JP2006140892A - Electronic still camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic still camera enabling a user to acquire a desired image without requiring a large storage capacity. <P>SOLUTION: Image signals acquired before and after a shutter release via a CCD 2 are stored in a buffer memory 5 by executing a slow preview mode. Consequently, an image photographed by releasing the shutter at the best moment can be captured regardless of a reaction time of a photographer. Photographed images in thirty nine frames can be displayed by switching at a relatively longer time interval of 0.5 seconds. Accordingly, the user can select the image photographed by releasing the shutter at the best moment without being nervous about a reaction time, and can store the image signal corresponding to the image in a memory card 10. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electronic still camera that stores an image signal captured via an imaging unit.

Recent electronic still cameras are provided with a continuous shooting function for continuously capturing image signals. If the continuous shooting function is executed, while the release switch is turned on, image signals corresponding to a plurality of images are continuously captured and stored in the buffer memory. Depending on the release switch being turned off, the buffer memory The image signals can be stored in a batch from the recording medium to the storage medium (see Patent Document 1).
JP 2001-230959 A

  However, according to the continuous shooting function, by displaying an image based on the image signal stored in the storage medium, an image obtained when the subject closes his eyes, for example, is eliminated by the user's operation. Although a preferable image can be selected, there are a number of unnecessary images, and there is a problem that the capacity of the storage medium cannot be effectively used. Although there is an idea that unnecessary images may be deleted each time, it takes time and effort to delete each image.

  Also, since there is a delay in reaction time from the time when the photographer determines that the composition is preferable to the time when the release switch is operated and the actual shooting is performed, even if the continuous shooting function is used, the photographer There is also a problem that it is not always possible to acquire an image that the user really wanted to capture. In contrast, a normal electronic still camera has a so-called preview mode that displays a subject image in real time based on an image signal captured from an image sensor regardless of whether the release switch is on or off. There is also an idea that all the image signals corresponding to the previewed image may be stored in the memory. However, storing all of the image signals corresponding to the previewed image requires an enormous amount of buffer memory, which is not practical.

  The present invention has been made in view of these problems, and an object thereof is to provide an electronic still camera that can acquire a desired image without requiring a large storage capacity.

The electronic still camera of the first invention is
An imaging unit that performs imaging to generate an image signal;
A first storage unit that stores in advance an image signal output from the imaging unit irrespective of a release operation, corresponding to a predetermined number of images;
A second storage unit for storing image signals;
A display unit that displays a through image based on the image signal output from the imaging unit,
In response to a first release operation, a predetermined amount of image signal stored in advance in the first storage unit is sequentially read out, and the image signal is displayed on the display unit at a different time interval from when the through image is displayed. And a slow preview mode in which an image signal corresponding to an image displayed at the time when the second release operation is performed is stored in the second storage unit.

The electronic still camera of the second invention is
An imaging unit that performs imaging to generate an image signal;
A first storage unit that stores in advance an image signal output from the imaging unit irrespective of a release operation, corresponding to a predetermined number of sheets;
A second storage unit for storing image signals;
A display unit for displaying an image based on the image signal,
When a release operation is performed, a specific image signal output from the imaging unit at a time point that is a predetermined reaction time after the release operation is read from the first storage unit, and the read image It is possible to set a back step view mode in which the display unit displays an image based on a signal.

The electronic still camera of the third invention is
An imaging unit that performs imaging to generate an image signal;
A first storage unit that stores image signals output from the imaging unit irrespective of a release operation, corresponding to a predetermined number of images;
A second storage unit for storing image signals;
A display unit for displaying an image based on the image signal,
When shooting a subject having a moving speed equal to or higher than a predetermined moving speed, the imaging timing is advanced or stored in the first storage unit compared to shooting a subject having a moving speed less than the predetermined moving speed. It is possible to set a quick play mode that increases an amount converted to the number of recorded image signals.

The electronic still camera of the fourth invention is
An imaging unit that performs imaging to generate an image signal;
A first storage unit that stores image signals output from the imaging unit irrespective of a release operation, corresponding to a predetermined number of images;
A second storage unit for storing image signals;
A display unit for displaying an image based on the image signal,
When shooting a subject having a moving speed less than a predetermined moving speed, the imaging timing is delayed or compared with the case of shooting a subject having a moving speed equal to or higher than the predetermined moving speed, or in the first storage unit. It is possible to set a slow play mode in which the amount converted into the number of recorded image signals to be stored can be set.

