JPS6354888A - Detection circuit for movement of composite video - Google Patents

Abstract

PURPOSE:To correctly and surely detect movement information even in the edge part of a picture by extracting a frequency component centering a chrominance sub-carrier frequency to obtain the movement information from a sum signal between the frames of a composite video signal. CONSTITUTION:A frame memory 3c and an adder 7a operate the sum signal between the frames of the composite video signal. Since the chrominance sub- carrier of the NTSC composite video signal has a phase inverted for every frame, it is cancelled by the sum between the frames if a chrominance signal component is not changed and the chrominance component is not displayed in the output of the adder 7a. When the chrominance signal component is changed, a significant signal appears. Accordingly, the movement information of the chrominance signal component is included in the sum signal between the frames. Generally, a luminance signal has a phase which is not inverted for every frame so that the sum signal between the frames includes a luminance signal component. Herein, the passing through a vertical BPF, a horizontal BPF consisting of line memories 4a, 4b and subtracters 8c, 8d, the luminance signal component included in the output of the adder 7a is removed and only the movement information of the chrominance signal component is extracted.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention provides a method for storing composite video signals in a frame memory, such as an interframe coding device, a cyclic noise removal device, a luminance signal/chrominance signal separation circuit, and a scanning line interpolation circuit. The present invention relates to a motion detection circuit for a composite video signal that detects motion information of the video signal in a device that processes the video signal using the video signal.

[Prior Art] FIG. 5 is a block diagram showing an example of a conventionally known motion detection circuit for an NTSC composite video signal. In the figure, (1) is a signal terminal for inputting a composite video signal. , (2) are signal terminals that output motion information. (3a) is a frame memory which stores the composite video signal input to the signal terminal (1) for one frame period (
525H) is delayed. (8) is a chroma inverter, and the output of the frame memory (3a) is:
The phase of only the color signal component is inverted. (8a) is a subtraction circuit, into which the composite video signal inputted to the signal terminal (1) and the video signal delayed by l frame period whose phase is inverted via the chroma inverter (9) are respectively inputted. The configuration is as follows.

FIG. 6 is a block diagram showing another conventional motion detection circuit disclosed in, for example, Japanese Patent Application Laid-Open No. 58-130685. ) delayed frame memory, (8
b) is a subtraction circuit that takes the difference between the input video signal and the output signal of the frame memory (3b), and (5a) is the subtraction circuit (8).
b) is a reduced pass filter (hereinafter referred to as LPF) that extracts the reduced frequency component of the output.

Next, the operation of each of the above-mentioned conventional examples will be explained.

In the NTSC composite video signal, the luminance component and color component are frequency multiplexed, and the phase of the color subcarrier is inverted by 1800 for each frame. Therefore, in the conventional example shown in FIG. 3, the video signal of one frame before, in which only the color components are phase-inverted by the chroma inverter (9), is equal to the current video signal when there is no movement between frames, and is subtracted. The output of the circuit (8a) becomes O. Further, in a moving part, since the correlation between signals between frames disappears, a significant signal is output from the subtraction circuit (8a). Chroma inverter (3)
Usually, it is equipped with a bandpass filter (hereinafter referred to as BPF) centered on the color subcarrier, which separates the luminance signal component and the color signal component from the composite video signal, inverts the sign of only the color signal, and adds it to the luminance signal. are doing.

Since the motion detection circuit shown in FIG. 6 does not include a chroma inverter, the output of the subtraction circuit (8b) includes information regarding motion (movement of the luminance signal and movement of the color signal) and color signal components (
static component of the color signal). Among these, the component related to one color signal has a high horizontal frequency, so L P F (5
a), and only the motion component of the luminance signal is delivered to the output terminal (2).

That is, the output of L P F (5a) becomes significant when there is no change in the luminance signal between frames (still part) and when there is a change in the luminance signal (moving part).

[Problem to be Solved by the Invention 1 Among the conventional composite video signal motion detection circuits configured as described above, the one shown in FIG. There is a problem in that the color signal components are not completely separated, and as a result, the color signals are not sufficiently inverted, and significant signals are lost at the edge portions of still images.

In addition, although the image shown in Figure 6 does not have the above-mentioned problems, there are problems such as the movement of the color signal is not detected and, for example, a moving image part where the brightness is constant and only the color changes is determined to be a still image. There was a point.

The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a motion detection circuit for a composite video signal that can correctly detect the motion of color signal components even at the edge portions of an image. With the goal.

[Means for Solving the Problems] A motion detection circuit for a composite video signal according to the present invention includes a circuit for calculating the sum of signals between frames, and a motion detection circuit for detecting motion in the screen vertical direction and screen horizontal direction with the color subcarrier frequency as the center of the band. It is characterized in that it is serially connected to a high-pass filter that extracts high-frequency components of direction signals.

[Operation] In the present invention, the inter-frame sum signal of the composite video signal delayed by one frame period by the frame memory and the current composite video signal is processed into a two-dimensional system that extracts the high frequency components of the signals in both the vertical and horizontal directions. By passing through a high-pass filter, the luminance signal component included in the interframe sum signal is removed, and only the motion information of the color signal component is extracted.

