JP2003244520A - Photographing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photographing device that can prevent wasteful automatic focus control operation and, in addition, can quickly start photographing, even when photographing instructions are given. <P>SOLUTION: This photographing device is constituted to discriminate the need for focus control by using an image obtained for live view display, etc. A correlation value computing section 230 acquires the latest image G1 for live preview display to be stored in an image memory 209 and its preceding image G2 and finds the correlation, corresponding to the difference image between the images G1 and G2. Then the computing section 230 controls an automatic focus control section 240, by discriminating the need for focus control, by comparing the correlation with a threshold stored in a threshold memory 236. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photographing device such as a digital camera.

[0002]

2. Description of the Related Art Generally, in a photographing device such as a digital camera, a shutter button has a two-step pushing structure, and when a user half-presses the shutter button, automatic focusing control is started. Then
It is configured to start the photographing operation when the full-pressed state is set. However, in the image capturing apparatus having such a configuration, even if the user performs a shutter button pressing operation (full pressing operation) at a timing at which the user wants to perform image capturing, the image capturing operation is not started until the automatic focusing operation is completed. There is a problem of a time lag from the start of the automatic focusing control to the start of the shooting operation.

In particular, when a contrast type automatic focusing control is performed in a digital camera, an operation is performed in which the taking lens is driven stepwise to specify a lens position at which the evaluation value such as contrast shows a peak. The time lag from the start of the automatic focusing control to the start of the shooting operation is relatively long compared to other methods, which is a particular problem.

As a technique for reducing such a time lag, there is a technique disclosed in Japanese Patent Laid-Open No. 64-42639. This publication discloses a technique in which when the user holds the camera, a distance measuring operation for automatic focusing is started, and when the user looks into the finder, the shooting lens is driven in synchronization with the finder.

[0005]

However, when the user actually shoots a subject using a shooting device such as a camera, after performing framing through the viewfinder, the shutter button is pressed down in anticipation of a shutter chance. (Shooting instruction). Therefore, it is considered that the shooting instruction is not given until the framing is determined, but it is desirable to always be prepared for the shooting instruction once the framing is determined. That is, considering the usage of the image capturing apparatus, it is best to start the automatic focusing control at the time when the framing is completed.

In the above publication, however, the distance measurement operation for focusing control is started when the user holds the camera, so that if the framing is changed later, the distance measurement operation must be redone, which is wasteful. It will be accompanied by movement. Further, when the distance measuring operation is performed again, the above-mentioned time lag occurs. Further, when the distance measuring operation is performed again, useless power is consumed.

Particularly in digital cameras, there is a great demand for reduction of power consumption, and it is desirable to avoid useless automatic focusing control operation.

Therefore, the present invention has been made in view of the above problems, and prevents unnecessary automatic focusing control and quickly starts a shooting operation even when a shooting instruction is given. The purpose is to provide a device.

[0009]

In order to achieve the above object, the invention as set forth in claim 1 is a photographing device for photographing an image through a photographing lens, wherein the posture variation of the photographing device is controlled. Attitude variation detecting means for detecting, evaluation means for evaluating whether or not the orientation variation amount detected by the orientation variation detection means is within a predetermined range, and the posture variation amount in the evaluation means is within the predetermined range. Focusing control means for starting an automatic focusing control operation for the photographing lens when it is determined that there is a focusing lens.

According to a second aspect of the present invention, there is provided a photographing device for photographing an image through a photographing lens, and a plurality of photographing means for photographing an image and a plurality of photographing means for photographing at different timings by the photographing means. The evaluation means for evaluating the degree of coincidence of the images, and the focus control means for performing the automatic focus control operation for the photographing lens according to the evaluation result by the evaluation means.

According to a third aspect of the present invention, in the photographing apparatus according to the second aspect, the evaluation means extracts an image component corresponding to a predetermined area from each of the plurality of images,
It is characterized in that the degree of coincidence of each image component obtained from each of the plurality of images is evaluated.

The invention according to a fourth aspect is the first to the third aspects.
In the photographing apparatus according to any one of items 1 to 5, the focusing control unit changes the focusing state of an image by gradually moving the photographing lens as the automatic focusing control operation, while changing the focusing state of the image to each lens position. It is characterized in that an evaluation value relating to the in-focus state is obtained from the obtained image, and the photographing lens is driven to the in-focus position based on the evaluation value.

The invention according to a fifth aspect is the first to the fourth aspects.
In the imaging device according to any one of 1 to 3, the evaluation operation in the evaluation unit is repeatedly performed until the user inputs a shooting instruction, and the automatic focusing control unit performs the automatic operation according to the evaluation result in the evaluation unit. The focus control operation is performed as needed.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will now be described in detail with reference to the drawings. In the following, a digital camera will be described as an example of the image capturing apparatus.

<1. Configuration of Digital Camera> FIGS. 1 and 2 are views showing an example of the external configuration of the digital camera 1. FIG. 1 is a front view and FIG. 2 is a rear view.

The digital camera 1, as shown in FIG.
It is composed of a box-shaped camera body 2 and a rectangular parallelepiped image pickup unit 3. A photographing lens 301 having a zoom lens function and an optical finder 31 are provided on the front side of the image pickup unit 3. On the front side of the camera body 2, a grip part 4 is provided at the left end, a built-in flash 5 is provided at the upper center, and a shutter button 8 is provided on the top side. The shutter button 8 is a two-step push-down detection type button, and is half-pressed by a user operation (S1 state).
And the fully pressed state (S2 state) can be distinguished from each other.

On the other hand, as shown in FIG.
On the back side of the LCD, a liquid crystal display (LCD: Liquid Crystal Displ
The display unit 10 composed of ay) or the like is provided. Below the display unit 10, a group of key switches 221 to 226 for operating the digital camera 1 and a power switch 2 are provided.
27 are provided.

Furthermore, on the back side of the camera body 2,
A mode setting switch 14 for switching the mode between the “shooting mode” and the “playback mode” is provided. The shooting mode is a mode in which a digital image is taken to generate a captured image of a subject, and the reproduction mode is a mode in which the captured image recorded in the memory card is read and reproduced and displayed on the display unit 10. The mode setting switch 14 is a two-contact slide switch, and is configured such that when it is slid and set to the lower position, the shooting mode functions and when it is slid and set to the upper position, the reproduction mode functions.

Further, a quad switch 260 is provided on the right side of the rear surface of the camera, and the button 26 is used in the photographing mode.
Pressing 1, 262 changes the zooming magnification, and pressing buttons 263, 264 corrects the exposure.

On the back surface of the image pickup unit 3, as shown in FIG.
Display button 32 for turning on / off the display 10
1 and a macro button 322 are provided. When the display unit button 321 is pressed, the display of the display unit is switched on / off. For example, when the display unit 10 is turned on in the shooting mode, live view display is performed on the display unit 10. With this live view display, the user can easily frame the subject. Further, at the time of macro shooting (close-up shooting), by pressing the macro button 322, the image capturing unit 3 becomes ready for macro shooting.

A card slot for mounting a detachable recording medium for recording photographed images and the like is provided on the bottom surface of the camera body 2.