  According to the electronic still camera of the first aspect of the present invention, in response to the first release operation, a predetermined amount of image signal stored in advance in the first storage unit is sequentially read out, and the image signal is displayed on the display. A slope for sequentially displaying an image signal corresponding to the image displayed at the time when the second release operation is performed in the second storage unit. Since the review mode can be set, if the slow preview mode is set, for example, the display unit can be controlled based on the image signal obtained from the imaging unit before and after the first release operation. Since an image is displayed at a predetermined interval, a photographer who has seen the image performs a second release operation when the most preferable image is displayed, so that an image signal corresponding to the image is displayed on the second image. For storage in 憶部, despite can acquire a desired image of the photographer, it is possible to suppress the storage capacity of the second storage unit. That is, in the normal slide view mode, for example, the image display is switched at 15 frames / second, so that even when the second release operation is performed at the time when the desired image is displayed, the predetermined display is performed as in the normal shooting. However, in the present invention, a desired image can be stored regardless of the reaction time by slowly switching the image display. Accordingly, the image display switching interval is, for example, 0.5 seconds or longer, more preferably 1 second or longer, which is longer than a general reaction time. Here, the “through image” refers to an image displayed on the display unit while being updated in real time based on image signals sequentially output from the imaging unit.

Furthermore, in the slow preview mode, a time interval at which the image signals stored in advance in the first storage unit are sequentially displayed on the display unit is longer than a time interval at which the through image is sequentially displayed. preferable.

  Furthermore, it is preferable that the first storage unit further stores the image signal output from the imaging unit by an amount corresponding to a predetermined number of sheets from the time when the first release operation is performed. This is because it may appear after the release, for example, when an image with the best photo opportunity is predicted and captured.

  Further, when the slow preview mode is set, if the subject movement is predicted and the focusing operation is predicted, the processing time is shortened and the imaging interval is shortened. More chances to get.

  Further, when the slow preview mode is set, if the exposure condition and the white balance adjustment are fixed, the processing time is shortened and the imaging interval is shortened, so that the photographer is more likely to obtain a preferable image. .

  Further, when the slow preview mode is not set, the through image is displayed on the display unit according to the first release operation, and output from the imaging unit according to the second release operation. When the obtained image signal is stored in the second storage unit, normal shooting can be performed according to the mode selection of the photographer.

  Further, after storing the predetermined number of image signals before the first release operation, the first storage unit erases the image signal stored most recently and stores a new image signal. So-called overwriting is preferable because the storage capacity of the first storage unit is low.

Furthermore, it is preferable that an image based on a predetermined amount of image signal stored in advance in the storage unit of the first part is displayed on the display unit instead of the through image from the time when the first release operation is performed. .

Further, after the second release operation is performed and the image signal is recorded in the second storage unit, or when the setting to the slow preview mode is canceled, the first storage unit stores the image signal in advance. It is preferable to erase the predetermined amount of the image signal because the storage capacity of the first storage unit can be secured.

  According to the electronic still camera of the second aspect of the present invention, when the release operation is performed, the specific image signal output from the imaging unit at a time point that is a predetermined reaction time from the time when the release operation is performed. Can be set from the first storage unit, and a back step view mode in which the display unit displays an image based on the read image signal can be set. In this case, the release is delayed by the photographer's response time, but the subject image that the photographer felt most preferable is obtained by using the image signal captured by the imaging unit at a point in time as far back as the response time. The captured image can be estimated. However, since there are individual differences in reaction time, this estimation is not always correct. Therefore, by automatically displaying an image based on the specific image signal, the photographer can check the estimated image and can take necessary measures as follows.

  Furthermore, it is preferable that an image based on the image signal output from the imaging unit can be displayed before and after the specific image signal is output. Since the predetermined reaction time is determined in advance, the image based on the specific image signal does not always capture the subject image that the photographer feels most preferable. Therefore, by displaying images captured before and after the image based on the specific image signal, it is possible to search for an image that captures the subject image that the photographer felt most preferable. Such display of images before and after may be automatically switched when the user does not perform any operation even if the image based on the specific image signal is displayed for a certain period of time. In that case, it is desirable to switch the image display at a relatively slow time such as an interval of 0.5 seconds as in the slow preview mode described above. On the other hand, the image display based on the specific image signal may be continued until the user operates.

  Further, when an image signal corresponding to the image displayed on the display unit is moved from the first storage unit to the second storage unit in accordance with the operation of the operation member, for example, the photographer estimates When the captured image captures the most preferable subject image at the time of imaging, the specific image signal can be saved or estimated by moving the specific image signal to the second storage unit according to the operation of the operation member. When the images captured before and after the captured image capture the most preferable subject image at the time of imaging, the specific image signal is moved to the second storage unit according to the operation of the operation member. Saving is possible. At this time, the other images stored in the first storage unit are unnecessary, and may be deleted automatically or manually.

