JPH07115586A - Device for correcting shake of image - Google Patents

Abstract

PURPOSE:To output a stable video image without a sense of incongruity even when fade processing of an image is conducted in the dampring operation of the picture. CONSTITUTION:The device is provided with a fade detection means 6 to detect a signal component representing the fade operation indicated in a signal S1 sent from a video reproduction device 1, and a signal S6 outputted from the fade detection means 6 is fed to a microcomputer 4 and when an output signal S6 is sent from the fade detection means 6 by the control of the microcomputer 4, dampling control is gradually weakened and the dampling control is stopped just before a motion vector S2 is disable by fading, then a video image is smoothly outputted even when detection accuracy of the motion vector S2 is deteriorated or detection is disable because of fade processing of the picture.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image shake correction apparatus, and more particularly to an image shake correction apparatus for correcting image shake caused by camera shake at the time of shooting in a video player, an editing apparatus, a communication transceiver, and the like.

[0002]

2. Description of the Related Art As an example of a video player having a function of correcting image blur caused by camera shake at the time of shooting, an image shake correcting apparatus as shown in FIG. 4 is disclosed in Japanese Patent Laid-Open No. 63-166370.
It is described in Japanese Patent Publication No.

In FIG. 4, a video reproducing device 1 is for reproducing a video signal and outputting the reproduced video signal S1. The image memory 2 is for temporarily storing the input video signal S1. The motion vector detection circuit 3 is for detecting a motion vector from the input video signal S1 and outputting a motion vector S2. The microcomputer 4 controls the image memory 2 and the image enlarging circuit 5, and outputs the read address S3 and the digital data S4 of the image enlarging ratio. The image enlarging circuit 5 enlarges the read image to a normal screen size and outputs the output video signal S5.

In the image shake correction apparatus thus constructed, the video signal S1 reproduced by the video reproducer 1 is
It is temporarily stored in the image memory 2 and is supplied to the motion vector detection circuit 3. This motion vector detection circuit 3
Detects a motion vector S2, which is information on the motion speed of an image, from the input video signal S1 and supplies it to the microcomputer 4. The microcomputer 4 determines the read address S3 of the image memory 2 based on the information of the motion vector S2, and reads the image information smaller than the original image from the image memory 2 while shifting the original image vertically and horizontally.

The image information read from the image memory 2 is supplied to the image enlarging circuit 5, and the image enlarging ratio S4 supplied from the microcomputer 4 is set so that the read image has a normal screen size. Will be fixed. By this series of operations, even if the reproduced video signal S1 has an image blur, it is compensated for, and a stable video signal S5 without shaking is output.

As a method of obtaining the motion vector S2,
The matching method is the most common. Matching method is 1
The correlation coefficient is obtained while shifting the recognition pattern before the field and the recognition pattern of the current field, and the shift amount that maximizes the correlation coefficient is used as the motion vector. The motion vector detection circuit 3 thus calculates the motion vector S2.

Further, the screen is divided into a plurality of block-like calculation regions for the purpose of transforming the subject in the screen, removing unprocessable subjects, and automatically determining the subject to be image-stabilized. However, motion vector detection is performed for each area block. In this case, the microcomputer 4 synthesizes the motion vector obtained for each area block by a method such as averaging or median processing to calculate the shake amount of the entire screen. Since the calculated value is a difference value between frames or fields with respect to the image position, the final image correction vector, that is, the read address S3 of the image memory 2 is determined by performing integration processing or low-pass filter processing. There is. The image enlargement ratio S4 normally uses a constant value for each shooting situation.

[0008]

However, according to the above-mentioned conventional example, when performing the image stabilization of the television image actually broadcast and the image recorded by the home video camera, the following will be described. There was a problem. That is,
A general television image editing device or camera has a function of fading an image. This has the effect of intentionally weakening the TV video signal during shooting or playback, processing it so that it has a specific color as a whole, and showing the transitions of the scene explicitly and comfortably. It is a function that has been frequently used as technology. Here, colorless colors such as white, black, and gray are often used as the specific colors.

As described above, since the image shake correction apparatus detects the image shake from the television image, the input image has a fade when the contrast of the image becomes low or when the image becomes plain. Therefore, the accuracy for detecting the image shake may be lowered, or the image may be undetectable suddenly. As a result, at the end of the scene, a phenomenon in which the image stabilization that had been able to perform image stabilization until then becomes unstable, or the image stabilization operation stops, causing a problem that the image becomes unsightly. there were.

