JP3302472B2 - Image blur correction apparatus and method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image blur correcting device and
The method is particularly suitable for use in a video player, an image receiver, or the like having a function of correcting image shake caused by camera shake during shooting.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. Sho 63-16637 discloses an example of a video player having a function (vibration-proof function) for correcting image shake caused by camera shake during shooting.
No. 0 publication. An image blur correction device to which this video player is applied is configured as shown in FIG.

In FIG. 9, 1 is a video player, 2 is an image memory, 3 is a motion vector detection circuit, 5 is an image enlargement circuit, and 30 is a microcomputer.
Further, s1 is a video signal reproduced by the video reproducer 1, s2 is a motion vector detected by the motion vector detection circuit 3, s30 is an address signal indicating a reading position of the video signal stored in the image memory 2, and s4. Is digital data representing an image enlargement ratio, and s5 is a video signal output from the image blur correction device.

[0004] In the image blur correction apparatus thus configured, the video signal s1 reproduced by the video reproducer 1 is used.
Are temporarily stored in the image memory 2. On the other hand, the video signal s1 reproduced by the video reproducer 1 is also input to the motion vector detection circuit 3, and the motion vector detection circuit 3 detects a motion vector s2, which is information on the motion speed of the image, from the video signal s1. Is done.

The motion vector s thus detected
2 is given to the microcomputer 30. Then, the microcomputer 30 determines an address signal s3 indicating the read position of the video signal stored in the image memory 2 based on the motion vector s2.

[0006] The video signal stored in the image memory 2 is read out according to the address signal s3. As a result, the video signal is read from the image memory 2 so that the image is shifted up, down, left, and right so that the shake of the image caused by camera shake or the like at the time of shooting is eliminated.

Next, the video signal thus read out is:
It is input to the image enlargement circuit 5. In the image enlargement circuit 5, the image read from the image memory 2 is corrected according to the image enlargement ratio data s4 so as to have a normal screen size. Then, the video signal s5 having the screen size corrected as described above is output to the signal processing circuit provided in the next stage.

As described above, a series of processing is performed on the video signal s1 reproduced by the video reproducing device 1, so that even if the reproduced video signal s1 has an image shake, there is no shake. A stable video signal s5 is output from the image blur correction device.

By the way, the subject in the screen is deformed,
It is common practice to divide a screen into a plurality of calculation regions (motion vector detection regions) and detect a motion vector for each of the plurality of calculation regions in order to remove an unprocessable subject.

In this case, the motion vector detection circuit 3 detects a motion vector for each calculation area. Then, the microcomputer 30 calculates the average value of the motion vector amounts detected in this way, or combines the motion vectors by a method such as a median process to calculate the shake amount of the entire screen. The shake amount of the entire screen represents a difference value between frames or fields of the image position.

Next, the shake amount of the entire screen is subjected to integration processing or low-pass processing by a low-pass filter, and the final image shake correction amount, that is, the image stored in the image memory 2. An address signal s30 indicating a signal reading position is determined. Note that a constant value is generally used as the data s4 of the image enlargement ratio.

[0012]

However, in the conventional image blur correction apparatus as described above, when correcting the blur of a television image actually broadcast or an image recorded by a home video camera, There were the following problems.

That is, a TV image that is actually being broadcast may be superimposed with character information such as a broadcast time, a broadcast title or a comment, or a Japanese translation. In addition, images recorded by a home video camera may have a superimposed character information indicating the date and time at the time of shooting or the details of shooting.

Then, the video signal s1 including the superimposed character information is input to the motion vector detection circuit 3, and when the video signal s1 is used as it is for detecting the motion vector, the superimposed In some cases, the movement of a given character is also detected as it is.

For example, when there is a character whose display position does not change in the screen, such as a date and time, a motion vector detection area around the display position,
In the motion vector detection area including the display position, the image shake may be detected as being smaller than the actual shake.

If there are characters moving in the screen among the titles and telops indicating the shooting conditions and the like, a motion vector detection area around the display position and a motion including the display position are displayed. In the vector detection area, such a moving speed of a character may be detected.

Therefore, if the image shake amount is calculated using the above-described conventional image shake correction apparatus, and the image shake correction is performed based on the calculated image shake amount, the image shake may occur during actual photographing. Therefore, there is a problem in that a process irrelevant to the process of correcting the shake of the image is performed, and the image becomes rather unsightly.

