JPH07298205A - Motion detection circuit - Google Patents

Abstract

PURPOSE:To prevent the motion mis-detection of a vertical edge part in a still picture by detecting an edge precisely without causing mis-detection of the edge in an edge detection circuit of the motion detection circuit limiting the area of motion detection to only the vertical edge. CONSTITUTION:The circuit detecting a motion of video signals within one frame is provided with plural field delay means 3a, 3b delaying the video signal by one field, a subtractor means 4a subtracting the video signal delayed by one frame from the video signal to provide an output of inter-1-frame difference signal, an absolute value means 5 taking an absolute value of the subtraction signal, a nonlinear conversion means 6 converting nonlinearly the absolute value output, an edge detection means 7a detecting edge information of an image locally by using inter-field correlation, and an edge control means 8 controlling a motion detection output based on the nonlinear conversion output and the edge detection output.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motion detection circuit in motion adaptive processing for adaptively switching (or mixing) still image processing and moving image processing in video signal processing such as television signals. The present invention relates to a motion detection circuit suitable for detecting a motion for one frame in motion adaptive scanning line conversion.

[0002]

2. Description of the Related Art In motion adaptive processing by motion adaptive scanning line conversion, scanning line conversion is performed by processing between fields for still images and within fields for moving images. In this case, in order to reduce the memory capacity and to reduce the unnaturalness of switching between still image processing and moving image processing, the area in which the motion adaptation processing is performed is limited, and when the moving image processing is performed, the image quality is greatly reduced. Scan line conversion is considered in which still image processing is performed only on the vertical edge portion of a still image that causes deterioration. The area control of this motion adaptive processing is performed by limiting the detection area during motion detection. That is, this motion detection circuit detects the vertical edge of the image, and edge control is performed so that the motion detection signal is output only to the vertical edge portion.

FIG. 5 is a block diagram showing an example of a conventional motion detection circuit in a motion adaptive scanning line conversion circuit. In the figure, 1 is an input terminal, 3a and 3b are 1-field delay circuits (1f), 4a is a subtractor, and 5 is an absolute value circuit (AB
S), 6 are non-linear conversion circuits, 7b is an edge detection circuit in the field, 8 is an edge control circuit, and 2 is an output terminal.

Next, the operation of the motion detecting circuit will be described. A digitized video signal is input to the input terminal 1. The subtractor 4a subtracts the signal delayed by one frame by the one-field delay circuits 3a and 3b from the input signal and the subtractor 4a to obtain a one-frame difference signal.
The one-frame difference signal is converted into an absolute value by the absolute value circuit 5 and input to the nonlinear conversion circuit 6. Non-linear conversion circuit 6
Has an input / output characteristic as shown in FIG. 6, for example, if the input value is a or less, it is cored as noise, and if there is a value of b or more, it is regarded as a moving image and is clipped at the c value. The output of the nonlinear conversion circuit 6 is input to the first input terminal of the edge control circuit 8.

FIG. 7 is a block circuit diagram showing the structure of the edge detection circuit 7b. 3d is a 1-line delay circuit and 4e is a subtracter. The edge detection circuit 7b obtains the vertical edge portion only by the in-field processing. That is, the input signal 1
The signal delayed from 01 by the 1-line delay circuit 3d is subtracted by the subtractor 4e, and the difference between the pixels on the upper and lower two lines in the field is obtained. The process for obtaining this difference is a vertical band pass filter operation, and is 525/4 cp as shown in FIG.
The vertical band pass filter characteristic is such that the gain is 1 at the frequency component of h (hatched portion). This edge detection circuit 7b
Is output to the second input terminal of the edge control circuit 8 as a vertical edge.

In the edge control circuit 8, the edge detection circuit 7
When b is detected as a vertical edge, the output of the non-linear conversion circuit 6 is output as a "motion detection value", and when it is detected as not a vertical edge, a motion detection value K = 1 when a complete moving image is detected. Is output.

