JPH0787597B2 - Motion detection circuit - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a motion detection circuit for extracting motion information of an image in a device which reproduces an NTSC composite television signal by digital processing, and more particularly, to a motion detection circuit for a luminance signal. The present invention relates to a motion detection circuit that can extract only motion information.

[Conventional technology]

FIG. 2 is a block diagram showing a conventional motion detecting circuit disclosed in, for example, JP-A-61-70888.
Reference numeral 1 is an input terminal for a digital NTSC signal, 2 is a frame memory for receiving a signal coming to the input terminal 1, 3 is a frame memory for receiving an output of the frame memory 2, 4
Is a subtractor that receives the signal arriving at the input terminal 1 and the output of the frame memory 2, 5 is a low-pass filter that receives the output of the subtractor 4, and 6 is the output of the low-pass filter 5. An absolute value circuit, 7 is a subtractor having the signal arriving at the input terminal 1 and the output of the frame memory 3 as inputs, 8 is a bandpass filter having the output of the subtractor 7 as input, and 9 is the output of the bandpass filter 8. An absolute value circuit that receives the input, 10 an adder that receives the output of the absolute value circuit 6 and an output of the absolute value circuit 9, and 11 an output terminal of the adder 10.

Next, the operation will be described. The digital amount of NTSC signal input to the input terminal 1 is input to the frame memories 2 and 3 of 1 frame capacity which are cascaded, and 1 frame period before,
And the difference from the signal two frames before is calculated by the subtracters 4 and 7. The inter-frame difference signal obtained by the subtractor 4 is input to the low-pass filter 5 and the luminance signal component having a low horizontal frequency is extracted. The pass band of the low pass filter 5 is set to the third
It is shown in FIG. The difference signal between the two frames calculated by the subtractor 7 is input to the bandpass filter 8 and the luminance signal component and the chrominance signal component having a high horizontal frequency are extracted. The pass band of the band pass filter 8 is shown in FIG.

Since the phase of the subcarrier of the color signal returns to the original in two frame periods, the output of the bandpass filter 8 becomes zero in the case of a still image. If there is any change in the high frequency components of the color signal and the luminance signal, a significant non-zero signal is obtained from the absolute value circuit 9 and can be used as motion information for the high frequency components of the color signal and the luminance signal. Similarly, in the case of a still image, the output of the low pass filter 5 becomes zero. Then, if there is any change in the low frequency component of the luminance signal, a significant non-zero signal is obtained from the absolute value circuit 6 and can be used as motion information for the low frequency component of the luminance signal. Therefore, the motion information obtained as the output of the absolute value circuit 6 and the motion information obtained as the output of the absolute value circuit 9 are added by the adder circuit 10 to output the output terminal 11 of the object included in the NTSC signal. Motion information is obtained.

[Problems to be Solved by the Invention]

Since the conventional motion detection circuit is configured as described above, there is a problem that it is difficult to obtain motion information only from the luminance signal component.

The present invention has been made in order to solve the above problems, and an object thereof is to obtain a motion detection circuit capable of satisfactorily extracting motion information of only a luminance signal component.

[Means for Solving the Problems]

A motion detection circuit according to the present invention is a motion detection circuit for extracting motion information of an object included in an NTSC composite television signal, comprising: a first frame memory for delaying an input signal by one frame period; A first absolute value output means for outputting an absolute value of a difference between low-frequency components in a luminance signal between frames from an output signal of the first frame memory and the input signal; and an output of the first frame memory. A second frame memory for delaying a signal for one frame period, and an interval between two frames for a signal including a component having a high horizontal frequency in a luminance signal and a chrominance signal component from an output signal of the second frame memory and the input signal. A second absolute value output means for outputting the absolute value of the difference, the input signal and the output signals from the first and second frame memories are input. And a third absolute value for outputting the absolute value of a component having a high horizontal frequency in the output signal of the filter, the filter having a pass band in a frequency region conjugate with the color signal component of the NTSC composite television signal Output means, determination means for inputting output signals from the second and third absolute value output means, and outputting any one of the input signals, output signal of the determination means, and the first absolute value And a logical operation means for obtaining a logical sum with the output from the value output means.

