KR100246400B1 - Moment detecting circuit for composite video signal - Google Patents

Abstract

The motion detection circuit of the composite video signal provided by the present invention includes, in addition to the circuit of the first embodiment, an I signal and a Q signal from the outputs of a band pass filter and a band pass filter which allow subcarrier signals to pass among the composite video signals. A demodulator for demodulating and extracting a portion having a high horizontal frequency from an I signal and a Q signal, and an edge amount detecting means for outputting a large value as the edge amount of the subcarrier signal, and a value according to the magnitude of the edge amount. And second subtracting means for subtracting the frame difference signal to obtain an operation amount.

Description

Motion Detection Circuit of Composite Video Signal

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motion detection circuit of a composite video signal, and more particularly to detect motion between frames of a composite video signal input to a three-dimensional Y / C separation circuit, a circuit noise canceling circuit, and other construction processing circuits. The present invention relates to a motion detection circuit of a video signal.

Fig. 1 is a block diagram showing a first embodiment of a conventional motion detection circuit of a composite video signal. The low-pass filter 61 passing a frequency band of 2 MHz or less and one frame of a luminance signal (Y signal) are shown. It consists of a one-frame delay circuit 62 and a subtractor 63 for delaying.

The operation is as follows.

The composite video signal is input to the low pass filter 61 to remove the subcarrier (C signal) and obtain a Y signal. The one frame delay circuit 62 delays the Y signal by one frame. Subsequently, the subtracter 63 subtracts the output of the one-frame delay circuit 62 from the Y signal output from the low pass filter 61 to obtain an operation signal.

Fig. 2 is a block diagram showing a second embodiment of a conventional motion detection circuit of a composite video signal, which is composed of one frame delay circuits 71 and 72 and a subtractor 73. Referring to the operation, the operation signal can be obtained by subtracting the delay of the composite image signal by two frames from the composite image signal.

3 is a block diagram showing a third embodiment of a motion detection circuit of a conventional composite video signal, which combines the conventional first embodiment and the conventional second embodiment. That is, the output of the motion detection circuit composed of the low pass filter 61, the one frame delay circuit 62, the subtractor 63, the motion detection circuit composed of the one frame delay circuits 71 and 72, and the subtractor 73. Among the outputs of, a maximum detection circuit 81 for outputting a large value is provided, and an operation signal is obtained from the output.

FIG. 4 is a waveform diagram illustrating a problem of the motion detection circuit of the conventional first embodiment shown in FIG. 4 shows a spectrum of an NTSC composite video signal, where Y is a luminance signal and C is a subcarrier signal. The luminance signal Y has a band of 0 to 5 MHz or more, and the subcarrier signal C has a band of ± 1.5 MHz around 3.58 MHz. By the low pass filter 61 which passes only components of about 2 MHz or less, most subcarrier signals, C, are removed, but at the same time, Y signals of about 2 MHz or more are also removed. Therefore, in the conventional circuit of FIG. 1, there is a problem in that a motion between a frame and a frame of a composite video signal including a Y signal having a horizontal frequency band of 2 MHz or more cannot be detected.

A low pass filter that passes components below about 2 MHz, depending on its characteristics, passes components below a slightly lower frequency than 2 MHz at high gain, but slightly below 2 MHz at low gain, as shown schematically in the figure. Pass the ingredients in. Therefore, the portion where the horizontal frequency band of the subcarrier signal C is high (part away from the center frequency of 3.58 MHz) cannot be removed by the 2 MHz low pass filter 61, and is a luminance signal passing through the low pass filter 61. It is mixed in Y. Since the subcarrier signal C is inverted in phase every frame, subtracting the signal delayed by one frame from the output of the low pass filter 61 even in the case of a stationary picture, C appears as a frame difference. For example, in the case of a still picture, if the value of the C signal passing through the low pass filter 61 at a certain point is c, the value of the C signal after one frame becomes -c. Therefore, the difference signal between frames becomes c-(-c) = 2c. As described above, in the first conventional embodiment, a difference signal between frames includes an error value due to mixing of the subcarrier signal C in a portion where the horizontal frequency of the subcarrier signal C is high (part away from the center frequency). Therefore, there is a problem in that the operation between the frames of the composite video signal cannot be accurately detected.

FIG. 5 is a diagram for explaining a problem in the motion detection circuit of the conventional second embodiment shown in FIG. In the circuit of Fig. 2, since the composite video signal itself is subtracted without performing the filter processing, there is no band where operation cannot be detected. In addition, since the subcarrier signal is in phase with the signal delayed by two frames, in the case of a still picture, the subcarrier signal in the composite video signal is subtracted from the subcarrier signal by two frames. There is no problem of error detection as in the embodiment.

