JPH10210350A - Shake correction device and method for video camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a correction device and method which can correct the shaking of a video camera by preventing the unnatural movements of a screen after the panning or tilting of the camera with no deterioration of image quality. SOLUTION: The output of an angular velocity sensor 7 is analyzed to decide whether shake of a video camera is caused by the panning or tilting or in a normal hand-held state of the camera. If the camera shake caused in its normal hand-held state is decided, the shake is corrected by shifting the segmenting position of an image-pickup screen, according with the camera movements by means of a horizontal shift circuit 3 and a vertical shift circuit 2, and not via an interpolation screen. If the camera shake caused after the panning or tilting of the camera is decided, an interpolation screen is formed by an electronic zoom circuit 5 and the segmenting position of the interpolation screen is shifted in response to the camera movements for correction of the camera shake. Thus, it is possible to eliminate conspicuous and unnatural movements of the screen after the panning or tilting of the camera, without the generation of deterioration in image quality in a normal photographing state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera shake correction apparatus and method for a video camera, and more particularly to a camera shake correction apparatus capable of performing camera shake correction without deteriorating the image quality and suppressing an unnatural screen movement after panning or tilting. The present invention relates to an apparatus and a method for preventing camera shake of a video camera.

[0002]

2. Description of the Related Art In particular, in a video camera which is reduced in size and weight, movement of a hand or an arm is transmitted to the video camera at the time of shooting, and a problem of camera shake is likely to occur. Therefore, many video cameras that are reduced in size and weight are equipped with a camera shake correction device. As such a camera shake correction device for a video camera, for example, while detecting the movement of the video camera by an angular velocity sensor,
An interpolation screen is formed by interpolating the image pickup signal, and for example, 1 according to the motion of the video camera detected by the angular velocity sensor.
It is known that the cutout position of the interpolation screen is shifted in units of / 256 pixels.

However, when the camera shake correction is performed using the interpolation screen, the deterioration of the image quality is inevitable. In view of this, it has been proposed that the output of the CCD image sensor can be shifted, for example, in units of one pixel without using an interpolation screen, so that camera shake correction can be performed. in this way,
If camera shake correction is performed so that the cutout position of the CCD image pickup device can be shifted, for example, in units of one pixel, the use of an interpolated screen is eliminated, so that image quality degradation does not occur in principle.

[0004]

However, in the case where the cutout position of the output of the CCD image pickup device is shifted, for example, in units of one pixel, and the camera shake is corrected, the screen is not displayed after panning or tilting. The problem of unnatural movement occurs. This is considered to be due to the fact that the camera shake correction filter is configured as an IIR digital filter.

That is, since the IIR digital filter includes a feedback loop, the correction data immediately after panning and tilting includes information on the camera movement before that. For this reason, after panning or tilting, the screen is moved by the motion information remaining in the IIR digital filter. This causes an unnatural screen movement after panning or tilting.

When camera shake correction is performed using an interpolation screen, the unnatural screen movement after panning or tilting is not so noticeable because the screen is an interpolation screen. However, when the camera-shake correction is performed by shifting the cut-out position of the output of the CCD image sensor in units of one pixel, for example, the unnatural motion of the screen after the panning or the tilting is conspicuous.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a video camera shake correction apparatus and method for preventing unnatural screen movement after panning or tilting without deteriorating image quality. .

[0008]

According to the present invention, there is provided a vibration detecting means for detecting a vibration of a video camera, and a first means for correcting a camera shake by shifting a cut-out position of an imaging screen according to an output of the vibration detecting means. A second image stabilizing means for interpolating an imaging screen to form an interpolated screen, shifting a cut-out position of the interpolated screen in accordance with an output of the fluctuation detecting means to perform a camera shake correction, and Photographing state detecting means for analyzing whether the video camera has been panned or tilting by analyzing the output of the detecting means; camera shake correction by the first camera shake correcting means according to the output of the photographing state detecting means; And a setting means for selecting the camera shake correction by the camera shake correction means.

