JP3081266B2 - Motion detection circuit - Google Patents

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,
In particular, the present invention relates to a motion detection circuit used for a motion adaptation process such as an IDSC or an EDTV of the NTSC system.

[0002]

2. Description of the Related Art Referring to FIG. 4, in a conventional motion detecting circuit 1 of this type, an absolute value of an inter-frame difference signal obtained by an absolute value circuit 2 is compared with a predetermined threshold value in a threshold value circuit 3. Obtain a motion signal. Threshold circuit 3 to remove noise
Is supplied to the low-pass filter 4, and the low-pass filter 4 outputs a motion signal.

[0003]

A conventional motion detection circuit 1
In the case where noise is mixed in, for example, a luminance signal leaks into a color signal, the noise cannot be removed only by the low-pass filter 4 and erroneous detection occurs. Therefore, a main object of the present invention is to provide a motion detection circuit capable of further reducing erroneous detection.

[0004]

SUMMARY OF THE INVENTION The present invention is directed to a first method for receiving composite video signals of adjacent frames, respectively.
And a second bandpass filter, a first and a second
First and second receiving the output of the
The absolute value circuit 2, the outputs of the first and second absolute value circuit
Subtraction circuit for obtaining an inter-frame difference signal by subtraction , a third absolute value circuit for obtaining an absolute value of the inter-frame difference signal, and a third absolute value
A threshold circuit that samples the output of the circuit at a frequency of 4 fs and compares it with a predetermined threshold to output data of “1” or “0”; and that the output data of the threshold circuit is “1” or “0”
And a signal output means for outputting a motion signal when an alternating pattern of the above or a continuous pattern of "1" is indicated.

[0005]

A color signal is extracted from each composite video signal by the first and second band-pass filters .
And the output of the second absolute value circuit is subtracted.
Then, the subtraction circuit obtains the difference between the color signals of the current frame and the previous frame and supplies the difference to the third absolute value circuit. The third absolute value circuit outputs the absolute value of the inter-frame difference signal . Third Absolute
The output of the value circuit is a predetermined frequency 4fs (fs: subcarrier frequency)
), Which is compared with a preset threshold in a threshold circuit. The threshold circuit outputs “1” when the absolute value exceeds the threshold, and outputs “0” when the absolute value does not exceed the threshold. “1” or “0” is a predetermined change pattern, for example, “10101”, “0101”
When it changes at "0" or "11111", it is determined that there is a motion, and a motion signal is output from the signal output means. This motion signal may be further input to a low-pass filter.

[0006]

According to the present invention, a motion signal is output only when the output of the threshold circuit changes in a predetermined pattern, and no motion signal is output when the output changes in a different pattern due to noise. Can be further reduced. The above and other objects of the present invention,
Features and advantages will become more apparent from the following detailed description of embodiments, which proceeds with reference to the accompanying drawings.

[0007]

Referring to FIG. 1, an NTSC composite video signal is input from an input terminal 12 to a motion detection circuit 10 of this embodiment. This signal is, for example, 3.58
The signal is supplied to a band-pass filter 14 having a center frequency of MHz and delayed by one frame by a delay 16, and then input to a similar band-pass filter 18. The band-pass filters 14 and 18 pass only the components in the color signal band of the composite video signal of the current frame and the composite video signal of the previous frame, whereby the color signal of the current frame and the color signal of the previous frame are extracted. You. The absolute values of these color signals are obtained by absolute value circuits 20 and 22, respectively. A subtraction circuit 24 obtains an inter-frame difference signal from these absolute values. As described above, the difference between frames is obtained after the absolute value of the color signal is obtained. Since the color signal is modulated by the subcarrier whose phase is inverted for each frame, the difference between frames is simply obtained. This is because an inter-frame difference signal cannot be obtained by using only the color signal, and the color signal itself is extracted and a motion is erroneously detected.

The frame difference signal is supplied to an absolute value circuit 2.
At 6, the absolute value is taken and input to the threshold circuit 28.
In the threshold circuit 28, the output of the absolute value circuit 28 is set to 4fs (f
s: sampling at subcarrier frequency 3.58 MHz)
Then, a preset threshold value is compared with the sampled absolute value, and “1” is output when the absolute value of the inter-frame difference signal exceeds the threshold value, and “0” is output when the absolute value does not reach the threshold value. Although a motion signal is output based on the output of the threshold circuit 28, in this embodiment, 5-bit data is output from the threshold circuit 28 for one frame, and the 5-bit data is output from the bit pattern detection circuit. 30. In the bit pattern detection circuit 30, the preset bit patterns "01010", "1"
0101 ”or“ 11111 ”, the threshold circuit 28
A motion signal is output only when the output changes.

