JPH1013734A - Image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high image quality still image with less noise in the case of picking up a still image. SOLUTION: A signal picked up by a CCD 1 is processed by a camera signal processing section 3 to obtain a motion extract signal 12 and a processed image signal 13. A motion detection section 4 detects a motion from the motion extract signal 12 to obtain a motion information signal 14. A motion correction section 5 uses the motion information signal 14 to correct the camera-shake component of the image signal 13 to obtain a corrected image signal 15. The image signal 13 or 15 is selected by a switch 6 and given to a noise reduction section 7, in which noise is reduced. In this case, the noise reduction section 7 is operated to reduce much noise when the motion is small based on the motion information signal 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup apparatus, and more particularly to an image pickup apparatus suitable for use in the field of picking up digital moving images and still images.

[0002]

2. Description of the Related Art A color CCD solid-state image pickup device often used in consumer video cameras and the like has a plurality of color filters of a plurality of colors on a surface of a large number of two-dimensionally arranged photoelectric conversion units. Mounted in a pattern. Therefore, the signal obtained from the CCD has luminance information and color information superimposed as a color carrier. Then, the camera signal processing section first separates the luminance information and the color information, performs the luminance signal processing and the color signal processing in parallel, and finally obtains a video signal conforming to a television standard such as NTSC or PAL. In many cases, a signal is obtained.

[0003]

However, in the above-mentioned conventional technique, a demodulated RGB signal obtained by demodulating a color carrier having a relatively small amplitude in a process of obtaining a color signal and amplifying the color carrier to a level equivalent to a luminance signal by a matrix operation. Is generated, so that there is a problem that noise of the color signal is larger than that of the luminance signal. In particular, in recent years, an image signal generated from a two-dimensional solid-state imaging device is output as a conventional moving image to a television monitor conforming to standards such as NTSC and PAL, and a medium other than television, such as a computer or a printer. There is an increasing tendency to output a still image to an information device, but in this case, the noise of the color signal appears as color unevenness in the still image, so that there is a problem that the image quality is more conspicuous as a deterioration in the quality of the moving image. As a method often used in the related art for such a color noise problem, a method of removing noise by taking an averaging using correlation in an image in a spatio-temporal direction has been attempted. However, this method has a problem that when taking a moving image, if the averaging is performed in the time axis direction, the dynamic resolution is reduced, so that sufficient noise cannot be removed.

The present invention has been made to solve the above-mentioned problem, and has as its object to obtain a high-quality image with little noise when the image has little motion.

[0005]

According to the present invention, there is provided an image pickup means for picking up an image of a subject and outputting an image pickup signal, and a signal processing for processing the image pickup signal and outputting a processed image signal and a motion extraction signal. Means, noise reduction means for reducing noise of the image signal processed by the signal processing means, and detecting the motion of the image from the motion extraction signal, and controlling the characteristics of the noise reduction means in accordance with the detected motion. And a motion detecting means for detecting the motion.

[0006]

According to the present invention, the noise reduction characteristic can be adaptively changed in accordance with the motion information of the captured image. A small number of high-quality still images can be obtained. That is, when the captured image is a moving image with a lot of motion, the noise reduction process as conventionally used is performed, and when the motion image is a little moving image and close to a still image, the noise reduction process is also performed in the time axis direction. By doing so, a high-quality image with little noise can be obtained when shooting a still image.

[0007]

FIG. 1 shows a first embodiment of the present invention. In FIG. 1, 1 is a CCD image sensor, 2 is A /
D converter, 3 a camera signal processing unit, 4 a motion detection unit, 5 a motion correction unit, 6 a signal selection switch, 7 a noise reduction unit, 8 a first interface unit, 9 a second interface unit, 10 is a printer, 11 is NTSC
A television monitor, 12 is a signal for motion extraction, 13 is an image signal processed by the camera signal processing unit 13, 14 is a motion information signal, and 15 is an image signal after motion correction.

Next, the operation will be described. An image signal obtained from the CCD image pickup device 1 is sampled by an A / D converter 2 to become a digital signal, and a predetermined process is performed by a camera signal processing unit 3 to obtain a motion extracting signal 12 and an image signal 13. Are generated. The signal 12 for motion extraction is sent to the motion detection unit 4, and the image signal 13 is sent to the motion correction unit 5 and the 0-side input of the signal selection switch 6. The signal selection switch 6 is switched by an on / off control of the motion compensation function from the outside, and is connected to the 0 side when the motion compensation function is off and the 1 side when the motion compensation function is on.

In the motion detecting section 4, a signal 12 for motion extraction is
, The motion information of the captured image is detected, and a motion information signal 14 is output. The motion information signal 14 is sent to the motion correction unit 5 and the noise reduction unit 7. The motion corrector 6 removes unnecessary motion such as camera shake contained in the captured image based on the motion information signal 14, and then sends the motion-corrected image signal 15 to one input of the signal selection switch 6.

On the other hand, the noise reduction unit 7 changes the noise reduction characteristic based on the motion information signal 14 so that the noise of the output image signal of the signal selection switch 6 is removed more as the image movement is smaller. Operate. Therefore,
When a still image is captured, a high-quality image with little noise can be obtained.