According to the present invention, a shake of a video camera is detected, and a detection output of the shake of the video camera is analyzed to determine whether the video camera has been panned or tilted.
In response to the judgment output, the first camera shake correction method of performing a camera shake correction by shifting the cutout position of the imaging screen based on the detection output of the shake of the video camera, and forming an interpolation screen by interpolating the imaging screen, This is a camera-shake correction method for a video camera in which a cut-out position of an interpolation screen is shifted by a shake detection output to perform a camera-shake correction.

By analyzing the output of the angular velocity sensor, it is determined whether the shake of the video camera is a shake after panning or tilting or a shake in a normal hand-held state. If it is determined that the camera is in a normal hand-held state, the camera shake correction is performed by shifting the cutout position of the imaging screen according to the motion of the video camera, without depending on the interpolation screen. If it is determined that the shaking has occurred after panning or tilting, an interpolated screen is formed, and the cutout position of the interpolated screen is shifted according to the motion of the video camera to perform camera shake correction. As a result, in a normal shooting state, image quality does not deteriorate, and unnatural screen movements become less noticeable after panning or tilting.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is CC
D imaging device. A lens (not shown) is disposed on the imaging surface of the CCD imaging device 1, and the subject image light is focused on the imaging screen of the CCD imaging device 1. From the CCD image sensor 1, an image signal based on the image screen is output.

A vertical shift circuit 2 and a horizontal shift circuit 3 are provided for the CCD image pickup device 1. CC
The cutout position of the screen in the vertical direction of the D imaging device 1 can be shifted by the vertical shift circuit 2 under the control of the controller 8. Further, the horizontal position of the cutout of the screen of the CCD image pickup device 1 can be shifted by the horizontal shift circuit 3 under the control of the controller 8.

An image output of the CCD image sensor 1 is supplied to a camera signal processing circuit 4. In the camera signal processing circuit 4,
A luminance signal and a color signal are formed from the image pickup signal, and processing such as gamma correction and aperture correction is performed. The output of the camera signal processing circuit 4 is supplied to the electronic zoom circuit 5.

The electronic zoom circuit 5 forms an interpolation screen from an image signal under the control of the controller 8. The electronic zoom circuit 5 can form a magnified interpolation screen. Further, by shifting the cutout position of the interpolation screen by the electronic zoom circuit 5 according to the output of the controller 8, the screen can be shifted in the horizontal direction and the vertical direction. The output of the electronic zoom circuit 5 is output to an output terminal 6
Output from

The movement of the video camera is detected by an angular velocity sensor 7. The output of the angular velocity sensor 7 is applied to a controller 8 via an integration filter 9 for converting the angular velocity to an angle.
Supplied to The controller 8 determines the correction amounts in the horizontal and vertical directions from the output of the angular velocity sensor 7.

The output of the controller 8 is supplied to the horizontal shift circuit 3 and the vertical shift circuit 2, and in accordance with the correction amount obtained by the controller 8, the horizontal and vertical directions of the image picked up from the CCD image sensor 1 are displayed. The cutout position is shifted. This makes it possible to perform camera shake correction independent of the interpolation screen, for example, in units of one pixel.

The output of the controller 8 is supplied to the electronic zoom circuit 5, and the electronic zoom circuit 5 shifts the cutout position of the interpolation screen in the horizontal and vertical directions. Thus, for example, camera shake correction using an interpolation screen can be performed in units of 1/256 pixels.

As described above, the video camera to which the present invention is applied is provided with two systems of camera shake correction circuits. 1
First, the CCD image sensor 1
The horizontal and vertical cutout positions of the imaging screen are shifted. In such a camera shake correction, since the interpolation screen is not used, the image quality does not deteriorate. However, in such a camera shake correction, unnatural screen movement after panning or tilting is likely to be noticeable.

The other one is to shift the cutout position of the interpolation screen formed by the electronic zoom circuit 5 according to the movement of the video camera. In such a camera shake correction, since an interpolation screen is used, image quality is deteriorated, but unnatural screen movement after panning or tilting is not so noticeable.

