JPH11136557A - Electronic camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide image data of a satisfactory photographing state such as less hand blurring on an electronic camera which image-picks up an object image and converts it into image data. SOLUTION: An image pickup means 1 which continuously image-picks up an object, a temporary storage means 2 which temporarily stores plural pieces of image data that are continuously image-picked up by the image pickup means 1, a photographing evaluation means 3 evaluating the propriety of the photographing state on image data which is image-picked up by the image pickup means 1, a still image selection means 4 selecting image data whose evaluation from the photographing evaluation means 3 is the highest among image data stored in the temporary storage means 2 and an image preservation means 5 preserving image data selected by the still image selection means 4 are provided for the electronic camera.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic camera which captures a subject image and records image data. In particular, the present invention relates to a technique for recording image data in a good shooting state such as low camera shake.

[0002]

2. Description of the Related Art Generally, in a case where a camera is photographed by hand, camera shake often occurs. When such a camera shake occurs, the object scene flows and is exposed, so that a blurred image is captured as a whole. In such a blurred image, fine details of the entire screen are lost, and an edge portion to be clearly photographed is blurred. Therefore, an image with a very poor impression is obtained.

Conventionally, a camera equipped with a camera shake correction mechanism has been known as a solution to such a problem caused by camera shake. FIG. 13 is a diagram showing this type of camera with a camera shake correction mechanism. In FIG. 13, a photographing lens 92 is attached to the front of a camera 91. Shooting lens 9
A shake correction optical system 93 is rotatably arranged in the second lens barrel.

The shake correcting optical system 93 receives the rotation of the two-axis coreless motors 94 and 95 and vibrates vertically and horizontally. On the camera 91 side, on the other hand, a shake amount detection sensor 96 for detecting the shake amount in the left-right direction and a shake amount detection sensor 97 for detecting the shake amount in the vertical direction are arranged. In the camera 91 having such a configuration, the shake amount detection sensor 9
The vibration of the camera body is detected by using 6,97. The camera 91 moves the coreless motor 9 in the direction opposite to the detected vibration.
4 and 95 to vibrate the optical axis of the blur correction optical system 93. As a result, the vibration of the photographing optical axis is canceled, and a good photograph in which camera shake is corrected can be taken.

[0005]

By the way, in such a conventional example, the blur correction optical system 93 is disposed in the photographing lens 92. Therefore, there is a problem that the photographing lens 92 becomes large and heavy. Further, a space for arranging the blur correction optical system 93 must be secured in the photographing lens 92, and there is a problem that the degree of freedom in designing the photographing lens 92 is reduced.

Further, the amount of internal reflection in the photographing lens 92 is increased by the provision of the blur correction optical system 93. for that reason,
There has been a problem that flare is likely to occur during backlit shooting. Further, there is a problem that the battery life is shortened because power is consumed when driving the blur correction optical system 93.

Further, there is another problem that a slight noise is generated when the blur correction optical system 93 is driven. On the other hand, the blurred image is not limited to the above-described camera shake, but also occurs in subject shake and out-of-focus. However, since the conventional camera shake correction mechanism only cancels the camera vibration, there has been a problem that such subject shake and out-of-focus cannot be prevented at all.

In particular, with the recent increase in resolution and miniaturization of image sensors, the light receiving area per pixel has been increasingly reduced, and the effective sensitivity of the image sensors has been reduced. Therefore, the exposure time of the image sensor generally tends to be longer, and the frequency of occurrence of camera shake and subject shake has become much higher. Therefore, in the case of an electronic camera in particular, measures against such camera shake and subject shake are urgently desired. In addition, it is very difficult to accurately prevent a subject from moving out of focus, such as a flower swaying in the wind, even in conventional AF (auto focus) photography. Therefore, there is a strong demand for an electronic camera that reliably eliminates defocus even under such bad conditions.

In order to solve the above-mentioned problems, the present invention provides an electronic camera capable of reliably obtaining image data in a good photographing state. The purpose is to do. In particular, it is an object of the present invention to provide an electronic camera capable of saving power.

It is another object of the present invention to provide an electronic camera capable of substantially reducing the worst value of the release time lag by half. It is another object of the present invention to provide an electronic camera having a simplified configuration. An object of the present invention is to reduce the storage capacity of a temporary storage unit (described later) or increase the number of samples of image data.

An object of the present invention is to provide an electronic camera which can omit a temporary storage means (described later). It is an object of the present invention to provide an electronic camera capable of obtaining good image data with little camera shake. It is an object of the present invention to provide an electronic camera capable of obtaining good image data with less subject blur and out of focus. It is an object of the present invention to provide an electronic camera capable of efficiently analyzing a spatial frequency component. It is an object of the present invention to provide an electronic camera capable of obtaining good image data with a small release time lag.

[0012]

[Means for Solving the Problems]

(Claim 1) FIG. 1 is a schematic block diagram for explaining the invention described in claim 1. According to the first aspect of the present invention, an imaging unit 1 that continuously captures an image of a subject, a temporary storage unit 2 that temporarily stores a plurality of pieces of image data that are continuously captured by the imaging unit 1, and an imaging unit 1 For image data to be imaged, a photographing evaluation unit 3 for evaluating the quality of a photographing state and a still image for selecting image data having the highest evaluation from the image data stored in the temporary storage unit 2. Image selecting means 4 and still image selecting means 4
Storage means 5 for storing the image data selected by the user
And characterized in that:

According to a second aspect of the present invention, there is provided the electronic camera according to the first aspect, wherein the temporary storage means is provided.
Is characterized by starting temporary storage of image data after a release operation of the electronic camera.

According to a third aspect of the present invention, there is provided the electronic camera according to the first aspect, wherein the temporary storage means comprises:
In the standby state of the release operation, new image data is sequentially taken in from the imaging means 1 and the temporarily stored image data is sequentially updated, and after the release operation of the electronic camera, the image data before and after the release operation is temporarily stored. It is characterized in that the data update is stopped at the point of time.

According to a fourth aspect of the present invention, in the electronic camera according to any one of the first to third aspects, the temporary storage means 2 and the image storage means 5 have the same storage. A feature is also used as a mechanism.

According to a fifth aspect of the present invention, in the electronic camera according to any one of the first to fourth aspects, the temporary storage means 2 continuously captures images by the imaging means 1. A plurality of pieces of image data to be differentially compressed and stored.

(Claim 6) FIG. 2 is a schematic block diagram for explaining the invention described in claim 6. According to a sixth aspect of the present invention, there is provided an imaging unit 1 for continuously imaging a subject.
A storage medium 10 capable of storing image data; a shooting evaluation means 3 for evaluating the quality of a shooting state of individual image data picked up by the imaging means 1; and a shooting evaluation means for image data in the storage medium 10 3 is compared with the evaluation of the new image data from the imaging unit 1 by the photographing evaluation unit 3. If the evaluation of the new image data is high by the comparison of the comparison unit 11, the storage medium 10 is provided with an image overwriting means 12 for overwriting and recording new image data.

