JPH07322285A - Motion detection circuit - Google Patents

Abstract

PURPOSE:To obtain the motion detection circuit in which a motion is accurately detected even at an edge of an object in which a 2-frame difference signal is produced. CONSTITUTION:An inter-two frame motion is detected from a difference between a current frame composite video signal and a composite video signal of two preceding frames by a subtractor 6. When there is correlation between two frames based on an edge signal detected by a current frame edge detection circuit 4 and an edge signal detected by a 2-preceding frame composite video signal by a 2-preceding frame edge detection circuit 7, a motion between the two frames is controlled by a 2-frame difference signal control circuit 11 based on the level of the edge signal detected by the current frame edge detection circuit 4. The controlled motion is used for a motion between two frames and a motion of the inter-two frame motion controlled as above and the low frequency component motion in the one frame detected by the subtractor 2 which is larger is used for a motion.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motion detection circuit for detecting motion information of an object, and more particularly to a motion adaptive Y / C separation circuit for separating a luminance signal and a carrier color signal in a television receiver or the like. A motion detection circuit that can be used.

[0002]

2. Description of the Related Art A conventional motion detection circuit digitizes a composite video signal into a digitized composite video signal (hereinafter referred to as a composite video signal), which is a composite video signal one frame before the composite video signal of the current frame. The motion amount for one frame is detected from the difference signal with the composite video signal of the current frame, and the composite video signal two frames before the composite video signal of the current frame is subtracted from the composite video signal of the current frame to obtain two frames. The contour difference part of the object is detected by detecting the period difference signal and the edge detection from the current frame composite video signal, and 2 when the edge part is detected.
The frame motion amount limiting circuit lowers the level of the differential signal for two frame periods to obtain a motion amount between two frames,
The larger of the amount of movement between frames and the amount of movement between two frames is output as the amount of movement.

[0003]

However, according to the conventional motion detection circuit, the characteristics of the TV camera and the A / D conversion are achieved even if there is a correlation between two frames when the subject is stationary, for example. There is a problem that a difference signal is generated for two frame periods at the contour edge portion of the object due to the characteristics of the container, and the object is erroneously detected as moving even though the object is stationary. For this reason, even when the subject is stationary, Y / C separation by complete three-dimensional processing is not performed, and a leak occurs between the luminance signal and the carrier color signal, causing the motion adaptive Y / C separation circuit. When applied, there is a problem that cross color and dot interference occur and the image quality deteriorates.

Further, when edge detection is performed by the composite video signal of the current frame and an edge portion is detected, a level limiting operation is performed based on the edge detection output.
Even when a two-frame motion amount limiting circuit that lowers the level of the frame period difference signal is provided, the level is lowered by the two-frame motion amount limiting circuit when an edge is detected from the current frame, so there is no motion when the subject moves. Therefore, there is a problem that a motion detection omission occurs at the edge portion of the subject, and as a result, an afterimage occurs.

An object of the present invention is to provide a motion detecting circuit capable of accurately detecting the amount of motion even at the edge portion of a subject where a 2-frame differential signal is generated.

[0006]

SUMMARY OF THE INVENTION A motion detection circuit of the present invention is a motion detection circuit for detecting motion information of a subject, which is one of a current frame digitized composite video signal and a current frame digitized composite video signal. The motion amount detecting means for detecting the motion amount of the low frequency component from the difference signal from the digitized composite video signal before the frame period, and the digitized composite video signal of the current frame.
Subtraction means for subtracting the digitized composite video signal before the frame period from the digitized composite video signal for the current frame, current frame edge detection means for detecting an edge signal from the digitized composite video signal for the current frame, and two frame periods before 2 frame preceding edge detecting means for detecting an edge signal from the digitized composite video signal, and edge level detecting means for detecting the level of the edge signal output from the current frame edge detecting means,
The level of the output signal of the edge correlation detection means for detecting the correlation between the edge signal output from the current frame edge detection means and the edge signal output from the two-frame previous edge detection means and the level of the output signal of the edge correlation detection means exceeds a predetermined level. The gate means that allows the output signal of the edge level detection means to pass therethrough, the two-frame difference signal control means that controls the output signal level of the subtraction means based on the output signal level from the gate means, and the motion amount detection means detect the difference. And a motion amount output means for outputting the higher level of the motion amount and the output signal of the two-frame difference signal control means.