The present invention has been made to solve such a problem, and prevents an error from occurring in an image blur correction operation due to the presence of a superimposed character in an image. It is another object of the present invention to always obtain a good image.

[0019]

According to the present invention, there is provided an image blur correcting apparatus according to the present invention.
One of the devices is an image shake correction device that corrects image shake.
And the characters in the image are superimposed
Detecting means for detecting an area in which
According to the number of areas detected by
It is characterized in that processing for correction is not performed.
I do.

Also, one of the image blur correction methods of the present invention is
Is an image shake correction method for correcting image shake,
Characters are superimposed in the image
A detection step of detecting a region; and
To correct the shake of the image according to the number of
And a step of not performing the processing.
And

Further , one of the image blur correction apparatuses of the present invention
Is an image shake correction device for correcting image shake,
Characters are superimposed in the image
Detecting means for detecting the area;
Without using the motion vector of the region
A process for correcting image shake is performed.
You.

Also, one of the image blur correction methods of the present invention is
Is an image shake correction method for correcting image shake,
Characters are superimposed in the image
A detection step of detecting a region; and
Of the image without using the motion vector of the
Performing a process for correcting shake.
Features.

[0023]

[0024]

[0025]

[0026]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a first embodiment of an image blur correction device according to the present invention. Note that, in FIG. 1, components denoted by the same reference numerals as those shown in FIG. 9 have the same functions, and thus detailed description thereof will be omitted.

The image blur correcting apparatus of the present embodiment is obtained by adding an imposed character detecting circuit 6 to the configuration of the conventional image blur correcting apparatus shown in FIG. Then, the microcomputer 4 determines an address signal s3 indicating the image reading position based on the detection signal s6 of the imposed character output from the imposed character detection circuit 6.

Here, the principle of the imposed character detection circuit 6 will be described. Generally, an image captured by a video camera is distributed in a frequency region that is considerably lower than a frequency band of a video signal. On the other hand, the above-described image of the imposed character is generally an image with white and sharp edges, and has a prominent frequency spectrum because it is concentrated in a certain narrow range in the screen. I have.

Further, even if there is a bright subject at the position where the imposed character is displayed, a function of automatically increasing the brightness of the imposed character so that the imposed character is easy to read, A superimpose circuit having a function of adding a black border or blur to the background around a character has been put into practical use.

Therefore, when the video signal photographed by the video camera is subjected to such processing by the superimposing circuit, the image photographed by the video camera and the image of the imposed character are compared with each other. Then, the difference of the frequency components becomes more remarkable.

The imposed character detection circuit 6 pays attention to such a difference between the frequency components of the two images, and extracts only the component of the imposed character from the video signal s1 reproduced by the video reproducer 1. It was done.

Next, FIG. 2 shows an example of the configuration of the imposed character detection circuit 6. 2, reference numeral 7 denotes a differentiating circuit, 8 denotes a low-pass filter, 9 denotes a binarizing circuit, and 10 denotes an isolated point removing circuit. In addition, s1 is a video signal reproduced by the above-described video reproducer 1, s7 is a video signal output from the differentiating circuit 7 with emphasized edges, s8 is a luminance information signal output from the low-pass filter 8, and s9 is 2 A binary video signal s6 output from the digitizing circuit 9 is a detection signal of the above-described imposed character.

In the imposed character detection circuit 6 having such a configuration, the input video signal s1 is given to the differentiating circuit 7 and the low-pass filter 8. Then, based on the video signal s1, a video signal s7 whose edge is enhanced by the differentiating circuit 7 is generated. Further, the low-pass filter 8 generates a luminance information signal s8 having average luminance information around the scanning pixel.

The video signal s7 and the luminance information signal s8
Are input to the binarization circuit 9 respectively. In the binarization circuit 9, the threshold level is appropriately changed according to the level of the luminance information signal s8 given from the low-pass filter 8. Then, the video signal s7 whose edge is provided from the differentiating circuit 7 is binarized by the threshold level.

The video signal s9 subjected to the binarization processing by the binarization circuit 9 is input to an isolated point removal circuit 10,
Noise generated suddenly is removed. Then, a portion where the video signal s9 is concentrated in a certain narrow range on the screen is detected, and the signal thus detected is
It is output to the microcomputer 4 provided at the next stage as the detection signal s6 of the imposed character.

