JP3740398B2 - Shake correction device, control device applied to shake correction device, control method applied to shake correction device, control program applied to shake correction device, imaging device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a shake correction device that corrects image shake, a control device thereof, a control method thereof, a control program thereof, and an imaging device such as a camera capable of taking a still image and / or moving image having an image shake correction function.
[0002]
[Prior art]
Currently, a video camera or the like equipped with a shake correction function includes at least a shake detection unit that detects a shake component and a shake correction unit that corrects the shake according to the detection result of the detection unit.
[0003]
The shake detection means is an electronic detection method for detecting the movement of an image by comparing an image between continuous fields or frames between a device that directly detects a shake component of an apparatus using an angular velocity sensor, an angular acceleration sensor, or the like. There is.
[0004]
As the shake correction means, there are an optical type that mechanically corrects the optical axis and an electronic type that performs correction by electronically selecting a range (cutout range) that is actually recorded or output from the obtained image. is there.
[0005]
In the electronic shake correction means, a captured image is stored in a memory, and a part of the image is cut out and enlarged, or an image sensor having a larger number of pixels than a standard image sensor required in a broadcast system is used. There is a system that cuts out the standard size of the broadcasting system.
[0006]
Considering the anti-vibration performance, the optical system that always performs correction is more advantageous than the electronic system that performs correction in units of fields, but conversely, an optical system that requires additional mechanical parts to perform correction. In contrast, the electronic type in which correction is performed by a CCD or a memory is advantageous for downsizing. Therefore, in a video camera or the like, when priority is given to downsizing, it is common to perform electronic shake correction.
[0007]
Therefore, here, a method of cutting out the broadcast system standard size using an image sensor having a larger number of pixels than the standard image sensor required for the broadcast system will be described regarding electronic correction.
[0008]
FIG. 11 is an image of the image pickup area of the image pickup device. Reference numeral 501 denotes the entire image pickup area of the image pickup device, and 502, 503, and 504 denote standard broadcast system sizes. Among these, when shake correction is not performed, the center 503 is cut out and output.
[0009]
When performing shake correction, an area to be cut out so as to remove the shake in accordance with a signal from the shake detection means is shifted to, for example, 502 or 504, and an image is output. The cutout position can be cut out from any position within the entire imaging area 501.
[0010]
FIG. 12 is a configuration diagram of a shake correction unit of an imaging apparatus such as a video camera equipped with a shake correction apparatus in which the detection means is an angular velocity sensor and the shake correction means is an electronic type. Hereinafter, an imaging apparatus equipped with a shake correction apparatus will be described with reference to FIG.
[0011]
Reference numeral 101 denotes a lens unit, and 102 denotes a solid-state imaging device (CCD). A subject image is formed on the CCD 102 by the lens unit 101, and photoelectric conversion is performed in the CCD 102. Here, the CCD 102 uses a CCD having a larger number of pixels than a standard CCD required in a broadcasting system (for example, the NTSC system). A CCD driving circuit 104 drives the CCD 102. The CCD drive circuit 104 is devised so that it can select from which line the area to be finally output is cut out in the V direction in accordance with a control command from the microcomputer 130 described later. In FIG. 11, 501 is an example of the total image size, and 502, 503, and 504 are examples of standard image sizes in accordance with the broadcasting system. For example, when valid from the ya + 1 line below the [Delta] ya line from the top line, the [Delta] ya line is read at high speed, and is read from ya + 1 at the same timing as when a standard size CCD is used for the vertical synchronization signal. Then, by reading out the remaining Δyb line again at high speed, it is possible to actually cut out a line having a standard image size in the V direction.
[0012]
Reference numeral 103 denotes analog signal processing, which performs predetermined processing on the signal obtained by the CCD 102 to generate an analog imaging signal. For example, a CDS circuit (co-related double sampling circuit), an AGC circuit, and the like. Reference numeral 106 denotes a memory, and the memory control circuit 107 can store a digital imaging signal for at least one line. Further, it is possible to read from a predetermined position (address). Reference numeral 105 denotes digital signal processing incorporating an A / D converter, which generates a final output video signal.