<2. Internal structure of digital camera> Next,
The internal configuration of the digital camera 1 will be described.
FIG. 3 is a block diagram showing the functional configuration of the digital camera 1.

An image pickup circuit having a CCD image pickup element 303 is provided at an appropriate position behind the taking lens 301 in the image pickup section 3. In addition, inside the image pickup unit 3, a zoom motor M1 for changing the zoom ratio of the photographing lens 301 and for moving the lens between the image pickup positions and the housing position, and an autofocus motor for automatically focusing ( AF motor) M2, diaphragm plate 30 provided in the taking lens 301
A diaphragm motor M3 for adjusting the opening diameter of No. 2 is provided. These zoom motor M1, AF motor M2,
The aperture motor M3 is driven by a zoom motor drive circuit 215, an AF motor drive circuit 214, and an aperture motor drive circuit 216 provided in the camera body 2.
The drive circuits 214 to 216 drive the motors M1 to M3 based on a control signal provided from the overall control unit 211 of the camera body 2.

The CCD image pickup device 303 is a photographing lens 30.
The optical image of the subject formed by 1 is R (red), G
Image signals of (green) and B (blue) color components (signals composed of a signal sequence of pixel signals received by each pixel) are photoelectrically converted and output.

The exposure control in the image pickup section 3 is performed by the diaphragm plate 30.
2 and the amount of exposure of the CCD image pickup element 303, that is, the charge accumulation time of the CCD image pickup element 303 corresponding to the shutter speed is adjusted. When an appropriate aperture and shutter speed cannot be set when the subject contrast is low, the level of the image signal output from the CCD 303 is adjusted to correct the inappropriate exposure due to insufficient exposure. That is, when the contrast is low, control is performed so that the exposure level becomes an appropriate level by combining aperture, shutter speed, and gain adjustment. The level adjustment of the image signal is performed by the signal processing circuit 3
This is performed in the gain adjustment of the AGC (Auto Gain Control) circuit 313b in 13.

The timing generator 314 generates a drive control signal for the CCD image pickup device 303 based on the reference clock transmitted from the timing control circuit 202 of the camera body 2. Timing generator 31
Reference numeral 4 denotes a clock signal such as a timing signal of integration start / end (exposure start / end), a read control signal (horizontal synchronization signal, vertical synchronization signal, transfer signal, etc.) of a light receiving signal of each pixel, and the CCD Output to the image sensor 303.

The signal processing circuit 313 is a CCD image pickup device 3
The image signal (analog signal) output from the circuit 03 is subjected to predetermined analog signal processing. Signal processing circuit 31
3 has a CDS (correlated double sampling) circuit 313a and an AGC circuit 313b. The CDS circuit 313a reduces the noise of the image signal, and the AGC circuit 313b.
The level of the image signal is adjusted by adjusting the gain with.

Next, the internal block of the camera body 2 will be described.

The timing control circuit 202 is configured to generate a reference clock, a clock for the timing generator 314. The timing control circuit 202 also generates a clock for the A / D converter 205. The timing control circuit 202 includes the overall control unit 2
Controlled by 11.

In the camera body 2, the A / D converter 205 converts each pixel signal of the image signal into, for example, a 10-bit digital signal. A / D converter 20
5 is an A / D input from the timing control circuit 202
Each pixel signal (analog signal) is converted into a digital signal of 10 bits or the like based on the conversion clock.

The image processing unit 206 includes a black level correction circuit,
The processing unit includes a WB (white balance) circuit, a γ correction circuit, and the like, and performs predetermined image processing on the image signal converted into a digital signal. In addition, the image processing unit 206
Performs YCbYCr by performing color conversion on an image signal of a color format represented by the RGB color system.
An image signal of a color format expressed in a color system is generated and output to the image memory 209. Incidentally, YC
In the color format expressed in the bYCr color system,
The color information for any two pixels in the image is represented by the luminance component value for two pixels and the color difference component value for one pixel.

The image memory 209 is a memory for temporarily storing the image signal output from the image processing unit 206. The image memory 209 has a storage capacity capable of storing at least two frames of images input from the image processing unit 206 during live view display. However, if the size of the shot image data generated during the main shooting operation is larger than the size of the image data for two frames during live view display, the image memory 209 stores the shot image data generated during the main shooting operation. You need the available storage capacity.

A VRAM (video RAM) 210 is a memory for buffering an image to be displayed on the display section 10. The VRAM 210 has a storage capacity capable of storing image data of a size corresponding to the number of display pixels of the display unit 10.

As described above, in the shooting standby state in the shooting mode, when the display of the display unit 10 is on, the live view display is performed on the display unit 10. At this time, in the digital camera 1, after various signals are processed in the A / D converter 205 and the image processing unit 206 for each image obtained from the image pickup unit 3 at predetermined intervals, the image is stored in the image memory. It is stored in 209. The image captured during live view display (this is referred to as “live view image”) is an image whose main purpose is to be displayed on the display unit 10. Therefore, the captured resolution is lower during live view display than during actual capture. The shooting process is performed in this state, and a live view image having a lower resolution than the shot image obtained during the main shooting is temporarily stored in the image memory 209. For example, even if the digital camera 1 is capable of shooting at a resolution of up to 1600 × 1200 at the time of actual shooting, if the number of display pixels on the display unit 10 is 640 × 480, the image memory is set by the shooting operation during live view display. The live view image for one frame stored in 209 also has a resolution of 640 × 480. The image memory 209 stores the latest live view image (latest image),
At least two frames of live view images from the immediately preceding live view image (previous image) are stored.

During live view display, the overall control unit 211 acquires the latest live view image stored in the image memory 209 and transfers it to the VRAM 210 to display the live view image on the display unit 10. .
Then, the overall control unit 211 updates the live view image displayed on the display unit 10 every predetermined time, so that the live view display is performed. This live view display makes it easy for the photographer to perform a framing operation or the like before pressing the shutter button 8.

However, in this embodiment, in the shooting standby state in the shooting mode, even if the display of the display unit 10 is off, the shooting operation of the live view image is continuously performed every predetermined time. The image memory 209 is configured to always store two frames of live view images including the latest live view image and the live view image immediately before it.

When the user presses the shutter button 8 all the way down, the overall control section 21 is activated.
1 will be given a shooting instruction. Then, the main photographing operation is performed in the digital camera 1, a high-resolution photographed image is generated, and the photographed image is recorded in the memory card 91 which is a kind of recording medium mounted in the card slot 17.

In the reproduction mode, the overall control unit 211 controls the image read from the memory card 91.
After the predetermined signal processing is performed in the VRAM 210,
And is reproduced and displayed on the display unit 10.

The operation section 250 includes the above-mentioned various switches and buttons including the shutter button 8, and the information input by the user is the operation section 25.
It is transmitted to the overall control unit 211 via 0.

The camera shake sensor 217 is a sensor for detecting the amount of camera shake of the digital camera 1 when the shutter button 8 is fully pressed and the main photographing operation is performed. The amount of camera shake detected here is the overall control unit. When the photographed image is recorded in the memory card 91, the overall control unit 2
In 11, the camera shake correction process and the like are performed.

