JPH1175106A - Still image camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a shake of a subject caused by movement of the subject at exposure for a long time. SOLUTION: A main frame memory 19 records plural digital image signals received sequentially from a movement correction circuit 17 for a prescribed period and records the sum. When the main frame memory 19 receives digital image signals i1 from an adder circuit 18 for plural prescribed number of times, recorded data are read from the memory 19 as digital image signals j1 and fed to a digital signal processing circuit DSP 20 and recorded data re cleared. A motion detection circuit 16 conducts timing control by a control pulse signal d1 from the DSP 20 and detects a movement of the subject by comparing the digital image signal h1 recorded in the main frame memory 19 with digital image signals e12 stored in a work frame memory 15 and provides an output of a control signal f1 used to control a mobile position of the movement correction circuit 17 to correct the movement denoted by the detection result.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a still image camera that captures a still image and converts the image into a video signal, and more particularly to a still image camera that can reduce a shake when a subject moves during long-time exposure.

[0002]

2. Description of the Related Art In recent years, with the spread of personal computers, still image cameras capable of capturing still images in a personal computer at low cost and in a short time have rapidly become widespread.

FIG. 4 is a block diagram showing such a conventional still picture camera.

In FIG. 4, reference numeral 71 denotes an image pickup lens. The image pickup lens 71 focuses light from a subject on a sensor section of an image pickup element 72.

[0005] An image pickup element 72 receives a control pulse signal d0 from a digital signal processing circuit (hereinafter referred to as DSP) 75.
, An image formed by the imaging lens 71 is captured, converted into an analog image signal a0, and supplied to a correlated double sampling circuit (hereinafter, referred to as a CDS circuit) 73.

The CDS circuit 73 performs timing control by the control pulse signal d0 from the DSP 75, performs CDS processing on the supplied analog image signal a0,
The analog image signal b0 subjected to the CDS processing is supplied to an analog / digital conversion circuit (hereinafter, referred to as an A / D conversion circuit) 74. The A / D conversion circuit 74 controls the timing by the control pulse signal d0 from the DSP 75, and
The analog image signal b0 from the S circuit 73 is converted into a digital image signal c0 and supplied to the DSP 75. DSP75
Denotes an image sensor 72, a CDS circuit 73, and an A / D conversion circuit 7.
4 to supply a control pulse signal d0 to perform timing control, to output a digital image signal c0 to the A / D conversion circuit 74 at a desired timing, perform a color process on the digital image signal c0, A digital color signal g0 is created and output. The digital luminance signal and digital color signal g0 are encoded by an encoder and displayed on a liquid crystal panel as an analog video output, and are also conversion-encoded via a discrete cosine conversion circuit or the like and recorded on a recording medium.

FIG. 5 is an explanatory diagram showing the operation timing of the image pickup device of FIG.

In FIG. 5, a video signal stored on an image sensor 72 is read in a single signal read period after an exposure period. The video signal (analog image signal a0) thus read out is subjected to the signal processing described with reference to FIG. 4, and is output as a digital luminance signal and a digital chrominance signal g0.

Here, in such a conventional still image camera, in order to obtain an image without vibration under a photographing condition in which a subject moves at a high speed (for example, photographing a running car, a belt conveyor flowing at a high speed). Requires a shorter exposure time (faster shutter speed). At this time, unless the subject is irradiated with a large amount of light, the signal level of the image sensor decreases, and the resulting video output has a poor signal-to-noise ratio.

[0010]

In the above-described conventional still image camera, an image having no shake can be obtained under photographing conditions in which a subject moves at a high speed (for example, photographing a running car, a belt conveyor flowing at a high speed, etc.). To achieve this, the exposure time must be reduced (shutter speed is increased). At this time, unless the subject is irradiated with a large amount of light, the signal level of the image sensor decreases, and the resulting video output has a poor signal-to-noise ratio.

SUMMARY OF THE INVENTION It is an object of the present invention to eliminate the above-mentioned problems and to provide a still image camera capable of reducing subject shake caused by movement of a subject during long-time exposure.