The output of the edge control circuit 7b is output from the output terminal 2 as the output of the motion detection circuit.

[0008]

Originally, the vertical frequency component of the video signal exists up to 525/2 cph. But,
In the conventional system, the edge detection is extracted by the calculation only within the field, so that only the region centered on 525/4 cph (FIG. 8) can be extracted. Therefore, 5
Although the frequency component near 25/2 cph is an edge, it cannot be detected as an edge. If it is not an edge, the motion detection circuit works to forcibly perform the moving image processing in the conventional system regardless of whether it is a still image or a moving image. Therefore, when this motion detection circuit is used for scanning line conversion, etc., it is around 525 / 2cph. At the edge part of the frequency, even a still image is processed as a moving image, resulting in a double image deterioration. This is a phenomenon in which the motion detection circuit causes a motion error in a still image.

The above-mentioned problems occur because the edges are not correctly detected. The object of the present invention is to detect an edge that is not detected as an edge by the conventional motion detection circuit.
It is an object of the present invention to obtain a motion detection circuit capable of detecting a frequency component near / 2 cph as an edge and, as a result, preventing false motion detection in this area.

[0010]

According to a first aspect of the present invention, there is provided a motion detection circuit, which comprises a plurality of field delay means for delaying a video signal by one field in a circuit for detecting the motion of one frame of the video signal. A subtracting means for subtracting the video signal and the video signal delayed by one frame by the plurality of field delay means and outputting a one-frame difference signal; an absolute value means for taking an absolute value of the output signal of the subtracting means; Non-linear conversion means for converting the output of the value means to non-linear, edge detection means for detecting correlation between fields and locally extracting edge information of the image, output of the non-linear conversion means and the edge detection means Edge control means for controlling the motion detection output on the basis of the output of 1.

A motion detection circuit according to a second aspect of the present invention is the motion detection circuit according to the first aspect of the invention, wherein a plurality of delay means delays the luminance signal by one field, and the luminance signal and the luminance signal delayed by one frame by the delay means. And a subtracting means for outputting a one-frame difference signal.

A motion detecting circuit according to a third aspect of the present invention is the motion detecting circuit according to the first aspect of the invention, wherein in the circuit for detecting the motion of one frame of the video signal, a filter for removing a color signal component from the composite color television signal is provided. A plurality of field delay means for delaying the filter output by one field, and a subtraction means for subtracting the filter output and the filter output delayed by one frame by the plurality of field delay means and outputting a one-frame difference signal. It is characterized by having and.

A motion detecting circuit according to a fourth aspect of the present invention is the motion detecting circuit according to the first aspect of the present invention, wherein an addition means for adding the video signal and the video signal delayed by one field by the field delay means and an addition means output are provided. A line delay means for delaying by one line, an adder means for adding the output of the adder means and an output of the line delay means to output a vertical low frequency component of the output of the adder means, and the adder means for subtracting the adder means from the video signal. And edge detection means for outputting as edge information of the image.

According to a fifth aspect of the present invention, there is provided a motion detecting circuit according to the first aspect of the present invention, in which it is determined that an image is an edge portion based on the outputs of the non-linear conversion means and the edge detection means. An edge control means is provided for outputting the output of the linear conversion means as a motion detection result, and forcibly outputting a value detected as a moving image as a motion detection result when it is determined that it is a non-edge portion. Is characterized by.

[0015]

According to the first aspect of the present invention, the limitation of the area for detecting the motion of the input video signal is performed by locally detecting the edge information of the image by detecting the correlation between the fields and detecting the edge by the above detection result. Since it is controlled, it is possible to accurately detect the above-mentioned area, and it is possible to prevent the edge area of a still image from being erroneously detected as a moving image.