[0013]
Note that the digital imaging signal stored in the memory still has a larger number of pixels than the standard image size. The memory control circuit 107 can select the top pixel to be read from the memory 106 in accordance with a control command from a microcomputer 130 described later, and is devised to read only the standard image size.
[0014]
A camera control microcomputer 130 controls the entire camera system. However, here, for simplification of the drawing, only the portion relating to shake correction is shown. In addition, the shake is detected with respect to two axes of the pitch (vertical) direction and the yaw (horizontal) direction, but since the same control is performed, only one direction is illustrated here.
[0015]
Reference numeral 121 denotes an angular velocity sensor that detects camera shake. An amplifier 123 amplifies the detected angular velocity signal.
[0016]
An A / D converter 125 is built in the microcomputer 130. Angular velocity signals in two directions are converted into digital signals by the built-in A / D converter 125 to become angular velocity data. Reference numeral 126 denotes an HPF (high pass filter) that performs DC cut, and 127 is a filter that performs phase compensation. Reference numeral 129 denotes an HPF capable of varying the cutoff frequency for performing panning control or the like. When panning is performed, the value of the integrator output sticks in one direction, and after the end of panning, it does not easily return to the original value, and the camera shake correction is not effective. Therefore, the correction control unit 131 determines the panning state based on the output level of the integrator 128, and shifts the cutoff frequency of the HPF 129 to the high frequency side according to the output level of the integrator 128 during panning. Therefore, the low frequency component generated during panning is cut to limit the integrator output from sticking. This makes it possible to perform good shake correction during and after panning.
[0017]
The angular velocity data is subjected to predetermined signal processing by the HPF 126, the phase compensation filter 127, and the HPF 129 capable of changing the cutoff frequency, and the integrator 128 generates a shake correction signal in the vertical and horizontal directions.
[0018]
From the output of the integrator 128, the correction system control unit 131 transmits a vertical shake correction signal to the CCD drive circuit 104 and a horizontal shake correction signal to the memory control circuit 107. As described above, the CCD drive circuit 104 and the memory control circuit 107 change the position to be cut out in accordance with the shake correction signal.
[0019]
By this series of operations, the standard image size can be cut out from the center as shown in FIG. 11, for example, 502 and 504, as shown in FIG. 11. As a result, it is possible to correct shake due to camera shake or the like. It becomes.
[0020]
[Problems to be solved by the invention]
However, when an electronic shake correction apparatus is employed, shake correction can be performed only on a field basis, so that shakes that occur during the CCD accumulation time remain as an image flow. If the shutter speed is increased, it is essentially inconspicuous. Conventionally, in an electronic shake correction apparatus, a method in which the shutter speed being corrected is always kept at a certain reference speed or more is generally used. However, due to recent miniaturization and weight reduction, the amplitude of camera shake is large and the frequency of shake tends to be high, and the flow of this image is not negligible. FIG. 13 is a diagram showing the shake remaining between fields when there is a shake with a frequency of 7.5 Hz. It can be seen that, even if the shutter speed is increased, the remaining shake increases if the shake is large. . In this way, if the amplitude of the shake is large, the flow amount of the image increases, and even though the image itself is corrected, a flowing image and a non-flowing image may be alternately displayed. Yes, it appears as if the focus is fluffy, and because the focus appears fluffy, the phenomenon that the shake correction section appears as if it is oscillating occurs. It is. The frequency at this time is 30 Hz at the maximum (because the shortest cycle is one frame) regardless of the frequency of camera shake of the photographer. For this reason, as the accuracy of camera shake correction increases, this picking becomes more conspicuous, and there is a problem in that the quality of the camera shake correction function and the autofocus function appears to deteriorate.
[0021]
The purpose of the present invention is to maintain the quality of normal camera shake correction, and when a large camera shake that clearly shows the flow of an image occurs, by intentionally reducing the suppression effect and leaving a little camera shake, Applicable to shake correction device that gives a good image that shows hand shake naturally and inconspicuous flickering feeling, control device applied to shake correction device, control method applied to shake correction device, shake correction device A control program and an imaging apparatus are provided.