The overall control unit 211 functions as a control means for organically controlling the driving of the above-mentioned members in the image pickup unit 3 and the camera body unit 2 to generally control the photographing operation of the digital camera 1. And the CPU (Central
Processing Unit) 220, RAM (Random Access Mem)
ory) 221, a ROM (Read Only Memory) 222, a correlation value calculator 230, and an automatic focusing controller 240.

The CPU 220 reads out a program stored in the ROM 222 and executes the program to centrally control the live view display processing in the photographing mode, the main photographing operation, the image reproducing processing in the reproducing mode and the like. , RAM 221 is used as a temporary memory during program execution processing.

Correlation value calculation unit 230 and automatic focusing control unit 2
Reference numeral 40 denotes a main part for performing automatic focusing in the digital camera 1, and each image stored in the image memory 209 is DMA (Direct Memory Acce).
ss) can be acquired by the transfer method, and the CPU 22
It is possible to quickly acquire an image without going through 0. The correlation value calculation unit 230 is configured to determine the necessity of the automatic focus control operation performed by the automatic focus control unit 240, and the timing for executing the automatic focus control in the shooting mode and the automatic focus control. The drive range of the taking lens 301 when performing control is specified. Automatic focusing control unit 240
Performs the automatic focusing control by driving the taking lens 301 based on the timing specified by the correlation value calculation unit 230 or the drive range specified by the correlation value calculation unit 230.

FIG. 4 is a block diagram showing a control structure of automatic focusing in the digital camera 1, and the correlation value calculation unit 23.
0 and the detailed configuration of the automatic focusing control unit 240 are shown.

The correlation value calculation section 230 comprises a correlation value calculation target area designation section 231, a luminance component extraction section 232, a correlation value calculation section 233, a correlation value memory 234, a correlation value evaluation section 235, and a threshold value memory 236. Image memory 20
The latest image G1 stored in 9 and the previous image G2, which is the image immediately before that, are acquired by DMA transfer, and the latest image G
1 and the previous image G2 based on the value corresponding to the change amount (difference image), the framing determination state by the user is evaluated, and the automatic focusing control operation in the automatic focusing control unit 240 is performed according to the evaluation result. Configured to determine.

The correlation value calculation target area designating section 231 instructs the luminance component extracting section 232 as an evaluation area for evaluating a change amount between the latest image G1 and the previous image G2. For example, the entire screen area is specified as the evaluation target area for both the latest image G1 and the previous image G2, or only a specific image area (specific area) included in the entire screen area is specified as the evaluation target area.

The luminance component extraction section 232 is provided in the image memory 209.
From each of the latest image G1 and the previous image G2 stored in, the luminance component value included in the designated evaluation target area is extracted for each pixel. Then, the brightness component value extracted from the evaluation target area is provided to the correlation value calculation unit 233.

In the correlation value calculation unit 233, if the brightness component value extracted from the latest image G1 is Y1, the brightness component value extracted from the previous image G2 is Y2, and the number of pixels included in the evaluation target area is N,

[0049]

[Equation 1]

The correlation value V between the latest image G1 and the previous image G2 is obtained by performing the calculation shown in the equation (3). However,
In the formula of Expression 1, the brightness component values Y1 and Y2 are the latest image G
It is the luminance component value of the pixel corresponding to the same position in the evaluation target area in each of 1 and the previous image G2.

By performing the calculation of the equation (1), the correlation value calculation unit 233 determines, as the correlation value V between the latest image G1 and the previous image G2, how much the latest image G1 changes compared with the previous image G2. The value that indicates whether or not

Generally, assuming that the framing of the digital camera 1 is fixed between the time when the last image G2 was taken and the time when the latest image G1 was taken, the previous image G2 and the latest image G1 are Since the images have almost the same contents, the image change is small. On the other hand, when the framing of the digital camera 1 is largely changed between the time when the previous image G2 was captured and the time when the latest image G1 was captured, the previous image G2 and the latest image G1 were changed.
The image changes greatly because the image has a completely different content from.

Therefore, the correlation value calculation unit 233 obtains the absolute difference value of the luminance component value between the corresponding pixels in the two consecutively photographed images, as shown in the equation (1), and Is cumulatively added to the evaluation target area and divided by the number of pixels included in the evaluation target area to obtain an average value of image changes in the evaluation target area, and the average value is used as a correlation value V to obtain the previous image. It is possible to evaluate the degree of framing change between the time when G2 is captured and the time when the latest image G1 is captured.

The correlation value V calculated by the correlation value calculation unit 233 is stored in the correlation value memory 234.

The correlation value evaluation unit 235 is provided in the correlation value memory 23.
The correlation value V stored in No. 4 is acquired, and the threshold value for evaluating the correlation value V stored in the threshold value memory 236 is acquired. Then, the correlation value V and the threshold value are compared to evaluate the framing change situation. The threshold value memory 236 stores in advance a plurality of threshold values (TH, TH1, TH2) applied according to the AF (autofocus) mode.

Then, the correlation value evaluation section 235 compares the correlation value V with the threshold value so that the latest image G1 becomes the previous image G2.
Is evaluated whether or not the change has occurred by a predetermined value or more, and the automatic focusing control unit 240 is controlled according to the evaluation result.

The automatic focusing control section 240 comprises an evaluation area designation section 241, an evaluation value calculation section 242, and a focus determination section 243, and the photographing lens 301 is stepwise at a predetermined pitch along the optical axis direction. The evaluation value is calculated from the image obtained at each lens position by moving the lens position to the lens position, the lens position at which the evaluation value shows a predetermined peak is specified, and the taking lens 301 is driven to that lens position. That is, the automatic focusing control section 240 performs an automatic focusing control operation based on the so-called contrast method.

The evaluation area designating section 241 is used for the photographing lens 30.
An AF evaluation area, which is an evaluation value calculation target area when an evaluation value is obtained from an image captured when 1 is at a certain lens position, is designated to the evaluation value calculation unit 242.

FIG. 5 is a diagram showing an example of the AF evaluation area R1. For example, as shown in FIG. 5, when the AF evaluation area R1 is set in advance in the central portion of the image G, the evaluation area designating unit 241 sends the designated AF evaluation area R1 to the evaluation value calculating unit 242. Will be specified. In addition,
While the user looks at the display screen of the display unit 10, the operation unit 25
When the position of the AF evaluation area R1 can be freely set via 0, the position and size of the AF evaluation area R1 designated by the user are given to the evaluation value calculation unit 242.

The evaluation value calculation unit 242 acquires an image photographed at a certain lens position from the image memory 209,
An image component included in the AF evaluation region R1 is extracted from the image, and an AF evaluation value is calculated. For example, when the contrast value is used as the evaluation value, the evaluation value calculation unit 242 calculates the sum of absolute differences between adjacent pixels included in the AF evaluation area R1 as the evaluation value. Then, the AF evaluation value calculated by the evaluation value calculation unit 242 is provided to the focus determination unit 243.