[0012]

SUMMARY OF THE INVENTION A still image camera according to the present invention comprises an image sensor for sequentially converting an exposed image into an analog image signal, and an analog / digital converter for converting an analog image signal from the image sensor into a digital image signal. A digital conversion circuit, a working frame memory for recording one frame of the digital image signal from the analog / digital conversion circuit, and reading the recorded digital image signal;
A movement correction circuit for moving the position of the entire image with respect to the digital image signal read from the working frame memory, and a plurality of digital image signals sequentially supplied from the movement correction circuit are recorded while being added for a predetermined period. The movement of the subject is detected by comparing the main frame memory with the digital image signal recorded by the main frame memory and the digital image signal recorded by the working frame memory, and the movement indicated by the detection result is corrected. A movement detection circuit that controls the movement position of the movement correction circuit, and a digital signal processing circuit that performs predetermined signal processing on a digital image signal recorded in the main frame memory and outputs a digital video signal. It is characterized by having.

[0013]

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

FIG. 1 is a block diagram showing a first embodiment of a still picture camera according to the present invention.

In FIG. 1, reference numeral 11 denotes an image pickup lens. The image pickup lens 11 forms an image of light from a subject on a sensor section of an image pickup device 12.

The image pickup device 12 is composed of, for example, a charge-coupled device (hereinafter, referred to as CCD), and a control pulse signal d from a digital signal processing circuit (hereinafter, referred to as DSP) 20.
An image formed by the imaging lens 11 is controlled by the control unit 1 and converted into an analog image signal a1 and supplied to a correlated double sampling circuit (hereinafter, referred to as a CDS circuit) 13. In this case, the image sensor 12 sequentially converts the exposed images into analog image signals a1 by reading out the exposed images by dividing the exposure period into several orders.

The CDS circuit 13 performs timing control by the control pulse signal d1 from the DSP 20, performs CDS processing on the supplied analog image signal a1, and
The CDS-processed analog image signal b1 is supplied to an analog / digital conversion circuit (hereinafter, referred to as an A / D conversion circuit) 14. The A / D conversion circuit 14 performs timing control by the control pulse signal d1 from the DSP 20, and performs CD control.
The analog image signal b1 from the S circuit 13 is converted into a digital image signal c1 and supplied to the working frame memory 15.

The work frame memory 15 includes a DSP 20
Is controlled by the control pulse signal d1 from the A / D converter 14, the digital image signal c1 from the A / D conversion circuit 14 is recorded for one frame, and the data of the same digital image signal recorded is read out at two different timings. The digital image signal e11 read at the first timing is supplied to the movement detection circuit 16, and the digital image signal e12 read at the next timing is transferred to the movement correction circuit 1.
7

The movement correction circuit 17 moves the position of the entire image (the center of gravity of the image) with respect to the digital image signal e11 read from the working frame memory 15 based on the correction control signal f1 from the movement detection circuit 16. By doing so, a digital image signal g1 with the subject shake corrected is created and supplied to the addition circuit 18. The addition circuit 18 adds the digital image signal g1 from the movement correction circuit 17 and the digital image signal h1 read from the main frame memory 19 to create a digital image signal i1 and supplies it to the main frame memory 19.

The main frame memory 19 includes a DSP 20
The timing control is performed by the control pulse signal d1 from the controller, and the working frame memory 15 stores the digital image signal e1
The image data recorded is read out as a digital image signal h1 in synchronization with the timing of reading out the data No. 2, but the data is not rewritten at this timing. The main frame memory 19 stores the digital image signal g1
Is read out as a digital image signal h1 in synchronism with the timing at which is read out, and the digital image signal i1 from the addition circuit 18 is written into the read-out recording area. Thereby, the main frame memory 19 records a plurality of digital image signals sequentially supplied from the movement correction circuit 17 while adding them for a predetermined period. Mainframe memory 19
Supplies the recorded data to the DSP 20 as the digital image signal j1 when the digital image signal i1 from the adder circuit 18 is supplied a predetermined number of times (the number of times in this case can be set to an appropriate value depending on the exposure time). With
Clear the recorded data.

The movement detection circuit 16 is controlled in timing by the control pulse signal d 1 from the DSP 20, and outputs the digital image signal h 1 recorded in the main frame memory 19.
And the digital image signal e12 recorded by the working frame memory 15 to detect a subject shake, and control the movement position of the movement correction circuit 17 so as to correct the subject shake indicated by the detection result. Control signal f
Outputs 1. In this case, as a method of detecting a subject shake, a method of detecting a subject movement at the center of the screen of the digital image signals h1 and e12 by detecting a displacement of an image at the center of the screen, A method of extracting a different image component between the digital image signals h1 and e12 and detecting a shift of the different image component to detect the movement of the subject can be considered.

