JPH0417488A - Movement detection circuit - Google Patents

Abstract

PURPOSE:To obtain movement information of an object accurately by interpolating a difference signal between two frames of a high frequency component of a luminance signal and a chrominance signal in terms of inter-frame so as to avoid the movement of the luminance signal and chrominance signal in duplicate. CONSTITUTION:A chrominance signal has a large significant difference for a period when an inter-frame significant difference is caused in a low frequency component of a luminance signal in the case of a moving object. Thus, an output of a maximum circuit 13 is in duplicate with an output of an absolute value circuit 6 when a difference is detected for outputs of the absolute value circuit 6. A selector 15 selects an output of the absolute value circuit 6 when the output of the absolute value circuit 6 is significant and selects an output of the maximum circuit 13 when the output of the absolute value circuit 6 is zero or a very small value close to zero.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a motion detection circuit that extracts motion information of a subject in an apparatus that reproduces an NTSC decoded television signal through digital processing.

[Conventional technology]

FIG. 2 is a block diagram showing a conventional motion detection circuit disclosed in, for example, Japanese Unexamined Patent Publication No. 61-70888. In the figure, 1 is an input terminal for a digital NTSC signal;
3 is a frame memory whose input is the signal arriving at input terminal l; 3 is a frame memory whose input is the output of frame memory 2; and 4 is a subtracter whose inputs are the signal arriving at input terminal 1 and the output of frame memory 2. , 5 is a low-pass filter that receives the output of the subtracter 4, and 6 is a low-pass filter 5.
7 is a subtracter that receives the signal arriving at input terminal 1 and the output of frame memory 3 as input; 8 is a bandpass filter that receives the output of subtractor 7;
9 is an absolute value circuit which receives the output of the bandpass filter 8 as an input; 10 is an adder which receives the outputs of the absolute value circuit 6 and the absolute value circuit 9; and 11 is an output terminal of the adder 10.

Next, the operation will be explained. The digital NTSC signal input to the input terminal l is input to a cascade-connected frame memory 2.3 with a capacity of one frame, and the difference between the signal from one frame period before and two frame periods before is sent to a subtracter 4.
．． It is calculated by 7.

The inter-frame difference signal obtained by the subtracter 4 is input to a low-pass filter 5, where a luminance signal component with a low horizontal frequency is extracted. The passband of the low-pass filter 5 is shown in FIG. 3(a). Further, the difference signal between the two frames calculated by the subtracter 7 is input to a band pass filter 8, and a luminance signal component and a color signal component having a high horizontal frequency are extracted. The passband of the bandpass filter 80 is shown in FIG. 3(b). Since the phase of the color signal subcarrier returns to its original state every two frames, 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 chrominance signal or the luminance signal, a 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 chrominance signal and the luminance signal. Similarly, in the case of a still image, the output of the low-pass filter 5 is zero. 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 motion information for the low frequency component of the luminance signal and motion information obtained as the output of the absolute value circuit 9 are obtained. By adding these in the adding circuit 10, the motion information of the subject included in the NTSC signal is obtained at the output terminal 11.

[Problem to be solved by the invention]

Since the conventional motion detection circuit is configured as described above, there is a problem that motion information between one frame cannot be obtained for the high-frequency components of the luminance signal and the color signal. There is a problem in that the motion information of the low frequency component and the motion information of the modulated color signal overlap, making it difficult to accurately obtain the motion information of the subject.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a motion detection circuit that can accurately determine motion information between frames of a subject.

[Means to solve the problem]

The motion detection circuit according to the present invention includes a first frame memory that delays an input signal by one frame period, and a one-frame difference between the output signal of the first frame memory and the low-frequency component of a luminance signal from the input signal. a first absolute value means for determining the absolute value; a comparator for comparing the output signal of the absolute value means with a set value; and a second frame memory for delaying the output signal of the first frame memory by one frame period. , a second absolute value means for calculating the absolute value of the difference between two frames between the high frequency component of the luminance signal and the color signal component from the output signal of the frame memory and the input signal; a third frame memory that delays by a frame period; an OR means for ORing the human input signal of the third frame memory and the output signal; and an output signal of the OR means and an output of the first absolute value means. It is equipped with a selector for selecting either one of the signal and the signal.

