high-pass AF filters 10_513 and 10_517 will be described later, these AF filters 10_513 and 10_517 have different high frequencies depending on the field luminance value (EV value) detected by the AE detection circuit 10_50. The characteristics are switched to the characteristics for allowing the image signals having the frequencies having the components to pass, and the image signals having the frequency components according to the characteristics are output to the ABS (absolute value) units 10_514 and 10_518.

  The image signals from the high-pass AF filters 10_513 and 10_517 are image signals representing the difference between the pixel values of adjacent pixels, and these image signals are input to the ABS (absolute value) units 10_514 and 10_518. The negative value is changed to a positive value, and the positive value passes through and is output toward the coring 10_515, 10_519.

  The coring 10_515, 10_519 performs noise removal by subtracting a predetermined constant value from the data from the ABS units 10_514, 10_518.

  The accumulating units 10_516 and 10_520 obtain the first and second evaluation values in the first and second bandpass filter characteristics by accumulating the noise-removed data. Based on these first and second evaluation values, focus control is performed as described later.

  FIG. 5 is a diagram showing the EV value of the field luminance detected by the AE detection circuit shown in FIG. 3 and the parameters set in the AF filter shown in FIG.

  The AF filters 1, 2, and 3 shown in FIG. 5 are the low-pass AF filter 10_512 and the high-pass AF filters 10_513 and 10_517 shown in FIG.

  FIG. 5 shows an EV value (less than 5 EV) of field luminance in a relatively dark place detected by the AE detection circuit 10_50 and an EV value (5 EV to 10 EV) of field brightness in a place with normal brightness. And an EV value (10 EV or more) of the field luminance in a relatively bright place. That is, EV values are shown in a place where the image signal representing the subject contains a lot of low frequency components, a place where a lot of intermediate frequency components are contained, and a place where a lot of high frequency components are contained. Here, the AF filters 1, 2 and 3 shown in FIG. 5 have parameters shown in FIG. 5 according to the EV value (less than 5 EV), (less than 5 EV to 10 EV), and (more than 10 EV) of the field luminance. S, A1, and A2 are set.

  FIG. 6 is a diagram showing the configuration of the low-pass AF filter shown in FIG.

  The low pass AF filter 10_512 shown in FIG. 6 includes multipliers 10_512a, 10_512b, 10_512c, 10_512d, delay circuits 10_512e, 10_512f, 10_512g, 10_512h, a subtractor 10_512i, adders 10_512j, 10_512k, and 10_512m. It has been.

  A parameter S (= 7) corresponding to the image signal in from the pre-gamma processing unit 10_511 shown in FIG. 4 and the EV value (for example, less than 5 EV) of the field luminance shown in FIG. 5 is set in the multiplier 10_512a. The multipliers 10_512b and 10_512c are set with parameters A1 (= 1) and A2 (= 5) corresponding to the EV value (less than 5 EV) of the field luminance.

  The low-pass AF filter 10_512 obtains an image signal by multiplying the image signal in and the parameter S by the multiplier 10_512a, delays the image signal by a predetermined time by the delay circuit 10_512e, and outputs it to the subtracter 10_512i. In the subtracter 10_512i, the image signal from the delay circuit 10_512e is converted into an image from a feedback path including the delay circuits 10_512f and 10_512g, the multiplier 10_512b in which the parameter A1 is set, the multiplier 10_512c in which the parameter A2 is set, and the adder 10_512j. The signal is subtracted and output to the adder 10_512k. The adder 10_512k adds this signal and the image signal from the feedforward path including the multiplier 10_512d and the adder 10_512m, and outputs the result as the image signal out via the delay circuit 10_512h. In this manner, the low-pass AF filter 10_512 having filter characteristics based on the parameters S, A1, and A2 set according to the EV value (less than 5 EV) of the field luminance is realized.

  FIG. 7 is a diagram showing the configuration of the high-pass AF filter shown in FIG.

  Note that the same components as those of the low-pass AF filter 10_512 shown in FIG.

  The high-pass AF filter 10_513 shown in FIG. 7 differs from the low-pass AF filter 10_512 shown in FIG. 6 in that the adder 10_512m is replaced with a subtractor 10_513m.