The focus determination unit 243 is the AF motor drive circuit 2
A driving signal is given to the photographing lens 301 so that the photographing lens 301 is moved stepwise at a predetermined pitch, and the evaluation value obtained at each lens position is acquired to obtain a peak evaluation value (focus position). Position) is specified, and a drive signal is given to the AF motor drive circuit 214 so as to move the taking lens 301 to the specified in-focus position. As a result, the taking lens 301 is driven to the lens position that realizes the in-focus state of the image, and the digital camera 1 is ready to take an in-focus image.

Digital camera 1 configured as described above
In the above, a plurality of AF modes are set as AF operation modes when performing automatic focusing. The AF modes in this embodiment include three AF modes, which are a “normal mode”, an “AF start mode based on a correlation value”, and a “continuous AF mode based on a correlation value”.
Automatic focusing control is performed based on the one AF mode selected by the user.

In the normal mode, when the conventional automatic focusing control is executed and the shutter button 8 is half-pressed, the automatic focusing control section 240 functions to move the taking lens 301 at a predetermined pitch. It is configured to drive the taking lens 301 by obtaining an evaluation value from an image obtained at each lens position to specify the in-focus position while gradually moving. The correlation value calculator 230 does not function in the normal mode.

Next, in the AF start mode based on the correlation value, the correlation value calculation unit 230 functions as a detection means for detecting that the framing of the digital camera 1 has changed,
The correlation value V is obtained by acquiring the latest image G1 and the previous image G2 at the time of live view display, and performing the calculation based on the equation of Formula 1, and the correlation value V and the threshold value TH (for example, TH = 3
0) and the correlation value V is smaller than the threshold value TH, it is determined that the framing is determined (fixed). When it is determined that the framing is determined, the automatic focusing control unit 240 is caused to function and the automatic focusing control operation is started.

On the other hand, when the correlation value V is equal to or greater than the threshold value TH and it is determined that the framing is not determined, the correlation value calculation unit 230 does not cause the automatic focusing control unit 240 to function and wasteful automatic The focus control operation is prevented from being performed.

In this way, the framing is determined by determining the framing fixed state from the image change amount between the latest image G1 and the previous image G2 and starting the automatic focusing control operation when it is determined that the framing is fixed. It is possible to prevent a wasteful automatic focusing control operation before being performed. As a result, power consumption can be reduced. Furthermore, since the focus control operation is automatically performed when the framing is fixed, it is considered that the focus state of the image has already been realized when the user performs the pressing operation of the shutter button 8. There is no problem with the time lag until the start of the shooting operation, and image shooting can be performed without missing a photo opportunity.

By the way, in the AF start mode based on the correlation value, when the correlation value calculation unit 230 determines whether or not the framing is decided, if only a part of the screen is focused, the entire screen is changed although the image change is large. When attention is paid to, it may be possible that the image does not change much. For example, when a landscape photograph is taken, when a large tree or the like having branches and leaves swaying in the wind in the center of the screen is framed, the image change is remarkably large in the center part of the screen, but the image change is not large in the entire screen. Therefore, in such a case, if a part of the entire screen is focused and it is determined whether or not the framing is determined, an erroneous determination may be made.

Therefore, in the AF start mode based on the correlation value, the correlation value calculation target area designating unit 231 causes the entire screen, that is, the latest image G1 stored in the image memory 209.
Also, it is preferable to set the whole of the previous image G2 (entire screen area) as an evaluation target area so that it can be accurately determined whether or not the framing is determined.

Next, continuous A based on the correlation value
In the F mode, while the half-pressed state of the shutter button 8 is continued, the automatic focusing control operation is continuously repeated until a shooting instruction is given. At this time, the correlation value calculation unit 230 functions as a detection unit that detects a change in the framing of the digital camera 1 and a detection unit that detects the movement of the subject, and first acquires the latest image G1 and the previous image G2 during live view display. Then, the correlation value is obtained by performing the calculation based on the formula of the equation 1.

When the correlation value is smaller than the threshold value TH1 by comparing the correlation value with the first threshold value TH1 (TH1 = 30, for example), the framing changes from the previous automatic focusing control operation. It is configured to determine that it is not. When it is determined that the framing has not changed, the correlation value calculation unit 230 causes the automatic focusing control unit 24
0 is not operated, and the lens position of the taking lens 301 is maintained at the current position. As a result, it is possible to prevent useless automatic focusing control operation.

On the other hand, if the correlation value is greater than or equal to the threshold value TH1, then the correlation value and the second threshold value TH2 (for example, TH2 =
100) to evaluate whether the correlation value is smaller than the threshold value TH2. Note that the relationship between the first threshold value TH1 and the second threshold value TH2 is TH1 <TH2.

If the correlation value is greater than or equal to the first threshold TH1 and less than the second threshold TH2, the correlation value evaluation unit 235 determines that the framing has not changed but the position of the subject on the screen has changed. Configured to judge. If it is determined that the position of the subject has changed although the framing has not changed, the correlation value calculation unit 230 instructs the automatic focus control unit 240 to limit the drive range of the taking lens 301 and perform automatic focus control. Command to take action.

Generally, the framing is almost constant, but it is considered that the distance between the digital camera 1 and the subject does not change abruptly when the subject itself on the screen moves. It is considered that a new focus position exists at a position relatively close to the lens position of the taking lens 301 specified as the position. Therefore, in this embodiment, the correlation value between the latest image G1 and the previous image G2 is equal to or greater than the first threshold value TH1 and the second threshold value TH2.
If it is less than, the correlation value calculation unit 230
The drive range of 01 is limited to about ± 10% of the total drive range of the taking lens 301 centering on the focus position up to that point, and the automatic focus control unit 240 is made to function. As a result, useless lens driving can be prevented, and the moved subject can be quickly brought into the in-focus state.

Further, when the correlation value is equal to or more than the threshold value TH2, it means that the contents of the latest image G1 and the previous image G2 are completely different, and the correlation value evaluation unit 235 has a large framing itself. It is configured to judge that it has changed. When the framing changes greatly, even if the previous image G2 is in focus, the latest image G1 is likely to be out of focus. Also,
When the framing changes significantly, the subject to be shot may change. Therefore, a new focus position is relatively close to the lens position of the shooting lens 301 that has been specified as the focus position. It is unlikely that there is a focal position. Therefore, in this embodiment, when the correlation value between the latest image G1 and the previous image G2 is equal to or larger than the second threshold value TH2, the correlation value calculation unit 23
0 sets the drive range of the photographing lens 301 to the entire drive range and causes the automatic focusing control section 240 to function. As a result, the automatic focusing control unit 240 can obtain an AF evaluation value from the entire driving range of the taking lens 301 and guide the image after the framing change to an appropriate focused state.

Then, the continuous A based on the correlation value
In the F mode, the correlation value between the latest image G1 and the previous image G2 is repeatedly obtained, and the first threshold TH1 and the second threshold T
By performing an evaluation in comparison with H2 and controlling the automatic focusing control operation at any time, even if the content of the image changes before the shutter button 8 is fully pressed by the user, the image is displayed. It becomes possible to always lead to an appropriate focused state.

