JPH10161591A - Motion detecting circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow to detect a highly precise motion vector even when the level of an input video signal is changed from its original one because of inclusion, etc., of noise. SOLUTION: A low-pass filter 30 is coupled with the preceding stage of a motion detecting circuit 10 which detects motion vectors by the block matching method. This low-pass filter 30 is composed from, for example, a one-frame delay 32, an adder 34 which adds the input video signal to the output of the delay 32, and a 1/2 multiplier 36 which multiplies the output signal of this adder 34 by a factor 1/2 to produce the output to the motion detecting circuit 10. Even when the level of the video signal inputted from an input terminal 14 is changed by the inclusion of noise between frames (e.g. between the present frame and the precedent frame), the signal in which noise is dispersed by averaging of levels due to the low-pass filter 30 is inputted into the motion detecting circuit 10. Hence highly precise motion vectors can be detected without being not susceptible to noise.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motion detecting circuit for detecting a motion vector used for moving image correction and the like. The motion vector detected by the motion detection circuit is displayed on a display device using a PDP (plasma display panel) or an LCD (liquid crystal display panel) (for example, a display device of an address / display separation type driving system). It is used for moving image correction to reduce a visual display shift that sometimes occurs.

[0002]

2. Description of the Related Art Recently, as a thin and lightweight display device, P
DP and LCD are attracting attention. The driving method of this PDP is completely different from the conventional CRT driving method, and is a direct driving method using a digitized input video signal. Therefore, the luminance gradation emitted from the panel surface is
It is determined by the number of bits of the signal to be handled.

[0003] PDPs are AC type and D type having different basic characteristics.
It is divided into two types of C type. In the AC type PDP, sufficient characteristics have been obtained with respect to luminance and life, but as for gradation display, only a maximum of 64 gradation display has been reported at the prototype level, but the address / display separation type driving method (ADS) A sub-field method) has been proposed. The drive sequence and drive waveform of the PDP used in this method are as shown in FIGS. 3A and 3B, for example.

FIG. 3A shows a drive sequence of 8 bits and 256 gradations. One frame has eight luminance ratios of 1, 2, 4, 8, 16, 32, 64 and 128. Subfields SF1, SF2, SF3, SF4, SF
5, SF6, SF7, and SF8, and a display of 256 gradations is performed by a combination of luminances of eight screens.

[0005] Each subfield is shown in FIG.
As shown in (1), an address period in which data for one refreshed screen is written and a sustain period for determining the luminance level of the subfield are constituted. In the address period, first, wall charges are initially formed on each pixel at the same time for the entire screen, and then a sustain pulse is applied to the entire screen to perform display. The brightness of the subfield is proportional to the number of sustain pulses and is set to a predetermined brightness. In this way, 256 gradation display is realized.

When a moving image is displayed on the display device of the address / display separation type driving system as described above, a visual display shift may occur. There is a moving image correction process using a vector. The motion detection circuit 10 for detecting such a motion vector has conventionally been configured as shown in FIG.

That is, in the motion detection circuit 10 shown in FIG. 4, the current frame screen based on the video signal (video data) input to the input terminal 14 by the frame memory 12
A video signal of a screen before a frame (hereinafter, referred to as a previous frame screen) is created, and the correlation value calculation unit 16 uses the unit block UB (for example, 8 ×) to be detected in the current frame screen.
8 dots), the correlation values (difference values) with all the unit blocks UB in the motion vector detection area of the previous frame screen are sequentially obtained. Generates a signal (hereinafter, simply referred to as a movement vector) indicating a moving direction and a moving amount from the unit block position to the detection target unit block position,
The movement vector is output from the output terminal 20 as the motion vector of the unit block to be detected.

[0008]

However, in the conventional example shown in FIG. 4, since the video signal is directly input to the motion detection circuit 10, the video signal (video data) between frames is mixed due to noise or the like. When the level changes (that is, when the video data fluctuates), an erroneous motion vector may be detected.