(Seventh Aspect) According to a seventh aspect of the present invention, in the electronic camera according to any one of the first to sixth aspects, the photographing evaluation means 3 includes at least one of a quality evaluation of a photographing state. One feature is that it is a means for detecting the amount of shake of the imaging means 1.

(Eighth Aspect) According to an eighth aspect of the present invention, in the electronic camera according to any one of the first to seventh aspects, the photographing evaluation means 3 includes at least one of a quality evaluation of a photographing state. One feature is that a spatial frequency component of the image data is determined.

According to a ninth aspect of the present invention, in the electronic camera according to the eighth aspect, the photographing evaluation means 3
Is characterized in that a high frequency component amount of a spatial frequency is determined based on a compression code amount of image data.

According to a tenth aspect of the present invention, in the electronic camera according to any one of the seventh to ninth aspects, the photographing evaluation means 3 includes at least one of a quality evaluation of a photographing state. One feature is that a release time lag, which is a time lag between a release operation of the electronic camera and a time point at which image data is captured, is determined.

<< Explanation of Operation for Each Claim >> In the electronic camera according to the first aspect, the imaging means 1 continuously captures a subject image. The image data of a plurality of images captured in this manner is temporarily stored in the temporary storage unit 2. On the other hand, the photographing evaluation means 3 evaluates the quality of the photographing state of each image data. The still image selection unit 4 selects image data captured during the period in which the evaluation of the shooting state is the highest from the image data stored in the temporary storage unit 2. The image storage unit 5 stores the selected image data.

According to the above operation, the electronic camera according to the first aspect can selectively obtain image data in a good shooting state. In particular, in the electronic camera according to the first aspect, during the photographing period, the temporary storage unit 2 temporarily stores the image data. Therefore, the image data selection processing only needs to be performed after the completion of the photographing, so that the processing operation during the photographing period can be reduced without difficulty.

In the electronic camera according to the second aspect, the temporary storage means 2 starts the temporary storage of the image data after the release operation of the electronic camera. Therefore, from the image data after the release operation, image data with a good shooting state is selected. In such an operation, the operation may be started after the release operation, and it is not necessary to constantly perform an imaging operation or the like. Therefore, power saving of the electronic camera can be achieved.

In the electronic camera according to the third aspect, while waiting for the release operation, the temporary storage means 2 sequentially takes in new image data from the imaging means 1. The temporary storage means 2
The new image data is used to update the image data, and the temporarily stored plurality of image data is kept up to date. When a release operation is performed on the electronic camera in this state, the temporary storage unit 2 suspends data updating when image data before and after the release operation is temporarily stored.

With such an operation, the sample section of the image data remaining in the temporary storage means 2 is a section that extends before and after the release operation. In particular, immediately before the release operation, there is almost no camera shake accompanying the release operation. Therefore, by adding such a period immediately before the release to the sample section, there is a very high possibility that image data with less camera shake can be selected. In addition, since the sample section of the image data extends before and after the release operation,
The worst value of the release time lag (corresponding to the time interval between the end point of the sample section and the time of the release operation) is almost halved compared to the case where the sample sections having the same time length are arranged only after the release operation.

In the electronic camera according to the fourth aspect, the temporary storage means 2 and the image storage means 5 share the same storage mechanism. Therefore, the configuration of the electronic camera is simplified.

In the electronic camera according to the fifth aspect, the temporary storage means 2 stores the image data continuously picked up by the image pickup means 1 by differential compression. The difference compression here is to obtain and compress difference data between images, for example, a simple difference compression between frames or a difference compression including a technique such as motion compensation prediction. Normally, image data continuously shot by the imaging means 1 has a very high correlation, although not as good as the frame correlation in a moving image.
Therefore, by the above-described differential compression, it is possible to further reduce the code amount of the image data.

Therefore, the number of image data samples that can be stored in the temporary storage means 2 can be increased. By increasing the number of samples of image data in this way, the possibility of selecting image data with a better imaging state increases. If the number of image data samples is not increased,
The storage capacity of the temporary storage means 2 can be reduced.

In the electronic camera according to the sixth aspect, the imaging means 1 continuously captures the subject image. At this time, the photographing evaluation means 3 evaluates the quality of the photographing state. Comparison means 1
1 compares the evaluation of the image data in the storage medium 10 with the new evaluation of the new image data from the imaging means 1. If the new evaluation is higher, the image overwriting means 12 overwrites the storage medium 10 with new image data. As a result, better image data in a shooting state remains in the storage medium 10. In particular, in the electronic camera according to the sixth aspect, it is not necessary to temporarily store all of a series of image data, and a large-capacity temporary storage unit is not required.

In the electronic camera according to the present invention, the amount of blur (such as the amount of vibration and the angular velocity) of the image pickup means 1 is detected as the quality of the photographing state. It can be evaluated that the smaller the amount of blurring of the imaging means 1 is, the smaller the camera shake is and the better the shooting state is. As described above, by performing the quality evaluation of the shooting state using the blur amount of the imaging unit 1 as a scale, it is possible to obtain image data with less camera shake.

In the electronic camera according to the eighth aspect, the spatial frequency component of the image data is used as a scale for evaluating the quality of the shooting state. Normally, in image data that is continuously imaged, the pattern itself is not significantly changed, and the distribution of the spatial frequency is assumed to be substantially unchanged. However, if a camera shake, a subject shake, a focus shift, or the like occurs in these image data, the image data is smoothed, and a high-frequency spatial frequency component is lost.

Therefore, in these image data,
The higher the spatial frequency component in the high frequency range, the less the camera shake, subject blur and out-of-focus, and it can be evaluated that the shooting state is better. in this way,
By performing the quality evaluation of the shooting state using the spatial frequency component of the image data as a scale, it becomes possible to accurately select image data in which camera shake, subject shake, and out-of-focus are totally small.

In the electronic camera according to the ninth aspect, the spatial frequency component of the image data is determined from the compression code amount. In general, it can be determined that the larger the compression code amount, the more spatial frequency components in the high frequency band. Therefore, it can be evaluated that, among image data that are continuously imaged, the larger the amount of compression code, the less the camera shake, subject shake and out-of-focus, and the better the shooting state. Further, since such a value of the compression code amount is obtained from the result of the conventional image compression processing, it is not necessary to add any special processing.

In the electronic camera according to the tenth aspect, a release time lag is detected as at least one of the quality evaluations of the photographing state. The smaller the release time lag, the closer to the shutter timing intended by the photographer, and the better the photographing state can be evaluated. As described above, by setting the release time lag as one item of quality evaluation, it is possible to select image data with a smaller release time lag.

In particular, a case in which image data with a small release time lag is selected in a state in which a captured image is temporarily stored before a release operation as in the third aspect of the present invention will be described. In this case, there is naturally a possibility that the exposure operation happens to occur at the moment of the release operation.
Therefore, it is possible to automatically select and obtain an image with a completely zero release time lag, which could not be obtained by single shooting with an electronic camera.