  Further, when the specific image signal is moved from the first storage unit to the second storage unit, the predetermined reaction time can be determined to be accurate for the photographer. It is preferable to keep the time unchanged. When the image signal acquired from the photographing unit before the specific image signal is moved from the first storage unit to the second storage unit, the predetermined reaction time is determined by the photographer. Since it can be determined that the time is too short, it is preferable to change the predetermined reaction time longer. Further, when the image signal acquired from the photographing unit after the specific image signal is moved from the first storage unit to the second storage unit, the predetermined reaction time is long for the photographer. Since it can be judged that it is too much, it is preferable to change the predetermined reaction time short.

  Further, when the back step view mode is not set, the through image is displayed on the display unit in response to a first release operation, and is output from the imaging unit in response to a second release operation. When the image signal is stored in the second storage unit, normal shooting can be performed according to the mode selection of the photographer.

  Further, after storing the image signal corresponding to the predetermined number before the release operation, the first storage unit erases the image signal stored most recently and stores a new image signal. Is preferable because the storage capacity of the first storage unit is low.

  According to the electronic still camera of the third aspect of the present invention, when shooting a subject having a moving speed equal to or higher than a predetermined moving speed, compared to shooting a subject having a moving speed less than the predetermined moving speed, Since it is possible to set a quick play mode that increases the amount converted into the number of recorded image signals stored in the first storage unit to advance the imaging timing, for example, when shooting a car or sports that moves at high speed, By using the quick play mode, the possibility of capturing the subject with the best shutter chance can be increased.

Further, in response to the first release operation, a predetermined amount of image signals stored in advance in the first storage unit are sequentially read out and displayed on the display unit at predetermined time intervals, and the second release operation is performed. When the image signal corresponding to the image displayed at the time when is stored in the second storage unit, the image was captured with the best photo opportunity from the images displayed based on the stored image signal. This is preferable because the user can select an image.

Furthermore, although the quick play mode is more user-friendly when automatically set by detecting the moving speed of the subject, the user may manually set the quick play mode.

  According to the electronic still camera of the fourth aspect of the present invention, when shooting a subject having a moving speed less than a predetermined moving speed, compared to shooting a subject having a moving speed equal to or higher than the predetermined moving speed, Since it is possible to set a slow play mode in which the imaging timing is delayed or the amount converted into the number of recorded image signals stored in the first storage unit can be set, for example, when shooting a slow-moving subject, it is best. Since the risk of missing a photo opportunity is reduced, the storage capacity of the first storage unit can be saved by using the slow play mode.

Further, in response to the first release operation, a predetermined amount of image signals stored in advance in the first storage unit are sequentially read out and displayed on the display unit at predetermined time intervals, and the second release operation is performed. When the image signal corresponding to the image displayed at the time when is stored in the second storage unit, the image was captured with the best photo opportunity from the images displayed based on the stored image signal. This is preferable because the user can select an image.

Furthermore, although the slow play mode is more user-friendly when automatically set by detecting the moving speed of the subject, the user may manually set the slow play mode.

  Hereinafter, an electronic still camera according to an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing a functional configuration of the electronic still camera 100. In FIG. 1, an electronic still camera 100 includes a photographing optical system 1, a CCD (Charge Coupled Device) 2, which is an imaging unit, an A / D conversion circuit 3, an image processing unit 4, a buffer memory 5 which is a first storage unit, Video memory 6, liquid crystal monitor 7 serving as a display unit, CCD drive circuit 8, compression / decompression circuit 9, memory card 10 serving as a second storage unit, mode switch 11, S1 release switch 12, S2 release switch 13, and the like And a CPU 14 for controlling the above.

  The CCD 2 photoelectrically converts an optical image of a subject that has passed through the photographing optical system 1 and formed on the light receiving surface, and outputs (generates) the photoelectrically converted image signal (analog signal) to the A / D conversion circuit 3. . The A / D conversion circuit 3 converts the input image signal from an analog signal to a digital signal and outputs it to the image processing unit 4. Image signals that have been subjected to processing such as white balance adjustment in the image processing unit 4 are stored in the buffer memory 5 by a predetermined number of frames. The image signal stored in the buffer memory 5 is output to the video memory 6, and an image based on the image signal is displayed on the liquid crystal monitor 7.