According to the second aspect of the invention, the limitation of the area for detecting the motion of the input luminance signal is to detect the correlation between the fields to locally extract the edge information of the image, and detect the edge based on the detection result. Since it is controlled, it is possible to accurately detect the above-mentioned area, and it is possible to prevent the edge area of a still image from being erroneously detected as a moving image.

According to the third aspect of the present invention, the limitation of the area in which the motion detection of the input composite color television signal is performed, the edge information of the image is locally extracted by detecting the correlation between the fields, and the detection result is obtained. Since the edge is controlled by the above, it is possible to accurately detect the above-mentioned area, and it is possible to prevent the edge area of a still image from being erroneously detected as a moving image.

According to the fourth aspect of the invention, since the edge information of the image is locally detected by utilizing the correlation between the fields, it is possible to accurately detect the edge of the image.

According to the fifth aspect of the present invention, since the motion detection is controlled based on the result of locally detecting the edge of the image by utilizing the correlation between the fields, more accurate motion detection can be output. You can

[0020]

【Example】

Example 1. FIG. 1 is a block diagram showing a motion detection circuit according to the first embodiment of the present invention. In the figure, 1 is an input terminal, 3a and 3b are 1-field delay circuits, 4a is a subtractor, 5 is an absolute value circuit, 6 is a non-linear conversion circuit, 7a is an edge detection circuit between fields, 8 is an edge control circuit, 2 is an output terminal.

FIG. 2 is a block diagram showing a configuration example of the edge detection circuit 7a in FIG. 1, 3c is a 1-line delay circuit 1H, 4b, 4c is an adder, and 4d is a subtractor.

Next, the operation of the motion detection circuit of the first embodiment will be described. A digitized video signal is input to the input terminal 1. The input signal 101 is delayed by 1 frame by the 1-field delay circuits 3a and 3b, and the 1-frame delay signal is subtracted from the input signal 101 by the subtractor 4a to obtain 1
An interframe difference signal is obtained. The one-frame difference signal is converted into an absolute value by the absolute value circuit 5 and input to the nonlinear conversion circuit 6. The absolute value of one frame difference represents the amount of motion, and the larger the value, the more the motion.

The non-linear conversion circuit 6 has an input / output characteristic as shown in FIG. 6, for example, as described above, if the input value is a or less, it is cored as noise, and if there is a value of b or more, all are converted. If it is a moving image, it is clipped at the c value. The output of the nonlinear conversion circuit 6 is input to the first input terminal of the edge control circuit 8.

On the other hand, the input signal 101 and the signal 102 delayed by one field by the one-field delay circuit 3a are input to the first and second input ends of the edge detection circuit 7a, respectively, and the edge of the image is detected from the correlation between the fields. Is detected.

The edge detection of the image in the edge detection circuit 7a is obtained by the following operation. Input signal 101
The 1-field delay signal 102 and the 1-field delay signal 102 are added by the adder 4b to obtain a low frequency component filtered in the time-vertical direction. The output of the adder 4b is delayed by one line by the one-line delay circuit 3c, and is added to the output of the adder 4b by the adder 4c to obtain a vertically filtered low frequency component. The output of the adder 4c is in the frequency region (hatched portion) shown in FIGS. 3A and 3B, and only the vertical low frequency region is extracted in the static region (f = 0).
The output of the adder 4c is the non-edge detection signal and the subtractor 4d
Is output to. The subtracter 4d subtracts the non-edge detection signal from the input signal 101 to obtain the edge detection signal. The output of the subtractor 4d is output to the second input terminal of the edge control circuit 8 as the edge detection result 103 of the edge detection circuit 7a.

The frequency domain of the edge detection result 103 is shown in FIG.
It is the area excluding the shaded areas in (a) and (b). Therefore, it is possible to detect an edge in the vicinity of 525/2 cph of the still region (f = 0), which has been missed by the conventional motion detection. In addition, there is a non-edge region that is a forced moving image in the vicinity of 525/2 cph where f ≠ 0, but since this region is originally a moving image region, there is no problem.

