Pulse or digital communications – Bandwidth reduction or expansion – Television or motion video signal
Reexamination Certificate
1999-09-13
2004-02-03
Philippe, Gims S. (Department: 2613)
Pulse or digital communications
Bandwidth reduction or expansion
Television or motion video signal
C382S266000, C348S620000, C348S625000
Reexamination Certificate
active
06687300
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a motion detection circuit for detecting motion in a video signal and a noise suppression circuit including the motion detection circuit.
2. Description of the Prior Art
A motion detection circuit for detecting motion in a video signal from a difference signal between the video signal and one-frame delayed video signal is known and a noise suppression circuit is also known. The noise suppression circuit includes the motion detection circuit, a circulation signal generation circuit for generating a circulation signal in accordance with the difference signal and the motion detection signal, and a subtractor for subtracting the circular signal from the video signal to output a noise suppressed video signal. Such a prior art motion detection circuit and a prior art noise suppression circuit are disclosed in Japanese patent application provisional publication No. 9-81754.
FIG. 9
is a block diagram of such a prior art noise suppression circuit including a prior art motion detection circuit.
The prior art motion detection circuit includes a frame memory
610
for generating a delayed video signal from the noise suppressed video signal Vo, a subtractor
602
for generating a difference signal (interframe difference signal) between the video signal Vi and the delayed video signal, a motion detection circuit
603
for detecting a motion from the video signal Vi and the delayed video signal to output a motion detection signal.
The noise suppression circuit further includes a subtractor
607
for generating the difference signal between the video signal Vi and the delayed video signal, a circulation amount determining circuit
608
for generating a circulation signal from the difference signal in accordance with the motion detection signal, and a subtractor
609
for obtaining a difference between the video signal Vi and the circulation signal to output a noise suppressed video signal Vo.
SUMMARY OF THE INVENTION
The aim of the present invention is to provide a superior motion detection circuit and a superior noise suppression circuit.
According to the present invention there is provided a first motion detection circuit including: a delay for generating a delayed video signal from a video signal, the delayed video signal being delayed by one frame from the video signal; a difference signal generation circuit for generating an interframe difference signal between the video signal and the delayed video signal; an edge detection signal generation circuit for detecting an edge from the video signal and the delayed video signal and generating an edge detection signal; and a motion judging circuit for judging a motion in the video signal at a target pixel from the interframe difference signal in accordance with the edge detection signal to output a motion detection signal.
The first motion detection circuit may further include a low-pass filter for low-pass-filtering the interframe difference signal and a selector for supplying either of an output of the low-pass filter or the interframe difference signal to the motion judging circuit as the interframe difference signal in accordance with a selection signal.
In a second motion detection circuit, the motion judging circuit mentioned in the first motion detection circuit may include a polarity deviation detecting circuit for detecting polarities of the interframe difference signal at each pixel of the video signal, detecting agreement of the polarities of all pixels at any of an upper left area of the target pixel, an upper right area of the target pixel, a lower left area of the target pixel, and a lower right area of the target pixel, and judging the motion in the interframe difference signal at the target pixel to be moving in the presence of the agreement, each of the upper left area, the upper right area, the lower left area, and the lower right area including M×N pixels of the video signal, M and N being natural numbers. In this case, the upper left area, the upper right area, the lower left area, and the lower right area include the target pixel or outside and adjacent to the target pixel.
In a third motion detection circuit, the motion judging circuit mentioned in the second motion detection circuit may further include: a peripheral pixel comparing circuit for detecting polarities of the interframe difference signal at each pixel at a predetermined area around the target pixel, detecting the number of positive polarities of the interframe difference signal at the predetermined area and the number of negative polarities of the interframe difference signal at the predetermined area, obtaining a difference in the number between the positive and negative polarities and an absolute value of the difference, comparing the absolute value with first and second different references to output a comparing result indicative of either of moving, intermediate movement, or stopping, wherein the polarity deviation detection circuit changes the comparing result from the intermediate movement to stopping in accordance with the agreement to output the motion detection signal when the comparing result is indicative of the intermediate motion and outputs the motion detection signal with the comparing result unchanged when the comparing result is indicative of the moving and stopping.
In the third motion detection circuit, the motion judging circuit may further include another polarity deviation detecting circuit for detecting polarities of the differential signal at each pixel of the video signal, detecting agreement of the polarities of all pixels at any of the upper left area, the upper right area, the lower left area, and the lower right area every the target pixel, and judging the motion in the interframe difference signal at the target pixel to be moving in the presence of the agreement and a switch for either supplying an output of the polarity deviation detecting circuit or another polarity deviation detecting circuit in accordance with a switch control signal to output the motion detection signal.
In a fourth motion detection circuit, the motion judging circuit mentioned in the second motion detection circuit may further include: a peripheral pixel comparing circuit for detecting polarities of the interframe difference signal at each pixel at a predetermined area around the target pixel, detecting the number of positive polarities of the interframe difference signal at the predetermined area and the number of negative polarities of the interframe difference signal at each pixel at the predetermined area, obtaining a difference in the number between the positive and negative polarities and an absolute value of the difference, comparing the absolute value with J−1 references to output a J-valued first result, the polarity deviation detection circuit changes the first result to stopping in accordance with the agreement when the absolute value is judged to be an intermediate value among J values to output a second result, and the motion judging circuit further comprises a majority detection circuit including a memory for detecting a majority of the Q second results of the polarity deviation detection circuit at Q pixels around the target pixels and judging the motion in the interframe difference signal at the target pixel in accordance with the detected majority with deviation to a side of stopping to output the motion detection signal.
In a fifth motion detection circuit, the edge detection signal generation circuit mentioned in the first motion detection circuit may include a first edge detection circuit for detecting an edge from the video signal, a second edge detection circuit for detecting an edge from the delayed video signal, and a third edge detection circuit for detecting an edge from the video signal and the delayed video signal, a switch responsive to a selection signal for outputting either of an output of the first, second, or third edge detection circuit as the edge detection signal.
In the fifth motion detection circuit, the edge detection signal g
Fujita Yukio
Kasahara Misa
Kato Noriyoshi
Matsushita Electic Industrial Co., Inc.
Philippe Gims S.
Woo Louis
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