  The memory card 10 is a memory that can store an image signal composed of a semiconductor memory or the like, and is a storage medium that stores the image signal stored in the buffer memory 5 after being compressed by the compression / decompression circuit 9.

  When the memory card 10 receives an image read instruction from the CPU 14, the memory card 10 outputs an image signal instructed to be read to the compression / decompression circuit 9, and the compression / decompression circuit 9 performs an expansion process on the input image signal. The data can be output to the buffer memory 5. Such an image signal is output to the video memory 6, and an image based on the image signal is displayed on the liquid crystal monitor 7.

  The compression / decompression circuit 9 compresses the image signal input from the buffer memory 5 by a predetermined encoding method, and the image signal input from the memory card 10 to display the image signal instructed to be read on the screen. And a decompression circuit for decrypting and decompressing. That is, the compression / decompression circuit 9 has a function as compression means.

  A CPU (Central Processing Unit) 14 reads various application programs related to photographing stored in a built-in flash memory to a work area (not shown), executes various processing such as photographing processing according to the program, and obtains processing results. Can be displayed on the liquid crystal monitor 7.

  The CPU 14 drives and controls the AE / AF processing unit of the image processing unit 4 according to, for example, half-pressing a release switch (not shown) (referred to as the S1 release switch 12), and determines the exposure condition from the obtained photometric value. At the same time, the photographic optical system 1 is driven to the in-focus position detected by the AF process, and the exposure process is executed in response to the full press of the release switch (referred to as the S2 release switch 12). Is subjected to image processing, temporarily stored in the buffer memory 5, and then the image signal is compressed by the compression / decompression circuit 9 according to a predetermined condition, and output to the memory card 10. The CPU 14 inputs a mode switching signal from the mode switch 11.

  Next, the operation of the electronic still camera 100 according to the present embodiment will be described with reference to the drawings. FIG. 2 is a flowchart showing the control of the operation of the electronic still camera 100. FIG. 3 is a data map in the buffer memory. FIG. 4 is a diagram schematically showing an image signal stored in the buffer memory 5 of the electronic still camera 100 as an image.

  First, if the main switch (not shown) is turned on in step S101 in FIG. 2, the CPU 14 performs mode determination in step S102. That is, when it is determined that the normal shooting mode is set according to the operation of the mode switch 11 by the user, the CPU 14 performs a normal preview display in step S103. This is because the CPU 14 performs control so that the image signal of one image is stored in the buffer memory 5 every 15 frames / second from the CCD 2 and the stored image signal is sequentially written in the video memory 6. 7 can display images while switching every 15 frames / second. In this case, as shown in FIG. 3A, the image signal stored in the buffer memory 5 is sequentially overwritten after being input to the video memory 6. The buffer memory has a capacity capable of recording image signals for three images, and new images are overwritten and updated sequentially.

  Further, in step S104, it waits for the signal of the S1 release switch 12 to be input. If the signal of the S1 release switch 12 is not input, the CPU 14 determines whether or not the main switch is turned off in step S113, and if the main switch is not turned off, the flow from step S104 is repeated again. If the main switch is off, the control flow is terminated.

  If it is determined in step S104 that the signal (S1 signal) of the S1 release switch 12 has been input, the CPU 14 performs AE processing to determine exposure conditions and performs AF processing in step S105, and performs the photographic optical system 1. Is driven to the in-focus position, and in step S106, a normal preview is displayed. In the subsequent step S107, the signal of the S2 release switch 13 is awaited. The image signal output at this time is recorded in the buffer memory in the same manner as in the normal preview described above. If it is determined that the signal of the S2 release switch 13 is input, the CPU 14 outputs an image signal from the imaging operation, that is, the CCD 2 and stores it in the buffer memory 5 in step S108, and stores it in the buffer memory 5 in step S109. Are displayed for 2 seconds (after-view), and in step S110, an image signal corresponding to the captured image is stored in the memory card 10 (see FIG. 3A).

  Thereafter, in step S111, the display returns to the normal preview display, and in step S112, the CPU 14 determines whether or not the main switch is turned off. If the main switch is not turned off, the flow from step S104 is repeated again. If the main switch is off, the control flow is terminated.

  On the other hand, if it is determined in step S102 that the slow preview mode is set according to the operation of the mode switch 11 by the user based on the mode determination result of the CPU 14, a normal preview display is performed in the same manner as described above in step S114. . Here, the difference between the slow preview mode and the normal shooting is that in step S115, an image signal corresponding to a predetermined number (for example, 30 frames) is stored in the buffer memory 5 in advance, that is, for 2 seconds if the imaging timing is 15 fps. Is to accumulate. In other words, the image signal obtained by imaging up to 2 seconds before the present time is always stored in the buffer memory 5.