In the edge control circuit 8, the edge detection circuit 7
The output of the nonlinear conversion circuit 6 is controlled according to the output value of a. When the output of the edge detection circuit 7a is E (0 ≦ E ≦ 1) and the output of the nonlinear conversion circuit 6 is k (0 ≦ k ≦ 1), the motion detection amount K (0 ≦ K ≦ 1) is output. K = 1− (1−k) · E That is, the edge detection circuit 7a is a vertical edge (E
= 1) is detected, K = k is output, and when not a vertical edge (E = 0), K = 1 is output.

The output of the edge control circuit 8 is output from the output terminal 2 as the output of the motion detection circuit.

Now, the motion detection value K will be described.
The motion adaptation process is a process of mixing (weighted average) still image processing and moving image processing according to the amount of motion. When this mixing coefficient (that is, the amount of motion detection) is K, the range of the value of K is 0 ≦ K ≦ 1. Here, since the value is 1 or more in the calculation when detecting the actual movement, it is normalized to the above range of 0 to 1. The mixing operation at this time is as follows. C = K · M (1−K) · S (M: moving image processing, S: still image processing) Therefore, when K = 0, that is, the ratio of moving images is 0%.
That is, when the image is a still image, C = S, and the still image processing is completely output. When K = 1, that is, when the ratio of the moving image is 100%, that is, when the image is a moving image, C = M and the moving image processing is completely output. In the middle, a mixed value according to the above equation is output according to the value of K. Therefore, the “value detected as a moving image” represents K = 1.

Next, the edge detection amount E will be described.
Since E is used as a mixing coefficient for mixing according to the edge detection amount, normalization is performed so that 0 ≦ E ≦ 1. In addition, when the edge detection control detects an edge (E =
In 1), the motion detection amount K based on the one-frame difference is output as it is, and when it is detected that it is not an edge (E = 0), K = 1 must be output so that the motion adaptation processing is forcibly a moving image processing. Therefore, the formula K = 1 as specified in the specification
-(1-K) · E. Here, the intermediate value is the mixed value represented by the formula.

Example 2. FIG. 4 is a block diagram showing a motion detecting circuit according to the second embodiment of the present invention. In the figure, the same parts as in FIG. 1 indicate the same or corresponding parts, and 9 is a color signal component removal filter.

FIG. 4 is different from FIG. 1 in the following points. Input terminal 1 has a composite color television signal 1
01 has been entered. Composite color television signal 1
In 01, the chrominance signal is multiplexed on the high frequency component of the luminance signal, and the carrier wave is inverted for each frame. Therefore, if the difference between the frames is calculated as it is, the color signal component leaks and the motion is erroneously detected. Further, the color signal is erroneously detected as an edge even in the edge detection between fields. The color signal component removing filter 9 removes a color signal component from the input composite color television signal. This filter 9
May use a filter having characteristics such as a horizontal low-pass filter or a two-dimensional comb filter. However, the more accurately the color signal of this filter can be extracted, the more accurately the motion detection circuit can detect the motion. Needless to say.

In the second embodiment, the color signal component removing filter 9 is provided to remove the color component from the composite color television signal. However, if the input signal is a luminance signal, the color signal component removing filter may be omitted. Accurate motion detection can be performed.

Although the present invention is particularly effective for motion adaptive scanning line conversion, the same effect can be obtained by using other motion adaptive processing, for example, a motion detecting circuit for luminance signal / color signal separation.

Further, the present invention can be sufficiently supported by a digital signal processor (DSP).

[0036]

According to the first aspect of the invention, the limitation of the area for detecting the motion of the input video signal is performed by detecting the correlation between the fields and locally extracting the edge information of the image. Since the edge control is performed, it is possible to accurately detect the above-mentioned region, and it is possible to prevent erroneous detection as a moving image despite the edge region of a still image.

