JP2003134386A - Imaging apparatus and method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging apparatus and an imaging method which can control resolution of a picked-up image. SOLUTION: In a monitor recording mode, an imaging part 12 outputs an image signal by interlaced reading drive in accordance with a driving signal supplied from a driving circuit 14, or outputs an image signal by all picture elements reading drive, and the image signal is stored in a storage device 20 after being processed by a signal processing circuit 18. Drive switching-over to the imaging part 12 is performed by a resolution switching-over signal 106 supplied from a decision processing part 24 of a control unit 22. The decision processing part 24 detects change of the amount of image information on the basis of the image signal stored in the storage device and an image signal precedent to it, and produces the resolution switching-over signal 106 corresponding to the changing amount, thereby performing reviewing process of resolution at prescribed intervals. The processed image signal is encoded by a compression encoding circuit 28 and stored in a storage medium 30.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup apparatus that generates and outputs image data representing the object scene image. For example, the generated image data is recorded in a recording medium, and the image data is transferred to another apparatus such as a computer and the recording medium. The present invention relates to an imaging device and an imaging method for recording in.

[0002]

2. Description of the Related Art As an image pickup device for picking up an image of a scene, for example, an image pickup device for recording picked-up moving image information on a recording medium, records a huge amount of information on the recording medium. It is possible to record only the image for the time corresponding to the information storage capacity on the recording medium. Therefore, in order to record a still image or a moving image with a larger number of frames and to record a moving image for a long time on a recording medium, by compressing and encoding the image information after converting it into a digital signal,
It is possible to record a larger number of frames or image data for a long time on the recording medium. For example, Japanese Patent Laid-Open No. 11-313
Japanese Patent Laid-Open No. 322 discloses an image signal processing device and method for performing a coding process by controlling a quantization rate according to the characteristics of a series of moving images when performing the moving image processing. Further, in this publication, for example, for input image data,
In the actual shooting after the trial coding, the preprocessing circuit 11 controls the passband characteristics of the frequency components to set the resolution conversion, or the pixel number conversion setting by thinning out the pixels. It was stated that they would do.

Generally, in a conventional digital camera for taking a still image, for example, in order to efficiently record the captured image information on a recording medium, a setting switching screen is called from the menu screen and the basic mode, By selecting the normal mode, the fine mode, or the non-compression mode, it is possible to switch the compression processing parameters in advance and manually select the recording data amount of the still image. Similarly, regarding the recorded image size, in the digital camera, the image size corresponding to all the effective pixels in the image sensor and the VGA size suitable for image display are manually set in advance, and the setting is performed. I was able to shoot a still image.

[0004]

However, when a moving image is recorded for a long time, if it is always recorded at a high resolution, the amount of data becomes enormous. Even if a moving image is recorded on a recording medium, the recording capacity of the recording medium is limited, and it is difficult to record and store all high-definition images. The same applies when not only moving images but also still images are obtained continuously or intermittently. Therefore, when monitoring the field for a long time and expecting to record and record for a long time like a surveillance camera, it is necessary to record only a low-resolution image with a small amount of information. It was difficult to reproduce the captured image at a certain point in the captured image in more detail, such as when the object was moved.

Further, in the digital still camera, since the menu setting for resolution switching is manually performed, in this case, for example, the resolution is automatically switched while the camera is away from the camera to perform the photographing. Was difficult.

An object of the present invention is to solve the above-mentioned drawbacks of the prior art and to provide an image pickup apparatus capable of autonomously controlling the resolution of an image at the time of image pickup. An image pickup apparatus and an image pickup method capable of obtaining a specific image with high definition and efficiently recording an image by outputting image data of a plurality of frames and a plurality of frames by image pickup and recording the image data on a recording medium, for example. The purpose is to provide.

[0007]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides an image pickup apparatus for picking up an image of a field and generating image signals of a plurality of frames. An image pickup means for picking up an image of a field for each image and generating an image signal representing a plurality of frames of picked-up images, a driving means for driving the image pickup means, a signal processing means for processing the image signal, and a signal processing Storage means for temporarily storing the image signal processed by the means, signal output means for outputting the image signal stored in the storage means, and image signal during image pickup according to the image signal stored in the storage means. The resolution is reviewed every second time interval, and the control means includes a control means for generating an image signal at the reviewed resolution. The control means detects a change in analog information at the time of imaging and switches the resolution according to the change. Or not It includes judging means for judging, and performing control for switching the resolution of the image signal according to the determination result of the determining means.