[Action]

According to the present invention, an input signal, a 1-frame delay signal, and a 2-frame delay signal are input, and an area that is conjugate with a color signal component when an NTSC composite television signal is expressed by vertical frequency and time frequency is defined. A determination circuit includes a spatio-temporal filter as a pass band, and a determination circuit determines an absolute value of a component having a high horizontal frequency of an output signal of the spatio-temporal filter and a difference between two frames of a high frequency component of a luminance signal and a color signal component Since any one of the absolute values is obtained as the motion detection data of the component of the luminance signal having a high horizontal frequency, the motion information of only the luminance signal component can be favorably extracted.

〔Example〕

 An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a motion detection circuit according to an embodiment of the present invention. In the figure, the same reference numerals as those in FIG. 2 are the same or corresponding parts, and 10 is the output of the absolute value circuit 6. An adder whose input is the output of the circuit 15 and 11 is an adder 10
Output terminal, 12 is a space-time filter having the inputs and outputs of the frame memory 2 and the output of the frame memory 3 as input, 13 is a band-pass filter having the output of the space-time filter 12 as input, and 14 is a band-pass filter 13 The reference numeral 15 designates an absolute value circuit which receives the output of the above-mentioned input, and the determination circuit 15 which receives the output of the absolute value circuit 9 and the output of the absolute value circuit 14.

Next, the operation will be described. An operation for obtaining an absolute value of a difference between one frame of a horizontal frequency component of the luminance signal from the output signal of the frame memory 2 and the input signal input to the input terminal 1, the output signal of the frame memory 3 and the input terminal 1
The operation of obtaining the absolute value of the difference between the two-frame difference between the high-frequency component of the luminance signal and the chrominance signal component from the input signal input to is the same as in the conventional example. Figure 4 (a)
Luminance signal when there is almost no movement (hereinafter referred to as Y)
And the vertical spatial frequency (hereinafter ν) component of the color signal (hereinafter C) and the temporal spatial frequency (hereinafter f)
The bands of the components are shown in FIG. 4 (b), which shows the bands of the ν component and the f component of Y and C when the movement is intense. In addition, the passbands (0 to 0) of the ν component and the f component of the output of the absolute value circuit 9
(-6 dB)) is shown in Fig. 5 (a). From FIGS. 4 (a) and 5 (a), it can be seen that the output of the absolute value circuit 9 is close to 0 when there is almost no movement. However, as can be seen from FIGS. 4 (b) and 5 (a), when the movement is vigorous, both the Y component and the C component are obtained as significant values in the output of the absolute value circuit 9. On the other hand, the spatiotemporal filter 12 is
The passband (0 to (-6d
(B)) is shown in Fig. 5 (b), and from Fig. 4 (b) and Fig. 5 (b), the output of the spatiotemporal filter 12 is obtained by extracting only the Y component when the movement is intense. You can see that

Next, a specific configuration example of the space-time filter 12 will be described with reference to FIG. The adder 16 receives an input signal arriving at the input terminal 1, a signal delayed by 1 frame of the signal at the input terminal 1 and a signal delayed by 2 frames of the signal at the input terminal 1, and multiplying each by (-1/4) times. , (1/2) times, (-1/4) times and add. Passband of ν component and f component of the output of the adder 16 (0 to
(-6 dB)) is shown in Fig. 7 (a). Line memory 17
Delays the output of the adder 16 by one horizontal scanning period. The line memory 18 delays the output of the line memory 17 by one horizontal scanning period. The adder 19 receives the output of the adder 16, a signal of one line delay of the output of the adder 16 and a signal of two line delay of the output of the adder 16, and multiplies each by (-1/4) times. , (1
/ 2) times, (-1/4) times and add. FIG. 7B shows the pass bands (0 to (−6 dB)) of the ν component and the f component of the output of the adder 19 with respect to the input of the line memory 17. The field memory 20 outputs the output of the adder 19 for one field period (26
3 horizontal scanning period) delay. The field memory 21 delays the output of the field memory 20 for one field period.
The adder 22 receives the output of the adder 19, the 1-field delay signal of the output of the adder 19 and the 2-field delay signal of the output of the adder 19 as input, and (-1/4) times, (1 /
2) times, (-1/4) times and add. Field memory 20
FIG. 7 (c) shows the pass bands (0 to (-6 dB)) of the ν component and the f component of the output of the adder 22 with respect to the input of. Passbands (0 to (-6 dB)) of the ν component and the f component of the output of the adder 22 with respect to the input of the input terminal 1 are shown in FIGS. 7 (a) to (c).
This corresponds to the pass band of the cascade connection of the filters of the pass band of (1) and thus corresponds to FIG. 5 (b). The band pass filter 13 is
Adder with the same frequency characteristics as the band pass filter 8
Of the 22 outputs, the component with high horizontal frequency is extracted.