In the above description of claims 7 to 10, for the sake of explanation, the pass / fail evaluation is performed using only one evaluation item, but the present invention is not limited to this. The pass / fail evaluation may be performed by assigning priorities to the plurality of evaluation items, or may be performed by performing a comprehensive evaluation by weighting the evaluation items. At this time,
Of course, evaluation items other than claims 7 to 10 may be included.

The electronic camera according to the first to tenth aspects is not limited to a single electronic camera. 2. Description of the Related Art In recent years, electronic cameras tend to be configured as a system of a plurality of devices, for example, separated into an imaging unit and an information device (such as a computer or an electronic organizer). In such a system configuration, the operation of the present invention can be appropriately shared among a plurality of devices.

For example, (1) The image pickup unit temporarily stores image data obtained by continuous shooting. (2) The information device can share operations such as selecting and saving an image from the series of image data in accordance with the evaluation of the shooting state. The operation of the information device in such a case is as follows.
"A step of acquiring the result of the pass / fail evaluation from the imaging unit or performing a pass / fail evaluation of the photographing state from the spatial frequency components of the image data" and a step of selectively storing the image data according to the result of the pass / fail evaluation "Can be realized using a program (a machine-readable recording medium on which is recorded) for causing an information device to execute the above.

[0040]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 3 is a block diagram showing a first embodiment. In the first embodiment,
This is an embodiment corresponding to the invention described in claims 1, 2, 4, 5, and 7. In FIG. 3, a photographing lens 22 is attached to the front of the electronic camera 21. The light receiving surface of the image sensor 23 is arranged on the image space side of the taking lens 22.

The image output of the image pickup device 23 is directly stored in an image memory 25 via an image processing unit 24 which performs color signal processing, A / D conversion, γ correction, image compression and the like.
In addition, the image memory 25 includes a microprocessor 26
The data is also read and written via the data bus. In the housing of the electronic camera 21, there are provided shake amount detection sensors 29a and 29b, each of which comprises an angular velocity sensor such as a piezoelectric gyro.
Is arranged. The shake amount detection sensor 29a detects the shake amount in the vertical direction (pitching). The other shake amount detection sensor 29b detects the shake amount in the left-right direction (yawing). These shake amount detection sensors 29a, 29
The output terminal of b is connected to the A / D input terminal of the microprocessor 26, respectively.

Further, a release button 30 is arranged on the upper surface of the housing of the electronic camera 21, and a switch output of the release button 30 is connected to the microprocessor 26. Further, a control signal of the electronic shutter from the microprocessor 26 is given to the CCD drive circuit 31. The CCD drive circuit 31 generates a drive pulse according to the control signal and supplies the drive pulse to the image sensor 23. Other, microprocessor 26
, A timer 32 and an infrared transfer interface 33 are connected.

As for the correspondence between the first, second, fourth, fifth and seventh embodiments and the first embodiment, the image pickup means 1 corresponds to the image pickup device 23 and the CCD drive circuit 31, The storage unit 2 has a “function of differentially compressing and temporarily storing image data” of the image memory 25 and the image processing unit 24.
And the photographing evaluation means 3 includes a blur amount detection sensor 29a,
29b, the still image selection means 4 corresponds to the "function of selecting image data based on the amount of blur" of the microprocessor 26, and the image storage means 5 corresponds to the "selected image data" of the image memory 25 and the microprocessor 26. Function to save the file. "

Next, the operation of the first embodiment will be described. FIG. 4 is a flowchart illustrating the operation of the first embodiment. First, when the main power of the electronic camera 21 is turned on, the microprocessor 26 waits until the release button 30 is pressed (NO in S1 in FIG. 4). Here, when the release button 30 is pressed (YES side of S1 in FIG. 4), the microprocessor 26 activates the CCD drive circuit 31, and
Unnecessary charges in the image sensor 23 are once discharged. After discharging such unnecessary charges, signal charges are newly accumulated in the image sensor 23 in accordance with the brightness of the subject image projected on the light receiving surface (S2 in FIG. 4).

During such a signal charge accumulation period, the microprocessor 26 acquires the vertical blur amount W1 from the blur amount detection sensor 29a. The shake amount W2 in the left-right direction is obtained from the other shake amount detection sensor 29b. The microprocessor 26 calculates the sum of the square values or the sum of the absolute values of the shake amounts W1 and W2, and sets the sum as the shake amount W of the electronic camera 21 (S3 in FIG. 4).

After a predetermined storage time has elapsed, the microprocessor 26 reads out image data from the image pickup device 23 via the CCD drive circuit 31 (FIG. 4S).
4). The image processing unit 24 performs an A /
After performing D conversion, γ correction, image compression, and the like, the image is recorded in a temporary storage area in the image memory 25 as it is. It should be noted that the image compression here employs differential compression similar to MPEG or the like. At this time, the microprocessor 26 records the blur amount W in association with the image data (FIG. 4S
5).

The above-described series of operations S2 to S5 are repeatedly executed until the time limit of 0.3 seconds elapses from the release operation (YES in S6 in FIG. 4). By the operation up to this point, the image data stored in the image memory 25 is 0.3 mm after the release operation.
The image data of a plurality of frames imaged in a second is recorded together with the blur amount W during the imaging period.

The microprocessor 26 searches for the smallest value from among these blur amounts W, and finds the image data A captured during the period in which the smallest blur amount W was detected (S7 in FIG. 4). FIG. 5 is a diagram showing a state of a general change in the amount of blur W with time. This figure 5
As you can see, at least once every 0.3 seconds,
It can be expected that the blur amount W is minimized. Therefore,
It is expected that the image data A selected as described above has sufficiently small camera shake and is good image data.

The microprocessor 26 records the image data A in a storage area in the image memory 25 (FIG. 4).
S8). Note that, without actually moving the image data A in the image memory 25, the saving process of the image data A may be completed by changing the management area or the file attribute of the image memory 25. If the image data A has been differentially compressed, the image is expanded and a new JPE
What is necessary is just to compress and store it by G.

According to the operation described above, in the first embodiment, the blur amount W
Selects the smallest image data. Therefore, image data with little camera shake can be obtained without using any camera shake correction mechanism as in the related art. Further, since it is not necessary to dispose an optical system for camera shake correction in the taking lens 22, the size and weight of the taking lens 22 can be easily reduced.

In addition, it is not necessary to secure a space in the photographing lens 22 for disposing the optical system for camera shake correction, and the degree of freedom in designing the photographing lens 22 is increased.
Therefore, the aberration performance of the photographing lens 22 can be improved without difficulty. Furthermore, since internal reflection by the optical system for camera shake correction is eliminated, flare and the like at the time of backlight shooting are also reduced.

In addition, since a drive mechanism for correcting camera shake is not required, it is possible to save power and extend the battery life. Further, the problem that noise and vibration are generated from the drive mechanism for camera shake correction is also eliminated.
Further, since the image memory 25 is also used for both temporary storage and storage of image data, there is no need to separately provide an image memory, and the configuration of the electronic camera 21 can be simplified.