The present invention has been made in view of the above problems, and it is possible to output a stable image without a feeling of discomfort even when image fading processing is performed during image stabilization operation. The purpose is to do.

[0011]

An image shake correcting apparatus of the present invention comprises a motion vector detecting means for detecting a motion vector from a video signal, and a screen protection based on the motion vector detected by the motion vector detecting means. Anti-vibration means for performing vibration, fade detection means for detecting fade operation, and anti-vibration means for controlling the anti-vibration characteristics of the anti-vibration means according to the fade operation detected by the fade detection means It is characterized by having a control means.

Another feature of the image shake correction apparatus of the present invention is that the image stabilization control means is configured to: when the input video signal is weakened by the fade operation,
It is characterized in that the image stabilizing operation for suppressing camera shake is gradually weakened, and when the input video signal is being strengthened by the fade operation, the image stabilizing operation for suppressing camera shake is gradually strengthened.

Another feature of the image shake correction apparatus of the present invention is that the image stabilization control means obtains a variation value of an information signal indicating a fade state and changes the image stabilization characteristic in accordance with the variation value. It is characterized by controlling the speed.

Another feature of the image shake correcting apparatus of the present invention is that the fade detecting means calculates the average brightness, brightest point, darkest point, and spectral component of each screen from the input video signal. It is characterized in that the amplitude of the modulated color signal is detected and the fade is judged from the correlation of the changing speed.

[0015]

Since the image shake correction apparatus of the present invention comprises the above-mentioned technical means, it becomes possible to control the image stabilization characteristic in accordance with the fade operation, which reduces the detection accuracy of the motion vector during the fade operation and prevents it. It is possible to eliminate the unstable shaking motion and the inability to detect the motion vector to stop the anti-shake motion, and to obtain a stable image with no discomfort even when fade processing is performed. It becomes possible to output.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the image shake correcting apparatus of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a schematic configuration of an image shake correction apparatus according to an embodiment of the present invention. In FIG. 1, a video player 1, an image memory 2, a motion vector detection circuit 3, a microcomputer 4, and an image enlarging circuit 5 are the same as those of the image shake correction apparatus shown in FIG.

In this embodiment, a fade detection circuit 6 is newly added to the image shake correction device shown in FIG.
The video signal S1 reproduced by the video player is input to the fade detection circuit 6, and the output signal S6 from the fade detection circuit 6 is output to the microcomputer 4. This video signal S1 is
As shown in FIG. 2, it comprises a luminance signal Y, a gate signal Gate, a vertical synchronizing signal VD, and a color signal C.

Next, the fade detection circuit 6 will be described with reference to FIG. FIG. 2 is a block diagram showing a schematic configuration of the fade detection circuit 6 in the embodiment of the present invention.

In FIG. 2, an average value detection circuit 11 is for obtaining an average brightness of an image, and is inputted with a luminance signal Y, a gate signal Gate and a vertical synchronizing signal VD, and an average value of the luminance signal Y. Interface circuit 1 for S7
Output to 6. The average value S7 of the luminance signal Y is calculated by
Gate signal Gat indicating that the scanning pixel is an effective pixel
Based on e and the vertical sync signal VD, this is performed only for the effective pixels in each field, and is completed by the start of the next field. Further, the calculation result is reset for each field.

The maximum value detection circuit 12 is for obtaining the brightness at the brightest point of the image, and is supplied with the brightness signal Y, the gate signal Gate and the vertical synchronizing signal VD, and the maximum value S8 of the brightness signal Y. Is output to the interface circuit 16. The calculation of the maximum value S8 of the luminance signal Y is also similar to the calculation of the average value S7 of the luminance signal Y, based on the gate signal Gate indicating that the scanning pixel is an effective pixel and the vertical synchronization signal VD, the effective of each field. It is done only for pixels and is finished by the start of the next field. Further, the calculation result is reset for each field.

The minimum value detection circuit 13 is for obtaining the brightness at the darkest point of the image, and is supplied with the brightness signal Y, the gate signal Gate and the vertical synchronizing signal VD, and the minimum value S9 of the brightness signal Y. Is output to the interface circuit 16. The calculation of the minimum value S9 of the luminance signal Y is performed only in the effective pixel of each field based on the gate signal Gate indicating that the scanning pixel is an effective pixel and the vertical synchronization signal VD, and before the start of the next field. Will be terminated. Further, the calculation result is reset for each field.