In order to solve the above-mentioned problems, the present invention provides an image pickup method for picking up an image of a field and generating image signals of a plurality of frames. An image capturing step for capturing an image field to generate an image signal representing a plurality of frames of captured images corresponding to the image capturing; a resolution reviewing step for reviewing the resolution of the image signal during image capturing every second time interval; It includes an image processing step of image processing, a compression encoding step of compression encoding the image signal processed in the image processing step, and an output step of outputting the image signal processed in the compression encoding step. The direct process is characterized by detecting a change in analog information at the time of imaging, determining whether to switch the resolution according to the change, and switching the resolution of the image signal according to the determination result.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of an image pickup apparatus and an image pickup method according to the present invention will be described in detail with reference to the accompanying drawings. Referring to FIG. 1, there is shown an embodiment of a digital camera which images a field and records the captured image data on a recording medium. This digital camera 10 is
Image information to be output by automatically adjusting and changing the image resolution at the time of image capture, that is, the image size, according to changes in the analog amount detected during the image capture of a moving image, for example, changes in the information amount of the captured video signal. It is a digital camera that controls the amount of information in. In the following description, the parts not directly related to the present invention will not be illustrated and described, and the reference numerals of signals will be represented by the reference numbers of the connecting lines in which they appear.

More specifically, the image pickup section 12 of the digital camera 10
Includes an image pickup lens and a solid-state image pickup device (not shown), photoelectrically converts a field image formed on the image pickup surface of the solid-state image pickup device by the image pickup lens, and outputs the converted and read electrical signal to an output 100. It is an image pickup unit for outputting. As the solid-state image sensor, for example, a CCD solid-state image sensor or a MOS type image sensor is applied. In the present embodiment, a two-dimensional color CCD image pickup device in which primary color filters are attached to each pixel in a predetermined array on the image pickup surface of the image pickup device is applied, and a drive supplied from the drive circuit 14 to the input 102 is applied. In response to the signal, a color image signal corresponding to the amount of light received by each pixel is sequentially output.

When the first drive signal is supplied from the drive circuit 14, the solid-state image pickup device thins out and reads out predetermined pixels from all the effective pixels in the image pickup device, and reads out the image size of all pixels. Thinning-out reading is performed by outputting a moving image signal of a small image size, for example, an image size of 1/4 thinned out in the horizontal and vertical scanning directions at 15 to 30 frames per second. At the time of this thinning-out reading, the pixel signal of the horizontal scanning line of the pixel to which the green component color filter is attached may be read out with emphasis. Further, in the solid-state imaging device, the second drive signal for reading all pixels is the drive circuit 14
When all the effective pixels in the image sensor are read, all pixels of the effective pixels are read and a high-definition image signal is output. In this case, the image sensor outputs an image signal corresponding to the second drive signal at a frame rate of several frames per second. In a still image shooting mode, which will be described later, the solid-state image sensor receives the second drive signal and outputs a still image signal for one frame.

The drive circuit 14 generates the first drive signal for performing the thinning-out reading and the second drive signal for performing the all-pixel reading in response to the control signal supplied from the control unit 22 to the input 104. To do. The drive circuit 14 generates a drive signal including various timing pulses such as a sweep pulse, a field shift pulse, and vertical and horizontal transfer clocks.
The drive circuit 14 outputs the first or second drive signal 102 according to the resolution switching control signal 106 supplied from the control unit 22.
Is supplied to the imaging unit 12 connected to. The first drive signal is generated by the control unit 22 after the low resolution is set, and the second drive signal is generated after the high resolution is set. Further, the drive circuit 14 generates a gain control signal for amplifying the output signal of the image pickup device in a variable gain in response to the control signal supplied from the control unit 22, and supplies the gain control signal to the image pickup unit 12.

The image pickup unit 12 performs an analog double sampling on the output signal of the solid-state image pickup device, amplifies the image signal subjected to the double correlation sampling according to the gain control signal, and clamps it to a reference level. (Not shown). The output of the analog circuit constitutes the output of the image pickup unit 12, and is connected to the A / D converter 16 via the connection line 100.

The A / D converter 16 is a conversion circuit for converting an image signal output from the image pickup section 12 and appearing at the input 100 into a digital signal in synchronization with a pixel clock. For example, each pixel value is 12 to 16 bits. Of the color data corresponding to the color filter array of the image sensor and output to the output 110. The output 110 of the A / D converter 16 is connected to the signal processing circuit 18.

The signal processing circuit 18 is a signal processing section for processing the image signal appearing at the input 110 into image signals suitable for recording and display. The signal processing circuit 18 is a circuit for performing various digital signal processing such as level adjustment such as white balance adjustment, gradation correction, contour correction, and luminance color difference (YC) conversion processing. In addition, the signal processing circuit 18
Has an image size adjustment function of adjusting the number of pixels in the horizontal and vertical scanning directions by reducing the number of pixels in the image signal.

