JP2004120576A - Digital camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a digital camera capable of taking pictures without a blurring in photograph even when the motion of a subject is quick and further capable of efficiently using a memory. <P>SOLUTION: A motion detection circuit 121 is provided to a control part 120. When the motion is detected while a release button is half-depressed, images in a fixed period from the moment when the release button is half-depressed to the moment when the release button is fully depressed are made into one file as a series of image signals and recorded on a recording medium. In this case, the blurring in the photography is suppressed by shortening the shutter speed by performing higher-sensitivity photography as the motion of the subject becomes quicker. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a digital camera that can perform moving image shooting or continuous shooting, and can record / reproduce image data obtained by moving image shooting or continuous shooting.
[0002]
[Prior art]
Conventionally, various types of digital cameras are known. Among them, there are digital cameras having a moving image shooting mode or a continuous shooting mode. In the following, it will be represented by the term continuous shooting, including video shooting. In a digital camera having a continuous shooting mode (including the concept of the video shooting mode), for example, continuous shooting and single shooting can be switched with a shooting mode dial or the like, while the release button is pressed when switching to continuous shooting, Continuous shooting is performed. While the release button is pressed and continuous shooting is performed, image data obtained by shooting is recorded on the recording medium one after another at predetermined intervals. Recently, there are cameras that automatically capture continuous movements when the subject moves. As such a camera, there is a surveillance camera. When an abnormal situation occurs, the camera captures the movement of the subject, and continuous shooting is performed while tracking the subject even if the captured subject moves (for example, patents). Reference 1).
[0003]
When shooting fast-moving subjects, the shooting time before and after the release button is pressed can be set freely, and there are cameras that continuously shoot the movement of the subject within the set shooting time. It has been proposed (for example, Patent Document 2).
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 06-165181 [Patent Document 2]
Japanese Patent Laid-Open No. 10-257365
[Problems to be solved by the invention]
The use of Patent Document 1 is limited to a surveillance camera, and an ordinary camera that takes a picture while holding the camera does not need to have a tracking function.
[0006]
In Patent Document 2, even if the subject does not move, continuous shooting is performed within the set time. Therefore, if the subject does not move, almost the same image signal is successively recorded on the recording medium. There is a problem that the recording area of the recording medium is uselessly recorded in the memory.
[0007]
An object of the present invention is to provide a digital camera that can use a recording area of a recording medium more efficiently by paying attention to the above points.
[0008]
[Means for Solving the Problems]
The camera of the present invention that achieves the above object is a digital camera that obtains an image signal representing a subject image by forming an image of light from the subject on an image sensor with a photographing optical system.
A release button having two operation modes of half-press and full-press,
A motion detector for detecting whether or not the subject has a motion at a predetermined speed or more based on the image signal,
When the motion detection unit detects a motion at a speed higher than a predetermined speed, continuous shooting is performed after the release button is pressed halfway, and still images are captured by pressing the release button halfway. A shooting mode is performed in which shooting is performed, and when the motion detection unit detects a motion at a speed less than a predetermined speed, continuous shooting is not performed but only the release button is fully pressed to perform still image shooting. It is characterized by that.
[0009]
According to the camera of the present invention, continuous shooting is performed when the motion detector detects a motion of a predetermined speed or more on the subject. In addition, when a motion with a speed less than the predetermined speed is detected, only still image shooting is performed, and continuous shooting is performed even if there is no movement of the subject as in the past, and the image is wasted in the memory. It is avoided that the signal is recorded.
[0010]
Here, it is preferable that a shooting sensitivity adjustment unit is provided that changes the shooting sensitivity according to the speed of movement of the subject detected by the motion detection unit during shooting in the shooting mode.
[0011]
When the subject movement is fast, the shutter speed is also changed when the photographing sensitivity is changed by the photographing sensitivity adjustment unit. Therefore, even if the subject moves fast, blurring hardly occurs.
[0012]
In addition, it is preferable to include an image recording unit that records a series of image signals representing a series of images obtained by one shooting operation in the shooting mode in one file.
[0013]
When a series of image signals when a subject moves and continuous shooting is performed are recorded on the storage medium, the series of image signals are recorded on the recording medium as one file. When a series of image signals are recorded on a recording medium as a single file in this way, the series of image signals recorded on the recording medium can be easily managed, and when the series of image signals are reproduced from the recording medium, the file All you have to do is specify the, and the handling of the image file becomes simple.