In the above-described embodiment, the storage area of the image memory 25 is fixedly allocated to the temporary storage area and the storage area. However, the present invention is not limited to this. For example, a temporary storage area in the image memory 25 may be dynamically allocated. In such a configuration, the temporary storage area is gradually divided into the storage areas so that the image memory 2
5 can be stored in the entire storage area. Next, another embodiment will be described.

(Second Embodiment) FIG. 6 is a block diagram showing a second embodiment. In the second embodiment,
This is an embodiment corresponding to the invention described in claims 1, 3, 7, and 10. In FIG. 6, on the front of the electronic camera 41,
The taking lens 42 is attached. This photographing lens 42
The light receiving surface of the image sensor 43 is arranged on the image space side of the image sensor.

An image output from the image sensor 43 is connected to a data input of an image memory 45 via an image processing section 44 for performing color signal processing, A / D conversion, and γ correction. on the other hand,
The data output from the image memory 45 is
6 data inputs. A memory card 48 is detachably connected to a data output terminal of the microprocessor 46 via an image recording unit 47.

On the other hand, inside the housing of the electronic camera 41, shake amount detection sensors 49a and 49b composed of angular velocity sensors such as piezoelectric gyros are arranged. The outputs of these shake amount detection sensors 49a and 49b are
A / D input terminals are connected. Further, a release button 50 is arranged on the upper surface of the housing of the electronic camera 41,
The switch output of the release button 50 is connected to the microprocessor 46.

The control signal of the electronic shutter from the microprocessor 46 is given to the CCD drive circuit 51. The CCD drive circuit 51 generates a drive pulse according to the control signal and supplies the drive pulse to the image sensor 43. In addition, a timer 52 is connected to the microprocessor 46.
In the correspondence between the first, third, seventh and tenth aspects of the present invention and the second embodiment, the image pickup means 1 corresponds to the image pickup element 43 and the CCD drive circuit 51, and the temporary storage means 2 Corresponding to the "function of temporarily storing image data before and after the release operation" of the memory 45 and the image processing unit 44,
The photographing evaluation means 3 corresponds to the “function for measuring the release time lag” of the blur amount detection sensors 49a and 49b, the timer 52 and the microprocessor 46, and the still image selection means 4 corresponds to the “image data based on the evaluation value of the microprocessor 46”. And the image storage means 5 corresponds to the image recording unit 47 and the memory card 48.

Next, the operation of the second embodiment will be described. FIG. 7 is a flowchart illustrating the operation of the second embodiment. First, when the main power supply of the electronic camera 41 is turned on, the microprocessor 46 once discharges unnecessary charges in the image sensor 43 via the CCD drive circuit 51. After such unnecessary charges are discharged, the image pickup device 43 accumulates signal charges according to the brightness of the subject image projected on the light receiving surface (S11 in FIG. 7).

During the accumulation period of the signal charge, the microprocessor 46 obtains the vertical blur amount W1 from the blur amount detection sensor 49a. The left-right blur amount W2 is obtained from the other blur amount detection sensor 49b. The microprocessor 46 calculates the sum of the squared values or the sum of the absolute values of the shake amounts W1 and W2, and sets the sum as the shake amount W of the electronic camera 41 (S12 in FIG. 7).

Next, the microprocessor 46 acquires the current time from the timer 52 as the imaging time Te (S13 in FIG. 7). In this state, when a predetermined accumulation time has elapsed, the microprocessor 46 reads out image data from the image sensor 43 via the CCD drive circuit 51 (S14 in FIG. 7).

The image processing section 44 subjects the image data to A / D conversion, γ correction, etc.
(S15 in FIG. 7). At this time, the microprocessor 46 stores the blur amount W and the imaging time Te in association with the image data (S17 in FIG. 7). At this time, if the image data in the image memory 45 has already reached seven frames (S16 in FIG. 7), the image memory 4
5 is overwritten with the latest data in place of the oldest data (S18 in FIG. 7).

Here, the microprocessor 46 determines whether or not the release button 50 has been pressed (S1 in FIG. 7).
9). When the release button 50 is pressed (Y in S19 in FIG. 7)
(ES side), the microprocessor 46 acquires the current time from the timer 52 and stores it as the release operation time Tr (S20 in FIG. 7).

The above operations S11 to S20 are repeatedly executed until the image data after the release operation is recorded for four frames (NO in S21 in FIG. 7). On the other hand, when the image data after the release operation is recorded for four frames (FIG. 7S
(YES side of 21), after stopping the imaging operation, the microprocessor 46 executes the selection of image data in the following procedure. First, the microprocessor 46 has an image memory 45.
The evaluation value E is calculated for each of the image data using the equation (1) (S22 in FIG. 7).

Evaluation value E = α · | Te−Tr | + β · | W | (1) Here, the first term on the right side relates to the release time lag, and the second term relates to the shake amount W. It is. The coefficients α and β weight the two terms (for example, α = 1 and β = 1 are set). The microprocessor 46 searches for the smallest value among the individual evaluation values E, and finds the image data A associated with the smallest evaluation value E (S23 in FIG. 7).

The microprocessor 46 reads out the image data A from the image memory 45 and compresses the image. The microprocessor 46 stores the compressed image data A
Is stored in the memory card 48 via the image recording unit 47 (S24 in FIG. 7). For image compression processing,
Instead of performing this step, steps S17 and S1 shown in FIG.
8 may be completed.

Next, the microprocessor 46 initializes the image memory 45 and the control data, and then returns to step S
The operation returns to 11 (S25 in FIG. 7). According to the series of operations described above, in the second embodiment, the image data with the smallest evaluation value E is selected from the continuously captured image data. Therefore, based on the evaluation value E, it is possible to obtain image data with little camera shake and a small release time lag.

Further, since image data is selected from among image data before and after the release operation, more appropriate image data can be selected without being limited after the release operation. In the above-described second embodiment, the temporary storage of the image data is started from the time when the main power is turned on, but the present invention is not limited to this. For example, if the microprocessor 46 has the release button 5
The half press of 0 may be detected, and the temporary storage of the image data may be started from the half press. In such a configuration, it is not necessary to always store the image data temporarily, so that the power consumption of the electronic camera can be reduced. Next, another embodiment will be described.

(Third Embodiment) FIG. 8 is a block diagram showing a third embodiment. In the third embodiment,
This is an embodiment corresponding to the sixth and seventh aspects of the present invention.
In FIG. 8, a photographing lens 62 is attached to the front of an electronic camera 61. The light receiving surface of the image sensor 63 is arranged on the image space side of the taking lens 62.

The image output of the image sensor 63 is supplied to the microprocessor 65 via an image processing section 64 for performing color signal processing, A / D conversion, γ correction and the like. An image memory 66 is connected to a data bus of the microprocessor 65. Further, a data output terminal of the microprocessor 65 is connected to a memory card 68 via an image recording unit 67.
Are detachably connected.