The output image signal of the noise reduction unit 7 is sent to an external printer 10 through a first interface unit 8, and is sent to an external N through a second interface unit 9.
It is sent to the TSC monitor 11 and provided as an actual image.

FIG. 2 shows a second embodiment of the present invention.
In FIG. 2, reference numeral 1 denotes non-addition reading (all-pixel reading) C
CD, 2 is an A / D converter, 3 is a camera signal processing unit,
4 is a motion detection block, 41 is a first field memory, 42 is a subtractor, 43 is an absolute value operation circuit, 44
Is an integrator, 45 is a motion vector generation circuit, 46 is a threshold value setting circuit, and 47 is a comparator. 5 is a motion correction unit, 7
Is a noise reduction unit, 71 is a second field memory, 72 is a line memory, 73 is a first adder, 74 is a second adder, and 70 is a switch. Reference numeral 8 denotes a first interface unit, 8 denotes a second interface unit, 16 denotes a first output unit, and 17 denotes a second output unit. Reference numeral 10 denotes a printer outside the video apparatus, and reference numeral 11 denotes an NTSC television monitor.

Next, the operation will be described. The image signal obtained from the non-addition reading CCD 1 is sampled by the A / D converter 2 to become a digital signal, which is input to the camera signal processing unit 3. The camera signal processor 3 outputs a luminance signal Y, a color difference signal RB, and a luminance signal Ym for motion detection from the image signal from the CCD 1. The signal Ym is a luminance signal obtained by extracting edge information of an image in which predetermined high-frequency components and low-frequency components have been suppressed so as to be convenient for detecting the motion of a captured image. The luminance signal Y
And the color difference signal RB are sent to the motion correction unit 5, and the motion detection luminance signal Ym is sent to the motion detection unit 4.

The motion detector 4 first stores the signal Ym in the first field memory 41, and the subtractor 42 calculates the difference between the current field Ym and the previous field Ym. This Ym difference is sent to the motion vector generation circuit 45, where the motion correction signal 14 is generated and
To correct unnecessary image motion such as camera shake contained in the luminance signal Y and the color difference signal RB.

On the other hand, the difference of Ym is calculated by an absolute value calculating circuit 4.
At 3, it is converted to an absolute value, and is integrated by the integrator 44 within a predetermined integration range. Here, if the captured image is stopped,
Since the difference is almost zero in the predetermined integration range, the integration result of the integrator 44 does not become a large value. If there is a moving part in the captured image, a part having a certain value in the difference appears, and the integral of its absolute value should be a certain value. The comparator 47 compares the integration result of the integrator 44 with a threshold value externally set in the threshold value setting circuit 46. If the integration result is smaller than the threshold value, the output voltage is changed to the low level. If the integration result is larger than the threshold value, the output voltage is set to Hi.
gh level. This output voltage is used for controlling the switch 75 of the noise reduction unit 7.

The RB of the luminance signal Y and the chrominance signal RB, which have been motion-compensated by the motion compensator 5, is input to the noise reducer 7, and the second field memory 71 and the line memory 7
2, the first adder 73 performs synchronous addition of the current field and the color difference signal of the previous field, and the second adder 74 performs synchronous addition of the current line and the color difference signal of the previous line. Accordingly, the noise of the color difference signal is reduced by two types of noise reduction characteristics. The color difference signal obtained from the first adder 73 is noise reduction using field correlation, and although the dynamic resolution is reduced, the noise reduction effect is large. On the other hand, the second adder 7
The color difference signal obtained from No. 4 is noise reduction using line correlation, and the effect of noise reduction is not great but does not affect the dynamic resolution.

As described above, the control of the switch 70 is connected to the 0 side by the comparator 47 when the picked-up image is stopped, and a color difference signal subjected to noise reduction of the field correlation is output by the comparator 47. If a moving part is included, a color difference signal subjected to noise reduction processing of line correlation is output. As described above, the luminance signal Y and the chrominance signal RB output with the noise reduction characteristics changed in accordance with the movement of the captured image are converted into a data format that matches information devices such as a computer and a printer by the first interface unit 8. After the conversion, from the first output unit 16,
Is output to the printer 11. After being converted into a video signal of the NTSC standard by the second interface unit 8, the video signal is output from the second output unit 17 to the NTSC television monitor 12.

FIG. 3 shows a third embodiment of the present invention.
In FIG. 3, the configurations of the motion detection unit 6 and the noise reduction unit 7 are different from those in FIG. 2, and the other parts are the same as those in FIG. 2. Therefore, only the different parts will be described. A duplicate description of is omitted. First, in the motion detector 4, the first threshold setting circuit 461,
A second threshold setting circuit 462, a third threshold setting circuit 463, a first comparator 471, a second comparator 472,
2 in that the third comparator 473 and the decoder 48 are provided.
Unlike this, the other parts are configured the same as in FIG. The noise reduction unit 7 includes a second subtractor 75, a third subtractor 76, a limiter 77, a coefficient multiplying circuit 78, a second field memory 79, a limit value control circuit 80, and a coefficient control circuit 81. I have.

