JPH0358238B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a motion detection circuit for a television signal, and particularly to a motion detection circuit for detecting motion of a subject included in a composite color television signal in which a color difference signal is superimposed on a luminance signal modulated at a subcarrier frequency. The present invention relates to a circuit for extracting motion information of a color signal portion of a color signal.

[Background of the invention]

In a composite color television signal, the polarity of the carrier color signal is reversed for each scan line, and is also reversed between the current scan line and the previous scan line. Therefore, when extracting object motion information contained in a television signal, a simple difference signal between frames contains a carrier color signal component, so a significant difference signal will appear even in a still image, and correct moving areas will be detected. could not be detected.

Figure 2a shows the configuration of a motion detection circuit used in a frame cyclic noise removal device, in which an NTSC color television signal input to input terminal 1 is delayed by one frame period in frame memory 12, and a color signal polarity inversion circuit is used. After the polarity of the carrier color signal is inverted in step 13 to make it the same polarity as the input color television signal, a subtraction circuit 14 subtracts it from the input television signal. If the absolute value of the subtraction result is taken by the absolute value circuit 15, the output terminal 1
1, when a subject moves, a signal corresponding to a change in luminance or color difference signal between frames can be obtained. In the above configuration, the color signal polarity inversion circuit 13:
For example, a carrier color signal is extracted by a bandpass filter BPF and its polarity is inverted. In this case, in edge portions or fine pattern portions of the image, high frequency components of the luminance signal may be mixed into the extracted carrier color signal, or a portion of the carrier color signal component may remain as the luminance signal. Therefore, the polarity of the carrier color signal is not correctly inverted at the edge portion of a still image, and a significant difference signal appears in the output of the subtraction circuit 14, causing the problem that it is assumed that there is movement.

FIG. 2b shows a known motion detection circuit shown in Japanese Patent Application Laid-Open No. 58-130685. In the figure, a subtraction circuit 16 obtains an interframe difference signal, which is input to a low pass filter LPF 17, and its low frequency component is used as motion information. In this case, the still image is correctly determined to have no motion. However, there is a problem in that when a subject whose brightness level is equal to that of the background and whose color is different only moves, no significant signal appears at the output terminal 11, and that part is also considered to be motionless.

FIG. 2c is a known example shown in Japanese Patent Application Laid-Open No. 55-123280. In the figure, a memory 18 with a capacity of 2 frames is installed, and a subtraction circuit 19 calculates the difference with a signal from 2 frame periods before, and outputs the absolute value as motion information. In this case, a still image is correctly determined to be motionless, but if a subject with strong contrast moves quickly, motion may not be detected because a signal from two frame cycles (67 ms) earlier is used. There is a problem.

[Purpose of the invention]

An object of the present invention is to solve the above-mentioned problems and provide a motion detection circuit that can accurately extract motion information of a subject in a composite color television signal.

[Summary of the invention]

In order to achieve the above object, the present invention provides motion detection for the low frequency component of the luminance signal and motion detection for the carrier color signal band, and obtains motion information of the low frequency component of the luminance signal from the frame difference signal, The motion information in the carrier color signal band is obtained from the difference signal between two frames.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG. In the same figure, input to input terminal 1
The NTSC color television signal is input to frame memories 2 and 3 with a capacity of 1 frame, which are connected in series.
Subtraction circuits 4 and 7 calculate the difference between the signal before the frame period and the signal before two frame periods. The interframe difference signal obtained by the subtraction circuit 4 is input to a low pass filter (LPF) 5, and its low frequency components are extracted. The difference signal between the two frames calculated by the subtraction circuit 7 is input to a band pass filter (BPF) 8, and its carrier color signal band component is extracted.
As already mentioned, the polarity of the carrier color signal returns to its original state every two frames, and in the case of a still image, the BPF
The output of 8 becomes zero. If there is any change in the color difference signal, a significant non-zero signal is obtained from the absolute value circuit 9 and can be used as motion information for the color signal. Therefore, by adding the motion information of the luminance signal obtained as the output of the absolute value circuit 6 and the motion information of the color signal obtained as the output of the absolute value circuit 9 in the adding circuit 10, the output terminal 11
The motion information of the subject included in the NTSC signal can be obtained.

〔Effect of the invention〕

According to the present invention, motion information of a frequency component centered on a carrier color signal of a composite color television signal is obtained from a carrier color signal band component of a difference signal with a signal delayed by two frame periods. Optimal video signal processing using motion information can solve the problem of image quality deterioration in video signal processing due to parts of the image being considered as moving images or parts of the video being considered as still images. can be realized, and it has a great effect on improving its performance.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of a color television signal motion detection circuit according to the present invention, and FIG. 2 is a block diagram of a conventional motion detection circuit. 1... Input terminal, 2, 3, 12, 18... Frame memory, 4, 7, 10, 14, 16, 19...
... Addition (subtraction) circuit, 5, 17 ... Low pass filter, 6, 9, 15 ... Absolute value circuit, 8 ... Band pass filter, 11 ... Output terminal, 13 ... Color signal polarity inversion circuit .

Claims (1)

[Claims] 1. In a circuit for extracting motion information of a subject included in a composite color television signal, a frame memory capable of delaying at least two frame periods of the television signal and a part of the frame memory are used to extract low frequency information of a luminance signal. a first means for extracting a frame difference signal corresponding to the component, a second means for extracting a two-frame difference signal corresponding to the carrier color signal band component using the frame memory, and the first and second means 1. A motion detection circuit for a color television signal, comprising: an addition means for adding the outputs of the above to obtain motion information.