  The multiplier 10_512a is set with a parameter S (= 27) corresponding to the image signal in from the pre-gamma processing unit 10_511 shown in FIG. 4 and the EV value (for example, less than 5 EV) of the field luminance shown in FIG. The multipliers 10_512b and 10_512c are set with parameters A1 (= −53) and A2 (= 22) according to the EV value (less than 5 EV) of the field luminance.

  The subtractor 10_512i constituting the high-pass AF filter 10_513 subtracts the image signal from the delay circuit 10_512e by the image signal from the feedback path described above and outputs the result to the adder 10_512k. The adder 10_512k adds this signal and the image signal from the feedforward path including the multiplier 10_512d and the subtractor 10_513m, and outputs the result as the image signal out via the delay circuit 10_512h. In this way, the high-pass AF filter 10_513 having filter characteristics based on the parameters S, A1, and A2 set according to the EV value (less than 5 EV) of the field luminance is realized. The configuration of the high-pass AF filter 10_517 shown in FIG. 4 is the same as the configuration of the high-pass AF filter 10_513. The high-pass AF filter 10_517 includes an EV value of the field luminance here. Parameters S (= 25), A1 (= −47), and A2 (= 19) corresponding to (less than 5 EV) are set.

  FIG. 8 is a flowchart showing AE processing and AF processing executed by the digital camera shown in FIG.

  When the user instructs photographing in the AE processing / AF processing, first, in step S1, AE processing (acquisition of luminance) is performed. Next, in step S2, a parameter for AF filter setting is selected according to the acquired luminance. Further, in step S3, AF processing described with reference to FIG. 9 is performed, and the process proceeds to the photographing sequence.

  FIG. 9 is a flowchart of the AF processing routine shown in FIG.

  First, in step S11, an AF area used for this AF process is set. Next, in step S12, the parameter and coring value of the selected AF filter are set. Further, an exposure value is set in step S13, and the process proceeds to step S14.

  In step S14, the focus lens is driven to the start position. Next, in step S15, an AF search is performed to move the focus lens back and forth in order to detect the focal point. Further, the focal point is calculated in step S16 and the process proceeds to step S17. In step S17, the focus position is corrected. In step S18, the focus lens is driven to the in-focus position, and this routine is terminated.

  FIG. 10 is a diagram illustrating a change in the AF evaluation value when the parameter set in the AF filter is changed.

  In FIG. 10, the parameters set for the low-pass AF filter are fixed, and the parameters set for the high-pass AF filter are changed from “slightly low frequency” parameters to “slightly high frequency” parameters. A case graph is shown.

  Graph A shows the AF evaluation value when the “slightly low frequency” parameter is set in the high-pass AF filter. On the other hand, the graph B shows the AF evaluation value when the “slightly high frequency” parameter is set in the high-pass AF filter. As described above, the output of the AF evaluation value is changed even in the same image by slightly changing the parameter set in the AF filter. Therefore, the AF filter setting for the AF filter is set based on the field luminance detected by the AE detection circuit 10_50. It is useful to select parameters.

  Here, the example in which the AF filter setting parameter is selected based on the field luminance detected by the AE detection circuit 10_50 has been described, but the brightness of the through image to be finally displayed on the liquid crystal monitor 10_34. The parameter for AF filter setting may be selected based on the above.

  FIG. 11 is an external perspective view of a digital camera, which is an embodiment of the second photographing apparatus of the present invention, seen from obliquely above the front surface.

  In the center of the front surface of the digital camera 110 shown in FIG. 11, a zoom lens barrel 110_1 having a photographing lens 110_1a, which is an optical zoom lens, is provided. Further, on the front upper portion of the digital camera 110, a flash light emitting device 110_2 that emits flash light in synchronization with photographing, and the light amount of the flash light to detect the amount of flash light from the flash light emitting device 110_2 are detected. A flash light control sensor 110_3 and an optical viewfinder objective window 110_4 are provided.

  Further, on the left side of the front surface of the digital camera 110, a grip 110_5 having a shape that can securely hold the digital camera 110, a self-timer lamp 110_6 that blinks when the self-timer is activated, and a microphone 110_7 that picks up sound. And are provided.