As will be described later, the controller 8
From the output of the angular velocity sensor 7 via the integration filter 9,
It is determined whether the shake of the video camera is a shake after panning or tilting, or a shake in a normal hand-held state. If it is determined that the camera is in a normal hand-held state, the horizontal and vertical cutout positions of the imaging screen of the CCD imaging device 1 are shifted according to the movement of the video camera, and, for example, camera shake in pixel units. Correction is performed. When it is determined that the shaking has occurred after panning or tilting, the cutout position of the interpolation screen formed by the electronic zoom circuit 5 is shifted in accordance with the movement of the video camera. Is performed. As a result, under normal shooting conditions, the image quality does not deteriorate, and after panning or tilting,
Unnatural screen movements are less noticeable.

Whether a shake after panning or tilting or a shake in a normal hand-held state can be determined by analyzing the detection signal indicating the movement of the video camera from the angular velocity sensor 7. .

That is, the angular velocity sensor 7 is provided to the controller 8 via the integration filter 9 for converting the angular velocity into an angle.
Is supplied. The integrated output of the angular velocity sensor 7 becomes a signal as shown in FIG. 2A because small swings are repeated in a steady hand-held state. On the other hand, after panning or tilting, a large swing slowly occurs, so that a signal as shown in FIG. 3A is obtained.

A comparison between the integrated output of the angular velocity sensor 7 in the steady hand-held state shown in FIG. 2A and the integrated output of the angular velocity sensor 7 after panning and tilting shown in FIG. It can be seen that the integral output of the angular velocity sensor 7 contains many short-period components, and the integral output of the angular velocity sensor 7 after panning or tilting has a long-period component. In other words, the integrated output of the angular velocity sensor 7 in a steady hand-held state contains many high-frequency components, and the angular velocity sensor 7 after panning or tilting.
Has a lot of low frequency components in the integrated output.

Therefore, in the controller 8, the integrating circuit 9
The differential output of the angular velocity sensor 7 passed through is differentiated, and the time during which the same code continues in the differential output is counted. If the time during which the same code continues is equal to or more than a predetermined threshold, the panning or tilting is performed. It is determined that the image is shaking.

That is, differentiating the integrated output of the angular velocity sensor 7 in the steady hand-held state shown in FIG.
As shown in B, the differential output of the same sign is hardly output continuously long. On the other hand, when the integral output of the angular velocity sensor 7 after panning or tilting shown in FIG. 3A is differentiated, as shown in FIG. 3B, a long-period swing occurs after panning or tilting. The differential output is continuously generated for a long time. From this,
By differentiating the integrated output of the angular velocity sensor 7 and determining whether or not the time during which the differential value of the same sign is continuously output is equal to or greater than a predetermined threshold value, it is possible to determine whether or not the image is shaken after panning or tilting. I can judge.

FIG. 4 is a flowchart showing the judgment algorithm at this time. In FIG. 4, the integral output of the angular velocity sensor 7 is read at every sampling interval (n / 4) V (n is appropriately about 12 and 16.7 msec when n is 4) (step ST1). ). The integral output of the angular velocity sensor 7 is differentiated (step ST
2). Then, a period during which the same code continues in the differential output is measured (step ST3). It is determined whether or not the period in which the same code continues is longer than a predetermined determination period k (k is suitably about eight times, and when k is 8, it is 400 msec) (step ST4). If the period during which the same code continues is longer than the predetermined determination period k, it is determined that panning or tilting has been performed, the pan flag is set to "1" (step ST5), and this pan flag is returned. (Step ST6).

In step ST4, if the period during which the same code continues is shorter than the predetermined determination period k, the pan flag is set to "0" (step ST7), and the pan flag "0" is set x times (x is, for example, 20h). It is determined whether the number is less than the number of times (step ST8). If the pan flag "0" is not less than x times (x is, for example, 20h times), it is determined that the hand is in a normal hand-held state, the pan flag is set to "0" (step ST9), and this pan flag is returned (step ST9). Step ST6).

At step ST8, the pan flag "0" is set to x
If less than x times (for example, 20h times), the pan flag is set to "1" (step ST9), and the pan flag is returned (step ST10).

The differential value of the integral output of the angular velocity sensor 7 is shown in FIG.
Suppose that it has changed as shown in FIG. In this case, in step ST1, the differential value of the integral output of the angular velocity sensor 7 is read at every sampling interval (n / 4) V.