As described above, according to the imposed character detection circuit 6 of the present embodiment, the position of the imposed character multiplexed on the video signal s1 reproduced by the video reproducing device 1 in the screen can be almost accurately determined. Can be detected.

Next, the configuration of another embodiment of the imposed character detection circuit 6 is shown in FIG. In FIG. 3, 11 is an image memory, 12 is a comparison circuit, 13 is a low-pass filter, 1
4 is a threshold circuit, and 15 is an AND circuit. Also, s
Reference numeral 10 denotes a comparison signal output from the comparison circuit 12, and reference numeral s11 denotes a binary signal output from the threshold circuit 14.

In the imposed character detection circuit 6 having such a configuration, the input video signal s1 is stored in the image memory 1
1 and one input terminal of the comparison circuit 12. This image memory 11 has a storage capacity of one frame.
This is an IFO (First In First Out) memory, and the image memory 11 always outputs a video signal of one frame before.

The video signal output from the image memory 11 is supplied to the other input terminal of the comparison circuit 12. As a result, two video signals of the current frame and the previous frame are input to the comparison circuit 12.

The comparison circuit 12 compares the two video signals thus input, that is, the video signal of the current frame and the video signal of the previous frame, for each pixel. When the two pixel signals to be compared are equal, “1” is given to one input terminal of the AND circuit 15 as the comparison signal s10. On the other hand, when the two pixel signals are not equal, “0” is given to one input terminal of the AND circuit 15 as the comparison signal s10.

That is, the comparison circuit 12 calculates the difference between the frames of the video signal between the current frame and the previous frame. Then, "1" is output as the comparison signal s10 in a portion where there is no difference between the frames, that is, in a portion where there is no motion of the image. On the other hand, in a pixel in a portion where the image moves, “0” is output as the comparison signal s10.

On the other hand, the video signal s1 reproduced by the video reproducer 1 is supplied to the low-pass filter 13 and the threshold circuit 1
4 is also input to one of the input terminals. The low-pass filter 13 and the threshold circuit 14 form a so-called adaptive binarization circuit.

That is, the average luminance information around the scanning pixel is calculated from the input video signal s1 by the low-pass filter 13. The luminance information calculated by the low-pass filter 13 is given to the other input terminal of the threshold circuit 14, and the threshold in the threshold circuit 14 is appropriately changed according to the luminance information. Then, the video signal s1 input to one input terminal of the threshold circuit 14 is binarized by the threshold.

As a result, in the pixel of the high luminance portion in the image, the binary signal s11 is input to the other input terminal of the AND circuit 15.
Is given as “1”, and “0” is given to other pixels. The AND circuit 15 performs a logical product (AN) of the comparison signal s10 and the binary signal s11.
D) is calculated, and the calculation result is output to the microcomputer 4 provided in the next stage as the detection signal s6.

The detection signal s6 represented by "1" indicates the position of a pixel having no motion in the image and having high luminance. Therefore, according to the imposed character detection circuit 6 of the present embodiment, an imposed character whose display position does not change in the screen, such as a date and a time, can be detected almost accurately.

The amount of motion of an image is detected by first obtaining a difference between frames of a video signal and dividing the value by a parameter (for example, image gradient or the like) representing the complexity of the image. It is common. However, in the case of the imposed character detection circuit 6 of the present embodiment, it is not particularly important to detect a precise movement of an image.

Therefore, in this embodiment, only the above-described calculation of the difference between frames is performed, and the calculation of the image gradient and the division by the image gradient are not performed. Thus, the gradient calculation circuit and the division circuit can be omitted, and the circuit scale can be reduced. In the case of this embodiment,
It goes without saying that the motion amount of the image may be detected by the above-described general method.

For example, when the reproduced video signal s1 is 8-bit digital data, the comparison circuit 12
Does not necessarily need to be performed using all of the 8-bit data. For example, it is often sufficient to perform a comparison operation using only upper 3 or 4 bits of data.

Further, in the above description, a case has been described as an example where all the motions of an image are detected in units of frames. However, detection may be performed in units of fields. In this case, the storage capacity of the image memory 11 is half that of the case where the motion of the image is detected on a frame basis.