The DSP 20 includes an image pickup device 12, a CDS circuit 13, an A / D conversion circuit 14, and a working frame memory 1.
5, the timing control is performed by supplying the control pulse signal d1 to the movement detection circuit 16 and the main frame memory 19,
The digital image signal j1 is output to the main frame memory 19 at a desired timing.
Performs color processing on the image data to generate and output a digital luminance signal and a digital color signal k1. The digital luminance signal and the digital chrominance signal k1 are encoded by an encoder, displayed as an analog video output on, for example, a liquid crystal panel, converted and coded via a discrete cosine conversion circuit or the like, and recorded on a recording medium.

With such a configuration, the movement correction circuit 17
Operates as an image moving circuit for moving the position of the entire image with respect to the digital image signal e11 read from the working frame memory 15, and the movement detecting circuit 16 detects the digital image signal h1 recorded by the main frame memory 19 and By comparing the digital image signal e12 recorded by the working frame memory 15 with the digital image signal e12, the displacement of the subject is detected, and the moving position of the video moving circuit is controlled so as to correct the displacement indicated by the detection result. The movement correction detection circuit outputs a control signal.

FIG. 2 is an explanatory diagram showing the operation timing of the image pickup device of FIG.

In FIG. 2, the total exposure time of the image pickup device 12 is divided into an eighth-order exposure period and a corresponding readout period. An output signal (frame) corresponding to each period of the eighth exposure period is sequentially referred to as a first frame, a second frame,..., An eighth frame.

The operation of the configuration example will be described below for each frame.

First, the digital image signal of the first frame is written to the main frame memory 19 without being processed by the movement detection circuit 16, the movement correction circuit 17, and the addition circuit 18 such as movement correction and addition. Next, the second frame is first written into the working memory, compared with the first frame on the main frame memory 19 by the movement detection circuit 16, and corrected for movement by the movement correction circuit 17. The result is added to the first frame on the memory 19 and written into the main frame memory 19 again. That is, assuming that the signal of the n-th frame is Sn and the signal of the n-th frame after movement correction is Sn (C), the data in the main frame memory 19 at this time is S1 + S
2 (C) + S3 (C) + S4 (C) + S5 (C) + S6
(C) + S7 (C) + S8 (C). Data after the second frame is always added after being corrected in accordance with the position of the subject in the first frame, so that the image on the main frame memory 19 is an image in which the shake of the subject has been sufficiently reduced.

According to the embodiment of the present invention, it is possible to reduce subject shake caused by movement of the subject during long-time exposure, and to give a good impression to the user.

Next, additional functions that can be easily realized by the same configuration will be described.

There is a problem that a fixed pattern noise such as white scratches and unevenness of the background due to dark current occurs in a semiconductor image pickup device, and this problem is particularly remarkable during long-time exposure or photographing at high temperature. This fixed pattern noise is
Correction can be made by subtracting dark data (data with the mechanical shutter closed, etc.) at the same exposure time immediately before or immediately after shooting from the shot data. From this, the fixed pattern noise is subtracted from the data in the main frame memory 19 and written into the main frame memory 19 only when the dark data is fetched by the adder circuit 18 in the embodiment of the present invention in FIG. Can be corrected.

FIG. 3 is a block diagram showing a second embodiment of the still picture camera according to the present invention.

In FIG. 3, reference numeral 31 denotes an image pickup lens. The image pickup lens 31 forms an image of light from a subject on a sensor section of an image pickup device 32.

The image pickup device 32 is controlled by a control pulse signal d2 from the DSP 40, takes in an image formed by the image pickup lens 31, converts it into an analog image signal a2,
It is supplied to the CDS circuit 33.