[0014]
Furthermore, an image display unit that displays an image based on the image signal is provided, and the image display unit displays a series of thumbnail images based on the image signal obtained by one shooting operation in the shooting mode. Is preferred.
[0015]
In this way, when the image display unit displays each thumbnail image of a large number of files side by side, the timing at which a series of images recorded in the file is confirmed by looking at the thumbnail images and still image shooting is performed. You can know the situation before and after.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described.
[0017]
FIG. 1 is an external view of a digital camera showing an embodiment of the present invention. 1A is a front view, FIG. 1B is a top view, FIG. 1C is a side view, and FIG.
[0018]
An image of a subject is guided from the lens 101 shown in FIGS. 1A to 1C to a CCD solid-state imaging device provided inside the camera 100. A flash light emitting unit 104 is also provided so that night photography can be performed. A light control sensor 104a for adjusting the amount of flash emission of the flash light emitting unit 104 is also provided.
[0019]
As shown in FIG. 1D, an operation unit for performing various operations when the user uses the digital camera is provided on the back of the digital camera of the present embodiment.
[0020]
This operation unit is provided with an operation panel group and an LCD panel 105a as a display. The operation switch group includes a power switch 102 for turning on the power for operating the digital camera, a shooting / playback switching lever 103 for enabling switching between shooting and playback, a zoom switch 106, a cross key 107, and a pop-up switch for a flashing unit. 109 and the like. A display unit 107a is provided inside the cross key, and operation contents are displayed on the display unit so that the operation of the cross key 107 can be easily performed. In the digital camera 100, shooting and playback can be switched by the shooting / playback switching lever 103. When shooting, the shooting / playback switching lever 103 is switched to the shooting side 103a by the user and shooting is performed. The playback switching lever 103 is switched to the playback side 103b.
[0021]
When the shooting / playback switching lever 103 is switched to the shooting side and the release button 108 shown in FIG. 1B is pressed, a shooting start instruction is transmitted to the signal processing unit inside the camera. Is provided with a photographing mode dial 110, and five photographing modes are prepared for this photographing mode dial.
[0022]
FIG. 2 is a diagram showing five shooting modes of the shooting mode dial.
[0023]
The five shooting modes are an A mode for automatic shooting, an M mode for manual shooting, a P1 mode in which continuous shooting (moving image) / still image can be automatically switched on the camera side according to the movement of the subject, There are five modes: a continuous shooting (moving image) / P2 mode for shooting still images, and a continuous shooting (moving image) shooting mode. It also has an S mode that can change the internal settings of the digital camera. When the P1 mode is selected here, an image difference between frames is detected according to the movement of the subject. If there is a movement between the frames, continuous shooting is performed, and a series of image signals are output to the recording medium. It is to be recorded.
[0024]
FIG. 3 is a configuration block diagram of a signal processing unit provided in the digital camera 100. The configuration of the signal processing unit in the digital camera 100 will be described with reference to FIG.
[0025]
In the digital camera 100 of the present embodiment, all processes are controlled by a control unit 120, for example, a CPU, and various switches of the operation unit shown in FIG. In FIG. 3, the various switches are described as operation switches 1000. The control unit 120 is provided with a RAM / ROM unit 130 including a ROM storing a program and a working RAM. The control unit 120 controls each unit of the camera control unit 140, the light control sensor 150, the display control unit 160, the memory control unit 170, and the external interface unit 180 according to the procedure of the program stored in the ROM.
[0026]
In addition, a motion detection unit 121 is provided in the control unit 120. When P1 is selected with the shooting mode dial 110, the difference between the previous frame and the current frame is selected by the motion detection unit 121. And the movement of the subject being photographed is detected. Further, the control unit 120 is provided with a continuous shooting control unit 122, and the continuous shooting control unit 122 is provided with a ring buffer capable of recording a predetermined number of frames. In this ring buffer, a series of image signals are recorded for a predetermined number of frames when continuous shooting is performed. A series of image signals are sequentially recorded in the ring buffer. When a predetermined number of frames are exceeded, a new image signal is overwritten on the image signal recorded at the oldest time.
[0027]
FIG. 4 is a diagram showing an image signal of the previous frame and an image signal of the current frame that are used when the motion detection unit 121 detects the motion of the subject.
[0028]
FIG. 4A shows an image signal of the previous frame (previous frame), and FIG. 4B shows an image signal of the current frame (current frame). When the photographic lens is directed in the same direction and the subject vehicle moves as shown in FIGS. 4A to 4B, the difference in the position of the vehicle is indicated by the difference.