The signal processing circuit 18 also has a function of performing arithmetic processing on the image signal input to the input 110 to calculate evaluation values for various controls. For example, the signal processing circuit 18
A brightness evaluation value for performing automatic exposure control is calculated based on the image signal, and the calculated evaluation value is notified to the control unit 22. Further, the signal processing circuit 18 calculates a contrast evaluation value for focusing the object scene image in the imaging unit 12 based on the image signal, and the generated contrast evaluation value is a control unit.
Notify 22. The control unit 22 refers to these evaluation values and performs automatic exposure control and automatic focus adjustment on the imaging unit 12.

The automatic exposure control is a function of adjusting the exposure time, that is, the electronic shutter speed by changing the drive signal to the solid-state image pickup device and changing the charge storage time of the image pickup device according to the evaluation value. Further, in the automatic focus adjustment, the position of the imaging lens is moved back and forth along the optical axis, and the focus state of the object scene is determined based on the contrast evaluation values generated at the plurality of positions, and This is a function of focusing the field image on the imaging surface of the image sensor.

Further, the signal processing circuit 18 includes a YC conversion circuit for converting the input image signal into a luminance signal (Y) and a color difference signal (C), and the signal processing circuit 18 stores the processed record for storage. The image signal is output to the memory 20 via the connection line 112.
Further, the signal processing circuit 18 outputs a display RGB image signal for display on a display device such as a liquid crystal display panel to the encoder 32 connected to the output 114. The signal processing circuit 18 outputs only a luminance signal (Y) or a specific color filter of the image sensor, for example, a green component (G) signal to the memory 20 when capturing a moving image, and a monochrome image when capturing a moving image. Alternatively, only the color image signal may be recorded on the recording medium, and the color image signal may be recorded on the recording medium 30 at the time of high-resolution shooting.

The memory 20 in this embodiment has a storage area for accumulating at least image signals for two frames at the time of reading all pixels, and the image signals for each frame are sequentially stored alternately in the other storage area and updated. It is a semiconductor memory circuit. The signal processing circuit 18 can perform various kinds of signal processing and evaluation value calculation processing on the image signal stored in the memory 20. The memory 20 connects the stored image signal to the connecting line 11
It outputs to the compression encoding circuit 28 connected via 6. Further, the memory 20 has a function of reading the stored image signal and transferring it to the control unit 22 connected via the connection line 118 in response to a request from the control unit 22.

The storage timing for storing the image signal in the memory 20 is not limited to storing each frame in sequence, but for example, under the control of the control unit 22, the image signal is extracted at a predetermined time interval or every plural frames. Can be stored in the storage area. In this embodiment, the image signals of each frame are sequentially stored in the storage area, and the stored frame image signals are read out from the storage area at every time interval according to the count value of the counter described later and output to the control unit 22. To do.
At this time, the current frame number of the image signal may be counted, and the image signal for each predetermined number of frames may be read from the storage area and output to the control unit 22.

If the memory 20 is provided with a storage area for accumulating image signals for only one frame, the output 112 of the signal processing circuit 18 is also connected to the determination processing unit 24 in the control unit 22 to be described later. Such a two-image comparison process may be performed by comparing the image accumulated in the storage area with the image currently output from the signal processing circuit 18.

The control unit 22 for controlling the entire camera 10 includes a central processing unit (CPU) and its peripheral circuits, and enters a setting mode set for the camera 10 according to a program for controlling each unit of the camera 10. Perform appropriate control and processing.

When the control section 22 detects the operation information corresponding to the operation of the release button (not shown), the control section 22 sets the still image shooting mode and generates a control signal for instructing the still image shooting to notify the drive circuit 14. . In this case, the control unit 22 shoots the field with the image size set in the menu and generates, for example, a control signal for driving the solid-state imaging device of the imaging unit 12 to read all pixels. When the operator sets the moving image shooting mode, the control unit 22 generates a control signal for instructing the moving image shooting for continuously shooting the field with the image size set in advance in the menu. Control unit 22
Supplies a control signal for controlling these shootings to the drive circuit 14 connected to the output 104.

The control unit 22 also generates a control signal for causing the image pickup unit 12 to perform automatic exposure control and automatic focus adjustment control based on the brightness evaluation value and the contrast evaluation value notified from the signal processing circuit 18. Then, the generated control signal is output to the output 104.

Further, when the monitor recording mode is set for performing long-time shooting / recording, the control unit 22 responds to a change in the amount of information of the image signal stored in the memory 20 in the moving image shooting mode. Decide whether to perform low resolution imaging or high resolution imaging. The control unit 22 stores the low resolution setting and the high resolution setting according to the determination, and notifies the drive circuit 14 of the switching control signal 106 for switching between the low setting and the high resolution setting when changing the current setting. This surveillance recording mode is an advantageous mode when, for example, the main camera 10 is fixed toward the object field and a long-time moving image signal is recorded on a recording medium, and the amount of information to be recorded is adaptively reduced. This is a shooting mode having an information amount reduction function.