[0022]
[Means for Solving the Problems]
In order to achieve the above object, the present invention according to claim 1 is directed to a shake detection unit, a shake correction unit that corrects a shake of an image based on an output of the shake detection unit, and an output of the shake detection unit. If it is greater than one predetermined amplitude and less than a second predetermined amplitude, it is limited by a first restriction that multiplies a predetermined attenuation factor so that the output at the first predetermined amplitude is continuous with the output. while, the second in the case of more than a predetermined amplitude so that the output of the second predetermined amplitude to the output is continuous, a more larger attenuation than the predetermined attenuation rate by the first restriction The shake correction apparatus is characterized by having a limiting means for multiplying by a predetermined attenuation rate to be given or by limiting the output by a second restriction having a constant amplitude.
[0023]
According to a fourth aspect of the present invention, in the control method applied to the shake correction apparatus that corrects the shake of the image by the shake correction means based on the output of the shake detection means, the output of the shake detection means is the first. If the amplitude is equal to or larger than the predetermined amplitude and smaller than the second predetermined amplitude, the output is limited by a first restriction that multiplies a predetermined attenuation factor so that the output at the first predetermined amplitude is continuous with the output. with, in the case of more than the second predetermined amplitude so that the output of the second predetermined amplitude to the output is continuous, providing a more larger attenuation than the predetermined attenuation rate by the first restriction A control method is characterized in that a predetermined attenuation rate is multiplied or the output is limited by a second restriction having a constant amplitude.
[0037]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0038]
FIG. 1 is a block diagram showing a configuration of an imaging apparatus according to an embodiment of the present invention. In FIG. 1, the same functions as those in FIG. 12 are denoted by the same reference numerals as those in FIG.
[0039]
In FIG. 1, reference numeral 140 denotes a block in the microcomputer, which is a limiter circuit capable of limiting the output data from the angular velocity sensor during the filtering operation. That is, in the present embodiment, the means (HPF 129) for limiting only the low frequency component according to the amplitude of the deflection displacement (output of the integrator 128) and the angular velocity signal itself (angular velocity regardless of frequency) from the angular velocity signal amplitude. This means that two different limiting means are combined with a means (limiter circuit 140) for limiting the whole signal). Further, 142 is a camera system control unit including a shutter speed control unit and the like, and 141 is a correction system control unit including a parameter calculation unit for determining the characteristics of the limiter circuit.
[0040]
With the above configuration, while performing conventional shake correction control including panning control, the characteristics of the limiter circuit are changed from the angular velocity amplitude, shutter speed, or shake frequency information for the output signal from the angular velocity sensor. You can do that.
[0041]
【Example】
(First embodiment)
As a first embodiment of the present invention, a case where the characteristics of the limiter circuit are changed according to the amplitude of the angular velocity signal will be described. A flowchart in the camera control microcomputer 130 relating to the present embodiment is shown in FIG. Hereinafter, the present embodiment will be described in detail according to the flowchart of FIG.
[0042]
In FIG. 2, S <b> 201 indicates processing by the HPF 126. In S202, it is first determined whether the output of the HPF 126 is equal to or greater than a predetermined value B. If the output of the HPF 126 is smaller than the predetermined value B, it is determined in S203 whether or not it is greater than or equal to the predetermined value A. Is smaller than the predetermined value A, in S204, as limiter output, and HPF output itself, the process proceeds to phase compensation processing S 207. The above flow is a process when the amplitude of camera shake is small. If it is determined in S203 that the value is equal to or greater than the predetermined value A, in S205, the limiter output Y is
Y = (X−A) × C + A
Then, the process proceeds to the phase compensation process of S207. Here, X is the output of the HPF 126, and A and B are the above-mentioned predetermined values, which are preset thresholds. C is the slope of the output when the output of the HPF 126 greater than or equal to the predetermined value A is input,
C <1
It has become.
[0043]
If the HPF output is greater than or equal to the predetermined value B in S202, the limiter output is set to Y = A + (B−A) × C (constant value) in S206.