Next, the configuration of still another embodiment of the imposed character detection circuit 6 is shown in FIG. In FIG. 4, reference numeral 16 denotes an addition circuit, 17 denotes a multiplication circuit, 18 denotes an image memory, 19 denotes a differentiation circuit, and 20 denotes a binarization circuit. Further, s12 is a video signal obtained by multiplying the video signal of the previous frame by a predetermined coefficient, and s13 is a video signal output from the addition circuit 16.

Here, the above-described addition circuit 16 and multiplication circuit 1
7 and the image memory 18
This is a circuit part for detecting the amount of motion of the image. Further, a circuit portion configured by the above-described differentiating circuit 19 and the binarizing circuit 20 is a circuit portion that detects edge information of an image.

In the imposed character detection circuit 6 having such a configuration, the input video signal s1 is added to the addition circuit 16
To one of the input terminals. Also, this addition circuit 1
The video signal s13 output from 6 is subjected to predetermined processing by the multiplication circuit 17 and the image memory 18, and then applied to the other input terminal of the addition circuit 16.

The above-described multiplication circuit 17 has a coefficient of 0 or more and 1 or less. Then, the multiplication circuit 17 multiplies the video signal s13 output from the addition circuit 16 by the above coefficient. Next, the video signal multiplied by the coefficient by the multiplication circuit 17 is given to the image memory 18 and temporarily stored. The image memory 18 is a FIFO memory having a storage capacity for one frame, like the image memory 11 described above.
The video signal before the frame is always output.

Therefore, in the adder circuit 16, the reproduced video signal s1 of the current frame supplied to one input terminal and
A video signal s12 obtained by multiplying the video signal of the previous frame supplied to the other input terminal by the above coefficient is added. Then, the video signal s13 obtained as a result of the addition is provided to the differentiating circuit 19.

As described above, the adding circuit 16, the multiplying circuit 17, and the image memory 18 form a temporal low-pass filter of the video signal. Such a temporal low-pass filter has such a characteristic that, of the input video signal s1, a pixel signal of a portion having a higher luminance and a smaller image movement outputs a larger value. In addition, the output level of an image having a slight movement is reduced, and the edge of the image is extremely dull.

Therefore, if there is a portion having a steep edge characteristic in the video signal s13 output from the temporal low-pass filter, the portion is originally steep, has no image movement, and is high. It can be inferred that the pixel has brightness. Therefore, the next-stage differentiation circuit 1
The circuit portion constituted by the binarization circuit 9 and the binarization circuit 20 detects a signal component having the above-described steep edge characteristic, and can encode the video signal s13 according to the result of the detection. It has such a configuration.

That is, the video signal s13 output from the above-mentioned addition circuit 16 is supplied to a differentiating circuit 19, which extracts an edge gradient of the video signal s13. Next, the binarizing circuit 20 converts the video signal s13 to 2 in accordance with the signal strength level of the edge gradient.
Valued. Then, the binary signal thus obtained is output to the microcomputer 4 provided at the next stage as a detection signal s6 of the imposed character.

As described above, according to the imposed character detection circuit 6 of this embodiment, from the input video signal s1,
It is possible to extract a component having no image movement, high luminance, and a sharp edge. As a result, for example, an imposed character whose display position does not change in the screen, such as a date and a time, can be detected almost accurately.

Note that also in this embodiment, the video signal s1
It is not always necessary to detect the motion of an image using the entire bit width of. Further, it is not always necessary to detect the motion of an image in units of a frame, but may be detected in units of a field. By doing so, the circuit scale can be significantly reduced.

As described above, according to the imposed character detection circuit 6 shown in FIG. 2, FIG. 3, or FIG. 4, only the signal component of the imposed character is almost accurately extracted from the video signal with a simple circuit configuration. can do.

Next, the operation of the entire image blur correction apparatus according to the first embodiment shown in FIG. 1 will be described with reference to the flowchart of FIG. Here, the image enlargement circuit 5
Is assumed to be constant.

First, in step P1 of FIG. 5, the motion vector detection circuit 3 specifies from which motion vector region in the image a motion vector is to be detected. Then, in step P2, the motion vector s2 of the area designated in this way is detected.

In step P3, it is detected whether or not an imposed character is multiplexed on the video signal s1 reproduced by the video reproducing device 1 in the area specified in step P1. The detection of this imposed character is
As described above, this is performed by the imposed character detection circuit 6 as shown in FIG. 2, FIG. 3, or FIG.