The high-pass filter 14 is for obtaining an edge component of the luminance signal Y containing a lot of noise. The luminance signal Y, the gate signal Gate, and the vertical synchronizing signal VD are inputted to the high-pass filter 14, and the high-frequency component of the luminance signal Y is inputted. The S10 is output to the interface circuit 16. The calculation of the high frequency component S10 of the luminance signal Y is performed only in the effective pixel of each field based on the gate signal Gate indicating that the scanning pixel is an effective pixel and the vertical synchronization signal VD, and by the start of the next field. Will be terminated. Further, the calculation result is reset for each field.

The amplitude detection circuit 15 is for obtaining the average amplitude of the color signals, and is composed of the color signal C and the gate signal Gat.
e, the vertical synchronizing signal VD is input, and the amplitude value S11 of the color signal C is output to the interface circuit 16. The calculation of the amplitude value S11 of the color signal C is performed only in the effective pixel of each field based on the gate signal Gate indicating that the scanning pixel is an effective pixel and the vertical synchronizing signal VD, and is started by the start of the next field. Will be terminated. Further, the calculation result is reset for each field.

The interface circuit 16 has an average value S7 of the brightness signal Y output from the average value detection circuit 11 and a maximum value S of the brightness signal Y output from the maximum value detection circuit 12.
8, the minimum value S9 of the luminance signal Y output from the minimum value detection circuit 13, the high frequency component S10 of the luminance signal Y output from the high pass filter 14, and the amplitude value S11 of the color signal C output from the amplitude detection circuit 15. , And each is supplied to the microcomputer 4 as a fade information signal S6.

Next, the processing in the microcomputer 4 will be described. The microcomputer 4 uses the fade information signal S6 sent from the fade detection circuit 6 to determine whether the fade is currently in progress. Here, a method of determining how the luminance signal Y and the color signal C change when a fade occurs in the input image and how the fade is detected based on the change will be described.

First, in the case of a fade to a general simple color, when the intensities of the luminance signal Y and the color signal C are shown between 0 and 1,
It is expressed by the following conditional expression. Yo = K · Yi + (1−K) Ya Co = K · Ci where Yi is the input signal of the luminance signal Y, Yo is the output signal of the luminance signal Y, Ci is the input signal of the color signal C, and Co is the output of the color signal C. The signal K indicates the fade coefficient Ya indicates the brightness of the screen after the fade.

Here, a case where a normal image is changed to a white image by a fade at the end of the scene will be described as an example. In this case, as the fade coefficient K decreases from 1 to 0 for each field, the contrast of the output signal gradually decreases, and finally the luminance signal Y matches the screen brightness Ya after the fade. Become.

FIG. 3 is a waveform diagram showing a change state of the video signal at the time of fading. The average value S7 of the luminance signal Y, the maximum value S8 of the luminance signal Y, the minimum value S9 of the luminance signal Y, and the luminance signal Y. The change state of the high frequency component S10 and the amplitude value S11 of the color signal C is shown. FIG. 3 shows the state of the image signal in one line at the center of the screen.
3B is a luminance signal Y including a synchronization signal, FIG. 3B is a modulated color signal C, FIG. 3C is a high-frequency component of the luminance signal Y, and FIG.
3D shows the fade coefficient K, and FIG. 3E shows the time t.

It is assumed that the signal state at the start of fading, that is, at time t = 0 has a signal value as shown in FIGS. 3 (a) to 3 (c). And the fade started,
When the fade coefficient K = 0.5, the difference between the maximum value S8 and the minimum value S9 of the luminance signal Y becomes small and approaches the average value S7. At the same time, the amplitude value S11 of the color signal C and the high frequency component S10 of the luminance signal Y also decrease.

However, the values of these signals may change due to changes in the shooting conditions, and it is often impossible to judge the fade based on the value of a single signal. Therefore, the image shake correction apparatus of the present embodiment accurately determines whether or not the fading is in progress by checking the correlation between the signals.

For example, although the contrast of the input image is reduced and the difference between the maximum value S8 and the minimum value S9 of the luminance signal Y is reduced, the amplitude of the high frequency component S10 of the luminance signal Y containing a lot of noise components. Also, the phenomenon that the same ratio is reduced at a similar rate is unlikely to occur in normal shooting other than fading, that is, changes in the illumination amount and changes in the aperture and focus.