According to the second aspect of the present invention, the area where the motion detection of the input luminance signal is performed is limited, and the edge information of the image is locally extracted by detecting the correlation between the fields, and the edge is detected based on the detection result. Since it is controlled, it is possible to accurately detect the above-mentioned region, and it is possible to prevent erroneous detection as a moving image despite the edge region of a still image.

According to the invention of claim 3, the limitation of the area for detecting the motion of the input composite color television signal, the edge information of the image is locally extracted by detecting the correlation between the fields, and the above detection result is obtained. Since the edge is controlled by the above, it is possible to accurately detect the above-mentioned region, and it is possible to prevent erroneous detection as a moving image despite the edge region of a still image.

According to the invention of claim 4, the edge information of the image is locally extracted by detecting the correlation between the fields, so that the edge of the image can be accurately detected.

According to the fifth aspect of the invention, since the motion detection is controlled based on the result of detecting the correlation between fields and locally extracting the edge of the image, more accurate motion detection can be output. You can

[Brief description of drawings]

FIG. 1 is a block diagram showing a motion detection circuit according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing an example of an edge detection circuit used in the first and second embodiments of the present invention.

FIG. 3 is a diagram showing a non-edge detection area in the edge detection circuit according to the first embodiment.

FIG. 4 is a block diagram showing a motion detection circuit according to a second embodiment.

FIG. 5 is a block diagram showing a conventional motion detection circuit.

FIG. 6 is a diagram showing input / output characteristics of a non-linear conversion circuit in the motion detection circuit according to the present invention and the related art.

FIG. 7 is a block diagram showing a conventional edge detection circuit.

FIG. 8 is a diagram showing an edge detection area in a conventional edge detection circuit 7b.

[Explanation of symbols]

3a, 3b 1 field delay circuit, 3c 1 line delay circuit, 4a, 4d subtractor, 4b, 4c adder, 5
Absolute value circuit, 6 nonlinear conversion circuit, 7a edge detection circuit, 8 edge control circuit, 9 color signal removal filter.

Claims (5)

[Claims] 1. A motion detection circuit for detecting a motion of a video signal during one frame, the delay means delaying the video signal by one frame by one field, and the video delayed by one frame from the video signal. A subtraction means for subtracting the signal, an absolute value means for taking the absolute value of the subtraction signal, a non-linear conversion means for converting the absolute value signal into a non-linear shape, and an image by detecting the correlation between the fields of the video signal. Edge detection means for extracting the edge information of the above, and edge control means for controlling the motion detection output by determining the edge portion and the non-edge portion based on the output of the non-linear conversion means and the output of the edge detection means. A motion detection circuit characterized in that 2. A delay means for delaying a luminance signal for one frame by one field, and a subtracting means for subtracting the luminance signal delayed by one frame by the delay means from the luminance signal. The motion detection circuit according to claim 1. 3. A motion detection circuit for detecting a motion of one frame of a video signal, wherein the filter removes a color signal component from a composite color television signal, and the output of this filter is delayed by one field by one frame. 2. The motion according to claim 1, further comprising a plurality of field delaying means for causing the filter output, and subtracting means for subtracting the output delayed by one frame from the filter output to output a one-frame difference signal. Detection circuit. 4. The edge detection means includes an addition means for adding the video signal and the video signal delayed by one field by the field delay means, a line delay means for delaying the addition output by one line, and the addition means. It is composed of adding means for adding the output and the output of the line delay means to obtain a vertical low-frequency component, and subtracting means for subtracting the vertical low-frequency component from the video signal to obtain edge information of an image. The motion detection circuit according to claim 1, wherein: 5. The edge control means outputs the output of the non-linear conversion means as a motion detection result when it judges that the image is an edge portion based on the outputs of the non-linear conversion means and the edge detection means, The motion detection circuit according to claim 1, wherein a value indicating a moving image is output as a motion detection result when it is determined to be a non-edge portion.