Next, in step P4, the detection signal s6 of the imposed character detected by the imposed character detection circuit 6 is applied to the motion vector detection circuit 3 in step P2.
Are taken into the microcomputer 4 together with the motion vector s2 detected by

Further, when there are a plurality of motion vector detection areas in the image, the process returns from the branch of step P5 to step P1, and the processes of steps P1 to P5 are repeated. As a result, the microcomputer 4 receives the motion vector s2 and the detection signal s6 of the imposed character for a required area.

When the motion vector s2 and the detection signal s6 of the imposed character for the required area are taken into the microcomputer 4, the microcomputer 4
In the next steps P6 to P10, image blur correction processing is performed.

That is, in step P6, the motion vector of the area where the imposed character is detected is calculated in step P7.
It is instructed not to be used for the subsequent processing. This instruction is performed, for example, by setting an invalid flag for a motion vector for each region.

Next, in step P7, an area to be subjected to image shake correction is determined based on the fluctuation value of the motion vector taken into the microcomputer 4 and the degree of uniformity in the image. At the time of this determination, only the motion vector of the area where the invalid flag is not set, that is, the area where the imposed character is not detected is used.

Next, in step P8, the average value of the motion vectors in the region where the invalid flag is not set, that is, the image shake amount in the entire screen is obtained. In the next step P9, an integration operation is performed on the average value of the motion vectors obtained in step P8, and a final image blur correction amount is calculated.

Further, in Step P10, Step P9
The address signal s3 indicating the read position of the video signal stored in the image memory 2 is determined based on the image shake correction amount calculated in the step (1), and the address signal s3 is output to the image memory 2. From the image memory 2, the video signal at the position specified by the address signal s3 is output to the image enlargement circuit 5 at the next stage. Then, the processing of steps P1 to P10 as described above is repeated for each field.

Here, the processing in step P6 described above is equivalent to the processing for removing the motion vector of the area including the imposed character from the motion vectors detected by the motion vector detection circuit 3. Therefore, in the processing after step P7, only the motion vector other than the removed motion vector is used, and the address signal s3 determined in step P10 is affected by the amount of character motion such as date and time. The value has not been received.

As described above, the image blur correcting apparatus according to the first embodiment is provided with the imposed character detecting circuit 6 for detecting the position of the imposed character on the screen. The feature is that the motion amount of the image is calculated by excluding the motion vector of the area including the imposed character.

By configuring the image blur correction device in this way, even if characters such as date and time are multiplexed in the video signal, only the amount of image blur at the time of shooting can be correctly detected. In addition, it is possible to perform image shake correction without malfunction.

Next, a description will be given of a second embodiment of the image blur correction apparatus according to the present invention. The image blur correction apparatus according to the second embodiment has been made in consideration of the following circumstances.

That is, of the imposed characters multiplexed in a television image actually broadcast or an image captured by a home video camera, the most common and frequently used characters are date and time. The time character. These characters are usually multiplexed mainly on the periphery of the screen, such as the lower right or lower left of the screen.

On the other hand, the imposed character detection circuit 6 as described in the first embodiment always contains a certain detection error. Therefore, the operation of image shake correction becomes unstable depending on the type of a captured image. Therefore, in the second embodiment, the above-described inconvenience is prevented by performing the following calculation in the process of step P8 in the flowchart shown in FIG.

FIG. 6 shows an example of a television screen for explaining the principle of the present embodiment. The TV screen of FIG. 6 shows a total of 60 motion vector detection areas of 6 rows and 10 columns. Hereinafter, the positions of these motion vector detection areas will be indicated by (i, j), where the row number is i (i = 1 to 6) and the column number is j (j = 1 to 10).

In FIG. 6, reference numeral 21 denotes an effective pixel area of a television image, 22 denotes an outermost first detection area among the 60 detection areas in the screen, and 23 denotes a first detection area 22. A second detection area 24 immediately inside is a third detection area innermost. Next, 25 is a date character multiplexed in the image, 26 is a time character, 2
7 is not a region of an imposed character, but is an erroneously detected region erroneously detected as a region of an imposed character.

By the way, the first detection area 22, the second detection area 23, and the third detection area 24 are, for example, in accordance with the probability that an imposed character is multiplexed in each area. Weighting factors such as 1.0, 0.9, and 0.1 are set so as to increase as they go outside the screen.

Therefore, in the present embodiment, in step P8 of the flowchart shown in FIG. 5, the weighting factor set in this manner is used to calculate each detection area by the following equation (1). The motion vector averaging operation is performed.