  If it is determined in step S116 that image signal accumulation has been completed, slow view mode completion display is performed in step S117. This is performed in order to allow the user to grasp the completion of preparation by displaying a symbol or sign (“SVM” or the like) indicating that the slow view mode is ready on the liquid crystal monitor 7. In step S118, the image signals acquired two seconds or earlier are erased in such a manner that they are sequentially overwritten (see FIG. 3B).

  Further, in step S119, it waits for the signal of the S1 release switch 12 to be input. If the signal of the S1 release switch 12 is not input, the CPU 14 determines whether or not the main switch is turned off in step S128. If the main switch is not turned off, the signal of the S1 release switch 12 is again returned in step S119. Wait for input. If the main switch is off, the control flow is terminated.

  If it is determined in step S119 that the signal (S1 signal) from the S1 release switch 12 has been input, the CPU 14 performs an image for 0.6 seconds (9 frames) from the signal input time in the S1 release switch 12 in step S120. Further signals are acquired and stored in the buffer memory 5. At this time, the total number of images stored in the buffer memory 5 is 39 frames. The number of frames can be changed arbitrarily.

  Further, the CPU 14 performs a slow preview display in step S121. More specifically, the 39 frames of image signals currently stored in the buffer memory 5 are output to the video memory 6, and the images are displayed in the order of F1, F2, F3... As shown in FIG. Are displayed on the liquid crystal monitor 7 in time series at intervals of 0.5 seconds. When the display for 39 frames is completed, the display is performed again from the first frame. Therefore, the user can carefully select the desired image in which the most preferable subject image is captured while viewing the slow preview display, and can further select the desired image by operating the S2 release switch 13. Note that the slow preview display may be performed while switching the images, for example, F30, F29, F28,.

  If it is determined in step S122 that the signal of the S2 release switch 13 has been input, the CPU 14 determines in step S123 an image signal corresponding to the image displayed when the signal of the S2 release switch 13 is input. Is read from the buffer memory 5, compressed by the compression / decompression circuit 9, and stored in the memory card 10. Further, in step S124, the CPU 14 displays the image selected by the user on the liquid crystal monitor 7 for 2 seconds (after-view), so that the user can check.

  Here, if the user operates a retry button (not shown), in step S125, the CPU 14 determines that the user desires to retry because the selection is wrong, and the slow preview display from step S121 is displayed again. It can be carried out. Note that an image selected by the same operation after retrying is preferably overwritten on an image previously stored in the memory card 10.

  On the other hand, if the retry button is not operated, the CPU 14 can prepare for the next slow preview by clearing the buffer memory 5 in step S126. The CPU 14 determines whether or not the main switch is turned off in step S127. If the main switch is not turned off, the CPU 14 executes the flow from step S102 again. If the main switch is turned off, the control flow ends. To do. The buffer memory 5 may be cleared when the slow preview mode is canceled or when the main switch is turned off.

  According to the present embodiment, by executing the slow preview mode, the image signal acquired via the CCD 2 before and after the shutter release can be accumulated in the buffer memory 5, regardless of the photographer's reaction time. Images with the best photo opportunity can be captured. In addition, since the captured 39 frames can be switched and displayed at a time interval longer than 0.5 seconds, which is longer than the reaction time, the user selects the image with the best photo opportunity regardless of the reaction time, and displays the corresponding image signal. It can be stored in the memory card 10.

  When the slow preview mode is set, the movement of the subject is predicted and the focusing operation is predicted (for example, in FIG. 4, the in-focus position at the time of F1 image capturing and the focus at the time of F2 image capturing). If the focus position at the time of F3 image capturing is predicted from the focus position), the processing time is shortened and the image capturing interval is shortened, so that the possibility that the photographer obtains a preferable image is further increased. Furthermore, when the slow preview mode is set, if the exposure conditions such as aperture, shutter, and imaging sensitivity and white balance adjustment are fixed, the processing time is shortened and the imaging interval is shortened. Is more likely to get.

The display image to be subjected to the slow preview does not necessarily include an image after the signal of the S1 release switch 12 is output.