Then, the process proceeds to the phase compensation process in S207. FIG. 3 is a diagram showing the input / output of the limiter circuit 140. Here, the signal that has passed through the limiter circuit 140 has a form as shown in FIG. After performing the phase compensation process, HPF calculation is performed in S208, which will be described later. In step S209, integration processing is performed. This is a portion corresponding to the integrator 128 in FIG. 1, and an actual shake displacement is calculated by integrating the angular velocity signal. The shake correction amount calculated as a result is a value as shown in FIG. As is apparent from FIG. 4, by adding the limiter circuit 140 and providing the limiter for the gyro signal, a normal correction amount is calculated when the amplitude is small, and when the amplitude becomes large, the correction amount becomes the actual amount. It becomes small with respect to runout.
[0044]
The above is the part that limits the angular velocity signal itself according to the magnitude of the angular velocity signal, and by performing this restriction, the effect of camera shake correction is weakened only when a large camera shake that makes an afterimage of the image stand out, It is possible to make an afterimage inconspicuous as a moving image to be recorded.
[0045]
Now, after performing the integration process in S209, it is determined in S210 whether or not the integration output is larger than the predetermined value D. The predetermined value D here is set to a value that is considerably larger than the possible range of the integrator output shown in FIG. This determination is a part for determining whether or not the panning state, but when panning is being performed, the integrator output increases in one direction, so the determination is made by looking at the output of the integrator 128. Is possible. If it is greater than the predetermined value D, the cutoff frequency of the HPF 129 that can vary the cutoff frequency is increased in S211. With this operation, when the image stabilization process is performed next, control is performed with a new cutoff frequency, and a signal close to DC is cut out of the angular velocity signal. As a result, it is possible to avoid sticking the output of the integrator 128 while maintaining the anti-vibration effect for the frequency of camera shake. In this embodiment, the cutoff frequency other than during panning is 0.1 Hz, and during panning, it is between about 0.1 Hz and 2.6 Hz depending on the amplitude level of the shake (integrator output level). Variable.
[0046]
If the integrator output is smaller than the predetermined value D in S210, it is determined that the panning has been completed, and in S212, the cutoff frequency of the HPF 129 is lowered to return to the normal state.
[0047]
The above is the part that limits the correction amount according to the amplitude of the shake displacement, that is, the part corresponding to panning. When the detected shake is not panning but only hand shake, as shown in FIG. 4, the amplitude of the shake displacement that is the output of the integrator 128 is always a reciprocating motion that crosses the zero point. In addition, since the predetermined value D for the panning determination is set to a considerably large value with respect to the amplitude of the shake displacement at the time of camera shake, there is no limitation by the amplitude of the shake displacement.
[0048]
As explained above, by performing shake correction control by two restriction means having different restriction characteristics, panning control is performed according to the shake amplitude during panning, and normal camera shake that is not panning is detected. If the camera shake is small, an image with no camera shake can be provided by applying a certain limit to the magnitude of the detected angular velocity signal. By reducing the suppression effect only in such a case, it is possible to make the afterimages inconspicuous as a recorded moving image.
[0049]
In the present embodiment, the limiter characteristics depending on the magnitude of the angular velocity signal have a simple configuration as shown in FIG. 3, and the data of the predetermined value B or more is constant, but the slope is further replaced with a straight line. It doesn't matter. Further, for example, as shown in FIG. 5, the same result can be obtained if a characteristic such that the output is attenuated with respect to an input of a certain value or more is obtained.
[0050]
(Second embodiment)
As a second embodiment of the present invention, the case where the characteristics of the limiter circuit 140 are changed according to the amplitude of the angular velocity signal and the shutter speed will be described. As described above, when electronic camera shake correction is performed, it is common to set the shutter speed fast. However, depending on the CCD sensitivity and the brightness of the lens, there may occur a situation in which a shutter speed of 1/60 must be selected. When the shutter speed becomes slow, as shown in FIG. 13, the flow of the image becomes large, so that the afterimage feeling also becomes large. On the other hand, when shooting in a very bright place, the shutter speed becomes faster, so that the feeling of afterimage becomes inconspicuous no matter how large the camera shake is. For this reason, in this embodiment, the characteristic of the limiter circuit 140 is changed in accordance with the amplitude of the angular velocity signal and the shutter speed to make the afterimage feeling inconspicuous.
[0051]
FIG. 6 is a flowchart of the camera control microcomputer 130 showing this embodiment. Hereinafter, this embodiment will be described in detail according to the flowchart of FIG.