  Further, on the upper surface of the digital camera 110, a shutter button 110_8, a mode dial 110_9 (corresponding to an example of a scene setting operator according to the present invention) for performing various settings, and a power button 110_10 are provided. Yes.

  Further, a speaker 110_11 is provided on the right side surface of the digital camera 110 shown in FIG.

  12 is an external view of the digital camera shown in FIG. 11 as viewed from above.

  In this digital camera 110, in addition to the flash light emitting device 110_2, the shutter button 110_8, the mode dial 110_9, and the power button 110_10 described above, a flash light emitting device is provided on an inclined surface provided from the top to the bottom of the digital camera 110. A pop-up button 110_12 for popping up 110_2 is provided. Further, the mode dial 110_9 includes a character AUTO indicating the auto mode, P indicating the program auto mode, S indicating the shutter speed priority auto mode, A indicating the aperture priority auto mode, M indicating the manual mode, and a picture indicating the moving image mode. , And four pictures showing four scene positions (night view, sports, landscape, person scene position) are printed. A desired mode can be set by rotating the mode dial 110_9. Here, each mode will be described.

  The auto mode (AUTO) is a mode for controlling all of exposure, white balance and the like on the camera side.

  The program auto mode (P) is a mode for automatically setting the shutter speed and the aperture.

  The shutter speed priority auto mode (S) is a mode for preferentially setting the shutter speed.

  The aperture priority auto mode (A) is a mode for preferentially setting the aperture.

  The manual mode (M) is a mode for freely setting the shutter speed and the aperture.

  The moving image mode indicated by the picture next to the manual mode (M) is a mode for moving image shooting.

  In addition, there are four scene position modes for selecting four shooting scenes (night view, sports, landscape, and person) clockwise as viewed from the moving image mode.

  The scene position mode for night view is a mode suitable for shooting taking advantage of the atmosphere such as sunset view and night view.

  The scene position mode for sports is a mode suitable for shooting a moving body including a sports scene.

  The scene position mode for landscape is a mode suitable for photographing landscapes in the daytime such as buildings and mountains.

  The scene position mode for a person is a mode suitable for portrait photography that can make skin color appear more beautiful.

  FIG. 13 is an external view of the digital camera shown in FIG. 11 viewed from the back.

  On the upper back of the digital camera 110 shown in FIG. 13, an optical viewfinder eyepiece window 110_22, a finder lamp 110_23 that lights up when the preparation for photographing is completed or blinks during photographing, and an exposure correction button 110_24 are pressed. Is provided with a wide-angle zoom button 110_25 that zooms up to the wide-angle side (wide side), a telephoto zoom button 110_26 that zooms up to the telephoto side (tele-side) when pressed, and a mode switch 110_27 that switches between the shooting mode and the playback mode. It has been.

  Further, below the mode switch 110_27, a photo mode button 110_30, a cross button 110_31, a menu / OK button 110_32, and a DISP / BACK button 110_33 are provided. Further, a liquid crystal monitor 110_34 is provided in the center of the back surface of the digital camera 110.

  The photo mode button 110_30 is a button for setting the number of pixels, sensitivity, color, number of prints, and the like.

  When a menu screen or the like is displayed on the liquid crystal monitor 110_34, the cross button 110_31 is operated by operating the four buttons of the cross key 110_31, the upper button 110_31a, the lower button 110_31b, the left button 110_31c, and the right button 110_31d. Menu selection can be made. The left button 110_31c is also a button for switching whether or not to perform macro shooting (corresponding to another example of the scene setting operation element according to the present invention). When pressed once, the macro shooting mode is set, and when pressed again, the macro shooting mode is set. Shooting mode is canceled. Further, the right button 110_31d is also a button that plays a role of a flash button. Each time the right button 110_31d is pressed, the flash state is changed as follows: auto flash → red eye reduction flash → forced flash → flash prohibition → slow shutter flash → auto flash. It is also a button for switching repeatedly.

  The menu / OK button 110_32 is a button for displaying various menus at the time of shooting or reproduction and determining a selected menu. The menu / OK button 110_32 corresponds to another example of the scene setting operation element according to the present invention, and the shooting scene can be changed by operating the menu / OK button 110_32.