Further, inside the housing of the electronic camera 61, shake amount detection sensors 69a and 69b including an angular velocity sensor such as a piezoelectric gyro are arranged. The outputs of these shake amount detection sensors 69a and 69b are
A / D input terminals are connected. Further, a release button 70 is arranged on the upper surface of the housing of the electronic camera 61,
The switch output of the release button 70 is connected to the microprocessor 65.

The control signal of the electronic shutter from the microprocessor 65 is given to the CCD drive circuit 71. The CCD drive circuit 71 generates a drive pulse according to the control signal and supplies the drive pulse to the image sensor 63. As for the correspondence between the invention described in claims 6 and 7 and the third embodiment, the image pickup means 1 corresponds to the image pickup device 63 and the CCD drive circuit 71, and the photographing evaluation means 3 corresponds to the shake amount detection sensor 6.
9a and 69b, and the storage medium 10 is an image memory 66
The comparison means 11 corresponds to the "function of comparing the blur amount between new and old" of the microprocessor 65, and the image overwriting means 12 corresponds to the "function of overwriting image data on the image memory 66" of the microprocessor 65. .

Next, the operation of the third embodiment will be described. FIG. 9 is a flowchart illustrating the operation of the third embodiment. First, when the main power supply of the electronic camera 61 is turned on, the microprocessor 65 determines the maximum allowable value of the blur amount based on the current shutter speed and the focal length (S31 in FIG. 9).

Next, the microprocessor 65 initializes the maximum allowable value thus determined to the minimum blur amount Wmin (S32 in FIG. 9). The microprocessor 65 returns to step S31 and periodically repeats the above operation until the release button 70 is pressed (NO in S33 in FIG. 9).
On the other hand, when the release button 70 is pressed (YE in FIG. 9S33).
(S side), the microprocessor 65 repeatedly executes steps S35 to S40 as follows during a period from the time of the release operation until 0.5 seconds elapse (S34 in FIG. 9).

First, the microprocessor 65 has a CCD
Unnecessary charges in the image sensor 63 are once discharged via the drive circuit 71. After such unnecessary charges are discharged, the image sensor 6
In 3, the signal charges are accumulated in accordance with the brightness of the subject image projected on the light receiving surface (S35 in FIG. 9). During the accumulation period of the signal charge, the microprocessor 65 acquires the vertical shake amount W1 from the shake amount detection sensor 69a. The left-right blur amount W2 is obtained from the other blur amount detection sensor 69b. The microprocessor 65 calculates the sum of the squared values or the sum of the absolute values of the shake amounts W1 and W2, and sets the sum as the shake amount W of the entire electronic camera 61 (S36 in FIG. 9).

Here, the microprocessor 65 compares the minimum shake amount Wmin with the shake amount W. As a result of such comparison, when the blur amount W is larger (S3 in FIG. 9).
7), the microprocessor 65 includes the image sensor 6
The operation returns to step S34 without reading the image data from step 3.

At the time of this determination, the microprocessor 65 may discharge unnecessary charges from the image sensor 63 so that charge accumulation of the next frame may be started as soon as possible. According to such an operation, useless accumulation time can be eliminated as much as possible, and the number of shots per unit time can be increased without difficulty. On the other hand, when the blur amount W is smaller (YES in S37 in FIG. 9), the microprocessor 65 reads out image data from the image sensor 63 after a predetermined accumulation time has elapsed (S38 in FIG. 9).

The microprocessor 65 includes the image processing unit 6
This image data is fetched through the
Is overwritten (step S39). Along with such overwrite recording, the microprocessor 65 sets the current blur amount W to the minimum blur amount Wmin (step S4).
0), and return the operation to step S34.

After repeatedly executing the above-described series of operations S34 to S40 until the time limit of 0.5 seconds elapses from the release operation, the microprocessor 65 shifts the operation to step S41. By the operation so far, the image memory 6
6 stores the image data with the smallest blur amount W among the image data captured for 0.5 seconds from the release operation.

In such a case (YES in S41 of FIG. 9)
(Side), the microprocessor 65 compresses the image data remaining in the image memory 66, and stores it in the memory card 68 via the image recording unit 67 (S43 in FIG. 9). In addition, instead of performing the image compression processing here,
Step S39 shown in FIG. 9 may be completed. After saving the image data in this way, the microprocessor 65 erases the image data in the image memory 66 in preparation for the next shooting operation (S44 in FIG. 9), and then returns to step S31.

If the blur amount W has never fallen below the maximum allowable blur amount, the image memory 66
No image data is recorded in the. As described above, when there is no image data in the image memory 66 (N in FIG.
(O side), the microprocessor 65 determines that the camera shake is too large, performs the process of “camera shake warning”, and then returns the operation to step S31 (S42 in FIG. 9).

According to the operation described above, in the third embodiment, image data with a smaller amount of blur is stored in the image memory 66.
Will be left. Therefore, image data with little camera shake can be obtained without using any conventional camera shake correction mechanism. Further, since the image data is successively overwritten and recorded in the image memory 66, it is sufficient that the image memory 66 has a capacity for storing at least one frame of image data.

In the third embodiment, image data having a smaller amount of blur is left in the image memory 66 based on the comparison of the amount of blur. However, the present invention is not limited to this. The image data to be left in the image memory 66 may be selected based on the evaluation value including the evaluation items of claims 7 to 10. In the third embodiment, no image data is recorded when the blur amount W does not fall below the “maximum allowable value of the blur amount”. However, the present invention is not limited to this. For example, the first image data or the like may be recorded for the time being, and thereafter, the image data may be updated each time the blurring amount W falls below. With such a configuration, image data with the smallest blur amount W can be finally recorded.

In the first to third embodiments, only one image data is stored based on the blur amount or the evaluation value. However, the present invention is not limited to this. For example, image data for a predetermined number of images from the top in the evaluation order may be stored based on the shake amount or the evaluation value. With such a configuration, the operator himself / herself can later select more preferable image data of the photo opportunity from the predetermined number of image data. Next, another embodiment will be described.

(Fourth Embodiment) FIG. 10 is a block diagram showing a fourth embodiment. The fourth embodiment is an embodiment corresponding to the first, second, and eighth aspects of the present invention. In FIG. 10, a zoom lens 102 is attached to the front of an electronic camera 101. On the image space side of the zoom lens 102, the light receiving surface of the image sensor 103 is arranged.

The image output from the image sensor 103 is performed by an image processing unit 10 which performs color signal processing, A / D conversion, γ correction, and the like.
4 and the image compression unit 10 via the image memory 105
6a. The output of the image compression unit 106a is
Connected to microprocessor 106. A memory card 108 is detachably connected to the microprocessor 106 via an image recording unit 107.

Further, a release button 110 and a photographing mode selection button 111 are arranged on the housing of the electronic camera 101, and switch outputs of these operation units are connected to the microprocessor 106. The microprocessor 10
The control signal of the electronic shutter from the CCD drive circuit 1
12 is given. The CCD drive circuit 112 generates a drive pulse according to the control signal and supplies the drive pulse to the image sensor 103.