For example, if the video data fluctuates in the frame direction due to the mixing of noise, the video data 1 in the unit block UB and the n + 1 frame in the n-th frame unit block UB in the case of a still image, although there is no change in the video data between frames. FIG. 5A shows a relationship between the video data 2 in the unit block UB and the video data 2.
A level change as shown in (b) appears, and there is a problem that a motion vector having a motion amount of 0 should be detected, but a motion vector other than 0 is detected.
The dots indicated by hatching in FIG. 5B represent dots whose level has changed due to noise mixing or the like. Even in the case of a moving image, if the video data fluctuates in the frame direction due to the incorporation of noise or the like, an erroneous motion vector is similarly detected.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and detects a highly accurate motion vector even when the level of an input video signal changes from an original level due to noise or the like. It is an object of the present invention to obtain a motion detection circuit which can perform the motion detection.

[0011]

According to the present invention, there is provided a motion detecting circuit which obtains a block level correlation value between a current frame screen and a previous frame screen based on an input video signal, and detects a motion vector based on the correlation value. , A low-pass filter is connected to a stage preceding the motion detection circuit, and the low-pass filter calculates and outputs an average value of a plurality of frames of the input video signal.

The low-pass filter includes, for example, a one-frame delay unit for delaying the input video signal by one frame, an adder for adding the input video signal and the output signal of the one-frame delay unit, and a coefficient 1 added to the output signal of the adder. 1/2 multiplied by / 2
A multiplier calculates an average value of two frames of the input video signal and outputs the result to the motion detection circuit. Therefore, even if the level of an arbitrary dot in one or both of the block levels of the current frame screen and the previous frame screen changes due to mixing of noise or the like, a signal in which noise is dispersed by averaging the levels is output by the motion detection circuit. , It is possible to detect a highly accurate motion vector with less influence of noise.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a motion detection circuit according to the present invention will be described below with reference to FIG. In FIG. 1, the same parts as those in FIG. In FIG. 1, 10
Is a motion detection circuit. The motion detection circuit 10 is configured in the same manner as in FIG. A low-pass filter 30 unique to the present invention is provided before the motion detection circuit 10.
Is provided.

The low-pass filter 30 has an input terminal 1
A one-frame delay unit 32 for delaying the video signal input to the input terminal 4 by one frame and outputting the same; an adder 34 for adding the input video signal input to the input terminal 14 and the output signal of the one-frame delay unit 32; The output signal of the adder 34 is multiplied by a coefficient １ ／ and output to the motion detection circuit 10 1 /
And a 2 multiplier 36.

Next, the operation of FIG. 1 will be described with reference to FIG. For convenience of description, the unit block UB is 3 × 5
As shown in FIG. 2 (a), a dot configuration is adopted, and video data 1 in a still image portion of n frames is a unit block U.
B is input to the input terminal 14 while maintaining the level of each dot in the original 2 and the video data 2 in the corresponding still image portion of the (n + 1) th frame is converted into the unit block UB as shown in FIG. It is assumed that noise is mixed into an arbitrary one of the dots and the level changes to 3 and is input to the input terminal 14.

The video signal input to the input terminal 14 is input to one input side of the adder 34 and is input to the other input side of the adder 34 after being delayed by one frame by the one-frame delay unit 32. Therefore, for the above-described still image portion, the adder 34 outputs a signal obtained by adding the video data 1 of the previous frame (n frame) and the video data 2 of the current frame (n + 1 frame). Is the adder 34
A signal obtained by multiplying the output data of by 動 き
Output to That is, as shown in FIG. 2C, video data 3 (= (video data 1 + video data 2) / 2) in which the level of each dot in the unit block UB is set to the original level of 2.
Are input to the motion detection circuit 10.

As described above, even if the video data 2 containing noise as shown in FIG. 2B is input to the input terminal 14, the noise is dispersed by the level averaging by the low-pass filter 30, and the original video is reproduced. Since the video data 3 that does not change compared to the data 1 is input to the motion detection circuit 10, the motion detection circuit 10 can detect a motion vector that is not affected by noise.