Therefore, the microcomputer 4 evaluates the changing speed of these values to judge the fade. That is, (a) variation value of (maximum value S8 of luminance signal Y−minimum value S9 of luminance signal Y), (b) variation value of average value S7 of luminance signal Y, and (c) amplitude value S11 of color signal C. Variation value of
(D) If the microcomputer 4 calculates the variation value of the high frequency component S10 of the luminance signal Y and these values are almost the same value, and the same value continues over the past several fields,
Judge as a fade. This relationship is the same when fading to black or gray or at the beginning of the scene.

Next, the image stabilization control when the fade is judged from the input image will be described. If the fade causes the input image to lose contrast at the end of the scene,
Although the detection accuracy of the motion vector detection circuit 3 is reduced, the noise included in the image is also reduced as described above, and thus the detection of the motion vector S2 is unlikely to be impossible immediately. Note that if the image stabilization control is suddenly stopped at this point, the image suddenly shakes while the scene of the input image is still visible.

On the other hand, immediately before the end of the fade-out, that is, when the fade coefficient K reaches about 0.1, the motion vector S2 cannot be detected suddenly at all.

Therefore, in the image shake correcting apparatus of the present embodiment, the fade detection means 6 indicates that the fade has started.
The image stabilization control is gradually weakened when is detected, and the image stabilization control is stopped until just before the detection of the motion vector S2 becomes impossible due to the fade. The appropriate speed for changing the image stabilization control can be obtained by predicting the time when the motion vector S2 cannot be detected from the variation value of each detection signal described above.

As a method of weakening the image stabilization control, there is a method of multiplying the correction vector obtained by the usual method, that is, the read address S3 of the image memory 2 by a coefficient of 1 or less.
In addition, in the integration calculation when obtaining the correction vector from the motion vector S2, a low-pass filter calculation of a first order or higher,
That is, it is also effective to perform a calculation in which Kc in the formula of [current field correction vector] = [current field motion vector] + [all field correction vector] × Kc is smaller than 1.

With the image stabilization control method described above, it is possible to output a smooth image without any discomfort even when there is a fade.

[0038]

As described above, the present invention is provided with the fade detecting means for detecting the fact that the fade operation is performed from the input video signal, and the anti-vibration means is operated based on the signal detected by the fade detecting means. Since the vibration characteristics are controlled, it is possible to output a stable image with no discomfort even when fade processing is performed, and the image stabilization operation suddenly stops or the screen suddenly shakes, resulting in an unsightly image. It will not end up becoming.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of an image shake correction apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a schematic configuration of a fade detection circuit according to an embodiment of the present invention.

FIG. 3 is a waveform diagram showing a change state of a video signal at the time of fading.

FIG. 4 is a block diagram showing a schematic configuration of a conventional image shake correction apparatus.

[Explanation of symbols]

 1 Video Player 2 Image Memory 3 and 11 Motion Vector Detection Circuit 4 Microcomputer 5 Image Enlargement Circuit 6 Fade Detection Circuit S1 Reproduced Video Signal S2 Motion Vector Digital Data S3 Read Address Digital Data S4 Image Enlargement Ratio Digital Data S5 Output video signal S6 Fade information signal 11 Average value detection circuit 12 Maximum value detection circuit 13 Minimum value detection circuit 14 High-pass filter 15 Amplitude detection circuit 16 Interface circuit S7 Average value of luminance signal S8 Maximum value of luminance signal S9 Minimum value of luminance signal S10 High-frequency component of luminance signal S11 Amplitude value of color signal

Claims (4)

[Claims] 1. A motion vector detecting means for detecting a motion vector from an input video signal, and a vibration damping means for stabilizing the screen based on the motion vector detected by the motion vector detecting means. A fade detection unit for detecting a fade operation from the video signal; and an image stabilization control unit for controlling the image stabilization characteristic of the image stabilization unit according to the detection signal detected by the fade detection unit. An image shake correction device characterized by: 2. The image stabilization control means, when an input video signal is weakened by the fade operation,
The image stabilizing operation for suppressing camera shake is gradually weakened, and when the input video signal is strengthened by the fade operation, the image stabilizing operation for suppressing camera shake is gradually strengthened. The image shake correction device described. 3. The image stabilization control means obtains a variation value of an information signal indicating a fade state, and controls a speed at which the image stabilization characteristic is changed according to the variation value. Image shake correction device. 4. The fade detection means, based on an input video signal, average brightness, brightest point, darkest point of each screen,
4. The image shake correction apparatus according to claim 1, wherein the amplitude of the spectral component and the modulated color signal is detected, and the fade is judged from the correlation of the changing speeds.