In addition, the electronic camera 101 includes a photometric unit 113 for measuring the luminance of the subject, a distance measuring unit 114 for measuring the subject distance, an encoder 115 for detecting the focal length from the lens position, and a flash unit (so-called strobe) 116. And are connected to the microprocessor 106 respectively. As for the correspondence between the first, second and eighth aspects of the present invention and the fourth embodiment, the image pickup means 1 corresponds to the image pickup device 103, the CCD drive circuit 112 and the zoom lens 102, and the temporary storage means 2 Corresponds to the image memory 105, the photographing evaluation means 3 corresponds to “the function of converting image data into spatial frequency components” of the image compression unit 106 a, and the still image selecting means 4 corresponds to “the function based on the spatial frequency components” of the microprocessor 106. The image storage means 5 corresponds to the image recording unit 107 and the memory card 108.

Next, the operation of the fourth embodiment will be described. FIG. 11 is a flowchart illustrating the operation of the fourth embodiment. First, when the main power of the electronic camera 101 is turned on, the microprocessor 106 waits until the release button 110 is pressed (NO in FIG. 11 S1). Here, when the release button 110 is pressed (YE in FIG. 11 S1).
(S side), the microprocessor 106 determines the current shooting mode (S2 in FIG. 11). If the current shooting mode is not one of the following (1) to (3), the microprocessor 106 executes the normal shooting (shooting for capturing and recording one frame) (step S3 in FIG. 11). The operation returns to S1.

(1) Night view photographing mode: a mode in which flash light is turned off, the focus is adjusted to infinity, and long-time exposure is possible. (2) Macro mode: The focal point of the lens is set in a macro area. Close-up shooting mode (3) Sports mode: A mode in which the exposure time is set as short as possible to shoot a fast-moving subject. On the other hand, if the current shooting mode is any of these shooting modes, camera shake will occur. The possibility of subject blur and out-of-focus occurring is particularly high.
6 executes the countermeasure operation from step S4.

First, the microprocessor 106
It instructs the D drive circuit 112 to continuously shoot a plurality of images (here, three frames as an example). The CCD drive circuit 112
Image data for three frames is read out from the image sensor 103 one by one. These three frames of image data are stored in the image processing unit 104.
After color signal processing and gamma correction are performed via
It is temporarily stored in the image memory 105 (S4 in FIG. 11).

Next, the microprocessor 106 instructs the image compression unit 106a to perform DCT (discrete cosine transform). The image compressing unit 106a performs a DCT transform on the image data of three frames in the image memory 105 by capturing a predetermined area of the screen (for example, the center of the screen) (FIG. 11).
S5). The microprocessor 106 takes in the spatial frequency component after the DCT transform, and selects image data including the highest spatial frequency component among the three frames (FIG. 11S).
6).

Here, when the selected image data is one (NO in S7 in FIG. 11), the microprocessor 106
Shifts the operation to Step S11. On the other hand, when there are a plurality of selected image data (YES side of S7 in FIG. 11), the microprocessor 106 selects the selected image data whose spatial frequency component in the high frequency band has the largest amplitude (S8 in FIG. 11). .

If the number of selected image data is one (NO in S9 of FIG. 11), the microprocessor 106
Shifts the operation to Step S11. On the other hand, when there is still a plurality of selected image data (YES in FIG. 11S9)
Side), the microprocessor 106 selects the first image data from the selected image data (S10 in FIG. 11).

After the image data has been reduced to one in this way, the microprocessor 106
Then, the image data is subjected to image compression via the CPU and recorded on the memory card 108 (S11 in FIG. 11). According to the operation described above, in the fourth embodiment, image data having the richest spatial frequency component in the high frequency band is selected and recorded from the image data captured continuously. Therefore, it is possible to appropriately select image data in which camera shake, subject shake, out-of-focus, and the like are relatively small.

In the fourth embodiment, the spatial frequency component of the image data is accurately determined by using the orthogonal transform such as the DCT, but the present invention is not limited to this. For example, a known spatial frequency filter (for example,
Of course, the spatial frequency component may be simply determined using a high-pass filter (for example, a difference between adjacent pixels) or contrast detection. Next, another embodiment will be described.

(Fifth Embodiment) The fifth embodiment is an embodiment corresponding to the first, second, eighth and ninth aspects of the present invention. Note that the configuration of the fifth embodiment is almost the same as that of the fourth embodiment (FIG. 10), and a description of the configuration will be omitted. FIG. 12 is a flowchart illustrating the operation of the fifth embodiment.

The operation of the fifth embodiment will be described below with reference to FIG. First, when the main power supply of the electronic camera 101 is turned on, the microprocessor 106 sets the release button 1
It waits until 10 is pressed (NO side in FIG. 12 S1).
Here, when the release button 110 is pressed (YES side of S1 in FIG. 12), the microprocessor 106
Then, the brightness of the subject is measured via the camera 3 and an exposure time for obtaining an appropriate exposure is determined (S2 in FIG. 12).

Next, the microprocessor 106 detects the focal length of the zoom lens 102 via the encoder 115. Further, the microprocessor 106 detects the subject distance via the distance measuring unit 114 (S3 in FIG. 12).
Here, the microprocessor 106 determines whether or not the current mode setting is the flash photography mode (FIG. 12S).
4). In the case of the flash photography mode, the possibility of camera shake or subject shake is low.
After performing the normal shooting (shooting for capturing and recording one frame) (S5 in FIG. 12), the operation returns to step S1. on the other hand,
If the current mode setting is other than the flash photography mode, the microprocessor 106 determines the following conditions (1),
Perform (2).

(1) The exposure time is longer than the predetermined time τ. (2) The image magnification (≒ focal length / subject distance) is equal to the predetermined magnification γ.
If none of these conditions is satisfied (N in FIG. 12S6)
On the O side), the microprocessor 106 determines that there is little risk of camera shake or subject shake, performs normal shooting (S5 in FIG. 12), and then returns to step S1.

On the other hand, when any one of these conditions is satisfied (YES side of S6 in FIG. 12), the microprocessor 106 executes a countermeasure operation from step S7. First, the microprocessor 106 instructs the CCD driving circuit 112 to continuously shoot a plurality of images (here, three frames as an example). The CCD drive circuit 112 sequentially reads out three frames of image data from the image sensor 103. These three frames of image data are temporarily stored in the image memory 105 after being subjected to color signal processing, gamma correction and the like via the image processing unit 104 (S7 in FIG. 12).

Next, the microprocessor 106 instructs the image compression section 106a to compress the image. Image compression unit 10
In step 6a, the image data of the first frame is trial-compressed, and an appropriate scale factor (a known parameter value defining a condition for quantization in image compression) is determined in order to approach a desired compression code amount. The image compressing section 106a sequentially compresses the image data of three frames by uniformly using the value of the scale factor (S8 in FIG. 12).