Here, in the continuous AF mode based on the correlation value, when the correlation value calculation unit 230 determines whether or not the subject moves, that is, when the correlation value is compared with the first threshold value TH1. It is preferable to detect the position change of the main subject in the image with high accuracy. However, when deciding whether or not the subject has moved, paying attention to the entire screen, the position of the main subject in the screen has changed to some extent, but it seems that the image does not change so much in the entire screen. There may be cases. For example, when the main subject (person, etc.) is relatively small in the center of the entire screen, the image of the main subject in the center of the screen changes significantly even though the position of the main subject changes significantly. The change is not big. Therefore, in such a case,
If the entire screen is focused and it is determined whether or not the subject has moved, an erroneous determination may be made.

Therefore, when the correlation value calculation unit 230 detects the movement of the object in the continuous AF mode based on the correlation value, the correlation value calculation target area designation unit 231 does not display the entire screen but a part of the screen. By setting the specific region as the evaluation target region and the correlation value calculation unit 233 obtaining the correlation value between the latest image G1 and the previous image G2 for the specific region which is a part of the screen, it is possible to accurately determine whether or not the subject has moved. It is preferable to configure so that it can be determined. In addition,
The correlation value regarding a part of the screen between the latest image G1 and the previous image G2 is referred to as a specific area correlation value V1.

Further, continuous A based on the correlation value
In the F mode, when the correlation value calculation unit 230 determines whether the framing has changed significantly, that is, when the correlation value is compared with the second threshold value TH2, the image change of the entire screen is detected with high accuracy. It is preferable. However, when deciding whether or not the framing has changed, if we focus on a part of the image components in the screen, there is not much image change in the entire screen, but the subject included in that part of the area There may be cases where there are large fluctuations. Therefore, in such a case, if a part of the screen is focused and it is determined whether or not the framing is greatly changed, an erroneous determination may be made.

Therefore, when the correlation value calculation unit 230 detects a change in framing in the continuous AF mode based on the correlation value, the correlation value calculation target area designating unit 2
31 sets not the part of the screen but the area of the entire screen as the evaluation target area, and the correlation value calculation unit 233 sets the latest image G1.
It is preferable that the correlation value between the image G2 and the previous image G2 be obtained for the entire screen so that it can be accurately determined whether or not the framing has changed. The correlation value between the latest image G1 and the previous image G2 for the entire screen is called the all-image correlation value V2.

As described above, in the continuous AF mode based on the correlation value, when the correlation value calculation unit 230 obtains the correlation value between the latest image G1 and the previous image G2, the correlation value calculation unit 233 sets the correlation value to the specific area correlation value. V1 and total image correlation value V
2, the correlation value evaluation unit 235 compares the specific area correlation value V1 with the first threshold value TH1 and the whole image correlation value V2 with the second threshold value TH2. Is a more preferable form.

When the correlation value calculation target area designating section 231 designates a partial area of the screen as an evaluation target area, the evaluation target area and the automatic focusing control section 240
A more preferable form is to match the AF evaluation region R1 when calculating the evaluation value for F. This is because the AF evaluation area R1 used in the automatic focusing control unit 240
Is an area that is set in order to appropriately bring the subject included in that area into the in-focus state. Therefore, the same as when the in-focus state is determined when the movement of the object is detected by the correlation value calculation unit 230. This is because it is desirable to determine the motion of the subject. Then, by matching the evaluation target area in the correlation value calculation unit 230 with the AF evaluation area R1 in the automatic focus control unit 240, it is possible to perform movement detection and focus control of the same target object. Therefore, it becomes possible to perform the automatic focusing control operation suitable for the user's intention of photographing.

In FIG. 4, when the correlation value calculation target area designating unit 231 designates a partial area of the screen as the evaluation target area, the same area as the AF evaluation area R1 is designated as the evaluation target area. For this purpose, the automatic focusing control unit 240
The evaluation area designating unit 241 is configured to give the information about the AF evaluation area R1 to the correlation value calculation target area designating unit 231. With such a configuration, the evaluation target area in the correlation value calculation unit 230 and the AF evaluation area R in the automatic focusing control unit 240
It becomes possible to match 1 with 1.

<3. Processing Sequence> Next, in the digital camera 1 configured as described above, the AF start mode based on the correlation value and the continuous A based on the correlation value.
The processing sequence when each of the F mode is set will be described.

<3-1. AF Start Mode Based on Correlation Value> First, the processing sequence in the AF start mode based on the correlation value will be described. FIG. 6 shows AF based on the correlation value.
7 is a flowchart showing a focus sequence in the digital camera 1 when the start mode is set. In the AF start mode based on the correlation value, when the digital camera 1 is changed to the shooting mode, the processing procedure shown in FIG. 6 is started.

First, the correlation value calculating section 230 functions and acquires the latest image G1 and the previous image G2 stored in the image memory 209 at high speed by DMA transfer at the time of live view display in the photographing mode (step S10).
0). Then, the correlation value V between the latest image G1 and the previous image G2 is obtained for the evaluation target area (for example, the entire screen area) specified by the correlation value calculation target area specifying unit 231 (step S101). Then, the correlation value V is a predetermined threshold value T
It is determined whether it is H or more (step S102).

If the correlation value V is greater than or equal to the threshold value TH, it is determined that the framing has not been determined (fixed), and the process returns to step S100 to wait for the framing determination.

On the other hand, in step S102, the correlation value V
If is less than the threshold value TH, the process proceeds to step S103, and the correlation value calculation unit 230 causes the automatic focusing control unit 240 to function to start the automatic focusing control operation.

In step S103, the automatic focusing control unit 2
40 moves the taking lens 301 stepwise at a predetermined pitch over the entire driving range of the taking lens 301, and sets A for the AF evaluation area based on the image obtained at each lens position.
The operation of obtaining the evaluation value for F and specifying the lens position showing the peak value is performed. The lens position where this evaluation value shows a peak value is the in-focus position that realizes the in-focus state of the subject included in the AF evaluation area.

When the in-focus position is specified by the automatic focusing control section 240, a drive signal to the in-focus position is sent to the AF motor drive circuit 214 to drive the taking lens 301 to the in-focus position (step). S104). As a result, the subject included in the AF evaluation area with the framing fixed is in focus.

Then, automatic exposure control is performed in the overall control section 211, and the aperture diameter of the diaphragm plate 302 and the shutter speed (charge accumulation time of the CCD image pickup device 303) are determined (step S105). The overall control unit 211 then drives the aperture motor M3 to drive the aperture motor M3.
A driving signal is supplied to the control unit 6 to drive the diaphragm plate 302, and the aperture diameter of the diaphragm plate 302 is set to the determined aperture diameter (step S106).

Next, the overall control unit 211 inspects whether or not the shutter button 8 has been fully pressed by the user and a shooting instruction has been input (step S107).

If the shooting instruction has not been input in step S107, the process returns to step S100. Therefore, even if it is determined that the user has decided the framing and the automatic focusing control operation has been performed once, if the shooting instruction is not input, the calculation and evaluation of the correlation value are repeatedly performed. Become. Therefore, as long as the framing fixed state is maintained, the automatic focusing control operation is repeatedly performed. On the other hand, when the framing changes, the automatic focusing control operation is not performed until the framing is fixed again, and it is effective to perform the unnecessary automatic focusing control operation while the framing is not determined. To be prevented.

