JPH0417489A - Movement detection circuit - Google Patents

Abstract

PURPOSE:To obtain movement information of an object by obtaining an absolute value of an inter-frame difference of a low frequency component of a luminance signal, obtaining an absolute value of a difference between two frames of a high frequency component of the luminance signal and a chrominance signal component, selecting either of them, delaying an output signal for one field period for ORing. CONSTITUTION:Moving information of an object moving at a frequency being frame frequency or over is missing in an output of a selector 13. Then an output of the selector 13 is inputted to a field memory 14. An output of the field memory 14 is inputted to a line memory 15. Then a maximum value circuit 16 selects and outputs a maximum value selected among the output of the selector 13, the output of the field memory 14 and the output of the line memory 15.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a motion detection circuit for extracting motion information of a subject in an apparatus that reproduces decoded television signals of the NTSC system 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 1, 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. A digital NTSC signal inputted to the input terminal 1 is input to a cascade-connected frame memory 2.3 with a capacity of 1 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 8 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 fields of the input signal cannot be obtained, and motion information of the low frequency component of the luminance signal and the modulated color There was a problem in that the motion information of the signals overlapped, making it difficult to accurately obtain the motion information of the subject.

The present invention was made to solve the above-mentioned problems, and it is an object of the present invention to provide a motion detection circuit that can accurately obtain motion information of a subject.

[Means to solve the problem]

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

[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. Select one of the output signals of the two absolute value means, select this signal, a signal obtained by delaying the selected output signal by one field period, and a signal obtained by further delaying the one field delayed signal by one horizontal period. Because it has a configuration that takes the logical sum of
It is possible to accurately obtain movement 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 a motion detection circuit according to an embodiment of the present invention. In the figure, the same reference numerals as in FIG.
Or a considerable portion. 12 is a comparator that receives the output of the absolute value circuit 6; 13 is a selector that receives the output of the absolute value circuit 9 and the input and output of the comparator 12; and 14 is a field memory that receives the output of the selector 13. , 15
16 is a line memory whose input is the output of the field memory 14, and 16 is the output of the selector 13 and the field memory 14.
This is a maximum value circuit serving as an OR means which receives the output of the line memory 15 and the output of the line memory 15 as inputs.

Next, the operation will be explained. Operations 1 to 9 are the same as in the conventional example. Comparator 12 determines whether the output of absolute value circuit 6 is a significant value. The selector 13 selects either the output of the absolute value circuit 6 or the output of the absolute value circuit 9 based on the output of 12. Generally, when a subject moves, in a region where a significant difference occurs between frames in the low-frequency components of the luminance signal, a significant difference also occurs in the color signal. Therefore, the area where the difference is detected in the output of the absolute value circuit 6 overlaps with the output of the absolute value circuit 9. 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 absolute value circuit 9, which overlaps with the output of the absolute value circuit 6, is the orthogonal two-phase modulated data. Since it is difference data obtained from different types of color signals,
The output of the absolute value circuit 6 captures the speed of movement of the subject better than the output of the absolute value circuit 9, which overlaps with the output of the absolute value circuit 6, and is suitable as motion information.

For the above reasons, the selector 13 selects the output of the absolute value circuit 6 when the output of the absolute value circuit 6 is a significant value, and selects the output of the absolute value circuit 6 when the output of the absolute value circuit 6 is zero or a very small value close to zero. selects the output of the absolute value circuit 9. In this way, the motion information of the input signal is obtained at the output of the selector 13. However, the output of the selector 13 lacks motion information of an object moving at a frequency higher than the frame frequency. Therefore, the output of the selector 13 is input to the field memory 14.

The output of this field memory 14 is manually input to a line memory 15. Then, the maximum value circuit 16 selector 13
output, field memory 14 output, and line memory 1
The maximum value among the 5 outputs is selected and output. A simple example will be explained with reference to FIG. #1 to #4 indicate each field number. If the current field is #4, the output of the maximum value circuit 16 will be a in FIG. Since the input signal is interlaced scanned, #1. Since there is no information corresponding to #3, it is not possible to obtain b in Figure 4, but
A signal corresponding to b in FIG. 4 can be obtained from the maximum value of the output of the field memory 14, which is the output of the selector 13 262H before, and the output of the line memory 15, which is the output of the selector 13 263H before. Therefore, the output of the maximum value circuit 16 becomes C in FIG. 4, and it is possible to supplement the motion information of #3, which is one field before the current field #4, without missing anything. In this way, inter-field motion information is obtained at the output terminal 11 of the maximum value circuit 16.

〔Effect of the invention〕

As described above, according to the present invention, the circuit is configured so that the motion information of the luminance signal and the color signal does not overlap, and the difference signal between one frame is interpolated between fields, so that the movement of the subject This has the effect of providing a motion detection circuit that accurately obtains information.

[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 an input terminal, 2.3 is a frame memory, 4°7 is a subtracter, 5 is a low-pass filter, 6 and 9 are absolute value circuits, 8 is a band-pass filter, 10 is an adder, 11 is an output terminal, 1
2 is a comparator, 13 is a selector, 14 is a field memory, 15 is a line memory, and 6 is a maximum value circuit. 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, comprising: a first frame memory that delays an input signal by one frame period; a first absolute value means for calculating the absolute value of the inter-frame difference of the low frequency component of the luminance signal from the input signal; a comparator for comparing the output signal of the first absolute value means with a set value; a second frame memory that delays the output signal of the first frame memory by one frame period; and a second frame memory that delays the output signal of the first frame memory for one frame period, and calculates 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 second frame memory and the input signal. The second step to find the absolute value
absolute value means; a selector for selecting one of the output signals of the first and second absolute value means; a field memory for delaying the output signal of the selector by one field period; A motion detection circuit comprising: a line memory that is delayed by a horizontal period; and an OR means for ORing an input signal and an output signal of the line memory and an output signal of the selector.