Here, the microprocessor 106 has 3
For the image data of the frame, the code amount after compression (compressed code amount) is compared in size, and the image data having the largest compressed code amount is selected (S9 in FIG. 12). If the number of selected image data is one (NO in S10 in FIG. 12), the microprocessor 106 shifts the operation to Step S12.

On the other hand, when there are a plurality of selected image data (YES side of S10 in FIG. 12), the microprocessor 10
No. 6 selects the image data shot first among the selected image data (S11 in FIG. 12). After the image data is reduced to one, the microprocessor 10
No. 6 records the selected image data (compressed) on the memory card 108 (S12 in FIG. 12).

According to the operation described above, in the fifth embodiment, the image data having the largest compression code amount is selected from the continuously captured image data and the memory card 108 is selected.
To record. Therefore, it is possible to record, on the memory card 108, image data that has the richest high-frequency spatial frequency components and has a small amount of camera shake, subject shake, and out-of-focus.

In the fifth embodiment, when the image magnification is larger than the predetermined magnification γ, a mode for selecting a good image (an image in a good shooting state) is set. However, the present invention is not limited to this. is not. For example, when the focal length is longer than a predetermined value, a mode for selecting a good image may be set. Further, in the above-described fifth embodiment, image data of three frames is image-compressed over the entire screen, but the present invention is not limited to this. For example,
Only a predetermined area in the screen (for example, the center of the screen) may be extracted from the three frames of image data and image compression may be performed to determine the compression code amount for evaluation. In such an operation, comparison of spatial frequency components is performed only within a predetermined area. Therefore, it is possible to accurately select clear image data in a predetermined area even under a photographing condition in which the background is blurred, such as telephoto photographing and panning photographing. Further, when obtaining the compression code amount for evaluation, it is sufficient to compress the image only in a predetermined area, so that the processing time for obtaining the compression code amount for evaluation can be significantly reduced.

Further, in the fifth embodiment described above, 3
After all the continuous shootings for the frames are completed, the image compression for the three frames is started, but the present invention is not limited to this. For example, by simultaneously performing the image compression of the previous frame and the imaging operation of the next frame in parallel, the number of images captured per unit time may be increased. In particular, in such an operation, the comparison of the old and new compression code amounts can be performed simultaneously and in parallel with the imaging operation. Therefore, a mode in which better image data is overwritten and recorded as in the invention according to claim 6 Can be configured.

In the above-described first to fifth embodiments,
Although the case where one good image is stored has been described,
The present invention can be applied to a case where a plurality of good images are stored. For example, in the case of exposure bracketing (a mode in which several images are taken while changing the exposure condition), the operation of storing one good image under the same exposure condition may be repeated while changing the exposure condition.

In the first to fifth embodiments described above,
Although the display function of the electronic camera is not specifically described,
Various displays can be made in connection with the present invention.
For example, on the monitor screen or viewfinder of an electronic camera,
"Mode for selecting an image according to the evaluation of shooting condition"
, Or the current number of samples of image data or the remaining number of samples may be displayed using pictures, characters, or the like. With such a configuration, it is possible to notify the photographer of the operation state of the electronic camera in detail.

In addition, the result of the quality evaluation of the photographing state (eg, the amount of blur) may be displayed using pictures, characters, or the like. At this time, the temporarily stored image data may be displayed (for example, a thumbnail display) together with the display of the pass / fail evaluation. With such a configuration, the photographer can appropriately select desired image data in consideration of the display of the image and the display of the quality evaluation. In addition, a warning display (including an alarm or the like) may be performed when the quality evaluation of the shooting state becomes equal to or less than the threshold value, or a display (including an alarm or the like) indicating that the quality evaluation has become maximum may be performed. In such a configuration, the quality of the shooting state is fed back to the photographer, so that a better shooting state can be achieved.

In the above-described embodiment, the electronic camera having a single structure has been described, but the present invention is not limited to this. For example, the present invention can be applied to an electronic camera separately configured with an imaging unit and an information device (such as a computer). As a specific example in that case, (1) image data obtained by continuous imaging on the imaging unit side is temporarily stored. (2) By executing the program on the computer side, the operation sharing such as selecting and saving an image from the series of image data in accordance with the evaluation of the imaging state is considered.

Further, when the application range of the present invention is extended to a computer, an "image selection program for selecting and saving an image from a series of image data according to the evaluation of the photographing state" on the computer side. It may be performed independently. Of course, such a configuration has disadvantages such as insufficient collection of shooting state information from the camera side.
Since the quality evaluation of the spatial frequency component can be performed by a single computer, it is possible to obtain the same operational effects as those of the configuration of the present invention.

[0113]

【The invention's effect】

(Claim 1) According to the first aspect of the present invention, image data picked up during a period in which the shooting state is the best is selected from image data shot continuously. Therefore, it is possible to obtain good image data in a shooting state without using any conventional camera shake correction mechanism or the like.

Therefore, the conventional optical system for camera shake correction can be omitted, and the size and weight of the taking lens can be reduced. In addition, the space for disposing the optical system for camera shake correction can be omitted from the taking lens. As a result, the degree of freedom in optical design is increased, and the aberration performance and the like of the photographing lens can be optimized without difficulty.

Also, the slight internal reflection that occurs in the conventional optical system for camera shake correction is eliminated. Therefore,
Flare during backlight shooting can be reduced, and the image quality can be further improved. In addition, it is possible to omit the conventional drive mechanism for camera shake correction and the like, and power saving of the electronic camera can be achieved. Further, the disadvantage that noise and vibration are generated from the drive mechanism for camera shake correction is also eliminated. In addition, since the image data selection process is performed after the photographing is completed, there is an advantage that the processing load during the photographing period does not increase so much, and the number of images photographed per unit time does not decrease so much.

(Claim 2) In the invention according to claim 2,
The temporary storage means starts the temporary storage of the image data after the release operation of the electronic camera. Therefore, it is possible to suspend the imaging operation before the release operation. Therefore, power saving of the electronic camera can be achieved.

(Claim 3) In the invention according to claim 3,
Temporary storage means stores image data before and after the release operation. Therefore, not only the image data after the release operation but also the image data with a better shooting state can be appropriately selected from the period before and after the release operation.

Immediately before the release operation, camera shake has not yet occurred with the release operation. Therefore, when camera shake is evaluated as a shooting state,
By adding the period immediately before the release operation to the sample section of the image data, it is possible to select image data with very little camera shake with a high probability. In addition, since the sample section of the image data is arranged before and after the release operation, the worst value of the release time lag (the sample section of the image data sample section) is compared with the case where the sample section of the same time length is arranged after the release operation. (Corresponding to an end point) can be almost halved.

(Claim 4) In the invention according to claim 4,
The temporary storage means and the image storage means share the same storage mechanism. Therefore, there is no need to provide a dedicated storage mechanism for the temporary storage means, and the configuration of the electronic camera can be simplified.