However, by subtracting the signal delayed by two frames from the input composite video signal, the frequency range of the detectable operation is about half that of the detectable operation when subtracting the signal delayed by one frame. (1 frame period is 1/30 second and 2 frame period is 1/15 second). That is, there is a problem that a fast operation of 15 Hz or more cannot be detected.

The conventional third embodiment shown in FIG. 3 solves the problems of the first and second embodiments of the related art, but has a problem that the circuit scale is large and expensive.

SUMMARY OF THE INVENTION An object of the present invention is to provide a motion detection circuit of a composite video signal which is inexpensive but accurately detects motion in view of the problems of the conventional example.

1 is a block diagram showing a conventional embodiment of a motion detection circuit of a conventional composite video signal.

2 is a block diagram showing a second conventional embodiment of the motion detection circuit of a conventional composite video signal.

3 is a block diagram showing a third conventional embodiment of the motion detection circuit of the conventional composite video signal.

Fig. 4 is a waveform diagram illustrating a problem of the motion detection circuit of the first preferred embodiment.

Fig. 5 is a diagram explaining a problem of the motion detection circuit of the conventional second embodiment.

6 is a block diagram of a motion detection circuit of a composite video signal according to a first embodiment of the present invention.

7 is a view for explaining the effect of the first embodiment of the present invention of FIG.

8 is a block diagram showing a second embodiment of the present invention in which the first embodiment of the present invention is applied to a two-dimensional Y / C separation circuit.

9 is a block diagram showing a third embodiment of the present invention in which the first embodiment of the present invention is applied to a circuit noise canceling circuit.

Fig. 10 is a block diagram showing a fourth embodiment of the present invention to which the first embodiment of the present invention, which consists of a sequential scan conversion circuit from an interlaced scan, is applied.

***** Brief description of drawing symbols *****

11: bandpass filter 12: demodulator

13, 14: edge detection circuit 15: edge amount detection means

16: multiplier 17: second subtractor

61: low pass filter 62: 1 frame delay circuit

63: first subtractor

Fig. 6 is a block diagram of the motion detection circuit of the composite video signal according to the first embodiment of the present invention, from 3.58MHz ± 1.5MHz bandpass filter 11 through which C, a subcarrier signal, and C, which is a subcarrier signal. Demodulator 12 for demodulating the I and Q signals, edge extraction circuits 13 and 14 for extracting a portion having a high horizontal frequency from the I and Q signals, and a larger value among the extracted portions is used as the edge amount of the subcarrier signal. An output edge amount detection means 15, a multiplier 16, a low pass filter 61 for passing a frequency band of 2 MHz or less, a one frame delay circuit 62 for delaying one frame of the luminance signal Y, And a subtractor 63 and a second subtractor 17 for subtracting a value corresponding to the magnitude of the edge amount to the frame difference signal output from the subtractor 63 to obtain an operation amount.

The operation is as follows.

First, similarly to the first embodiment of the related art shown in FIG. 1, a complex signal including the luminance signal Y and the subcarrier signal C is passed through a 2 MHz low pass filter 61 to remove the C component, which is the subcarrier signal, and the luminance signal. Get Y. The subtractor 63 subtracts Y, which is a luminance signal, and Y, which is a luminance signal, by only one frame, to obtain a frame difference signal * 1.

As described above, when the C component, which is the subcarrier signal, is removed by the 2 MHz low pass filter 61, the portion where the horizontal frequency of C, which is the subcarrier signal, is high is not completely removed, but is incorporated into the luminance signal Y. Since the subcarrier signal C is inverted in phase every frame, subtracting the signal delayed by one frame from the output value c of the low pass filter 61 results in a frame difference of 2c even in the case of a still picture.

As such, the frame difference signal * 1 includes an error value due to the mixing of the C subcarrier signal.

In the above embodiment of the present invention, since the component having a high horizontal frequency of C whose error value is a subcarrier signal is mixed at the output of the low pass filter 61, the high frequency component is removed and the frame difference signal (* 1) is removed. In order to eliminate the error value, a circuit (11..17) was installed.

That is, the composite video signal is passed through a band pass filter 11 of 3.58 MHz ± 1.5 MHz to obtain a subcarrier signal C, and the subcarrier signal C is demodulated by the demodulator 12 into an I signal and a Q signal. The edge extraction circuits 13 and 14 extract the edges of the I and Q signals, respectively. The larger edges are selected by the edge amount detecting means 15 and input to the multiplier 16. The multiplier 16 multiplies the selected edge by the coefficient α and inputs the result to the second subtractor 17. The second subtractor 17 subtracts the output of the multiplier 16 from the frame difference signal * 1 which is the output of the first subtractor 63. As a result, an operation signal obtained by mostly eliminating an error signal included in the frame difference signal is obtained.

The coefficient α value input to the multiplier 16 is set to an appropriate value by the 2 MHz low pass filter 61 in consideration of the attenuation amount of C, which is a subcarrier signal, and the gain of the IA demodulation embodiment.