[0030] In FIG. 5, in the period T _1, the period in which the differential value of the same symbols is output becomes longer than a predetermined determination period k, is determined to be after the panning and tilting in step ST5, the "1" The pan flag is returned. Therefore, as shown in FIG. 5B, the period T _1, regardless of the interpolation screen, image stabilization, such as shifting the cutout position of the image pickup screen in accordance with the movement of the video camera is performed.

In the period T ₂ , the period during which the differential value of the same sign is output is shorter than the predetermined judgment period k, so that “0” is set.
Is returned. Therefore, as shown in FIG. 5B, the period T _2, to form an interpolation screen, image stabilization, such as shifting the cutout position of the interpolation screen in accordance with the movement of the video camera is performed.

In the period T ₃ , a pan flag of “1” is returned, and a camera shake correction is performed to shift the cut-out position of the imaging screen in accordance with the movement of the video camera, regardless of the interpolation screen, and in the period T ₄ In, a pan flag of “0” is returned, an interpolation screen is formed, and camera shake correction is performed such that the cutout position of the interpolation screen is shifted according to the motion of the video camera.

By the way, when the period during which the differential value of the same code is output is measured to determine the image fluctuation after panning or tilting, the differential value of the same code continues. If the determination time k is increased, the time required to make the determination is increased, and the determination is continued even after the image shaking after panning or tilting ends. . If the determination period k is shortened, it is possible to determine in a short time whether or not the image is shaking after panning or tilting, but the number of determination errors increases. Therefore, the length of the determination period k when measuring the time during which the differential value of the same code is continuously output is important.

Further, even after panning or tilting, the sign of the differential output is reversed in a short period of time at the initial stage. For this reason, as described above, when a period during which the same code continues during the differential output is measured and it is determined whether or not the image is shake after panning or tilting, camera shake correction of different methods is alternately performed. As a result, the screen may be rattled.

[0035] That is, in FIG. 6, the period duration T ₁₁ is a hand-held state, the period during panning in the period T _12, the period T ₁₃
Is a period during which image fluctuation occurs after panning. FIG. 6A
As shown in the following, the differential value of the integral output of the angular velocity sensor 7 is
In the period T ₁₂ in the panning from the period T ₁₁ of the hand-held state,
The signal fluctuates in a short period. Then, after the panning period, the sign changes in a long cycle, but during the initial stage, the sign of the differential output is inverted before a predetermined judgment period. Therefore, the flag changes as shown in FIG. 6B, and based on this flag, the camera shake correction method changes as shown in FIG. 6C, and the camera shake correction of a different method is alternately repeated.

Therefore, a certain period after the inversion of the flag is determined to be an image shaking after panning or tilting even in the determination period. By doing so, the flag changes as shown in FIG. 6C with respect to the differential value of the integral output of the angular velocity sensor 7 as shown in FIG. 6A, and based on this flag, as shown in FIG. Then, the camera shake correction method changes. As shown in FIG. 6D, in this case, the correction method does not change between the initial stages after the panning period.

[0037]

According to the present invention, the output of the angular velocity sensor is analyzed to determine whether the shake of the video camera is a shake after panning or tilting or a shake in a normal hand-held state. ing. If it is determined that the camera is in a normal hand-held state, the camera shake correction is performed by shifting the horizontal and vertical cutout positions of the imaging screen in accordance with the motion of the video camera, regardless of the interpolation screen. . If it is determined that the shaking has occurred after panning or tilting, an interpolated screen is formed, and the cutout position of the interpolated screen is shifted in accordance with the motion of the video camera to perform camera shake correction. For this reason, under normal shooting conditions, the image quality does not deteriorate, and unnatural motion of the screen is not noticeable immediately after panning or tilting.

[Brief description of the drawings]

FIG. 1 is a block diagram of an example of a video camera to which the present invention has been applied.

FIG. 2 is a waveform diagram used to describe an example of a video camera to which the present invention is applied.

FIG. 3 is a waveform diagram used to describe an example of a video camera to which the present invention is applied.

FIG. 4 is a flowchart used to describe an example of a video camera to which the present invention is applied.