More specifically, the control unit 22 includes a counter for counting the elapsed time during moving image shooting, and reads the image signal stored in the memory 20 at every time interval (T seconds) corresponding to the count value of the counter. . The control unit 22 calculates the information change amount based on the input image signal and temporarily stores it. Specifically, the control unit 22, the image signal once stored in the memory 20,
After a lapse of T seconds thereafter, the difference with the image signal stored in the memory 20 is calculated, and the difference value of the calculation result is summed up for one screen and temporarily stored. The control unit 22 determines the difference value between the image signals captured with the same image size as the time interval (T
Every second). Therefore, the control unit 22 does not detect the amount of information change caused by switching the image size of the captured image.

The control unit 22 is provided with a judgment processing unit 24, and the judgment processing unit 24 uses the difference value for one screen of the calculation result as the information change amount, and this information change amount is set as a standard reference. It is compared with the value and, according to the comparison result, it is determined whether or not the input signal has a large change in the information amount of a predetermined value or more. In this way, the determination processing unit 24 determines whether or not the information change amount exceeds a predetermined threshold value that is a preset reference value, and determines that there is a large information amount change according to the determination result. When the determination is made, the switching signal 106 for switching the captured image size to a control with large resolution, for example, reading all pixels is generated. Note that the control unit 22 transfers the image signal at a high speed at the time of setting the low resolution to perform 1/4 thinning-out reading from the solid-state image sensor, and at the time of setting the high resolution, changes the drive and frame rate to read the image signal by all pixels. Is output.

Note that the control unit 22 forcibly switches from the high resolution setting to the low resolution setting when the information change amount is less than the threshold value for a predetermined time (T seconds) during the high resolution setting. Switching control signal to return to low resolution setting
106 is generated and supplied to the drive circuit 14.

As described above, the control unit 22 automatically switches between the high resolution and the low resolution of the captured image size at the time of image capturing in accordance with the information change amount of the image capturing signal in the monitor recording mode. Therefore, when the information change in the picked-up image is large, it is possible to perform control so that the image is picked up at a high resolution, and when the amount of information change is small, control is performed so that the image is picked up at a low resolution.

The switching control signal 106 output from the control unit 22
Are supplied to the drive circuit 14, and the drive circuit 14 supplies the drive signal corresponding to the low resolution setting or the high resolution setting represented by the switching control signal 106 to the image pickup unit 12. The drive circuit 14 generates the first drive signal when the low resolution is set, and generates the second drive signal when the high resolution is set.

A microphone 26 for converting voice into an electric signal is further connected to the control unit 22 via a connection line 120. The control unit 22 has a function of detecting the voice signal 120 as a release signal, for example. Have. The control unit 22 generates a release signal when a sound pressure equal to or higher than a predetermined level is detected, and starts still image shooting or moving image shooting according to the menu setting. The control unit 22 also detects the detected audio signal 120.
Has a function of performing digital signal processing, audio coding through the compression coding circuit 28, and then recording it on the recording medium 30. In this case, the audio signal at the time of capturing the moving image and the still image is recorded by, for example, the MPEG system. It can be recorded on a recording medium.

The change amount of the audio signal 120 can be used as the change information of the analog amount detected when the moving image is picked up. Control unit in monitoring recording mode
22 calculates, for example, a root mean square as an average value of the audio signal 120, and compares this with a predetermined threshold value to determine whether or not the change amount of the information amount at the time of imaging is large at predetermined time intervals. judge. The control unit 22 sets the high resolution when the determination result indicates that the information change amount is large, and sets the low resolution setting when the determination result indicates that the information change amount is small.

The compression encoding circuit 28 connected to the memory 20 via the connection line 116 is a processing circuit for compression encoding the image signal read from the recording area of the memory 20. The compression encoding circuit 28 performs appropriate encoding processing according to the input moving image signal and still image signal.

Specifically, in the moving image shooting mode, the compression encoding circuit 28, when a moving image signal is input to the input 116, encodes the moving image signals of consecutive frames into intraframe and / or interframe codes. It has a function of sequentially encoding by the encoding processing. Examples of this moving image coding processing include the MPEG system and the coding standard (I
TU-T H.261) etc. are advantageously applied, and the compression encoding circuit 28
Detects a motion vector and performs motion compensation predictive coding.