[0007]

In the motion detecting circuit of the present invention, the motion amount detecting means detects the digitized composite video signal of the current frame and 1
The amount of motion of the low frequency component is detected from the difference signal from the digitized composite video signal before the frame period. Also, the subtraction means subtracts the digitized composite video signal of two frame periods before from the digitized composite video signal of the current frame to obtain a two-frame period difference signal,
That is, the amount of movement between two frames is detected. The current frame edge detecting means detects the edge signal of the current frame, the two-frame delayed edge detecting means detects the edge signal of two frames before, and the correlation between the current frame and the two frames is detected from the detected both edge signals. That is, the correlation between two frames is detected. When the correlation is high, the edge signal of the current frame is output from the gate means, and the motion amount between the two frames is controlled based on the level of the edge signal of the current frame output, and the controlled two frames are controlled. The amount of movement between the two frames is transmitted as the amount of movement between two frames. This control is performed so that the amount of movement between two frames decreases as the level of the edge signal of the current frame increases. The larger of the amount of motion between two frames as a result of this control and the amount of motion of the low frequency component is output as the amount of motion.

Therefore, in this case, when there is a correlation between the edge signals between the two frames, the motion amount controlled by the two-frame difference signal control means based on the level of the edge signal of the current frame becomes the motion amount between the two frames. Therefore, even if the difference signal between the two frames is detected when the subject is stationary, if there is a correlation between the edge signals between the two frames, the movement amount between the two frames is controlled to be small. As a result, it will not be erroneously detected that the subject has moved. Further, when there is no correlation between the edge signals between the two frames, the amount of movement between the two frames is not controlled, so that it is no longer determined that the subject is stationary even though it is moving.

[0009]

EXAMPLES The present invention will be described below with reference to examples. Figure 1
FIG. 3 is a block diagram showing a configuration of an embodiment of a motion detection circuit according to the present invention.

In the motion detecting circuit 20 of the present embodiment, the composite video signal sampled and digitized by a sampling pulse having a frequency of 4 fsc (fsc is the frequency of the color subcarrier) is input to the input terminal to output the composite video signal. 1 frame memory 1 for delaying 1 frame period, subtracter 2 for subtracting 1 frame period before composite video signal output from 1 frame memory 1 from the input current composite video signal, and output from subtracter 2 A low-frequency component including a low-pass filter for receiving a difference signal, and when the output level of the low-pass filter is high, a low-level correlation output is transmitted, and when the output level of the low-pass filter is low, a high-level correlation output is transmitted. The low frequency component correlation detection circuit 3 for detecting the correlation of The composite video signal output from the memory memory 1 one frame before is subtracted from the current composite video signal by the subtractor 2, and the subtractor 2 detects a differential signal for one frame period, that is, a motion amount between one frames, The low-frequency correlation detection circuit 3 detects the correlation signal of the low-frequency component in the motion amount for one frame.

Here, the one-frame memory 1, the subtractor 2, and the low-frequency component correlation detection circuit 3 correspond to the motion amount detection means. The reason why the correlation of the low frequency component is detected by the low frequency component correlation detection circuit 3 is to prevent the influence of the high frequency component, and to detect the influence of the chrominance signal component leaking into the luminance signal. This is to remove it. Further, when the output level from the low frequency component correlation detection circuit 3 is high, the motion amount is small, and when the output level is low, the motion amount is high, and the low frequency component correlation detection circuit 3 detects the motion amount. It will be.

The motion detection circuit 20 includes a 1-frame memory 1
A 1-frame memory 5 for further delaying the composite video signal output from the 1-frame period by 1 frame period; and a subtractor 6 for subtracting the composite video signal output from the 1-frame memory 5 from 2 frames period before from the current composite video signal. Then, the composite video signal of two frames before output from the 1-frame memory 5 is subtracted from the current composite video signal in the subtractor 6, and the subtracter 6 outputs 2
The frame period difference signal, that is, the amount of motion between two frames is detected. Here, 1 frame memories 1 and 2,
The subtractor 6 corresponds to subtraction means.