In addition, the moving speed of the subject in the screen can be automatically determined from the relative movement in the frame of the image of interest in the image data, or the user can be subdivided in a dedicated mode (called quick play mode). Depending on the result, the predetermined number of images corresponding to the image signal recorded in the buffer memory 5 or the timing for recording the image signal from the CCD 2 in the buffer memory 5 may be changed. Good. By advancing the imaging timing, it is possible to capture a larger number of images while going back 2 seconds from the time when the S1 release switch 12 is operated, or the time going back from the time when the S1 release switch 12 is operated. By setting a longer value, the amount of image signals to be recorded can be increased in terms of the number of sheets, thereby increasing the possibility of capturing a subject with a fast moving speed with the best photo opportunity. Also, when capturing a fast-moving subject while looking at the monitor, it is best to record for a longer time than usual if the subject is always moving into the monitor while moving the camera itself. Increases the possibility of shooting a scene.

  For example, in the case of shooting a subject having a predetermined moving speed or higher in a scene such as a car race or sports, the amount of image signals stored in advance can be stored more than usual for 4 seconds, or the CCD 2 By accelerating the recording timing of the image signal output from the recording medium, the both can be used together, the amount of image signals to be recorded can be increased in terms of the number of sheets, and the image signal captured at a shorter timing can be recorded. As a method of advancing the recording timing, it is conceivable to shorten the exposure time of the CCD 2 and shorten the exposure interval by increasing the gain, or shorten the processing time by reducing the number of pixels used by the CCD 2. Not limited.

On the other hand, if the slow play mode is set automatically or manually for an object with a slow moving speed that is less than the predetermined moving speed, the amount of image signal stored in advance can be reduced. It is possible to reduce the storage capacity of the buffer memory by reducing the number of images or by delaying the recording timing of the image signal output from the CCD 2. To delay the imaging timing is to widen the imaging interval (for example, 10 fps), and for images captured without changing the imaging interval, for example, 1 frame (memory), 2 frames (discard), 3 frames (memory) ... including thinning out.

  Next, a second embodiment will be described. FIG. 5 is a flowchart showing control of the operation of the electronic still camera 100. In the present embodiment, it is assumed that the CPU 14 stores a predetermined reaction time T = 1.0 seconds in advance when the electronic still camera 100 is manufactured.

  First, if the main switch (not shown) is turned on in step S101 in FIG. 5, the CPU 14 performs mode determination in step S102. In other words, when it is determined that the normal shooting mode is set in accordance with the operation of the mode change switch 11 by the user, the processing of steps S103 to S113 is performed. To do.

  On the other hand, if it is determined in step S102 that the back step view mode is set according to the operation of the mode switch 11 by the user based on the mode determination result of the CPU 14, the normal preview display is performed in the same manner as described above in step S114. Do. Here, the difference between the back step view mode and the normal shooting is that in step S115, an image signal corresponding to 2 seconds (30 frames) is stored in the buffer memory 5. In other words, the image signal obtained by imaging up to 2 seconds before the present time is always stored in the buffer memory 5.

  If it is determined in step S116 that image signal accumulation has been completed, back step view mode completion display is performed in step S117. This is performed in order to allow the user to grasp the completion of preparation by displaying a symbol or a sign (“BSM” or the like) indicating the completion of preparation of the back step view mode on the liquid crystal monitor 7. In step S118, the image signals acquired two seconds or earlier are erased in such a manner that they are sequentially overwritten (see FIG. 3B).

  Further, in step S119, it waits for the signal of the S1 release switch 12 to be input. If the signal of the S1 release switch 12 is not input, the CPU 14 determines whether or not the main switch is turned off in step S128. If the main switch is not turned off, the signal of the S1 release switch 12 is again returned in step S119. Wait for input. If the main switch is off, the control flow is terminated.

  If it is determined in step S119 that the signal of the S1 release switch 12 (S1 signal) has been input, the CPU 14 in step S201 starts from the signal input time of the S1 release switch 12 for a predetermined reaction time T = 1.0 seconds. At the time of going back, the image signal obtained by the CCD 2 is identified as another specific image signal. For example, in FIG. 4, when an image signal corresponding to the image of F19 is output from the CCD 2 at the time of release, the CPU 14 obtains the image signal from the CCD 2 at a time T = 1.0 seconds later. The image signal (corresponding to the image of F4) is used as the specific image signal.

  Further, the CPU 14 performs a back step view display in step S202. More specifically, a specific image signal is read from the buffer memory 5 and output to the video memory 6 instead of the image at the time of release (F19 in this case), and an image based on the signal (here F4) is displayed on the liquid crystal monitor 7. To do. Note that before the image (F4) based on the specific image signal is displayed, the image (F19) at the time of release is reversed in time from the image (F19) at the time of release, and the image is switched at high speed in a moving image. The display switching may be stopped with.