[0052]
In FIG. 6, S <b> 601 indicates an operation performed by the HPF 126. In S602, the predetermined value A and the predetermined value B set according to the shutter speed are read. The shutter speed is set by the camera system control unit 142 in the camera system control microcomputer 130, and is read from a data table as shown in FIG. 7, for example, according to the setting state. This table shows the ratio of the limiter circuit output at each shutter speed when the maximum HPF output value is 100 (%). Steps S603 and after are the same as those in the first embodiment. If the HPF output is greater than or equal to the predetermined value B in S603, the flow is different in S607. In S605, the limiter circuit output is set, and the data is passed to the phase compensation processing unit in S608. As a result of this processing, the output of the limiter circuit based on the shutter speed is as shown in FIG. 8, and the anti-shake effect changes according to the shutter speed and the amplitude of the angular speed signal, and at a slow shutter speed where the afterimage is more likely to appear. Since the anti-vibration effect is weakened, the afterimage feeling can be made inconspicuous, and a more natural moving image can be obtained.
[0053]
In this embodiment, the threshold for changing the characteristics of the limiter circuit is read from the data table. However, it is also possible to calculate the threshold using a function with the shutter speed as a parameter. In calculating the limiter output, it is also effective to change the output gradient in accordance with the shutter speed.
[0054]
(Third embodiment)
The third embodiment of the present invention is an example in which attention is also paid to the frequency component of shake. FIGS. 9A and 9B are diagrams showing the remaining unswing during the CCD accumulation time when the frequency is 7.5 Hz and when the frequency is 10 Hz. As can be seen from this figure, even with the same amplitude, the flow of the image increases as the frequency increases. Therefore, in the present embodiment, the characteristics of the limiter circuit 140 are changed according to the amplitude of the angular velocity signal and the vibration frequency. FIG. 10 shows a flowchart of the camera control microcomputer 130 according to this embodiment. Hereinafter, the present embodiment will be described in detail according to the flowchart of FIG.
[0055]
In FIG. 10, S <b> 701 indicates an operation in the HPF 126. In S702, it may be set according to the frequency calculated by the correction system control unit 141, or a data table corresponding to the frequency may be referred to. Then, based on the calculated predetermined values A and B, data processing similar to that described above is performed in S703 to S707. The output is processed by the phase compensation circuit 127 in S708. In the scene where the integrator output finally calculated by the above processing becomes higher as the vibration frequency is higher and the amplitude of the angular velocity signal is larger, the attenuation rate of the output becomes higher, and as a result, the afterimage feeling increases. By suppressing the image stabilization effect, the afterimage feeling can be made inconspicuous, and a more natural moving image can be obtained.
[0056]
Here, the method of changing the characteristics of the limiter circuit in accordance with the amplitude of the angular velocity signal and the frequency of the shake has been described. Naturally, the shutter speed is taken into account as a parameter for calculating the threshold level (predetermined value) of the limiter circuit. Needless to say, more natural vibration control can be achieved.
[0057]
According to the embodiment described above, by changing the characteristics of the limiter circuit according to the amplitude of the angular velocity signal, the shutter speed, and the shake frequency, a good shake correction function can be provided when the shake is small. When is large, it is possible to intentionally lower the vibration suppression effect and obtain a high-quality moving image with no afterimage.
[0058]
The above is the description of the embodiment of the present invention. However, the present invention is not limited to the configuration of this embodiment, and a configuration capable of achieving the functions of the claims or the configuration of the embodiment. Anything can be applied.
[0059]
For example, the software configuration and the hardware configuration in the above embodiments can be appropriately replaced.
[0060]
In addition, you may make it this invention combine the said each Example or those technical elements as needed.
[0061]
In addition, the present invention may be configured such that the scope of the claims or the whole or part of the configuration of the embodiment forms one device or is combined with another device. It may be an element constituting the apparatus.
[0062]
The present invention also includes various types of cameras such as electronic cameras such as video cameras that can shoot moving images or still images, silver salt cameras that use film, single-lens reflex cameras, lens shutter cameras, and surveillance cameras. Furthermore, imaging devices other than cameras, optical devices, other devices, devices applied to these cameras, imaging devices, optical devices, other devices, and elements constituting these devices, of these devices The present invention can also be applied to a control method, a control program, and a medium such as a storage medium that supplies the control program.