[0029]
In this way, in order to obtain the difference between frames, the control unit 120 is provided with a frame memory, and the image signal of the previous frame shown on the left side of FIG. 4 is stored in the frame memory. The image signal stored in the memory is supplied to a difference calculation unit included in the motion detection unit. On the other hand, the difference calculation unit is also supplied with the image signal of the current frame, and the difference calculation is performed between the two image signals. As a result of the difference calculation, when it is determined that the subject is moving, information on sensitivity is supplied to the camera control unit 130. The camera control unit 130 gives an instruction of sensitivity to the photographing sensitivity adjustment unit provided in the camera control unit based on the information on the sensitivity. For example, a pixel mixing unit is provided in the photographing sensitivity adjustment unit of the camera control unit, and a plurality of pixels, for example, four pixels are mixed in the pixel mixing unit to adjust the sensitivity. When high sensitivity is set in this way, the subject moves, so it is necessary to adjust the shutter speed to shorten it. In the digital camera of this embodiment, when the difference detected by the motion detector is large and it is determined that the movement of the subject is fast, the photographing sensitivity adjustment unit is set to high sensitivity photographing and is given to the CCD solid-state image sensor. Even if the amount of light emitted is small, it is possible to shoot a high-quality image, and the timing generator included in the camera control unit 140 is instructed to shorten the shutter speed, so that even if the subject moves quickly I try not to blur the shooting.
[0030]
In this way, in order to perform motion detection in the motion detection unit 121 in synchronization with shooting, the camera 100 according to the present embodiment has two operation modes on the release button 108 that signals the start of shooting. The two operation modes are a half-pressed state and a full-pressed state, and different processing is performed in the control unit 120 according to each operation mode. When P1 (continuous shooting (moving image) / still image shooting mode) is set with the shooting mode dial 110 shown in FIG. 2 and the release button 108 is half-pressed, continuous shooting is started, and the current frame and the previous frame are displayed. The difference calculation from the frame is performed by the difference calculation unit of the motion detection unit 121. As a result of the difference calculation, when it is determined that the subject moves fast, image signals representing a series of images are successively recorded in the ring buffer in the continuous shooting control unit 122. When the release button is fully pressed, recording from the ring buffer in the continuous shooting control unit 122 to the recording medium is performed. At this time, the still image when fully depressed S2 is also written in the ring buffer, and after the full depression, continuous shooting is continued for a predetermined time and sequentially written in the ring buffer. After the release button is fully pressed, a series of image signals are written to the ring buffer, and a series of already written image signals are read from the ring buffer and recorded in the memory card 190 one after another. Here, as described above, when a series of image signals written in the ring buffer exceeds a predetermined number of frames, a new image signal is overwritten on the image signal recorded at the oldest time.
[0031]
That is, in the half-pressed state, the motion detection unit 121 detects a motion, and when fully pressed, either the still image or the continuous shooting is performed according to the motion of the subject detected during the half-pressed period. The selected image is taken. When the subject moves, not only a series of images from when they are half-pressed to when they are fully pressed, but also images after a certain period from when they are fully pressed are added to the recording media as image files. If the subject is recorded and there is no movement, only the still image when fully pressed is recorded on the recording medium.
[0032]
In addition, the memory control unit 170 of the digital camera is provided with a compression / decompression unit, and the image data compressed by the compression unit is recorded on the memory card as an image file. In this compression unit, compression information and shooting information when one frame of image data is compressed is recorded as a header, and when reading, the decompression unit performs decompression based on the contents of the header to reproduce the image data. The This memory control unit corresponds to the image recording unit referred to in the present invention.
[0033]
In this header part, compression information, shooting information, recording information, etc. when a series of image signals are compressed and recorded as an image file are written. When playing back, the header information is first read out and played back. Is done. In the header portion, there is an area called a thumbnail area, and a thumbnail image is recorded as file information in the thumbnail area.
[0034]
When continuous shooting is performed, the size of the head image signal of a series of image signals continuously shot is reduced and the compressed image signal is recorded in the thumbnail area of the header portion. At this time, a series of image signals is recorded as a JPEG image file in a recording area different from the recording area of the header.
[0035]
When still image shooting is performed, the size of the still image is reduced, compressed and recorded in the thumbnail area, and the still image is recorded on the recording medium as a JPEG file.