[0081]

(Equation 1)

Here, MVa is the calculation result of averaging, and MVa
Is a motion vector value of each detection area, T is an invalid flag (0 or 1) indicating whether an imposed character is detected in each detection area, and W is a first detection area 22 to a third detection area 24. Are shown, respectively.

According to the averaging operation shown in the above (Equation 1), in the (5, 10) detection area where the date character 25 is multiplexed, the invalid flag T (= 1) is assigned a weight of 1.0. The coefficient W is multiplied, so that the motion vector of this detection area is not used for the averaging operation. Similarly, the invalid flag T (= 1) is multiplied by a weighting factor W of 1.0 for the detection area of (6, 10) in which the time character 26 is multiplexed, and the motion vector of this detection area is subjected to the averaging operation. Will not be used.

On the other hand, in the (4, 5) detection area including the erroneous detection area 27, the invalid flag T (= 1) is multiplied by the weight coefficient W of 0.1, and as a result, the motion vector becomes 0.9.
Will be evaluated. In other words, this (4,
In the detection area 5), even though an imposed character is erroneously detected, its motion vector is used for the averaging operation almost as usual.

As described above, according to the second embodiment, it is determined whether or not the motion vector detected by the imposed character detection circuit 6 is due to erroneous detection based on the weighting factor set for each detection area. be able to. Therefore, even if the imposed character detection circuit 6 has a certain detection error, it is possible to prevent the image blur correction operation from becoming unstable.

By applying the technique of the second embodiment, the threshold level of the binarization circuit 9 shown in FIG. 2 is lowered in the outermost first detection area 22 in the screen. Set as follows. Alternatively, the first detection area 22 is set so that the isolated point removal capability of the isolated point removal circuit 10 is reduced. By doing so, it is also useful that the imposed character detection circuit 6 can easily detect a small imposed character or an imposed character having a low luminance level.

Next, a description will be given of a third embodiment of the image blur correction apparatus according to the present invention. As described above, the imposed character detection circuit 6 erroneously detects that even a normal subject is an imposed character, and rarely generates the imposed character detection signal s6. If the detection signal s6 erroneously detected as described above is used as it is in the image blur correction process, the operation of correcting the image blur (vibration-proof operation) becomes unstable.

Therefore, the image blur correction device of this embodiment is
The configuration is such that such inconvenience can be prevented. Specifically, the image blur correction apparatus of the present embodiment is configured as shown in FIG.

In FIG. 7, the microcomputer 28 determines whether or not the imposed character detection signal s6 detected by the imposed character detection circuit 6 is correct. Decide whether to continue the crop.

The operation of the image blur correction apparatus according to the present embodiment will be described below with reference to the flowchart of FIG. In FIG. 8, the processing of steps P1 to P5 is as follows.
This is the same as the processing of steps P1 to P5 in the flowchart shown in FIG. When the processing in steps P1 to P5 is completed, the microcomputer 28 performs the processing in steps P6 to P10 described below.

That is, the microcomputer 28 first determines whether or not the motion vector detection circuit 3 has generated the imposed character detection signal s6 in step P6, that is, the imposed character detection circuit 6 detects the imposed character. Is determined. At this point, if it is determined that no imposed characters have been detected, the process proceeds to step P9, and the anti-shake operation is continued.

On the other hand, if it is determined that an imposed character has been detected, the process proceeds to step P7, and it is determined whether or not there are n or more areas in which the imposed character has been detected. In addition,
For example, when there are 60 motion vector detection areas in an image, n is about 10 numbers.

If it is determined in this step P7 that there are n or more areas in which the imposed character is detected, the imposed character is considered to be a title character displayed large on the screen. , Step P10
Proceed to to stop the anti-vibration operation. On the other hand, when the number of the areas where the imposed characters are detected is less than n, step P8
Proceed to.

In step P8, the motion vector value MVt of the area where the imposed character is detected is compared with the motion vector value MVn of the other area. Here, when MVt ≒ MVn (Expression 2) holds, it means that “the background subject and the imposed character are moving at the same speed”.

That is, in this case, it can be estimated that the normal subject is erroneously detected as the imposed character by the imposed character detection circuit 6. Further, even if the imposed character is correctly detected by the imposed character detection circuit 6, as described above,
The imposed character and the normal subject can be considered to be moving on the screen at the same speed.