The timing of the CDS circuit 33 is controlled by a control pulse signal d2 from the DSP 40, and the CDS circuit 33 performs a CDS process on the supplied analog image signal a2.
The CDS-processed analog image signal b2 is supplied to the A / D conversion circuit 34. The A / D conversion circuit 34 includes a DSP 40
The timing control is performed by the control pulse signal d2 from the first and second analog image signals b2 from the CDS circuit 33 into a digital image signal c2, and the first (eight in this embodiment) frame memory is used. To the eighth frame memories 5-1, 5-2, 5-3... 5-8.

First to eighth frame memories 5-1 and 5
.., 5-8, the timing is controlled by the control pulse signal d2 from the DSP 40, and the digital image signal c2 from the A / D conversion circuit 34 is sequentially recorded for one frame each, and the imaging is performed. After completion of the exposure by the element 32, the recorded digital image signals e2-1 and e2-
2, e2-3... E2-8 are read. In this case, the reading order is as follows. First, only the first frame memory 5-1 performs reading at the first timing, and then, the first frame memory 5-1 and the second frame memory 5-1 at the second timing. 5-2 perform reading simultaneously, and then the third
The first frame memory 5-1 and the third frame memory 5-3 perform readout at the timing of, and similarly, at the fourth to eighth timings, the first frame memory 5-1 always performs readout. Perform dashi and the fourth
The eighth to eighth frame memories 5-4 to 5-8 are switched and sequentially read.

The digital image signal e2-1 read from the first frame memory 5-1 is supplied to a first input terminal of the movement detection circuit 36. The digital image signals e2-2, e2-3,..., E2-8 read from the second through eighth frame memories 5-2, 5-3,. Supplied to

The movement detection circuit 36 supplies a digital image signal e2 from the first frame memory 5-1 to a first input terminal.
When -1 is supplied and the digital image signal is not supplied to the second input terminal, the digital image signal e2-1 from the first input terminal is directly supplied to the movement correction circuit 37 as the digital image signal f2. At the same time, a movement detection signal m2 indicating that the movement amount is 0 is supplied to the movement correction circuit 37. The movement detection circuit 36 has a first input terminal supplied with the digital image signal e2-1 from the first frame memory 5-1 and a second input terminal connected to the second to eighth frame memories. 5-2, 5-3 ... 5-8
, E2-3,... E2-8
Is detected, the subject shake is detected by comparing the digital image signal e2-1 of the first input terminal with the digital image signal of the second input terminal, and the subject indicated by the detection result is detected. A control signal m2 for controlling the movement position of the movement correction circuit 37 so as to correct the shake is output, and the digital image signal of the second input terminal is supplied to the movement correction circuit 37 as a digital image signal f2.

The movement correction circuit 37 moves the position of the entire image (the center of gravity of the image) with respect to the digital image signal f2 from the movement detection circuit 36 based on the correction control signal m2 from the movement detection circuit 36. The digital image signal g2 in which the subject shake is corrected is created and supplied to the adding circuit 38. The addition circuit 38 adds the digital image signal g2 from the movement correction circuit 37 and the digital image signal h2 read from the main frame memory 39 to create a digital image signal i2 and supplies it to the main frame memory 39.

The main frame memory 39 includes a DSP 40
The timing control is performed by the control pulse signal d2 from the controller 30 and the movement correction circuit 37 outputs the digital image signal g2.
And the writing of the digital image signal i2 from the adder circuit 38 is performed in the read recording area. Accordingly, the main frame memory 39 records a plurality of digital image signals sequentially supplied from the movement correction circuit 37 while adding them for a predetermined period. When the digital image signal i2 from the adding circuit 38 is supplied a predetermined number of times (8 times in the case of the embodiment of the present invention), the main frame memory 39 supplies the recorded data to the DSP 40 as a digital image signal j2. At the same time, the recorded data is cleared.

The DSP 40 includes an image sensor 32, a CDS circuit 33, an A / D conversion circuit 34, first to eighth frame memories 5-1, 5-2, 5-3... 5-8, and a main frame memory 39. A timing control is performed by supplying a control pulse signal d2, a digital image signal j2 is output to the main frame memory 39 at a desired timing, and color processing is performed on the digital image signal j2 to obtain a digital luminance signal and a digital color signal k2. And output.