  The DISP / BACK button 110_33 serves as both a DISP button and a BACK button. In the case of the role of the DISP button, it is a button for switching the state of the screen displayed on the liquid crystal monitor 110_34. For example, the display of the liquid crystal monitor 110_34 is turned on / off during shooting, and the character display is turned on / off during playback. To do. On the other hand, in the case of the role of the BACK button, it becomes a button for returning or canceling the operation state by the MENU / OK button 110_32 or the like.

  The liquid crystal monitor 110_34 displays an image composed of image data generated by capturing the subject light with the digital camera 110, information at various settings, and the like.

  14 is a block diagram showing a circuit configuration of the digital camera shown in FIG.

  It should be noted that the same components as those of the digital camera 10 shown in FIG.

  The circuit configuration of the digital camera 110 is different from the circuit configuration of the digital camera 10 shown in FIG. 3 in that a mode dial 110_9 is added.

The digital camera 110 has an AF filter that extracts a signal in a predetermined frequency region based on an analog image signal obtained by the CCD 10_41, and focuses on the maximum contrast point by contrast detection based on the signal that has passed through the AF filter. AF detection circuit 10_51 to tailor, CPU10_47, and includes a focus adjustment means comprising a motor driver 10_49, and the focus lens 10_1A _1, and a mode dial 110_9.

  The CPU 10_47 also serves as a filter control unit that switches the AF filter characteristics according to the shooting scene set by the mode dial 110_9.

  FIG. 15 is a diagram showing shooting scene modes that can be switched by a mode dial or a cross button, and parameters to be set in an AF filter provided in the AF detection circuit.

  FIG. 15 shows a landscape mode, a portrait mode, a night view mode, other modes (sport mode, auto mode) switched by the mode dial 110_9, a macro mode switched by the cross button 110_31, and AF corresponding to these modes. Parameters S, A1, and A2 for setting the filters 1, 2, and 3 are shown. In the landscape mode, a far object is often taken, and a far object is photographed small. As a result, the image signal contains a lot of high frequency components. Therefore, the “slightly high frequency” parameter is set in the AF filters 1, 2 and 3. By setting, a clear image can be obtained. In the person mode and macro mode, it is necessary to pick up the low frequency component contained in the image signal representing the skin of a nearby person rather than the high frequency component contained in the image signal representing the background in the distance. 1 ”is set in the AF filters 1, 2 and 3. Further, since a dark scene should be taken in the night view mode and the contrast is assumed to be lowered, a low frequency component included in the image signal is necessary. Therefore, the “slightly low frequency 2” parameter is set in the AF filters 1, 2, and 3, and the “standard” parameter is set in the AF filters 1, 2, and 3 in the other modes. By doing so, an appropriate image can be obtained in each mode.

  FIG. 16 is a flowchart of a mode dial change processing routine.

  When the user performs an operation of changing the mode dial 110_9, a mode dial change processing routine is executed in step S21. In this mode dial change processing routine, AF filter setting parameters (see FIG. 15) are selected according to the changed mode. Thereafter, this routine is terminated.

  Next, when the user instructs photographing in the AE process / AF process, the AE process is performed. Thereafter, the selected parameter is set for the AF filter, and the AF process shown in FIG. 9 is performed. Finally, the focus lens is driven to the in-focus position, and the process proceeds to a predetermined shooting sequence.