Therefore, in such a case, even if the image stabilizing operation is continued, an unsightly image in which only the imposed characters move around the screen does not occur. Therefore, when the above-mentioned (Equation 2) is satisfied, the process proceeds to step P9 to continue the image stabilizing operation.

On the other hand, when the above (Equation 2) does not hold, the following two situations are conceivable. That is, when MVt << MVn (Equation 3) holds, it is considered that “the image has a shake and the imposed characters are multiplexed at a fixed position”. In such a case, if the image stabilization operation is continued, there is a problem that image shake correction cannot be performed accurately.

On the other hand, when MVt >> MVn (Equation 4) holds, "imposed characters displayed while moving in a flowing manner on an image with little vibration are multiplexed. And it is not possible to perform accurate shake correction in the same manner as described above.

Therefore, in these cases, that is, when the above-mentioned (Equation 2) does not hold, step P
Proceeding to 10, the anti-vibration operation is stopped. Then, the processing of steps P1 to P10 as described above is repeated for each field.

The image blur correction apparatus according to the third embodiment is based on the assumption that the imposed character detection circuit 6 has a certain detection error. However, if the detection accuracy of the imposed character in the imposed character detection circuit 6 is completely reliable, the anti-shake operation may be stopped as soon as the imposed character is detected.

In this case, in step P6 of FIG.
If it is determined that an imposed character has been detected, the process of steps P7 and P8 is not performed, and the process immediately proceeds to step P10.
To stop the anti-vibration operation.

As described above, according to the third embodiment, for example, even if superimposed characters are multiplexed in a video signal during recording, only the imposed characters move around the screen. Unpleasant images can be prevented.

[0103]

According to the present invention, the superimposed
Accurate shaking that is not affected by the movement of the characters
Correction process, which results in a good image.
Obtainable.

[0104]

[0105]

[Brief description of the drawings]

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

FIG. 2 is a block diagram illustrating an example of a configuration of an imposed character detection circuit in the image blur correction device illustrated in FIG. 1;

FIG. 3 is a block diagram showing another example of the configuration of the imposed character detection circuit in the image blur correction device shown in FIG.

FIG. 4 is a block diagram showing still another example of the configuration of the imposed character detection circuit in the image blur correction device shown in FIG.

FIG. 5 is a flowchart illustrating an operation of the image blur correction device according to the first embodiment.

FIG. 6 is a diagram showing an example of a television screen for explaining the principle of a second embodiment of the image blur correction device according to the present invention.

FIG. 7 is a block diagram showing a configuration of a third embodiment of the image blur correction device of the present invention.

FIG. 8 is a flowchart illustrating an operation of the image blur correction device according to the third embodiment.

FIG. 9 is a block diagram illustrating a configuration of a conventional image blur correction device.

[Explanation of symbols]

 Reference Signs List 3 motion vector detecting circuit 4 microcomputer 6 imposed character detecting circuit 7 differentiating circuit 8 low-pass filter 9 binarizing circuit 10 isolated point removing circuit 11 image memory 12 comparing circuit 13 low-pass filter 14 threshold circuit 15 logical product circuit 16 adder circuit 17 Multiplication circuit 18 Image memory 19 Differentiation circuit 20 Binarization circuit 28 Microcomputer s1 Reproduced video signal s2 Motion vector s3 Read address signal s6 Imposed character detection signal

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04N 5/91-5/956 H04N 5 / 21,5 / 278

Claims (4)

(57) [Claims] 1. An image shake correction apparatus for correcting image shake, comprising: detection means for detecting an area in which characters are superimposed in the image, wherein the area detected by the detection means is provided. An image shake correcting apparatus that does not perform processing for correcting the image shake according to the number of images. 2. An image shake correction method for correcting image shake, comprising: a detection step of detecting an area where a character is superimposed from the image; and a number of areas detected by the detection step. A step of not performing a process for correcting the shake of the image according to the method. 3. An image shake correction apparatus for correcting image shake, comprising: detection means for detecting an area in which a character is superimposed from the image, and an area detected by the detection means. An image shake correcting apparatus for performing a process for correcting the image shake without using the motion vector. 4. An image shake correction method for correcting image shake, comprising: a detection step of detecting an area in which characters are superimposed from the image; and a motion of the area detected by the detection step. Performing a process for correcting the shake of the image without using a vector.