The circuit b composed of the multiplier 16 and the second subtractor 17 may use a lookup table using a ROM or a RAM, or a method of attenuating the frame difference signal by multiplying the coefficient according to the edge size of the subcarrier signal C, which is a subcarrier signal. .

7 is a view for explaining the effect of the first embodiment of the present invention.

For motion detection of a color bar image (still screen), error detection is shown in comparison with the prior art example 1. FIG. That is, in the case of the conventional example 1, the motion detection signal is detected between the colors shown in (A), but in the embodiment of the present invention, as shown in (B), the motion detection signal is almost the same. Since the edge extraction signal of C, which is a subcarrier signal of the same magnitude, is obtained from the output of the multiplier 16 and subtracted from the frame difference signal, the motion detection signal is close to zero as shown in (C), compared with the conventional example. This reduces the error detection.

Fig. 8 is a circuit diagram when the operation amount detection of the present invention is applied to a three-dimensional Y / C separation circuit. As is well known, the three-dimensional Y / C separation circuit includes a three-line comb filter 31 through which C, a subcarrier signal, is passed from the composite video signal, and a one-frame delay circuit 32 that delays the composite signal by one frame. And a subtractor 33 for subtracting the one-frame delay signal from the composite signal to obtain a subcarrier signal C, and a subtractor 35 for subtracting the output of the motion adaptive mixing circuit 34 based on the subcarrier signal C. . Even in the three-dimensional Y / C separation circuit, dot disturb occurs at the portion where motion is detected, but the occurrence of dot disturb can be reduced by applying the present invention.

That is, the subcarrier signal C obtained by the output of the three-line comb filter 31 is input to the demodulator 12, and the subtractor 36 subtracts the subcarrier signal C, which is the output of the three-line comb filter 31, from the composite signal. Thus, Y, which is a luminance signal, is obtained. Thus, in FIG. 6, the circuit a including the band pass filter 11 and the low pass filter 61 may be replaced by the three-line comb filter 31 and the subtractor 36 in the existing three-dimensional Y / C separation circuit. . As in FIG. 6, an operation output signal is obtained at the output of the subtractor 17, and input to the operation adaptive mixing circuit 34 in the three-dimensional Y / C separation circuit, and the operation adaptive mixing circuit 34 is a motion detection signal. By adjusting C, which is an output subcarrier signal, C, which is a subcarrier signal with little dot interference, and Y, which is a luminance signal, can be obtained.

9 is a circuit diagram of the operation amount detection of the present invention applied to a cyclic noise cancellation circuit. Even when motion detection is applied to the circuit-type noise canceling circuit, the part that incorrectly detects motion reduces the noise canceling effect. However, by using the motion detection signal obtained by the circuit of FIG. Less than the method

That is, the cyclic noise removing circuit for removing noise from Y, which is a luminance signal obtained at the output of the low pass filter 61, is a luminance signal output from the low pass filter 61 at the output of the one-frame delay circuit 42. A subtractor 41 is used to subtract Y. In addition, a counter is applied to the output of the counter 43 and the subtractor 41, which receive the output of the subtractor 17, which is the output of the circuit of FIG. A multiplier 44 for multiplying 1-β and an adder 45 for adding the output of the multiplier 44 and the output of the one-frame delay circuit 42 are added. As a result, the reduction ratio of the noise canceling effect is smaller than that of the conventional method.

Fig. 10 is a circuit diagram in which the motion detection of the present invention is applied to a sequential scan conversion circuit from an interlaced scan.

The output of the sequential scan conversion circuit 51 and the output of the sequential scan conversion circuit 52 between frames is multiplied by the adder 56, respectively, to convert to sequential scan. The obtained output is obtained. However, by obtaining the motion adaptation coefficients β and 1-β by the motion adaptation counter 53, which is calculated based on the output of the subtractor 17, a higher quality sequential scan output can be obtained.

As can be seen from the above description, since the error signal included in the frame difference signal detected from the composite signal including the luminance signal and the subcarrier signal can be reduced, the three-dimensional Y / C separation circuit and the cyclic noise Errors in the detection of removal circuits and other space-time processing circuits can be reduced, and inexpensive but accurate detection can be performed.

Claims (1)

A low pass filter for passing the luminance signal mainly among a composite image signal including a luminance signal and a subcarrier signal, First subtracting means for subtracting the output of the low pass filter by one frame delay to obtain a frame difference signal; A band pass filter through which the subcarrier signal is passed among the composite video signal; A demodulator for demodulating the I and Q signals from the output of the band pass filter; Edge amount detecting means for extracting a portion having a high horizontal frequency from the I signal and the Q signal, respectively, and outputting a large value among the extracted portions as an edge amount of the subcarrier signal; And second subtracting means for subtracting a value corresponding to the magnitude of the edge amount from the frame difference signal to obtain an operation amount.

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