[0036]
Here, when it is determined that there is movement at the full-press timing S2, an image signal representing a series of images obtained by continuous shooting is recorded in a file for a few seconds before the full-press timing S2 of the release button. An image signal representing a still image at the full-press timing S2 is also recorded in the file, and an image signal representing a series of images obtained by continuous shooting is also recorded in the file for a few seconds after the full-press timing S2. Is done. Therefore, when the file is designated, the image signals before and after the release button full-press timing S2 are reproduced. At this time, if the first image signal of the thumbnail image of the still image at the full-press timing S2 and the image signal representing a series of images before and after the full-press timing S2 is created as a thumbnail image, the still image is captured. The situation before and after is confirmed by the thumbnail images, and management of shooting records and the like becomes simple.
[0037]
FIG. 5 is a diagram showing a thumbnail image compressed by reducing the aspect ratio of the photographed image.
[0038]
When the shooting / playback switch shown in FIG. 1D is tilted to the playback side, the playback mode is entered and the file list of the image file recorded on the memory card 190 is selected from the selection menu, the thumbnail of FIG. The file name is displayed in the form of a folder on the LCD panel 105a together with the image. FIG. 6 is a diagram showing the folder and the moving image files and still image files under the folder. When a thumbnail image recorded in the thumbnail area in the header portion is used as a folder and the folder is designated by a cursor or the like, a continuous shooting file or a still image file designated by the cursor is reproduced. Here, when continuous shooting is performed, still image shooting is always performed when the release button is fully pressed, so the situation before and after the time when the still image was shot is shown by the thumbnail image. When displayed side by side on the LCD screen, the situation before and after taking a still image can be confirmed at a glance.
[0039]
FIG. 7 is a flowchart showing a procedure of processing performed by the CPU when the P1 mode is selected as the photographing mode. The symbol S1 used in this flowchart indicates half-pressing of the release button, and symbol S2 indicates full-pressing of the release button.
[0040]
First, in step S71, the release button is half-pressed S1, and if it is determined as Y, in the next step, the motion detection unit 121 in the control unit 120 determines from the image signal of the previous frame and the image signal of the next frame. Difference detection is performed. The image signal of the previous frame is stored in the frame memory, and when the image signal of the next frame is supplied from the frame memory to the difference calculation unit, the image signal of the next frame is also supplied to the difference calculation unit. Is detected. The difference between the two image signals increases as the movement increases, and the difference between the two image signals decreases as the movement decreases.
[0041]
In step S73, the magnitude of this difference is determined. When the magnitude of the difference is medium in this step S73, the process proceeds to step S74 and high sensitivity setting such as ISO800 is performed. On the other hand, when the magnitude of the difference is large, the process proceeds to step S75, and a high sensitivity setting such as ISO 1600 is further performed. When the high sensitivity setting is performed as described above, processing is performed by a pixel mixing unit included in the imaging sensitivity adjustment unit in the camera control unit, the S / N ratio is improved, and imaging with high sensitivity is performed. At this time, pixel mixing is performed and the S / N ratio is improved, so that an image with good image quality can be obtained without applying such a large amount of light to the imaging surface of the CCD solid-state imaging device. Therefore, if the subject has a fast movement and the high sensitivity setting is performed by the photographing sensitivity adjustment unit, the photographing is performed with the shutter speed shortened, and the blurring of the photographing is suppressed even if the subject moves.
[0042]
If it is determined in step S73 that the difference is small, it is determined that the subject is a still image, and the ISO 400 sensitivity is selected in step S76. In the next step S77, it is determined whether or not the full press S2 has been performed. If it is determined Y in step S77, still image shooting is performed in step S78. That is, if the subject does not move, an image signal representing a still image when the release button is fully pressed (at S2) is recorded on the recording medium in step S79.
[0043]
If it is determined in step S73 that the difference is medium or large, high sensitivity is set in step S74 or S75, and continuous shooting is started in step S80. The flow chart is the same for both ISO 800 and ISO 1600 sensitivities, but the number of pixels to be mixed changes, and the S / N improvement degree changes.