Further, the compression encoding circuit 28 is connected to a recording medium via a connection line 130, and has a function of controlling writing and reading of information with respect to the recording medium 30 including a semiconductor memory or the like in this embodiment. The compression encoding circuit 28 outputs the processed encoded data to the output 130 and sequentially writes the encoded data in a predetermined storage area of the recording medium. The parameter for information amount compression that determines the compression rate such as the quantization coefficient in the compression encoding circuit 28 is the menu operation and control unit 22.
Is set in advance in this embodiment, and in the present embodiment, it is configured so that it cannot be changed midway during the capturing and recording of the moving image encoded data. However, as will be described in an example described later, it is possible to change the compression amount in the compression process during the image pickup, depending on the information change amount at the time of image pickup.

Further, the compression encoding circuit 28 has a function of performing still image compression encoding processing on an image signal representing a still image of one frame when a still image signal is input in the still image capturing mode. ing. As the still image compression encoding processing, for example, a standardized JPPG method or the like is advantageously applied.

Further, the compression encoding circuit 28 performs the above-described moving image compression encoding processing on the low resolution moving image signals of the continuous frames output from the image pickup section 12 by the first drive signal in the monitor recording mode, Second with high resolution setting
The still image compression processing described above is performed on the image signal output from the image pickup unit 12 by the drive signal of. As described above, also in the compression encoding circuit 28, the compression process is switched when the resolution is switched.

In the surveillance recording mode,
In addition to the case where the image signals of consecutive frames are recorded on the recording medium, one of the frames of the moving image signal is intermittently thinned out in order to reduce the amount of information recorded on the recording medium, that is, at every predetermined interval. Only the frame image can be extracted and recorded in the recording medium 30. In this case, the recording interval can be set in advance by the control unit 22. Alternatively, interval shooting may be performed during still image shooting, and the shooting recording interval itself may be changed according to the degree of information change. As a result, for example, when the amount of change in the information is greatly increased or decreased, it is possible to record an image with a short frame interval on the record, and when the amount of change in the information is less increased or decreased, the frame interval is longer, or the frame interval is made longer. Such an image can be recorded on the recording medium 30.

The recording medium 30 may be an information recording medium having a semiconductor memory, a rotating recording medium such as an optical disc and a (optical) magnetic disc, and a recording medium such as an optical card. A recording medium such as a magnetic tape may be used. The camera 10 includes a recording / reproducing circuit suitable for the recording medium 30 used. Alternatively, the image signal obtained by photographing may be output to an external device so that the image signal is recorded by the external device.

The encoder 32 connected to the output 114 of the signal processing circuit 18 is a conversion circuit for converting the signal format output from the D / A converter 34 into a signal format suitable for the display device 40. For example,
When the display device 40 is a video device that inputs a composite video signal, the encoder creates a composite video signal by adding a synchronization signal or the like to the image signal output from the signal processing circuit 18.
Output to the D / A converter 34.

The part of the operation of the digital camera 10 in the present embodiment having the above-mentioned configuration, which is related to the resolution switching at the time of image pickup, will be described. First, when the monitor recording mode is selected, a resolution switching signal for driving the imaging unit 12 in the low resolution setting is supplied from the control unit 22 to the drive circuit 14. The image pickup device in the image pickup unit 12 is driven by 1/4 pixel thinning in response to the first drive signal supplied from the drive circuit 14, and pixel values corresponding to the amount of light received by each pixel are sequentially read out. Be done. These pixel values are subjected to processing such as amplification by an analog circuit in the image pickup section 12 and output as image signals to the output 100, and are converted into digital values by the A / D converter 16. The converted digital image signal is subjected to various corrections and adjustments in the signal processing circuit 18, and further converted into a YC image signal.

The image signal converted by the signal processing circuit 18 is accumulated in the storage area of the memory 20. This image signal is sequentially read and input to the compression encoding circuit 28, and the low resolution moving image signal of each frame is compression encoded.

On the other hand, the control unit 22 inputs the image signals sequentially accumulated in the memory 20 and the image signals stored before the image signals and calculates the difference between them. More specifically, as shown in FIG. 2, the control unit 22 has been
In step 200, the count value of the counter is reset, and in the following step 202, it is determined whether or not the count value indicates that T seconds have elapsed. If it is determined that T seconds have elapsed, the routine proceeds to step 204, where the difference between the image signals for the two frames stored in the memory 20 is calculated, and the change in the information amount from the two frame images is sent to the determination processing unit 24. Detected. The determination processing unit 24 further determines whether or not the calculated change amount of the information change is larger than a predetermined threshold value (step 20).
6).

As a result of this judgment processing, when the change amount is smaller than the threshold value, the routine proceeds to step 208, where the control unit 22 sets the low resolution. With this low resolution setting, the low resolution image signal is compressed by the moving image encoding process and finally recorded on the recording medium 30.