It is the external appearance perspective view which looked at the digital camera which is one Embodiment of the 1st imaging device of this invention from the front diagonally upward. It is the external appearance perspective view which looked at the digital camera shown in FIG. 1 from back diagonally upward. It is a block diagram which shows the circuit structure of the digital camera shown in FIG. It is a figure which shows the structure of AF circuit shown in FIG. FIG. 5 is a diagram showing an EV value of field luminance detected by an AE detection circuit shown in FIG. 3 and parameters set in the AF filter shown in FIG. 4. FIG. 5 is a diagram illustrating a configuration of a low-pass AF filter illustrated in FIG. 4. FIG. 5 is a diagram illustrating a configuration of a high-pass AF filter illustrated in FIG. 4. 4 is a flowchart showing AE processing and AF processing executed by the digital camera shown in FIG. 3. 9 is a flowchart of an AF processing routine shown in FIG. It is a figure which shows the change of AF evaluation value at the time of changing the parameter set to AF filter. It is the external appearance perspective view which looked at the digital camera which is one Embodiment of the 2nd imaging device of this invention from the front diagonally upward. It is the external view which looked at the digital camera shown in FIG. 11 from the top. It is the external view which looked at the digital camera shown in FIG. 11 from the back. It is a block diagram which shows the circuit structure of the digital camera shown in FIG. It is a figure which shows the mode of the imaging | photography scene switched by a mode dial or a cross button, and the parameter set to the AF filter with which the AF detection circuit was equipped. It is a flowchart of a mode dial change processing routine.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10,110 Digital camera 10_1,110_1 Zoom lens barrel 10_1a Shooting lens 10_1a ₁ Zoom lens 10_1a ₂ Focus lens 10_2, 110_2 Flash light emitting device 10_3, 110_3 Flash light control sensor 10_4, 110_4 Optical viewfinder objective window 10_5 Power switch 10_6 Illumination lamp 10_7 , 110_8 Shutter button 10_8 Microphone 10_9, 110_11 Speaker 10_10 USB terminal 10_11 External power supply terminal 10_22, 110_22 Optical viewfinder eyepiece 10_23, 110_23 Viewfinder lamp 10_24 Mode switch 10_25, 110_7 Macro button 10_26 Zoom button 10_27 Flash button 10_28 Flash button 10_28 LCD monitor 10_29 MENU / OK button 10_30 BACK button 10_31 DISP button 10_32 photo mode button 10_33 housing lid 10_34 strap lug 10_41 imaging device (CCD)
10_42 A / D conversion circuit 10_43 Image input controller 10_44 Image signal processing circuit 10_45 Compression processing circuit 10_46 Video encoder 10_47 CPU
10_48, 10_49 Motor driver 10_50 AE detection circuit 10_51 AF detection circuit 10_52 Memory (SDRAM)
10_53 Media controller 10_54 Recording medium 10_100 Bus line 10_511 Pre-gamma processing unit 10_512 Low-pass AF filter 10_513, 517 High-pass AF filter 10_514, 10_518 ABS (absolute value) unit 10_515, 10_519 Coring 10_516, 10_512 Accumulation unit 10_512 10_512c, 10_512d Multiplier 10_512e, 10_512f, 10_512g, 10_512h Delay circuit 10_512i, 10_513m Subtractor 10_512j, 10_512k, 10_512m Adder 110_5 Grip 110_6 Self-timer button 110_9 Pop-up dial button 110_9 10_24 exposure compensation button 110_25 wide-angle zoom button 110_26 telephoto zoom button 110_27 mode switch 110_30 photo mode button 110_31 cross button 110_31a on the button 110_31b under button 110_31c left button 110_31d right button 110_32 menu / OK button 110_33 DISP / BACK button

Claims (2)

In a photographing apparatus that forms a subject image on an image pickup device by a photographing optical system and generates and records an image signal representing the subject by the image pickup device,
A focus adjusting unit that has a filter that extracts a signal in a predetermined frequency region from an image signal obtained by the image sensor, and that focuses on the maximum contrast point by contrast detection based on the signal that has passed through the filter;
A photometric means for measuring the field luminance,
The photographing apparatus, wherein the focus adjustment unit further includes a filter control unit that switches the characteristics of the filter in accordance with the field luminance measured by the photometry unit. In a photographing apparatus that forms a subject image on an image pickup device by a photographing optical system and generates and records an image signal representing the subject by the image pickup device,
A focus adjusting unit that has a filter that extracts a signal in a predetermined frequency region from an image signal obtained by the image sensor, and that focuses on the maximum contrast point by contrast detection based on the signal that has passed through the filter;
With a scene setting operator to select the shooting scene,
The photographing apparatus according to claim 1, further comprising a filter control unit that switches the characteristics of the filter according to a photographing scene set by the scene setting operator.

Images