[0044]
In step S81, it is determined whether or not the release button has been fully pressed. If it is determined as Y, still image shooting is performed when the release button is fully pressed in step S82. Then, shooting is continued for a certain time from when the button is fully pressed in the next step S83, and recording on the recording medium is performed in step S84. In other words, when it is half-pressed, motion is detected by the motion detection unit, continuous shooting with high sensitivity begins to be performed, and when the release button is fully pressed, the image when fully pressed is shot as a still image, Thereafter, continuous shooting is performed for a certain period of time, and after a certain period of time, the shooting is finished. At this time, the high sensitivity setting is performed and the shutter speed is shortened, so that there is no blurring of shooting. Also, if it is determined that the subject does not move and is a still image, only the still image when it is fully pressed is recorded on the memory card, so the memory area of the memory card is not wasted and memory is efficiently stored. Card can be used. Furthermore, in order to make efficient use of the image data recorded in this memory, the digital camera of this embodiment uses the image signal obtained by one shooting operation on the recording medium as one file. Since recording is performed, the captured image signal is recorded as an image file in an orderly manner in the recording medium. Also, in the thumbnail area of the header part in the image file, if continuous shooting is used, the aspect ratio of the first image is reduced and if the compressed image signal is a still image, the aspect ratio of the still image is reduced. Each compressed image signal is recorded. Therefore, when the recording media control unit accesses a file recorded on the recording media and reads the header of the file to display the file list, the thumbnail image of each file is read from the header and displayed on the LCD panel. can do. At this time, since thumbnail images of a large number of files can be displayed side by side on the LCD panel, if any of the large number of thumbnail images is selected with the cursor, A still image file is played.
[0045]
As described above, when the subject moves and the movement is fast, the shooting sensitivity is set to a high sensitivity such as ISO800 and ISO1600, and the shutter speed is shortened, so that even if the subject moves fast, the shooting blurs. It becomes difficult.
[0046]
Also, if it is determined that there is no movement and the image is still, the image signal when the release button is fully pressed is only recorded on the recording medium, so that efficient recording is possible without performing unnecessary recording on the recording medium. The recording area of the media is used.
[0047]
Furthermore, it is possible to efficiently manage image files recorded on a recording medium by using thumbnail images as folders. In addition, when an image file is reproduced from a recording medium, if a folder to be displayed as a thumbnail image is designated, an image file corresponding to the folder is reproduced from the recording medium, so that the reproduction can be easily performed. In addition, when the still image when the release button is fully pressed and the images before and after it are displayed side by side with thumbnail images when continuous shooting is performed, the situation before and after the still image was shot can be confirmed at a glance. The effect that you can do it also comes out.
[0048]
【The invention's effect】
As described above, according to the camera of the present invention, a digital camera that can efficiently use the recording area of the recording medium can be provided.
[Brief description of the drawings]
FIG. 1 is an external view of a digital camera according to an embodiment of the present invention.
2 is a diagram showing a shooting mode dial in FIG. 1; FIG.
3 is a block diagram illustrating a configuration of a signal processing unit of the digital camera of FIG. 1. FIG.
FIG. 4 is a diagram illustrating an image signal of a previous frame and an image signal of a current frame.
FIG. 5 is a diagram showing a hierarchy of files recorded on a recording medium.
FIG. 6 is a diagram showing thumbnail images.
FIG. 7 is a flowchart showing processing when P2 is selected as a shooting mode.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 100 Digital camera 120 Control part 121 Motion detection part 122 Movie / continuous shooting control part 130 RAM / ROM part 140 Camera control part 160 Display control part 170 Memory control part 180 External interface 190 Memory card (recording medium)

Claims (4)

In a digital camera that obtains an image signal representing a subject image by focusing light from the subject on an image sensor with a photographing optical system,
A release button having two operation modes of half-press and full-press,
A motion detector for detecting whether or not the subject has a motion at a predetermined speed or more based on the image signal;
When the motion detecting unit detects a motion at a speed equal to or higher than a predetermined speed, a video or continuous shooting is performed after the release button is half-pressed, a still image is shot with the full press, and again after the still image is shot. When a motion picture or continuous shooting is performed, and the motion detection unit detects a motion less than a predetermined speed, only the still image is captured by pressing the release button fully without performing the motion picture or continuous shooting. A digital camera characterized by having a photographing mode to perform. The digital camera according to claim 1, further comprising a photographing sensitivity adjustment unit that changes photographing sensitivity according to a speed of movement of the subject detected by the motion detection unit during photographing in the photographing mode. 2. The digital camera according to claim 1, further comprising an image recording unit that records a series of image signals representing a series of images obtained by one shooting operation in the shooting mode in one file. An image display unit that displays an image based on an image signal is provided, and the image display unit displays a series of thumbnail images based on a series of image signals obtained by one shooting operation in the shooting mode. The digital camera according to claim 1.

Images