[Example] Hereinafter, an example of the present invention will be described based on the drawings.

FIG. 1 is a block diagram showing a motion detection circuit for a composite video signal according to an embodiment of the present invention.

In the figure, (1) is a signal terminal that inputs a composite video signal, and (2) is a signal terminal that outputs motion information.

(3c) is the composite video signal for one frame period (525H)
A frame memory for delaying, (7a) an adder for adding the output from the frame memory (3c) and the input composite video signal, (4a) an adder for adding the composite video signal for one scanning period (IH)
A line memory for delaying, (8c) a subtracter for subtracting the output of the adder (7a) from the output from the line memory (4a), and (4b) a subtracter for subtracting the output of the adder (7a) from the output from the line memory (4a); A line memory for delaying the scanning period (IH), (8d) a subtracter for subtracting the output of the subtracter (8C) from the output from the line memory (4b), (6a)
) is a BPF that extracts the high frequency component of the output of the subtracter (8d).

Next, the operation of the above configuration will be explained.

The frame memory (3C) and adder (7a) calculate an interframe sum signal of the composite video signal. By the way, NTS
Since the phase of the color subcarrier of the C composite video signal is reversed for each frame, if there is no change in the color signal component, it will be canceled by the sum between frames, and the 5-envelope component will appear at the output of the adder (7a). In addition, when there is a change in the color signal component, a significant signal is generated. Therefore, the interframe sum signal includes motion information of the color signal component.

On the other hand, since the luminance signal generally does not have a phase inversion for each frame, the interframe sum signal also includes a luminance signal component. However, usually, the color signal component (C) and the luminance signal component (
The spectrum of Y) exists in the region shown in FIG. 3 when considered on the horizontal-vertical frequency plane. Therefore, line memory (
4a), (4b) and subtractor (8c), (8
d) and a horizontal BPF with the characteristics shown in Figure 4, the luminance signal component contained in the output of the adder (7a) is removed and only the motion information of the color signal component is extracted. will be done.

FIG. 2 is a block diagram showing a motion detection circuit for a composite video signal according to another embodiment of the present invention, which is obtained by adding a circuit for extracting motion information of a luminance signal to the circuit in FIG. It is something.

In Figure 2, a frame memory (3d), an adder (7
b), line memory (4c), (ad), subtractor (
8f).

(8g) and B P F (8b) are the same as the motion detection circuit shown in FIG. In other parts, (8e) is a subtracter that subtracts the composite video signal from the output of the frame memory (3d), (4e) is a line memory that delays the output of the subtractor (8e) by one horizontal scanning period, ( 5b) is an LPF that inputs the output of the line memory (4e), (7C) is B P F (8b)
This is an adder that adds the outputs of and L P F (5b). The parts consisting of the frame memory (3d), subtracter (8e), line memory (4e), and L P F (5b) are the same as the conventional example shown in Fig. 4, except for the line memory (4e). .

Therefore, in the embodiment shown in FIG. 2, the motion component of the luminance signal and the motion component of the chrominance signal are added together by the adder (7C) and output, resulting in motion information of the input composite video signal.

Note that the line memory (4e) is for compensating the delay time of the vertical BPF included in the color signal motion detection section.

[Effects of the Invention] As described above, according to the present invention, by passing the inter-frame sum signal of a composite video signal through a two-dimensional BPF, the luminance signal component can be removed and only one color signal component can be reliably extracted. Therefore, the motion information of the color signal component can be accurately and reliably detected even at the edge portions of an image.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a motion detection circuit for a composite video signal according to an embodiment of the present invention, FIG. 2 is a block diagram showing a motion detection circuit for a composite video signal according to another embodiment of the invention, and FIG. is an explanatory diagram showing the spectra of the luminance signal and color signal of the NTSC system, Fig. 4 is an explanatory diagram showing the frequency characteristics of the BPF in Figs. 1 and 2, and Figs. FIG. 3 is a block diagram showing the configuration of a motion detection circuit. (1)...Input terminal, (2)...Output terminal, (3a
)~(3d)...Frame memory, (4a)~(4
e)...Line memory, (5a), (5b)...
・L P F, (8a), CF3b)...-B P
F, (7a) to (7c)...adder, (8a) to (
8g)...Subtractor, (9)...Chroma inverter. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] (1) A circuit that extracts motion information of a color signal component from a composite video signal in which a color signal component and a luminance signal are frequency multiplexed, and includes a frame memory that delays the composite video signal by one frame period, and a frame memory that delays the composite video signal by one frame period, and A line memory for delaying a scanning period, a high-pass filter whose band is centered at the color subcarrier frequency, and an addition/subtraction circuit are provided, and the frequency component centered at the color subcarrier frequency is extracted from the interframe sum signal of the composite video signal. A motion detection circuit for a composite video signal, characterized in that the circuit extracts the motion of a composite video signal.