On the other hand, if it is determined in step S107 that the shooting instruction has been input, the overall control unit 21
1 controls the main photographing operation comprehensively, and starts the main photographing operation in the digital camera 1 (step S108).
At this time, the overall control unit 211 sends a control signal to the timing control circuit 202 so that the shutter speed determined in step S105 is achieved. By this main shooting operation, the digital camera 1 shoots a high-resolution shot image to be recorded on the memory card 91.

Then, the overall control section 211 records the photographed image stored in the image memory 209 by the main photographing operation in the memory card 91 (step S109).

Thus, the processing until the photographing operation is completed in the photographing mode is completed.
When the process of 109) is completed, the process may return to step S100 to prepare for the next shooting operation.

As described above, when the AF start mode is set based on the correlation value, based on the correlation value V between the latest image G1 obtained every predetermined time for live view display and the previous image G2 which is the image immediately before the latest image G1. And operates to detect whether the framing has changed. Here, detecting whether or not the framing has changed means in other words, whether or not the posture of the digital camera 1 has changed. Therefore, when the AF start mode is set based on the correlation value, the correlation value evaluation unit 235 in the correlation value calculation unit 230 also functions as a posture variation detection unit that detects a posture variation of the digital camera 1, and the digital camera 1 has Whether or not the posture variation amount is within a predetermined range is evaluated, and if it is determined that the posture variation amount is within the predetermined range, the photographing lens 301 is drive-controlled to start the automatic focusing control operation. ing.

Therefore, when the AF start mode based on the correlation value is set in the digital camera 1, the automatic focusing control operation is not performed in a state where the framing is not fixed, and the automatic focusing control operation is performed when the framing is fixed. Will be configured to do. Therefore, useless automatic focusing control operation is not performed, and the shooting operation can be started promptly when the shooting instruction is given.

Further, since it is configured to detect whether or not the framing has changed by using the image obtained at every predetermined time for the live view display, the configuration peculiar to the digital camera is effectively used. Becomes That is,
By executing the processing procedure as described above, the degree of coincidence of a plurality of images captured at different timings by the CCD image sensor 303 in the digital camera 1 is evaluated,
Since the automatic focusing control operation is performed according to the evaluation result, it is not necessary to provide a complicated constituent member for detecting a change in framing.

Then, in the evaluation of the degree of coincidence of a plurality of images, if the value based on the difference image of the plurality of images is smaller than a predetermined threshold value TH, it is determined that the framing has been decided. Since the automatic focusing control operation is started when it is determined that is determined, it is possible to relatively easily and quickly determine the necessity of the automatic focusing control operation.

In the above description of the AF start mode based on the correlation value, the case where the determination of the framing is detected and the automatic focusing control operation is started has been described. Is configured to detect the motion (movement) of the subject by obtaining the correlation value V for the evaluation target region that matches the AF evaluation region of, and the automatic focusing control operation is performed when the subject is determined to be still. May be configured to start.

<3-2. Correlation Value Based Continuous AF Mode> Next, a processing sequence in the correlation value based continuous AF mode will be described.
FIG. 7 is a flowchart showing a focus sequence in the digital camera 1 when the continuous AF mode based on the correlation value is set.

In the continuous AF mode based on the correlation value, the automatic focusing control operation is started when the shutter button 8 is half pressed in the photographing mode. Therefore, the overall control unit 211 first detects that the shutter button 8 is half-pressed (step S200), and when the shutter button 8 is half-pressed, the process proceeds to step S201.

In the continuous AF mode based on the correlation value, the automatic focusing control section 240 first functions to perform the automatic focusing control operation (step S201). At this time, the automatic focusing control unit 240 moves the taking lens 301 stepwise at a predetermined pitch over the entire driving range of the taking lens 301,
An operation is performed in which an AF evaluation value for the AF evaluation area is obtained based on an image obtained at each lens position, and a lens position (focus position) indicating the peak value is specified.

When the in-focus position is specified by the automatic in-focus control section 240, a drive signal to the in-focus position is sent to the AF motor drive circuit 214 to drive the photographing lens 301 to the in-focus position (step). S202). As a result, A
The subject included in the F evaluation area is in focus.

Then, automatic exposure control is performed in the overall control unit 211, and the aperture diameter of the diaphragm plate 302 and the shutter speed (charge accumulation time of the CCD image pickup device 303) are determined (step S203).

Next, the correlation value calculation unit 230 functions, and the image memory 209 is displayed during live view display in the photographing mode.
The latest image G1 and the previous image G2 stored in are acquired at high speed by DMA transfer (step S204). Then, the correlation value between the latest image G1 and the previous image G2 is obtained for the evaluation target area designated by the correlation value calculation target area designation section 231 (step S205). At this time, the correlation value calculation target region designating section 231 designates two regions, that is, the entire screen region and the specific region which is a part of the entire screen, as the evaluation target regions. The correlation value calculation unit 233 then
The correlation value is calculated based on each of the three areas. As a result, in step S205, the total image correlation value V2 obtained for the entire screen area of the latest image G1 and the previous image G2, and the specific area obtained for the specific partial area of the latest image G1 and the previous image G2 Correlation value V1 and 2
Two correlation values will be obtained.

Then, the correlation value evaluation unit 235 determines whether or not the total image correlation value V2 is equal to or larger than the second threshold value TH2 (step S206).

Here, the total image correlation value V2 is the second threshold value T
If it is H2 or more, it is determined that the framing has changed significantly, so there is a high possibility that the lens position at which the taking lens 301 was driven in step S202 at the previous time is already out of focus. Therefore, the total image correlation value V
If 2 is greater than or equal to the second threshold TH2 and it is determined that the framing has changed significantly, the process returns to step S201 and the automatic focusing control operation is performed again for the entire driving range of the taking lens 301.

On the other hand, if the total image correlation value V2 is less than the second threshold TH2, it is determined that the framing has not changed significantly. Therefore, since it is not necessary to perform the automatic focusing control operation for the entire driving range of the taking lens 301, the process proceeds to step S207.

Next, the correlation value evaluation unit 235 determines whether or not the specific area correlation value V1 is the first threshold TH1 or more (step S207).

Here, if the specific area correlation value V1 is equal to or larger than the first threshold value TH1, it is determined that the main subject included in the specific area has moved (changed) although the framing has not changed significantly. Therefore, it is considered highly likely that the lens position at which the taking lens 301 was driven in the previous step S202 is already out of the in-focus position.
However, when the main subject moves, it is assumed that a new focus position exists near the lens position where the taking lens 301 was driven in step S202 last time.
Therefore, when the specific area correlation value V1 is equal to or larger than the first threshold value TH1 and it is determined that the main subject has changed, the process proceeds to step S208.