FIG. 5 is a waveform diagram used to describe an example of a video camera to which the present invention has been applied.

FIG. 6 is a waveform diagram used to describe an example of a video camera to which the present invention has been applied.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... CCD image sensor, 2 ... Vertical shift circuit, 3 ... Horizontal shift circuit, 5 ... Electronic zoom circuit, 9 ... Angular velocity sensor, 8 ... Controller

Claims (12)

[Claims] 1. A shake detecting means for detecting a shake of a video camera, a first shake correcting means for performing a shake correction by shifting a cut-out position of an imaging screen in accordance with an output of the shake detecting means, A second camera shake correcting unit for forming an interpolated screen by interpolating the screen, shifting a cutout position of the interpolated screen in accordance with an output of the swing detecting unit to perform a camera shake correction, and an output of the swing detecting unit; And a shooting state detecting means for determining whether the video camera has been panned or tilted, and a camera shake correction by the first camera shake correcting means according to an output of the shooting state detecting means; A camera shake correction device for a video camera, comprising: a setting unit for selecting the camera shake correction by the camera shake correction unit. 2. An apparatus according to claim 1, wherein said swing detecting means is an angular velocity sensor. 3. The photographing state detecting means measures a cycle of a signal based on the shaking of the video camera detected by the shaking detecting means, and determines whether the video camera is in a state after panning or tilting. Claim 1.
A camera shake correction device for a video camera according to the above. 4. The photographing state detecting means differentiates a signal based on the shaking of the video camera detected by the shaking detecting means, measures a period during which the differential value has the same sign, and performs panning or tilting. 2. The apparatus according to claim 1, wherein it is determined whether or not the camera is in a state. 5. When the setting means determines from the output of the photographing state detecting means that the state is after panning or tilting, the second camera shake correcting means performs camera shake correction. 2. The camera shake correction device for a video camera according to claim 1, wherein the camera shake correction is performed by the first camera shake correction means. 6. When the setting means determines from the output of the photographing state detecting means that the state is after panning or tilting, the second camera shake correcting means performs camera shake correction. In other cases, the first image stabilization means is set to perform image stabilization, and a predetermined time after the image stabilization is set by the second image stabilization means, regardless of the output of the photographing state detection means. 2. The image stabilizing device for a video camera according to claim 1, wherein the image stabilization is held in the image stabilization by the second image stabilizing means. 7. A shake of a video camera is detected, and a detection output of the shake of the video camera is analyzed to determine whether the video camera is after panning or tilting. The first camera shake correction method of shifting the cut-out position of the imaging screen by the shake detection output to perform camera shake correction, and the interpolation screen is formed by interpolating the imaging screen, and the interpolation is performed by the shake detection output of the video camera. A camera-shake correction method for a video camera, wherein a camera-shake correction method for selecting a second camera-shake correction method for performing a camera shake correction by shifting a cutout position of a screen. 8. The method according to claim 7, wherein the shaking of the video camera is detected by an angular velocity sensor. 9. A determination as to whether the video camera has been panned or tilted is performed by measuring a period of a shake detection signal of the video camera to determine whether the video camera is in a state after panning or tilting. 8. The method according to claim 7, wherein the camera shake is corrected. 10. A determination as to whether or not the video camera has been panned or tilted is performed by differentiating a shake detection signal of the video camera, measuring a period during which the differential value has the same sign, and performing panning or tilting. 8. The method according to claim 7, wherein the method is performed by judging whether or not the camera is in a state. 11. When it is determined that the state is after panning or tilting, the camera shake is corrected by the second camera shake correction method, and otherwise, the camera shake correction is performed by the first camera shake correction method. 8. The method according to claim 7, wherein the setting is performed. 12. When it is determined that the state is after panning or tilting, the camera shake correction is performed by the second camera shake correction method, and otherwise, the camera shake correction is performed by the first camera shake correction method. In a predetermined time after the camera shake correction in the second camera shake correction method is set, the second camera shake is performed irrespective of the determination result as to whether or not the video camera is after panning or tilting. 8. The method according to claim 7, wherein the camera shake is maintained in a correction method.