(Claim 5) In the invention according to claim 5,
After differentially compressing image data that is continuously captured, the image data is temporarily stored. Therefore, the code amount of the image data can be reduced, and the storage capacity of the temporary storage unit can be reduced as much as possible. If the storage capacity of the temporary storage unit is not changed, it is possible to increase the number of image data samples that can be temporarily stored. In this case, since a selection is made from a larger number of image data, the possibility of obtaining image data with a better shooting state is further increased.

(Claim 6) In the invention according to claim 6,
Image data having a better shooting state is selectively left from the image data that is successively captured. Therefore, it is possible to obtain good image data in a shooting state without using any conventional camera shake correction mechanism or the like. Further, since the image data is overwritten and recorded on the storage medium, it is sufficient that the storage medium has a capacity for storing at least one image data. Therefore, there is no need to provide a large-capacity storage medium for temporary storage, and the configuration of the electronic camera can be simplified.

(Claim 7) In the invention according to claim 7,
As the quality evaluation of the shooting state, the blur amount of the imaging means is detected. As a result, it is possible to appropriately select and save image data with less camera shake.

(Claim 8) In the invention according to claim 8,
The spatial frequency component of the image data is used as a criterion for evaluating the quality of the shooting state. As a result, it is possible to appropriately select and save image data in which camera shake, subject shake, defocus, and the like are totally small. In particular, since the quality evaluation of such a spatial frequency component can be executed by calculation, a piezoelectric gyro for detecting camera shake becomes unnecessary. Therefore, even if the invention described in claim 8 is adopted, it is not particularly necessary to add a sensor component or the like to the conventional electronic camera.
The effects of the present invention can be obtained at low cost and with a simple configuration.

In particular, it is extremely difficult to completely prevent a subject from moving out of focus, such as a flower swaying in the wind, which exhibits unpredictable movement only by normal AF (auto focus) photography. However, according to the invention described in claim 8, even under such a bad condition, it is possible to reliably select and store image data with a small focus shift based on the spatial frequency component.

(Claim 9) In the invention according to claim 9,
The amount of the high frequency component of the spatial frequency is determined from the amount of compression code.
Since such a value of the compression code amount can be obtained from the result of the conventional image compression processing, it is not necessary to add a special operation processing, and it is possible to reduce the operation processing amount and the processing time. Becomes

(Claim 10) In the invention according to claim 10, a release time lag is used as one of the quality evaluations of the photographing state. As a result, it is possible to select and store good image data having a relatively small release time lag. In particular, in a case where image data with a small release time lag is selected in a state where the captured image is temporarily stored before the release operation, it is possible to obtain image data with a release time lag extremely close to zero.

[Brief description of the drawings]

FIG. 1 is a principle block diagram for explaining the invention described in claim 1;

FIG. 2 is a principle block diagram for explaining the invention described in claim 6;

FIG. 3 is a block diagram showing the first embodiment.

FIG. 4 is a flowchart illustrating the operation of the first embodiment.

FIG. 5 is a diagram showing a change over time of a blur amount.

FIG. 6 is a block diagram showing a second embodiment.

FIG. 7 is a flowchart illustrating the operation of the second embodiment.

FIG. 8 is a block diagram showing a third embodiment.

FIG. 9 is a flowchart illustrating the operation of the third embodiment.

FIG. 10 is a block diagram showing a fourth embodiment.

FIG. 11 is a flowchart illustrating the operation of the fourth embodiment.

FIG. 12 is a flowchart illustrating the operation of the fifth embodiment.

FIG. 13 is a diagram showing a conventional example of a camera with a camera shake correction mechanism.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 imaging means 2 temporary storage means 3 shooting evaluation means 4 still image selection means 5 image storage means 10 storage medium 11 comparison means 12 image overwriting means 21, 41, 61, 91, 101 electronic camera 22, 42, 62, 92 shooting lens 23, 43, 63, 103 Image sensors 24, 44, 64, 104 Image processing units 25, 45, 66, 105 Image memories 26, 46, 65, 106 Microprocessors 29a, 49a, 69a Blur amount detection sensors 29b, 49b, 69b Blur amount detection sensor 30, 50, 70, 110 Release button 31, 51, 71, 112 CCD drive circuit 32, 52 Timer 33 Infrared transfer interface 47, 67 Image recording unit 48, 68 Memory card 93 Blur correction optical system 94 Coreless Motor 95 Coreless motor 96 Shake amount detection Capacitors 97 shake amount detection sensor 102 zoom lens 106a image compression unit 111 image capturing mode selection button 113 photometry unit 114 distance measuring unit 115 encoder 116 flash unit

Claims (10)

[Claims] An imaging unit configured to continuously capture an image of a subject; a temporary storage unit configured to temporarily store a plurality of image data continuously captured by the imaging unit; and an image data captured by the imaging unit. A photographing evaluation unit that evaluates the quality of a photographing state; a still image selecting unit that selects image data having the highest evaluation of the photographing evaluation unit from image data stored in the temporary storage unit; An electronic camera, comprising: image storage means for storing image data selected by the image selection means. 2. The electronic camera according to claim 1, wherein said temporary storage means starts temporary storage of image data after a release operation of said electronic camera. 3. The electronic camera according to claim 1, wherein the temporary storage unit sequentially acquires new image data from the imaging unit and sequentially updates the temporarily stored image data in a standby state of a release operation. An electronic camera characterized in that after the release operation of the electronic camera, the data update is paused when image data before and after the release operation is temporarily stored. 4. The electronic camera according to claim 1, wherein said temporary storage means and said image storage means share the same storage mechanism. 5. The electronic camera according to claim 1, wherein the temporary storage unit performs differential compression on a plurality of image data continuously imaged by the imaging unit. An electronic camera, characterized in that the electronic camera is means for storing. 6. An image capturing means for continuously capturing an image of a subject, a storage medium capable of storing image data, and a photographing evaluation means for evaluating the quality of a photographing state of each image data captured by the image capturing means. A comparison unit that compares the evaluation of the imaging evaluation unit with respect to image data in the storage medium and the evaluation of the imaging evaluation unit with respect to new image data from the imaging unit; An electronic camera, comprising: image overwriting means for overwriting and recording new image data in the storage medium when the evaluation of the image data is high. 7. The electronic camera according to claim 1, wherein the photographing evaluation unit detects a blur amount of the image pickup unit as at least one of the evaluations of the photographing state. An electronic camera, characterized in that the electronic camera is a means for performing. 8. The electronic camera according to claim 1, wherein the photographing evaluation unit determines a spatial frequency component of the image data as at least one of quality evaluations of the photographing state. An electronic camera characterized by making a determination. 9. The electronic camera according to claim 8, wherein the photographing evaluation unit determines a high frequency component amount of a spatial frequency based on a compression code amount of the image data. 10. The method according to claim 1, wherein:
In the electronic camera described in the section, the photographing evaluation means, as at least one of the quality evaluation of the photographing state, determines a release time lag that is a time lag between a release operation of the electronic camera and a time point at which image data is captured. Electronic camera featuring.