In the above embodiment, the low-pass filter includes a one-frame delay unit for delaying the input video signal by one frame, an adder for adding the input video signal and the output signal of the one-frame delay unit, and an output of the adder. Coefficient 1/2 of signal
Has been described, the present invention is not limited to this. The average value of a plurality of frames of the input video signal is calculated. What is necessary is just to output to a motion detection circuit.

For example, a one-frame delay unit that delays an input video signal by one frame, a first multiplier that multiplies the output signal of the one-frame delay unit by a factor 、, and multiplies the input video signal by a factor ２. A second multiplier, a first multiplier and a second
The present invention can also be used in a case where a low-pass filter is configured by an adder that adds the output signals of the multipliers and outputs the result to the motion detection circuit. Alternatively, N (an integer of 2 or more) 1-frame delay units and input video signals of 1, 2,
.., An adder for adding the signal delayed by N frames and the input video signal, and 1 / (N +
It can also be used when a low-pass filter is configured with a multiplier that multiplies 1).

[0020]

According to the present invention, a low-pass filter is connected before a motion detection circuit for detecting a motion vector by a block matching method. This low-pass filter is used for averaging a plurality of frames (for example, two frames) of an input video signal. It is configured to calculate a value and output the calculated value to the motion detection circuit. For this reason, even if the level of the video signal changes between frames (for example, between the current frame and the previous frame) due to noise mixing or the like, a signal in which noise is dispersed by averaging the levels by the low-pass filter is sent to the motion detection circuit. Since the input is made, it is possible to detect a highly accurate motion vector with less influence of noise.

[Brief description of the drawings]

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

FIG. 2 shows a low-pass filter 30 when a video signal whose level has been changed due to noise input is input to an input terminal 14 of FIG.
7A is an explanatory diagram of a signal level output from the control unit 10 to the motion detection circuit 10, (a) is an explanatory diagram of a level of each dot in a unit block UB of an n-frame screen before noise is mixed, and (b) is an (n + 1) -frame screen after noise is mixed. Corresponding unit block U
FIG. 3C is a level explanatory diagram of each dot in the unit block UB corresponding to a signal output from the low-pass filter 30 to the motion detection circuit 10;

FIG. 3 illustrates a subfield lighting method.
(A) is an explanatory diagram of a drive sequence in a 256-tone method, and (b) is a drive waveform diagram.

FIG. 4 is a block diagram of a conventional motion detection circuit.

5A and 5B are explanatory diagrams of a block level when a video signal whose level has changed due to noise mixing is input to the input terminal 14 in FIG. 4; FIG. 5A illustrates each dot in a unit block UB of an n-frame screen before noise mixing; (B) is a corresponding unit block U of the (n + 1) th frame screen after noise mixing
FIG. 9 is a level explanatory diagram of each dot in B.

[Explanation of symbols]

10: motion detection circuit, 12: frame memory, 14
... video signal input terminal, 16 ... correlation value calculator, 18
... Motion vector generator, 20 ... Motion vector output terminal, 30 ... Low pass filter, 32 ... One frame delay unit, 34 ... Adder, 36 ... 1/2 multiplier, UB
... unit block.

Claims (3)

[Claims] 1. A motion detection circuit which calculates a block level correlation value between a current frame screen and a previous frame screen based on an input video signal and detects a motion vector based on the correlation value. And a low-pass filter, the low-pass filter calculating and outputting an average value of a plurality of frames of the input video signal. 2. The low-pass filter according to claim 1, wherein an average value of two frames of the input video signal is calculated and output by combining an adder, a one-frame delay unit and a 乗 算 multiplier. Motion detection circuit. 3. A low-pass filter includes a one-frame delay unit for delaying an input video signal by one frame, an adder for adding the input video signal and an output signal of the one-frame delay unit, and an output signal of the adder. 3. A 乗 算 multiplier for multiplying by a coefficient ２ and outputting the result to a motion detection circuit.
The motion detection circuit as described.