On the contrary, when the change amount is larger than the threshold value, the process proceeds to step 210, and the high resolution is set. In this high resolution setting, the image pickup device in the image pickup unit 12 is driven to read all pixels and output from the high resolution image signal pickup unit 12, and the compression encoding circuit 28 is passed through the signal processing circuit 18 and the memory 20.
Entered in. The high resolution image signal input to the compression encoding circuit 28 is compression encoded for each frame and finally recorded on the recording medium 30.

Next, the routine proceeds to step 212, where it is judged whether or not to continue the image pickup processing in this monitoring recording mode. If it continues, the routine returns to step 200, and thereafter the same judgment processing is carried out at step 200 to step 212. Is performed,
Resolution setting and switching processing are performed according to the determination result.

In the present embodiment, if it is determined in step 206 that the amount of change is small as a result of the change amount determination, the low resolution is set in step 208, so the high resolution photographing process continues for a predetermined time or longer. Even if a high-resolution image signal of multiple frames is recorded, if it is detected and determined that the amount of change is small after T seconds, the low-resolution setting is switched to high-resolution shooting with a large amount of information. It is prevented from continuing.

As described above, in the first embodiment, the drive for the image pickup unit 12 is switched according to the change of the analog information amount at the time of image pickup to switch the resolution of the image signal. The resolution of the image can be automatically switched by switching the compression encoding processing for the signal. More specifically, as shown in FIG. 3, the digital camera 300 according to the present embodiment has a memory 2
The selector 302 is connected to the output 116 of 0, one output 304 of the selector 302 is connected to the first compression encoding circuit 28a, the other output 306 is connected to the second compression encoding circuit 28b, and the control It differs from the camera 10 shown in FIG. 1 in that the output 106 of the section 22 is connected to the selector 302. Since other configurations may be the same as the configurations of the same reference numerals shown in FIG. 1, the description thereof will be omitted and only different points will be described.

Selector 3 connected to output 116 of memory 20
02 is the resolution switching signal 1 for the image signal input to the input 116.
It is a switching circuit that responds to 06 and switches to output 304 or output 306 and outputs. The selector 302 displays the resolution switching signal 106
Outputs the image signal to the output 304 when the low resolution setting is instructed, and outputs the image signal to the output 306 when the resolution switching signal indicates the high resolution setting.

The first compression encoding circuit 28a compresses the moving image signal input to the input 304 in the monitoring recording mode at a high compression rate, similarly to the compression encoding circuit 28 shown in FIG. Perform processing. The other second compression encoding circuit 28b
Performs compression coding of the image signal at a compression rate lower than that in the first compression coding circuit 28a in the monitoring recording mode. It should be noted that the second compression encoding circuit 28b may be configured to perform only the encoding process so as to perform the non-compression encoding under the control of the control unit 22 in the monitoring recording mode. First and second compression encoding circuits 28a, 28b
Records the encoded image data in the recording medium 30.

In the present embodiment, the control unit 22 outputs a control signal for picking up an image of a field with an image size preset in the menu to the output 104 and supplies it to the drive circuit 14, and at the same time, the moving image shooting mode, the still image Drive circuit for control signals to control shooting mode, automatic focus adjustment, automatic exposure, etc.
Supply to 14. The drive circuit 14 generates a drive signal according to the control of the control unit 22 and supplies the drive signal to the imaging unit 12.

In the second embodiment shown in FIG. 3, the change in the information amount at the time of image pickup is detected in the same manner as in the first embodiment, and the compression rate in the compression coding process is changed according to the change amount. However, in addition to this, the resolution switching for the image pickup unit 12 described in the first embodiment is performed by the resolution switching signal 106.
May be supplied to both the drive circuit 14 and the selector 302 to switch both the image size and the compression rate.

Further, in the first and second embodiments,
Although the configuration has been described in which the image signal subjected to the image pickup processing is recorded in the recording medium 30, the present invention is not limited to this. For example, as in the digital camera 400 shown in FIG. 4, a communication interface (I / F) is provided at the output of the compression encoding circuit 28. 402 connected to another processing device, for example, a personal computer 4 connected to the communication interface 404.
In 06, the image signal can be transferred via the transmission cable 408 by a standardized transfer method. In the third embodiment shown in FIG. 4, the digital camera shown in FIG.
The components denoted by the same reference numerals as 10 may have the same configurations, and are therefore denoted by the same symbols, and detailed description thereof will be omitted. In this digital camera 400, the output 410 of the D / A converter 34 is connected to the communication interface 402, and the image signal processed by the encoder 32 can be transferred to the personal computer 406 via the transmission cable 408.