With such a configuration, the movement detection circuit 36
Represent a plurality of frame memories 5-1, 5-2, 5-3,.
By comparing the digital image signal of the first frame memory and the digital image signals of the remaining frame memories among the digital image signals recorded by -8, the movement of the subject in the remaining plurality of frame memories is performed. The movement is detected and a movement detection signal indicating the detection result is output. The movement correction circuit 37 moves the position of the entire image based on the detection result from the movement detection circuit 36 with respect to the digital image signals read from the remaining plurality of frame memories. The main frame memory 39 is a circuit means for adding and recording at least two of the plurality of digital image signals via the movement correction circuit 37 and the digital image signals of the first frame memory.

In the embodiment of the present invention, there are as many frame memories as frames for storing each frame read by the image pickup device 32 by dividing the exposure time by dividing the exposure period.

In the embodiment of the present invention, the same effects as those of the embodiment of the invention shown in FIG. 1 are obtained. In addition, after the end of the exposure time, the movement detection, the movement correction, and the addition are collectively performed. Since a time margin occurs when performing the correction calculation, it is suitable when complicated movement detection is required.

In the embodiments of the present invention shown in FIGS. 1 to 3, a charge-coupled device is used as the image pickup device in consideration of generality and cost performance.
For example, an area BASIS or the like may be used.

[0045]

According to the present invention, it is possible to reduce the subject shake caused by the movement of the subject during long-time exposure, and to give a good impression to the user.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of a still image camera according to the present invention.

FIG. 2 is an explanatory diagram showing operation timings of the image sensor of FIG. 1;

FIG. 3 is a block diagram showing a still image camera according to a second embodiment of the present invention.

FIG. 4 is a block diagram of a conventional still image camera.

FIG. 5 is an explanatory diagram showing operation timings of the image sensor of FIG. 4;

[Explanation of symbols]

 Reference Signs List 11 imaging lens 12 imaging element 13 CDS circuit 14 A / D conversion circuit 15 work frame memory 16 movement detection circuit 17 movement correction circuit 18 addition circuit 19 main frame memory 20 DSP

Claims (5)

[Claims] An imaging device for sequentially converting an exposed image into an analog image signal; an analog / digital conversion circuit for converting an analog image signal from the imaging device into a digital image signal; and an analog / digital conversion circuit. A working frame memory for recording the digital image signal for one frame and reading the recorded digital image signal, and a movement for moving the position of the entire image with respect to the digital image signal read from the working frame memory A correction circuit; a main frame memory for recording a plurality of digital image signals sequentially supplied from the movement correction circuit while adding them for a predetermined period; a digital image signal recorded by the main frame memory and the work frame memory being recorded Movement of the subject by comparing with the digital image signal A movement detection circuit that detects and controls the movement position of the movement correction circuit so as to correct the movement indicated by the detection result; and performs predetermined signal processing on the digital image signal recorded in the main frame memory, and A digital signal processing circuit for outputting a video signal; and a still image camera. 2. An image pickup device for sequentially converting an exposed image into an analog image signal, an analog / digital conversion circuit for converting an analog image signal from the image pickup device into a digital image signal, and an analog / digital conversion circuit. The digital image signals are recorded one frame at a time.
A plurality of frame memories for reading out the recorded digital image signals; and a digital image signal of the first frame memory and a digital image signal of the remaining plurality of frame memories among the digital image signals recorded by the plurality of frame memories. A movement detection circuit that detects the movement of the subject in the remaining plurality of frame memories and outputs a movement detection signal indicating the detection result; and a digital image read from the remaining plurality of frame memories. A movement correction circuit for moving a position of the entire image based on a detection result from the movement detection circuit with respect to a signal; a plurality of digital image signals via the movement correction circuit; and a digital image signal of the first frame memory A main frame memory for adding and recording at least two of the main frames; A digital signal processing circuit that performs predetermined signal processing on a digital image signal recorded in a memory and outputs a digital video signal. 3. The image pickup device according to claim 1, wherein the image pickup device sequentially converts the exposed images into analog image signals by reading out the exposed images by dividing the exposure period into several orders. The still image camera according to any one of the above. 4. The digital signal processing circuit according to claim 1, wherein the digital signal processing circuit performs color processing on the digital image signal recorded in the main frame memory and outputs a digital luminance signal and a digital color signal. The still image camera according to any one of the above. 5. The still image camera according to claim 1, wherein a charge-coupled device is used as the image pickup device.