If the current image is not colored but the image one frame before is colored, for example, if a colored object moves out of the area, From the value circuits 20 and 22, respectively, FIG.
An absolute value as shown in FIG. 2A and FIG. 2B is output. Therefore, the absolute value circuit 26 outputs an absolute value as shown in FIG. When this absolute value is compared with the threshold value by the threshold circuit 28, as shown in FIG.
8 changes. The change pattern in this case is “01
010 ".

When the absolute value shown in FIG. 2C is sampled with a phase shift of 45 °, compared with a threshold value and converted into bit data, as shown in FIG. 2E, “11111” is obtained.
Is the change pattern. If the current image is colored but the image one frame before is not colored, for example, if a non-colored image contains a colored object, the absolute value circuit 20 and 22 output the absolute values shown in FIGS. 2B and 2A, respectively. At this time, the absolute value circuit 26 outputs an absolute value as shown in FIG.
The change pattern is also as shown in FIG.
It becomes "01010" or "11111".

Further, although the current image and the image one frame before are colored, when the color changes, that is, when the phase of the color signal changes, the absolute value circuits 20 and 22 output FIG. 2 (f) and FIG.
The absolute value shown in (g) is output. Therefore, the absolute value circuit 26 outputs an absolute value as shown in FIG.
The threshold circuit 28 outputs “10101” as shown in FIG.
Is output.

When sampling is performed with the phase shifted by 45 ° from the case of FIG. 2 (i) and compared with a threshold value and converted into bit data, the change pattern becomes “01” as shown in FIG. 2 (j).
010 ". Thus, the threshold circuit 2 for a moving image
8 are “01010” and “1010”.
1 "or" 11111 ". Therefore, these three types of bit patterns need only be detected by the bit pattern detection circuit 30.

As shown in FIG. 3, such a bit pattern detection circuit 30 includes three AND gates 32,
34 and 36 can be used. AND gate 3
2 represents a bit pattern “11111” and an AND gate 3
4 detects the bit pattern "10101", and the AND gate 36 detects the bit pattern "01010". However, in FIG. 3, a circuit part associated with timing adjustment such as a data latch is omitted. The output from the AND gate 32, 34 or 36 is output through the OR gate 38.

As described above, when the bit pattern detection circuit 30 detects that the data from the threshold circuit 28 has changed according to any of the three types of bit patterns, a high-level motion signal is output. If the output of the threshold circuit 28 does not match any of the three types of bit patterns, it is determined that the image is a still image, and a low-level signal is output. Then, the bit pattern detection circuit 3
The output of 0 is input to the low-pass filter 40 as in the related art, and is output from the output terminal 42 after noise removal.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a waveform chart for explaining the operation of this embodiment.

FIG. 3 is a circuit diagram showing an example of a bit pattern detection circuit of the embodiment of FIG.

FIG. 4 is a block diagram showing a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Motion detection circuit 14,18 ... Band pass filter 16 ... Delay 20,22,26 ... Absolute value circuit 24 ... Subtraction circuit 28 ... Threshold circuit 30 ... Bit pattern detection circuit 40 ... Low pass filter

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04N 9/44-9/78 H04N 11/00-11/24

Claims (1)

(57) [Claims] 1. A first and a second band-pass filter for respectively receiving a composite video signal of an adjacent frame, and an output of the first and the second band-pass filters.
First and second absolute value circuits respectively receiving said first and second subtraction circuit output by subtracting obtain difference signal between frame <br/> over arm of the absolute value circuit, the inter-frame difference signal A third absolute value circuit that takes an absolute value, and samples the output of the third absolute value circuit at a frequency of 4 fs.
And compare it with a predetermined threshold to determine if it is a "1" or "0" .
Threshold circuit outputs the over data, and output data <br/> over data of the threshold circuit is "1" and alternating pattern or "0" and "1"
A motion detection circuit comprising signal output means for outputting a motion signal when a continuous pattern is shown.