In the personal computer 406, the transferred image signal is stored in the main memory to display the image, and the image signal is stored in the auxiliary storage device such as a fixed disk device. When the transmission bandwidth of the communication interface 402 is wide, for example, the compression encoding circuit 28 may not perform the compression encoding process, and the personal computer 406 side may perform the compression encoding process. In this case, information regarding resolution switching is included in the transmission data from the control unit 22 and transferred to the personal computer 406, so that the compression rate at the time of compressing and coding the image signal by the processing software in the personal computer 406 can be switched automatically. Can be configured to.

As described above, by using the digital camera 400 whose image size and resolution can be arbitrarily switched and changed, and the personal computer 406 as a recording medium, a surveillance system for constructing an image of the object scene in the surveillance recording mode is constructed. Therefore, the digital camera 400 can be installed at any place, and can be used as, for example, a surveillance camera in a room. In addition, by installing a personal computer and a camera at a remote place and connecting them with a transmission cable, it is possible to record remote image information and record the image information at a remote place. The camera
The 400 and the personal computer 406 may be configured to intervene a network between communication interfaces to transmit and receive image signals and the like. The resolution switching signal is sent to the PC 40
It may be generated on the side of 6 and the image pickup unit 12 and the compression encoding circuit 28 of the camera may be controlled by the resolution switching signal.

As described above, in each of the above embodiments,
Detects changes in analog information when capturing multiple frames,
Since the image resolution during image capturing and signal processing is automatically switched according to the information change amount of the video signal and the audio signal, the image resolution can be controlled independently during image capturing. When the amount of information change over time is large, a high-definition image with a large image size can be obtained. When the amount of information change during imaging is small, an image with a small image size is generated and The processed image signal can be recorded and output. As a result, the image signals of a plurality of frames can be efficiently recorded on the recording medium, and can be used as a camera for monitoring the inside and outside of the room, for example.

The image size may be reduced by adding adjacent pixels and averaging them in the signal processing circuit 18. In this case, the S / N ratio is improved,
In addition, the sensitivity can be increased, which is advantageous for shooting in a dark place. Regarding pixel addition, the solid-state image sensor may be driven so as to add pixels in the vicinity on the vertical charge transfer path in the solid-state image sensor.

Further, in each of the above-described embodiments, the monitoring recording mode has been described based on the moving image shooting mode as a basic structure in which the moving image capturing and recording is performed at a low resolution. The monitoring recording mode can be applied not only to shooting but also to shooting a still image for each frame. Specifically, in a digital still camera, 1
The present invention can be applied during interval shooting in which shooting and recording for each frame is performed at predetermined intervals. in this case,
Depending on the degree of change in the information amount of the captured image, the resolution can be switched by the image size switching process when capturing an image. Further, it is possible to control the compression ratio to variably control the resolution. Further, by changing the resolution according to the change in the amount of information, important data after the change can be recorded at a high resolution, and data that does not change or little changes can be recorded at a low resolution. , It has a great effect when applied to a surveillance camera.

[0059]

As described above, according to the present invention, there is provided an image pickup apparatus capable of autonomously switching resolutions during image pickup. In the configuration in which the image size is changed by switching the drive of the solid-state image sensor, the resolution of the captured image can be automatically controlled by changing the output signal itself from the image capturing unit. Further, in the configuration in which the compression encoding process is switched to switch the resolution, the resolution of a predetermined frame can be automatically changed by an image signal having a constant image size.

In this way, changes in the input image signal and the audio signal are detected, the resolution is reviewed at a predetermined interval,
The resolution of the image signal can be automatically switched according to the result of this review. The resolution switching control can use a method of changing the image size or a method of changing the compression rate at the time of image compression, and these methods can be used together.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a digital camera to which an image pickup apparatus and an image pickup method of the present invention are applied.

2 is a flowchart showing an example of resolution switching control of the digital camera shown in FIG.

FIG. 3 is a block diagram showing a second embodiment of the digital camera.

FIG. 4 is a block diagram showing a third embodiment of the digital camera.

[Explanation of symbols]

10 digital camera 12 Imaging unit 14 Drive circuit 18 Signal processing circuit 20 memory 22 Control unit 24 Judgment processing unit 28 Compression coding circuit 30 recording medium

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Claims (20)