In step S208, the taking lens 301
The automatic focusing control unit 240 is caused to function by limiting the driving range of (1) to about ± 10% of the total driving range of the taking lens 301 centering on the current lens position, and the automatic focusing control operation is executed. As a result, the automatic focusing control unit 240 drives the taking lens 301 within the limited driving range, and specifies the peak position of the AF evaluation value guided within the limited range as the focusing position. Then, returning to step S202, the photographing lens 301 is driven to the specified in-focus position, and the moved subject can be appropriately brought into the in-focus state.

As described above, when it is considered that the main subject has moved, the focusing range of the main subject is quickly realized by limiting the drive range of the taking lens 301 and performing the automatic focusing control operation. be able to. Moreover, since the drive range is limited, there is no unnecessary lens drive, and it is possible to reduce power consumption.

On the other hand, if the specific area correlation value V1 is less than the first threshold value TH1 in step S207, it is determined that the framing has not changed and the subject has not moved. Therefore, it is considered that the lens position where the taking lens 301 was driven in the previous step S202 still maintains the in-focus position. Therefore, the process proceeds to step S210 to prepare for the main photographing operation.

In step S210, the overall control unit 211
Supplies a drive signal to the diaphragm motor drive circuit 216 to drive the diaphragm motor M3 to drive the diaphragm plate 302,
The aperture diameter of the diaphragm plate 302 is set to the aperture diameter determined in step S203.

Next, the overall control unit 211 inspects whether or not the shutter button 8 has been fully pressed by the user and a shooting instruction has been input (step S211).

When the photographing instruction is not input in step S211, the process returns to step S203. Therefore, when the shooting instruction is not input, the calculation and evaluation of the correlation value are repeatedly executed. Then, when a change in the framing or a movement of the subject is detected, the automatic focusing control operation (step S201 or S208) is repeated again. Further, when the change of the framing and the movement of the subject are not detected, the automatic focusing control operation is not performed, and the wasteful automatic focusing control operation is effectively prevented.

On the other hand, if it is determined in step S211 that a shooting instruction has been input, the overall control unit 21
1 controls the main photographing operation comprehensively, and starts the main photographing operation in the digital camera 1 (step S212).
At this time, the overall control unit 211 sends a control signal to the timing control circuit 202 so that the shutter speed determined in step S203 is achieved. By this main shooting operation, the digital camera 1 shoots a high-resolution shot image to be recorded on the memory card 91.

Then, the overall controller 211 records the photographed image stored in the image memory 209 by the main photographing operation on the memory card 91 (step S213).

With the above, the processing until the photographing operation is completed in the photographing mode is completed, but the image recording (step S
When the process of 213) is completed, the process may return to step S200 again to prepare for the next shooting operation. Also,
In the above flowchart, steps S200 to S2
When the half-pressed state of the shutter button 8 is released during the processing of 11, the processing from step S200 may be repeated again.

As described above, when the continuous AF mode based on the correlation value is set, the correlation value between the latest image G1 obtained at every predetermined time for live view display and the previous image G2 which is the image immediately before that is set to the correlation value. Based on this, it operates so as to detect changes in framing and movement of the main subject. Then, when the shutter button 8 is half-pressed, an automatic focusing control operation is first executed, and unless a framing change or subject movement is detected from there,
The automatic focusing control operation is not executed.

In the general continuous AF mode, the automatic focusing control operation is repeatedly performed at regular time intervals while the half-pressed state of the shutter button 8 is maintained. In the nuisance AF mode, since the automatic focus control operation is performed again only when the framing changes and when the main subject moves, there is no unnecessary automatic focus control operation performed. Further, when a shooting instruction is given, the shooting operation can be started immediately.

Further, since the framing change and the movement of the subject are detected by using the image obtained every predetermined time for the live view display, the configuration peculiar to the digital camera is effectively used. Becomes That is, by executing the processing procedure as described above, the degree of coincidence between a plurality of images captured by the CCD image sensor 303 in the digital camera 1 at different timings is evaluated, and the automatic focusing control is performed according to the evaluation result. Since it is realized so as to perform an operation, it is not necessary to provide a complicated constituent member for detecting a change in framing or movement of an object.

Then, in the evaluation of the degree of coincidence of a plurality of images, when the value based on the difference image of the plurality of images is smaller than the first threshold value TH1, it is determined that the framing does not change, If it is determined that the framing has not changed, the focus control operation is not performed,
Since the lens position of the taking lens 301 is maintained at the current position, useless automatic focusing control operation is not performed.

Further, when the value based on the difference image is not less than the first threshold TH1 and less than the second threshold TH2, it is determined that the framing has not changed but the subject is moving and the focus is deviating. When it is determined that the focus is deviating, the driving range of the photographing lens 301 is limited to perform the automatic focusing control, so that the focused state of the image can be efficiently realized. It is possible.

Furthermore, when the value based on the difference image is equal to or larger than the second threshold value TH2, it is configured to judge that the framing has changed, and when it is judged that the framing has changed, Since the automatic focusing control is performed without limiting the driving range of the taking lens 301, it is possible to appropriately bring the subject after the framing is changed into the focused state.

<4. Modifications> Although the embodiments of the present invention have been described above, the present invention is not limited to the above description.

For example, in the above description, the digital camera 1 has been described as an example of the photographing device, but the present invention is not limited to this, and the photographing device may be another camera such as a silver halide film camera.

Further, in the above, the case where the change in the framing is detected based on the change in the image used for the live view display has been exemplified, but other detection methods are also possible. For example, the camera shake sensor 217 is used as a posture variation detection unit that detects a posture variation of the digital camera 1 to evaluate whether or not the amount of posture variation of the digital camera 1 detected by the camera shake sensor 217 is within a predetermined range. This also makes it possible to detect a change in framing.

The specific embodiments described above include the inventive concept having the following configuration.

(1) In the photographing device according to the second aspect, when the evaluation means evaluates the degree of coincidence of the plurality of images, the value based on the difference image of the plurality of images is smaller than a predetermined threshold value. In this case, the focusing control means is configured to determine that the framing is determined, and the focusing control means starts the focusing control operation when the framing is determined by the evaluation means. apparatus.

With this structure, it is possible to prevent the unnecessary automatic focusing control operation and start the photographing operation promptly, and it is possible to relatively easily and promptly judge the necessity of the automatic focusing control operation. be able to.

(2) In the photographing device described in (1),
The evaluation unit is configured to determine that the determined framing does not change when the value based on the difference image is continuously smaller than the predetermined threshold value, and the focus control unit is the An imaging device, wherein the focusing control operation is not performed when the evaluation means determines that there is no change in framing.

With this structure, it is possible to favorably prevent useless automatic focusing control operation.

(3) In the photographing apparatus according to the second aspect, when the evaluation means evaluates the degree of coincidence of the plurality of images, the value based on the difference image of the plurality of images is first.
When it is smaller than the threshold value of, it is configured to determine that there is no change in framing, the focusing control means,
A photographing apparatus, characterized in that, when the evaluation means judges that there is no change in framing, the focus control operation is not performed and the lens position of the photographing lens is maintained at the current position.

With this structure, it is possible to appropriately prevent useless automatic focusing control operation and start the photographing operation promptly.