  Here, the user can confirm whether or not the displayed image (here, F4) is a desired image captured with the best photo opportunity. As a result of the confirmation, if it is determined that the desired image is an image before the displayed image, the user can select “front” by operating an operation member (not shown). Then, in step S203, the CPU 14 can determine that the displayed image (here, F4) is not the desired image captured with the best photo opportunity, but the desired image is further ahead. The previous image (here, F3) is displayed, and 15/100 seconds are added to the predetermined reaction time T, and the nonvolatile internal memory in the CPU 14 is overwritten. Thereafter, in step S203, the determination of the user is awaited again.

  On the contrary, if the user determines that the desired image is an image after the displayed image, the user can operate the operation member (not shown) to select “after”. Then, in step S206, the CPU 14 can determine that the displayed image (here, F4) is not the desired image captured with the best photo opportunity, but the desired image is further behind. The later image (here, F5) is displayed, and 15/100 seconds are subtracted from the predetermined reaction time T, and the nonvolatile built-in memory in the CPU 14 is overwritten. Thereafter, in step S203, the determination of the user is awaited again.

  Furthermore, if the user determines that the desired image is the displayed image, the user can select “Yes” by operating an operation member (not shown). Then, in step S208, the CPU 14 can determine that the currently displayed image is a desired image captured with the best shutter chance, and in step S209, the image signal corresponding to the image is read from the buffer memory 5. The data is compressed by the compression / decompression circuit 9 and stored in the memory card 10. At this time, the stored reaction time T is maintained at the previous value. It should be noted that some reaction times can be stored, for example, selected according to the photographer.

  Thereafter, the CPU 14 can prepare for the next back step view mode by clearing the buffer memory 5 in step S209. The CPU 14 determines whether or not the main switch is turned off in step S210. If the main switch is not turned off, the CPU 14 executes the flow from step S102 again. If the main switch is turned off, the control flow ends. To do.

  According to the present embodiment, by executing the back step view mode, the specific image signal acquired via the CCD 2 is selected retroactively from the shutter release time by the time of the photographer's reaction, and the specific image is selected. Displaying an image based on the signal increases the possibility of capturing the best photo opportunity image regardless of the photographer's reaction time. If the image corresponding to the specific image signal is not the best photo opportunity image, the photographer can select the image with the best photo opportunity by searching the images before and after the image. The predetermined reaction time T determined in advance is corrected, that is, the reaction time can be learned. The corrected reaction time T is used at the time of photographing in the next back step view mode.

  The present invention has been described above with reference to the embodiments. However, the present invention should not be construed as being limited to the above-described embodiments, and can be modified or improved as appropriate. For example, the control shown in FIG. 2 and the control shown in FIG. 3 may be arbitrarily selected with a mode switch.

2 is a block diagram illustrating a functional configuration of the electronic still camera 100. FIG. It is a flowchart which shows control of the operation | movement of the electronic still camera 100 concerning 1st Embodiment. It is a data map in the buffer memory. 2 is a diagram schematically showing an image signal stored in a buffer memory 5 of the electronic still camera 100 as an image. FIG. It is a flowchart which shows control of the operation | movement of the electronic still camera 100 concerning 2nd Embodiment.

Explanation of symbols

1 Shooting optical system 2 CCD
3 A / D conversion circuit 4 Image processing unit 5 Buffer memory 6 Video memory 7 Liquid crystal monitor 8 CCD drive circuit 9 Compression / decompression circuit 10 Memory card 11 Mode switch 12 S1 release switch 13 S2 release switch T Reaction time

Claims (21)