Further, the motion detection circuit 20 outputs the composite image of the previous frame output from the current frame edge detection circuit 4 and the 1-frame memory 5, which is composed of a digital high-pass filter for detecting an edge signal from the composite image signal of the current frame. A two-frame front edge detection circuit 7 comprising a digital high-pass filter for detecting an edge signal from the signal, and the current frame edge detection circuit 4 detects an edge signal from the composite video signal of the current frame. 7, the edge signal is detected from the composite video signal of the frame two frames before. Here, the current frame edge detection circuit 4 corresponds to the current frame edge detection means, and the 2-frame front edge detection circuit 7 corresponds to the 2-frame front edge detection means.

Here, the digital high-pass filter constituting the current frame edge detection circuit 4 and the two-frame front edge detection circuit 7 is a digital high-pass filter having a pass band at a frequency exceeding the carrier color signal band. By using a filter, it is possible to detect an edge with high accuracy without detecting an edge by mistake due to the influence of the frequency component of the carrier color signal. Further, instead of the digital high pass filter, a digital band trap filter that removes frequency components in the carrier color signal band may be used. When a digital band trap filter is used, the edges are not erroneously detected due to the influence of the frequency component of the carrier color signal, and the correlation between two frames of the luminance signal low frequency component can also be detected, enabling highly accurate edge detection. Becomes

Further, the motion detection circuit 20 detects the correlation between the edge signal detected by the current frame edge detection circuit 4 and the edge signal detected by the two-frame preceding edge detection circuit 7, and an edge correlation detection circuit 8. An edge level detection circuit 9 for detecting the level of the edge signal detected by the current frame edge detection circuit 4 and an AND gate 10 whose gate is opened by the output of the edge correlation detection circuit 8 are provided.

The edge correlation detection circuit 8 detects the difference between the edge signal detected by the current frame edge detection circuit 4 and the edge signal detected by the two-frame preceding edge detection circuit 7, and the output of the subtractor. It is composed of a comparator for detecting that it is above a predetermined level, and when the correlation value is above a predetermined level, it outputs an output as having correlation.
That is, the edge correlation detection circuit 8 detects the correlation between two frames. The edge level detection circuit 9 is provided with a plurality of thresholds having different values, compares the edge signal detected by the current frame edge detection circuit 4 with the respective thresholds, and determines the edge signal detected by the current frame edge detection circuit 4. It is configured to output a signal at a level corresponding to the maximum threshold value that is exceeded. Therefore, the edge signal detected by the current frame edge detection circuit 4 is converted into an edge level signal having a threshold interval by the edge level detection circuit 9 and output.

Here, the edge correlation detecting circuit 8 corresponds to the edge correlation detecting means, the edge level detecting circuit 9 corresponds to the edge level detecting means, and the AND gate 10 corresponds to the gate means.

Further, the motion detection circuit 20 uses the edge level signal output from the AND gate 10 as a control signal to control the level of the output of the subtracter 6, that is, the amount of motion between two frames. 11 and
The frame correlation decoder 1 which sends out the larger one of the motion amount output from the 2-frame difference signal control circuit 11 and the motion amount output from the low-frequency component correlation detection circuit 3 as the motion amount.
2 and. Here, the 2-frame difference signal control circuit 11 corresponds to 2-frame difference signal control means, and the frame correlation decoder 12 corresponds to motion amount output means.

The two-frame difference signal control circuit 11 includes a storage circuit in which the output edge level from the edge level detection circuit 9 output via the AND gate 10 and the multiplication coefficient are stored in the form of a table shown in FIG. , The output edge level output from the edge level detection circuit 9 output via the AND gate 10 is referred to, the corresponding multiplication coefficient is read from the storage circuit, and the read multiplication coefficient and the output of the subtractor 6 are read. And a multiplier for multiplying the level, that is, the amount of movement between two frames. In FIG. 2, the output edge level (denoted as a control signal in FIG. 2) output from the edge level detection circuit 9 via the AND gate 10 is indicated by a1, a2, ..., An, and the respective output edge levels are indicated. Is a1>a2>,...,> an
, And bn, and the respective multiplication coefficients (simply described as coefficients in FIG. 2) are b1 <b2 <, ..., <bn.