[Effect]

In this invention, the first absolute value means calculates the absolute value of the difference between one frame of the low frequency component of the luminance signal, and the first absolute value means calculates the absolute value of the difference between two frames between the high frequency component of the luminance signal and the color signal component. Since the output signal of the absolute value means 2 is delayed by one frame period and one of the signals obtained by calculating the logical sum before and after the delay is selected, it is possible to accurately obtain the motion information of the subject. .

〔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 in FIG. 2 indicate the same or corresponding parts. 12 is an absolute value circuit 9
13 is a maximum value circuit serving as an OR means that receives the output of the absolute value circuit 9 and the output of the frame memory 12 as input, and 14 is a comparator that receives the output of the absolute value circuit 6 as input. , 15 is a selector whose inputs are the output of the absolute value circuit 6, the output of the maximum value circuit 13, and the output of the comparator 14.

Next, the operation will be explained. Operations 1 to 9 are the same as in the conventional example. The output of the absolute value circuit 9 is sent to the frame memory 12.
is input. The maximum value circuit 13 selects and outputs the maximum value of the input and output of the frame memory 12. A simple example will be explained with reference to FIG. FIG. 4 shows an example in which a small object moves horizontally, and #1 to #4 indicate each frame number.

If the current frame is #4, the output of the absolute value circuit 9 will be a in FIG. On the other hand, the output of the frame memory 12 is
Since this is the output of the absolute value circuit 9 one frame before, it becomes b in FIG. Therefore, the output of the maximum value circuit 13 becomes C in FIG. 4, which completely supplements the motion information of #3, which is one frame before the current frame #4. Comparator 14 determines whether the output of absolute value circuit 6 is a significant value. Selector 15
selects either the output of the absolute value circuit 6 or the output of the maximum value circuit 13 based on the output of the comparator 14.

Generally, when a subject moves, in a region where there is a significant difference between frames in the low frequency components of the luminance signal, there will also be a significant difference in the color signal. Therefore, the area where a difference is detected in the output of the absolute value circuit 6 overlaps with the output of the maximum value circuit 13. Furthermore, while the output of the absolute value circuit 6 is differential data obtained only from the low-frequency components of the luminance signal, the output of the maximum value circuit 13, which overlaps with the output of the absolute value circuit 6, is quadrature two-phase modulated. Since it is differential data obtained from two types of color signals, the output of the absolute value circuit 6 captures the speed of the subject's movement better than the output of the maximum value circuit 13, which overlaps with the output of the absolute value circuit 6. , is suitable as motion information. For the above reasons, the selector 15 selects the output of the absolute value circuit 6 when the output of the absolute value circuit 6 is significant, and selects the maximum value when the output of the absolute value circuit 6 is zero or a very small value close to zero. Select the output of circuit 13. In this way, the motion information of the subject included in the NTSC signal is obtained at the output terminal 11 of the selector 15.

〔Effect of the invention〕

As described above, according to the present invention, the difference signal between two frames of the high frequency component of the luminance signal and the color signal is interpolated between frames,
Since the circuit is configured so that the movements of the luminance signal and the color signal do not overlap, the effect is that movement information of the subject can be accurately obtained.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a motion detection circuit according to an embodiment of the present invention, FIG. 2 is a block diagram showing a conventional motion detection circuit, FIG. 3 is a frequency characteristic diagram of a horizontal filter, and FIG.
The figure is a diagram for explaining the operation of the motion detection circuit of the present invention. 1 is the input terminal, 2, 3.12 is the frame memory, 4.7
5 is a summer filter, 5 is a reduced pass filter, 6.9 is an absolute value circuit, 8 is a band pass filter, 10 is an adder, 11 is an output terminal, 13 is a maximum value circuit, 14 is a comparator, and 15 is a selector. be. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] (1) A motion detection circuit that uses digital processing to extract motion information of a subject contained in an NTSC decoded television signal, which includes a first frame memory that delays an input signal by one frame period; The first step is to calculate the absolute value of the difference between frames of the reduced component of the luminance signal from the output signal and the input signal.
a comparator for comparing the output signal of the first absolute value means with a set value; a second frame memory for delaying the output signal of the first frame memory by one frame period; a second absolute value means for calculating the absolute value of the difference between two frames of the high frequency component of the luminance signal and the color signal component from the output signal of the second frame memory and the input signal; a third frame memory delayed by one frame period; an OR means for ORing the input signal and the output signal of the third frame memory; and the output signal of the OR means and the output of the first absolute value means. A motion detection circuit comprising a selector for selecting one of the signals and the signal.