Next, the operation will be described. The image signal obtained from the non-addition reading CCD 1 is processed by the camera signal processing unit 3 via the A / D converter 2, and the luminance signal Y, the color difference signal RB, and the luminance signal Ym for motion detection are processed as in FIG. Is output.

In the motion detecting section 4, the signal Ym is stored in the first field memory 41, and the difference between the current field Ym and the previous field Ym is calculated by the subtracter 42. The difference is calculated by the motion vector generating circuit 45. The motion correction signal 14 is generated and sent to the motion correction unit 5 to correct unnecessary image motion such as camera shake contained in the luminance signal Y and the color difference signal RB.

On the other hand, the difference of Ym is calculated by the absolute value calculation circuit 4.
The value is converted to an absolute value by 3 and is integrated by the integrator 44 in a predetermined integration range. Here, if the captured image is stopped, since the difference is almost zero in the predetermined integration range, the integration result does not become a large numerical value, and if there is a moving part in the captured image, A part having a certain value in the difference appears, the integral of its absolute value also becomes a certain value, and the integral value increases as the movement part increases.

Then, each of the comparators 471 to 473 compares the integration result of the integrator 44 with each threshold value externally set in each of the threshold value setting circuits 461 to 463. If the value is smaller than the threshold value, the output voltage is set to the low level. If the integration result is larger than the threshold value, the output voltage is set to the high level. Then, the decoder 48 operates to control the limit value control circuit 80 and the coefficient control circuit 81 of the noise reduction unit 7 from the state of the output of each of the comparators 471 to 473.

On the other hand, of the luminance signal Y and the chrominance signal RB which have been motion-compensated by the motion compensator 5, RB is equal to a second subtractor 75.
In step (2), a difference from the RB value one field before input to the second field memory 79 is obtained, and the difference value is sent to the limiter 77. If the input difference does not exceed the predetermined absolute value, the limiter 77 regards it as noise, and if the input difference exceeds the predetermined absolute value, considers the difference as a result of image motion. Correct to 0. Here, the limit value control circuit 80 includes the motion detection unit 4
The smaller the movement of the image detected in the step, the smaller the limiter 7
Set the limit value of 7 larger. Therefore, when the motion of the image is small, noise is more effectively detected.

The noise components thus detected include:
A predetermined coefficient is multiplied by a coefficient multiplier 78 and a third subtractor 76
, The noise component is actually subtracted. Here, the predetermined coefficient is 0 to 1
The noise removal effect increases as the value approaches 1, and the afterimage increases when the image has motion. Therefore, when the motion of the image detected by the motion detection unit 4 is small, the above coefficient is set to a value close to 1; when the motion of the image is small, noise is effectively removed; It works to keep it low.

As described above, it is possible to obtain the luminance signal Y and the color difference signal RB output by changing the noise reduction characteristics according to the movement of the captured image and the set photographing mode. The luminance signal Y and the color difference signal RB can be sent to a printer or an NTSC television monitor in the same manner as in FIG.

[0026]

As described above, according to the present invention,
If you shoot in a stopped subject or still image shooting mode,
A high-quality still image with little noise can be obtained, and when a moving subject is photographed by a normal photographing method, a conventional moving image can be obtained. For this reason, it is possible to output a conventional moving image to a television monitor of a standard such as NTSC or PAL as a conventional moving image and to supply a high-quality still image to an information device such as a computer or a printer.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a block diagram showing a second embodiment of the present invention.

FIG. 3 is a block diagram showing a third embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 CCD image pickup device 3 Camera signal processing unit 4 Motion detection unit 5 Motion correction unit 6 Signal selection switch 7 Noise reduction unit 12 Motion extraction signal 13 Image signal processed by camera signal processing unit 14 Motion information signal

Claims (5)

[Claims] An imaging unit configured to image a subject and output an imaging signal; a signal processing unit configured to process the imaging signal and output a processed image signal and a motion extraction signal; Imaging apparatus comprising: a noise reduction unit configured to reduce noise of a detected image signal; and a motion detection unit configured to detect a motion of an image from the motion extraction signal and control a characteristic of the noise reduction unit in accordance with the detected motion. apparatus. 2. The image pickup apparatus according to claim 1, wherein said noise reduction means removes a large amount of noise when the movement of the image is small. 3. A motion compensator for compensating the motion of the image signal processed by the signal processor in accordance with the detected motion of the image, and processing the motion-compensated image signal by the signal processor. 2. The image pickup apparatus according to claim 1, further comprising a selection unit that selects one of the selected image signals and outputs the selected signal to the noise reduction unit. 4. An image pickup apparatus according to claim 1, wherein said image signal processed by said signal processing means comprises a luminance signal and a color difference signal, and said noise reduction means reduces noise of said color difference signal. . 5. The noise reduction unit according to claim 1, wherein the noise reduction unit selectively performs a noise reduction operation using a field correlation and a noise reduction operation using a line correlation according to the detected motion of the image. Item 2. The imaging device according to Item 1.