The absolute value circuit 14 outputs the absolute value of the output of the bandpass filter 13. The determination circuit 15 compares the output value of the absolute value circuit 9 and the output value of the absolute value circuit 14 to determine the motion detection data of the component having a high horizontal frequency of the luminance signal. For example, when the output value of the absolute value circuit 9 is small, it corresponds to the case of FIG. 4 (a), and therefore the output of the absolute value circuit 9 is directly used as the output of the determination circuit 15. When the output value of the absolute value circuit 9 is large, the output of the absolute value circuit 14 is used as the output of the determination circuit 15 because it is the case other than that shown in FIG. Thus, the motion detection data of the low horizontal frequency component of the luminance signal is converted into the absolute value circuit 6
The motion detection data of the horizontal frequency component of the luminance signal is output to the output of the determination circuit 15. These are adders
Since they are added in 10, the motion detection data of the luminance signal is output to the output terminal 11.

〔The invention's effect〕

As described above, according to the present invention, since the motion detection is performed by the configuration in which only the change amount of the high frequency component of the luminance signal is extracted by the filter to determine the motion amount, the influence of the color signal is exerted. There is an effect that motion information of only the luminance signal can be accurately obtained.

[Brief description of drawings]

FIG. 1 is a block diagram of a motion detecting circuit according to an embodiment of the present invention, FIG. 2 is a block diagram of a conventional motion detecting circuit, and FIGS. 3 (a) and 3 (b) are horizontal in the low range and high range, respectively. Frequency characteristics of the directional filter, FIGS. 4 (a) and 4 (b) show vertical and temporal frequency characteristics of luminance signal and chrominance signal when the movement is small and large, respectively.
(B) is a frequency characteristic diagram showing the vertical and temporal passbands of the absolute value circuit 9 and the space-time filter 12, respectively. FIG. 6 is a block diagram of the space-time filter, and FIG. 7 is each part of the space-time filter. 6 is a frequency characteristic diagram in the vertical direction and in the time direction in FIG. 1 …… input terminal, 2,3 …… frame memory, 4,7 …… subtractor, 5 …… low pass filter, 6,9,14 …… absolute value circuit, 8,
13 …… Band pass filter, 10,16,19,22 …… Adder, 11…
… Output terminal, 12… Spatiotemporal filter, 15… Judgment circuit,
17,18 ... Line memory, 20,21 ... Field memory. The same reference numerals in the drawings indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A motion detection circuit for extracting motion information of an object contained in an NTSC composite television signal, comprising: a first frame memory for delaying an input signal by one frame period; and a first frame memory. From the output signal and the input signal, the first absolute value output means for outputting the absolute value of the difference in the horizontal direction frequency component of the luminance signal between the frames, and the output signal of the first frame memory for the one frame. A second frame memory delayed for a period, and an absolute value of a difference between two frames with respect to a signal including a component having a high horizontal frequency in a luminance signal and a chrominance signal component from an output signal of the second frame memory and the input signal. A second absolute value output means for outputting the input signal and the input signals and the output signals from the first and second frame memories, respectively, and the NTSC system A filter having a pass band in a frequency region conjugate with a color signal component of the composite television signal, third absolute value output means for outputting an absolute value of a component having a high horizontal frequency in an output signal of the filter, A determination means for inputting the output signals from the second and third absolute value output means and outputting any one of the input signals, an output signal of the determination means and the first absolute value output means. A motion detection circuit comprising: a logical operation means for obtaining a logical sum with an output.