An imaging unit that performs imaging to generate an image signal;
A first storage unit that stores in advance an image signal output from the imaging unit irrespective of a release operation, corresponding to a predetermined number of images;
A second storage unit for storing image signals;
A display unit that sequentially displays through images at predetermined time intervals based on the image signal output from the imaging unit;
In response to a first release operation, a predetermined amount of image signal stored in advance in the first storage unit is sequentially read out, and the image signal is displayed on the display unit at a different time interval from when the through image is displayed. And a slow preview mode in which an image signal corresponding to the image displayed when the second release operation is performed can be stored in the second storage unit. Still camera. In the slow preview mode, a time interval in which the image signals stored in advance in the first storage unit are sequentially displayed on the display unit is longer than a time interval in which the through image is sequentially displayed. The electronic still camera according to claim 1.   The first storage unit further stores the image signal output from the imaging unit by an amount corresponding to a predetermined number of sheets from the time when the first release operation is performed. The electronic still camera according to 1 or 2.   The electronic still camera according to claim 1, wherein when the slow preview mode is set, the movement of the subject is predicted and the focusing operation is predicted.   5. The electronic still camera according to claim 1, wherein when the slow preview mode is set, exposure conditions and white balance adjustment are fixed.   When the slow preview mode is not set, the through image is displayed as it is on the display unit according to the first release operation, and is output from the imaging unit according to the second release operation. 6. The electronic still camera according to claim 1, wherein the image signal is stored in the second storage unit.   The first storage unit stores the image signal corresponding to the predetermined number before the first release operation, and then erases the image signal stored most recently and stores a new image signal. The electronic still camera according to any one of claims 1 to 6, From the time when the first release operation is performed, instead of the through image, an image based on a predetermined amount of image signal stored in advance in the storage unit of the first unit is displayed on the display unit. An electronic still camera according to any one of claims 1 to 7. After the second release operation is performed and the image signal is recorded in the second storage unit, or when the setting to the slow preview mode is canceled, the image is stored in the first storage unit in advance. 9. The electronic still camera according to claim 1, wherein a predetermined amount of the image signal is erased. An imaging unit that performs imaging to generate an image signal;
A first storage unit that stores in advance an image signal output from the imaging unit irrespective of a release operation, corresponding to a predetermined number of images;
A second storage unit for storing image signals;
A display unit for displaying an image based on the image signal,
When a release operation is performed, the specific image signal output from the imaging unit is read out from the first storage unit and read out at a time point that is a predetermined reaction time after the release operation is performed. An electronic still camera, wherein a back step view mode in which an image based on an image signal is displayed by the display unit can be set.   The electronic still camera according to claim 10, wherein an image based on the image signal output from the imaging unit can be displayed before and after the specific image signal is output.   The image signal corresponding to the image displayed on the display unit is moved from the first storage unit to the second storage unit in accordance with an operation of an operation member. The electronic still camera described in 1.   When the specific image signal is moved from the first storage unit to the second storage unit, the predetermined reaction time is unchanged, and the image acquired from the photographing unit before the specific image signal When the signal is moved from the first storage unit to the second storage unit, the predetermined reaction time is changed longer, and the image signal acquired from the imaging unit after the specific image signal is The electronic still camera according to any one of claims 10 to 12, wherein when the first storage unit is moved to the second storage unit, the predetermined reaction time is changed short.   When the back step view mode is not set, the through image is displayed on the display unit in response to a first release operation, and is output from the imaging unit in response to the second release operation. The electronic still camera according to claim 10, wherein an image signal is stored in the second storage unit.   The first storage unit stores an image signal corresponding to a predetermined number before the release operation, and then erases the image signal stored most recently and stores a new image signal. The electronic still camera according to claim 10. An imaging unit that performs imaging to generate an image signal;
A first storage unit that stores image signals output from the imaging unit regardless of a release operation, corresponding to a predetermined number;
A second storage unit for storing image signals;
A display unit for displaying an image based on the image signal,
When shooting a subject having a moving speed equal to or higher than a predetermined moving speed, the imaging timing is advanced or stored in the first storage unit compared to shooting a subject having a moving speed less than the predetermined moving speed. An electronic still camera, characterized in that a quick play mode for increasing the amount converted into the number of recorded image signals can be set. In response to the first release operation, a predetermined amount of image signals stored in advance in the first storage unit are sequentially read out and displayed at predetermined time intervals on the display unit, and a second release operation is performed. The electronic still camera according to claim 16, wherein an image signal corresponding to an image displayed at the time point is stored in the second storage unit.   The electronic still camera according to claim 16 or 17, wherein the quick play mode is automatically set by detecting a moving speed of the subject. An imaging unit that performs imaging to generate an image signal;
A first storage unit that stores image signals output from the imaging unit regardless of a release operation, corresponding to a predetermined number;
A second storage unit for storing image signals;
A display unit for displaying an image based on the image signal,
When shooting a subject having a moving speed less than a predetermined moving speed, the imaging timing is delayed or compared with the case of shooting a subject having a moving speed equal to or higher than the predetermined moving speed, or in the first storage unit. An electronic still camera, characterized in that a slow play mode in which an amount converted to the number of recorded image signals is reduced can be set. In response to the first release operation, a predetermined amount of image signals stored in advance in the first storage unit are sequentially read out and displayed at predetermined time intervals on the display unit, and a second release operation is performed. The electronic still camera according to claim 19, wherein an image signal corresponding to an image displayed at a point in time is stored in the second storage unit. The electronic still camera according to claim 19 or 20, wherein the quick play mode is automatically set by detecting a moving speed of the subject.

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