Therefore, the higher the output edge level output from the edge level detection circuit 9 through the AND gate 10, the level of the output of the subtractor 6, that is, 2
The amount of motion between frames is multiplied by a small multiplication coefficient, and the amount of motion is compressed to generate a 2-frame difference signal control circuit 11
Is output from the low-frequency component correlation detection circuit 3 and the 2-frame difference signal control circuit 11
The larger amount of motion output from is output from the frame correlation decoder 12 as the amount of motion.

As a result, when there is a correlation between the edge signals between the two frames, the movement amount controlled by the two-frame difference signal control circuit 11 based on the level of the edge signal of the current frame is set as the movement amount between the two frames. Therefore, even if the difference signal between the two frames is detected when the subject is stationary, the movement amount between the two frames is controlled to a small movement amount when there is a correlation between the edge signals between the two frames. As a result, it will not be erroneously detected that the subject has moved. When there is no correlation between the edge signals between the two frames, the amount of movement between the two frames is not controlled, so it is no longer possible to determine that the subject is stationary although it is moving.

The output of the subtracter 2 of the above-mentioned embodiment is set to 3
It can also be used for dimensional carrier color signal separation. Also,
The 1-frame memories 1 and 5 may be configured by using line memories.

[0023]

As described above, according to the motion detecting circuit of the present invention, when there is a correlation between the edge signals between frames in detecting the motion amount, the two-frame difference signal control means sets the level of the current frame edge. Since the amount of movement between the two frames is controlled based on this, it is not erroneously detected that the subject has moved, and when there is no correlation between the edge signals between the two frames, the amount of movement between the two frames is controlled. Since there is no such a case, it is possible to obtain the effect that it is not judged that the subject is stationary even if the subject is moving.

When the current frame edge detection means and the two-frame front edge detection means are digital high-pass filters having a pass band at a frequency higher than the carrier color signal band,
An edge is not erroneously detected due to the influence of the frequency component of the carrier color signal, and it is possible to detect an edge with high accuracy. When the current frame edge detection means and the two-frame previous edge detection means are digital band trap filters for removing the carrier color signal band, the edges are not erroneously detected due to the influence of the frequency component of the carrier color signal. , Luminance signal low frequency component 2
There is an effect that the correlation between frames can be detected and the edge can be detected with high accuracy.

[Brief description of drawings]

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

FIG. 2 is a schematic diagram for explaining the configuration of a two-frame differential signal control circuit in one embodiment of the motion detection circuit according to the present invention.

[Explanation of symbols]

 1 and 5 1 Frame memory 2 and 6 Subtractor 3 Low frequency component correlation detection circuit 4 Current frame edge detection circuit 7 2 Frame front edge detection circuit 8 Edge correlation detection circuit 9 Edge level detection circuit 10 AND gate 11 2 Frame difference signal control Circuit 12 Frame correlation decoder 20 Motion detection circuit

Claims (3)

[Claims] 1. A motion detection circuit for detecting motion information of an object, comprising one of a current frame digitized composite video signal and a current frame digitized composite video signal.
The motion amount detecting means for detecting the motion amount of the low frequency component from the difference signal from the digitized composite video signal before the frame period, and the digitized composite video signal two frames before the current frame digitized composite video signal Subtraction means for subtracting from the digitized composite video signal of the current frame, current frame edge detection means for detecting an edge signal from the digitized composite video signal of the current frame, and edge signal from the digitized composite video signal of two frame periods ago Two-frame front edge detecting means for detecting, edge level detecting means for detecting the level of the edge signal output from the current frame edge detecting means, edge signal output from the current frame edge detecting means and two-frame front edge detecting means From the edge signal output from Output edge correlation detection means, gate means for passing the output signal of the edge level detection means when the level of the output signal of the edge correlation detection means exceeds a predetermined level, and subtraction means based on the output signal level from the gate means 2 frame difference signal control means for controlling the output signal level of the above, and a motion amount output means for outputting the larger one of the motion amount detected by the motion amount detection means and the output signal of the 2 frame difference signal control means. A motion detection circuit characterized by being provided. 2. The motion detection circuit according to claim 1, wherein the current frame edge detection means and the two-frame delay edge detection means are digital high-pass filters having a pass band in a frequency band exceeding the carrier color signal band. Motion detection circuit. 3. A motion detecting circuit according to claim 1, wherein the current frame edge detecting means and the two frame delay edge detecting means are digital band trap filters for removing frequency components of a carrier color signal band. Detection circuit.