[0063]
【The invention's effect】
As described above, according to the present invention, when a large camera shake that clearly shows the flow of an image is maintained while maintaining the quality of a normal camera shake correction, the camera shake is intentionally lowered to reduce the shake effect. By leaving a little, the shake correction device that makes the camera shake look natural and the good image with inconspicuous flickering feeling is obtained, the control device applied to the shake correction device, the control method applied to the shake correction device, It is possible to provide a medium for supplying a control program applied to the shake correction apparatus and an imaging apparatus.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an image pickup apparatus according to an embodiment of the present invention. FIG. 2 is a flowchart according to a first embodiment of a camera control microcomputer 130 shown in FIG. FIG. 4 is a diagram showing input / output characteristics according to the first embodiment of the limiter circuit 126. FIG. 4 is a diagram showing correction output according to the first embodiment. FIG. 5 is a diagram illustrating a first implementation of the limiter circuit 126 shown in FIG. FIG. 6 is a diagram showing other input / output characteristics according to an example. FIG. 6 is a flowchart according to a second embodiment of the camera control microcomputer shown in FIG. 1. FIG. 7 is a data table used in the second embodiment of the present invention. FIG. 8 shows another input / output characteristic according to the second embodiment of the limiter circuit 126 shown in FIG. 1. FIG. 9 shows a case where the frequencies according to the third embodiment of the present invention are different. Fig. 10 shows the rest of shaking during the CCD accumulation time. FIG. 11 is a flowchart showing electronic image stabilization by clipping. FIG. 12 is a block diagram showing a configuration of an imaging apparatus according to a conventional example. Figure showing the remaining vibration during CCD accumulation time when there is a fluctuation of frequency 7.5Hz.
101 Lens unit 102 CCD
104 CCD drive circuit,
105 camera signal processing unit 106 line memory 107 memory control circuit 121 angular velocity sensor 126 HPF
127 Phase Compensation Circuit 128 Integrator 141 Correction System Control Unit 142 Camera System Control Unit 130 Camera Control Microcomputer

Claims (8)

When the shake detection means, the shake correction means for correcting the shake of the image based on the output of the shake detection means, and the output of the shake detection means are greater than or equal to the first predetermined amplitude and less than the second predetermined amplitude Is limited by a first restriction that multiplies a predetermined attenuation rate so that the output at the first predetermined amplitude is continuous with the output, and when the output exceeds the second predetermined amplitude, as the output at the second predetermined amplitude is continuous with respect to, or applying a predetermined attenuation rate that gives a more larger attenuation than the predetermined attenuation rate by the first limit, the output and constant amplitude And a restricting means for restricting by the second restriction.   The shake correction apparatus according to claim 1, wherein the first predetermined amplitude and the second predetermined amplitude are set to be smaller as the imaging time of the subject optical image becomes longer.   3. The shake correction apparatus according to claim 1, wherein the first predetermined amplitude and the second predetermined amplitude are set smaller as the output frequency becomes higher. In the control method applied to the shake correction apparatus that corrects the shake of the image by the shake correction unit based on the output of the shake detection unit, the output of the shake detection unit is equal to or greater than a first predetermined amplitude and a second predetermined value. When the amplitude is less than the amplitude, the output is limited by a first limit that is multiplied by a predetermined attenuation rate so that the output at the first predetermined amplitude is continuous with the output, and when the output is equal to or greater than the second predetermined amplitude. as the output at the second predetermined amplitude to said output is continuously in either applying a predetermined attenuation rate that gives a more larger attenuation than the predetermined attenuation rate by the first limit, the output The control method is characterized by being limited by a second limitation with a constant amplitude.   The control method according to claim 4, wherein the first predetermined amplitude and the second predetermined amplitude are set to be smaller as the imaging time of the subject optical image becomes longer.   6. The control method according to claim 4, wherein the first predetermined amplitude and the second predetermined amplitude are set smaller as the frequency of the output becomes higher.   A control program for executing the control method according to claim 4.   A storage medium storing the control program according to claim 7.

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