(4) In the photographing apparatus described in (3),
When the value based on the difference image is equal to or more than the first threshold value and less than the second threshold value, the evaluation unit is configured to determine that the framing does not change but the focus is shifting, and the focusing control is performed. An image taking apparatus, characterized in that the means limits the drive range of the taking lens to perform automatic focusing control when the evaluation means determines that the framing does not change but the focus is deviating.

With this configuration, it is possible to efficiently realize the focused state of the image.

(5) In the photographing device described in (4),
The evaluation unit is configured to determine that the framing has changed when the value based on the difference image is equal to or more than the second threshold value, and the focusing control unit changes the framing in the evaluation unit. If it is determined that the photographing lens is used, automatic focusing control is performed without limiting the driving range of the photographing lens.

With this structure, it is possible to properly bring the subject after the framing is changed into the in-focus state.

(6) In the photographing apparatus described in (4) or (5), the evaluation means sets the object for which the difference image is to be obtained among the plurality of images when performing the evaluation regarding the first threshold value. And a target area for which the difference image is to be obtained when the evaluation regarding the second threshold is performed is the entire image area of the plurality of images.

With this configuration, the evaluation means can make a more accurate judgment.

(7) A photographing device for photographing an image through a photographing lens, the subject motion detecting means for detecting the motion of the subject, and the variation amount of the subject detected by the subject motion detecting means are predetermined. An evaluation unit that evaluates whether or not it is within a range, and when the evaluation unit determines that the variation amount is within the predetermined range, drives and controls the photographing lens to start an automatic focusing operation. An imaging device comprising: focus control means.

With this structure, it is possible to prevent the unnecessary automatic focusing control operation and start the photographing operation promptly.

[0145]

As described above, according to the first aspect of the invention, it is detected by the posture variation detecting means,
When it is determined that the attitude variation amount of the image capturing apparatus is within the predetermined range, the automatic focusing control operation for the shooting lens is started, so that the timing at which the shooting instruction is input is predicted and the automatic focusing is performed. The focus control operation can be started early, and the shooting operation can be started promptly even when the shooting instruction is given. It is also possible to prevent useless automatic focusing control operation.

According to the second aspect of the invention, the degree of coincidence of a plurality of images photographed at different timings by the image pickup means is evaluated, and the automatic focusing control operation for the photographing lens is performed according to the evaluation result. Therefore, it is possible to appropriately detect a change in the framing and the movement of the subject to prevent a useless automatic focusing control operation, and to quickly start the shooting operation even when a shooting instruction is given.

According to the third aspect of the present invention, image components corresponding to a predetermined area are extracted from each of the plurality of images and the degree of coincidence of each image component obtained from each of the plurality of images is evaluated. Focusing on the area where the main subject is present, it is possible to detect the change in framing and the movement of the subject with higher accuracy.

According to the fourth aspect of the present invention, the focusing control means performs the automatic focusing control operation by changing the focusing state of the image by moving the photographing lens stepwise and changing the position of each lens. It is configured to obtain an evaluation value related to the in-focus state from the image obtained in step 3 and drive the taking lens to the in-focus position based on that evaluation value. Since it takes a very long time, it is necessary to properly detect changes in framing and movement of the subject to prevent useless automatic focusing control operation, and to start shooting operation promptly even when a shooting instruction is given. Will be especially beneficial.

According to the fifth aspect of the invention, the evaluation operation in the evaluation means is repeatedly performed until the user inputs a photographing instruction, and the focus control means automatically operates according to the evaluation result in the evaluation means. Since the focusing control operation is performed at any time, it is possible to prevent the useless automatic focusing control operation until the shooting instruction is input and to quickly start the shooting operation even when the shooting instruction is given. An automatic focusing control operation is performed.

[Brief description of drawings]

FIG. 1 is a front view showing an example of the external configuration of a digital camera.

FIG. 2 is a rear view showing an example of an external configuration of a digital camera.

FIG. 3 is a block diagram showing a functional configuration of a digital camera.

FIG. 4 is a block diagram showing a control structure of automatic focusing in a digital camera.

FIG. 5 is a diagram showing an example of an AF evaluation area.

FIG. 6 is a flowchart showing a focus sequence of the digital camera when the AF start mode is set based on the correlation value.

FIG. 7 is a flowchart showing a focus sequence of the digital camera when a continuous AF mode is set based on a correlation value.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Digital camera (imaging device) 8 Shutter button 10 Display unit 209 Image memory 211 Overall control unit 217 Shake sensor (posture change detection means) 230 Correlation value calculation unit (posture change detection means, subject movement detection means) 231 Correlation value calculation target Area designation unit 232 Luminance component extraction unit 233 Correlation value calculation unit 235 Correlation value evaluation unit (evaluation means) 240 Automatic focusing control unit (focusing control means) 301 Photographing lens 302 CCD image pickup device (image pickup means) G1 Latest image G2 Previous time image

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kenji Nakamura             2-3-3 Azuchi-cho, Chuo-ku, Osaka-shi, Osaka Prefecture               Osaka International Building Minolta Co., Ltd. (72) Inventor Shinichi Maehama             2-3-3 Azuchi-cho, Chuo-ku, Osaka-shi, Osaka Prefecture               Osaka International Building Minolta Co., Ltd. (72) Inventor Tomonori Sato             2-3-3 Azuchi-cho, Chuo-ku, Osaka-shi, Osaka Prefecture               Osaka International Building Minolta Co., Ltd. F term (reference) 2H011 BB03 CA24                 2H051 CE14 CE16 DA22 EA10                 5C022 AA13 AB22 AC32 AC54 AC69                       AC74

Claims (5)

[Claims] 1. A photographing apparatus for photographing an image through a photographing lens, comprising: posture variation detecting means for detecting posture variation of the photographing apparatus; and posture variation amount detected by the posture variation detecting means. An evaluation unit that evaluates whether or not it is within a predetermined range; and a combination that starts an automatic focusing control operation for the taking lens when the posture variation amount is determined by the evaluation unit to be within the predetermined range. An imaging device including a focus control unit. 2. A photographing device for photographing an image through a photographing lens, wherein an image pickup means for photographing an image and a degree of coincidence between a plurality of images photographed by the image pickup means at different timings are evaluated. And an in-focus control unit that performs an automatic in-focus control operation for the imaging lens according to the evaluation result of the evaluation unit. 3. The photographing apparatus according to claim 2, wherein the evaluation unit extracts an image component corresponding to a predetermined area from each of the plurality of images, and extracts each image component obtained from each of the plurality of images. An imaging device characterized by evaluating the degree of coincidence. 4. The image taking apparatus according to claim 1, wherein the focusing control unit performs the automatic focusing control operation by focusing the image by moving the taking lens stepwise. An imaging apparatus, wherein an evaluation value regarding a focus state is obtained from an image obtained at each lens position while changing the state, and the photographing lens is driven to the focus position based on the evaluation value. 5. The photographing apparatus according to claim 1, wherein the evaluation operation in the evaluation unit is repeated until the user inputs a shooting instruction, and the evaluation result in the evaluation unit is displayed. Accordingly, the automatic focusing control operation by the focusing control means is performed at any time.