[Claims] 1. An image pickup apparatus for picking up an image of a field to generate image signals of a plurality of frames, wherein the apparatus takes an image of the field for each first time interval and sets a plurality of frames according to the image pickup. Image pickup means for generating an image signal representing the photographed image, driving means for driving the image pickup means, signal processing means for processing the image signal, and temporarily storing the image signal processed by the signal processing means. A storage unit, a signal output unit for outputting the image signal stored in the storage unit, and a resolution of the image signal during imaging is reviewed every second time interval in accordance with the image signal stored in the storage unit. And a control unit for generating the image signal at the reviewed resolution, the control unit detecting a change in analog information at the time of imaging, and determining whether to switch the resolution according to the change. Judgment Includes a stage, an imaging apparatus characterized by performing control for switching the resolution of the image signal according to the determination result of said determining means. 2. The image pickup apparatus according to claim 1, wherein the control unit switches the driving of the image pickup unit according to the determination result of the determination unit to capture an image with a low resolution or a high resolution image size. A characteristic imaging device. 3. The image pickup apparatus according to claim 2, wherein the drive unit thins out and drives the image pickup unit when the control unit takes an image with the low resolution image size. Imaging device. 4. The image pickup device according to claim 3, wherein the driving unit thins out and reads out the image pickup unit and outputs the image signal from the image pickup unit at a high transfer rate. Imaging device. 5. The image pickup device according to claim 2, wherein the drive unit drives the image pickup unit to read all pixels when the control unit takes an image with the high resolution image size. Image pickup device. 6. The image pickup apparatus according to claim 1, wherein the signal output unit includes a compression encoding unit that encodes the image signal stored in the storage unit, and the control unit includes:
An image pickup apparatus, wherein the compression rate in the compression encoding means is switched according to the determination result of the determination means. 7. The image pickup apparatus according to claim 1, wherein the control means includes a first image signal processed by the signal processing means and a second image signal processed before the first image signal. An image pickup apparatus, which compares an image signal and detects the amount of change in the analog information based on the first and second image signals. 8. The image pickup apparatus according to claim 7, wherein the storage means has a storage area for storing at least two frames of the image signal, and the control means stores 2 areas stored in the storage area. An image pickup apparatus, characterized in that the amount of change in the analog information is detected based on an image signal for a frame. 9. The image pickup apparatus according to claim 7, wherein the control unit calculates a difference value as a difference between the first image signal and the second image signal, and calculates the difference value and a predetermined value. An image pickup apparatus, characterized in that a comparison is made with a threshold value, and the determination means performs control to switch the resolution of the image signal according to the result of the comparison. 10. The image pickup apparatus according to claim 1,
The image pickup apparatus, wherein the control means inputs a voice signal representing a voice when the image pickup means picks up an image, and detects a change amount of the analog information based on a change of the voice signal. 11. The imaging device according to claim 1, wherein:
The image pickup apparatus, wherein the signal output unit includes a communication unit that transfers the image signal stored in the storage unit to an external processing device via a transfer cable. 12. The image pickup device according to claim 11, wherein the communication unit outputs an image signal read from the storage unit and encoded by the compression encoding unit to the transfer cable. Image pickup device. 13. The image pickup apparatus according to claim 1,
The signal output means transmits a resolution switching signal for controlling the resolution switching of the image signal according to the determination result of the determination means to the external processing device via the transfer cable. . 14. An imaging method for capturing an image of a scene and generating image signals of a plurality of frames, the method comprising: capturing an image of a scene at a first time interval and displaying a plurality of frames according to the image capture. An image capturing step for generating an image signal representing the captured image, a resolution reviewing step for reviewing the resolution of the image signal during image capturing every second time interval, an image processing step for image-processing the image signal, The method includes a compression encoding step of compression encoding the image signal processed in the processing step, and an output step of outputting the image signal processed in the compression encoding step, wherein the resolution reviewing step is performed at the time of imaging. An imaging method comprising detecting a change in analog information, determining whether or not to switch the resolution according to the change, and switching the resolution of the image signal according to the determination result. 15. The image pickup method according to claim 14, wherein in the resolution review step, driving of an image pickup unit for picking up an object scene is switched to pick up an image with a low resolution or a high resolution. Imaging method. 16. The image pickup method according to claim 14, wherein the resolution review step changes the compression rate of the compression encoding process in the compression encoding step to switch the resolution of the image signal. Imaging method. 17. The image-capturing method according to claim 14, wherein the resolution review step includes a captured first image signal and a second image captured before the first image signal and temporarily stored. An image pickup method comprising: comparing with an image signal, and detecting the amount of change in the analog information based on the first and second image signals. 18. The image pickup method according to claim 17, wherein in the resolution review step, a difference value is calculated as a difference between the first image signal and the second image signal, and the difference value is calculated as the difference value. An image pickup method comprising: comparing with a predetermined threshold value, and switching the resolution of the image signal according to the comparison result. 19. The image pickup method according to claim 14, wherein the resolution review step detects the amount of change in the analog information based on a change in a voice signal representing a voice during image pickup. Imaging method. 20. The image pickup method according to claim 14, wherein in the output step, a resolution switching signal for performing control for switching the resolution of the image signal in accordance with the determination result in the resolution review step is provided to the external processing device. The image is transmitted via the transfer cable to the image capturing method.