Matsushita Electric Industrial Co., Ltd.

Misa Kasahara

Yukio Fujita

Noriyoshi Kato

Makoto Sube

Kenji Tabei

Toshiyuki Sano

Keiji Toyoda

Jun Ebisawa

A pixel data outputting circuit outputs center and peripheral pixel data from a video signal. A difference calculation circuit calculates differences of the peripheral pixel data from the center pixel data. A correlation pixel data detecting circuit detects a portion of the peripheral data showing high correlation according to the differences and a threshold value. A counter counts the portion of the peripheral data showing high correlation. A selecting circuit responsive to the correlation pixel data detecting circuit selectively outputs a portion of the differences of the portion of the peripheral data. A summing circuit obtains a sum of the portion of the differences in accordance with the counting result. A dividing coefficient generating circuit generates a dividing coefficient of 2 according to the counting result. A dividing circuit divides the sum with the dividing coefficient. An adding circuit adds the dividing result to the center pixel data to generate an output video signal. A weighting circuit weights each of the portion of differences according to the predetermined priority, wherein the summing circuit obtains the sum from the weighted differences. The corresponding method and the corresponding recording medium storing the method are also disclosed.

Video signal noise reduction apparatus, a method of reducing a noise in a video signal, and a recording medium storing a program of the method

A video signal including illumination flicker component is integrated at each of unit areas (horizontal lines) in a frame (field) of the video signal. The integrated level at each of the unit areas at the frame and the integrated level at the corresponding unit area of an adjacent frame are averaged. Dividing is effected between results of the averaging and integrating every unit area. It is judged whether flicker exists in the video signal by frequency-analyzing results of the dividing result at the unit areas. The unit area may be plural adjacent lines where flickering are negligible. The averaging circuit may be circulation type of or FIR filter. Threshold level for judging the flicker is changed according to a shutter speed control signal. Flicker compensation may be executed by controlling shutter speed or the AGC according to flicker judging result. A still condition at a block in a frame may be detected from the integration result at plural frames. When the block is judged to be still, the flicker is judged. An ac line frequency detection is also disclosed to detect the frequency of the ac line from a video signal generated under illumination including flicker. An imaging circuit may be provided to generate the video signal therein.

ILLUMINATION FLICKER DETECTION APPARATUS, AN ILLUMINATION FLICKER COMPENSATION APPARATUS, AND AN AC LINE FREQUENCY DETECTION APPARATUS, METHODS OF DETECTING ILLUMINATION FLICKER, COMPENSATING ILLUMINATION FLICKER, AND MEASURING AC LINE FREQUENCY

In a motion detection circuit, a difference signal between the video and one-frame delayed video signals is generated Edge signals are generated from the video and delayed video signals. Motion in a target pixel is judged from the interframe difference signal according to the edge signals. A motion judging circuit further includes an LPF and a selector for supplying an output of the LPF or the difference signal. The motion judging circuit includes a polarity deviation detecting circuit for judging the motion as moving in the presence of agreement of the polarities of all pixels at any of peripheral areas around the target pixel. The size of the peripheral areas are controlled. The motion judging circuit may further includes a peripheral pixel comparing circuit (may be bypassed) for detecting motion at the pixel by checking polarities of the difference signal at an area around the target pixel and a majority detection circuit (may be bypassed) for detecting a majority of the results of the polarity deviation detection circuit to judge the motion with deviation to a side of stopping. The polarity deviation circuit may compensate the result of the peripheral pixel comparing circuit. Width of the edge signals are controlled. A noise suppression apparatus including a motion detection circuit mentioned above is also disclosed.

Motion detection circuit and a noise suppressing circuit including the same

In a motion detection circuit, a difference signal between the video and one-frame delayed video signals is generated. An Edge signal is generated from the video and delayed video signals. Motion in a target pixel is judged from the interframe difference signal according to the edge signal. A motion judging circuit further includes an LPF and a selector for supplying an output of the LPF or the difference signal. The motion judging circuit may further includes: a peripheral pixel comparing circuit (may be bypassed) for detecting motion at the pixel by checking polarities of the difference signal at an area around the target pixel; a majority detection circuit (may be bypassed) for detecting a majority of the results of the polarity deviation detection circuit to judge the motion with deviation to a side of stopping; and a polarity deviation detecting circuit for judging the motion as moving in the presence of agreement of the polarities of all pixels at any of peripheral areas around the target pixel. The size of the peripheral areas are controlled. The polarity deviation circuit may compensate the result of the majority detection circuit. Width of the edge signal is controlled. A noise suppression apparatus including a motion detection circuit mentioned above is also disclosed.

An interframe difference signal is generated from the video signal and its one-frame delayed video signal. A filter removes a carrier color signal from the interframe difference signal to output the interframe difference luminance signal. A first motion judging circuit judges a motion in the video signal at a target pixel from the interframe difference luminance signal to output a first motion judging result in accordance with a first edge detection signal. A second motion judging circuit judges a motion in the video signal at the target pixel from a luminance signal and the carrier signal in the interframe difference signal to output a second motion judging result in accordance with a second edge detection circuit. The first and second motion judging results are combined. A majority determining circuit determines majority of the combined result from adjacent Q pixels in accordance with a third edge detection signal. A circular signal generation circuit generates a coefficient K according to the result of the majority determining circuit. The interframe difference signal is multiplied with k to generate a circulation signal. A subtractor subtracts the circulation signal from the video signal to generate an output video signal of which noise is suppressed.

Motion detection circuit and a noise suppression circuit including the same

A video signal processing circuit for processing a video signal including a noise is disclosed which comprises: an edge enhancement signal generation circuit for generating an edge enhancement signal from the video signal; a noise reduction circuit for reducing a level of the noise to generate a noise reduced video signal; and an adder for adding the edge enhancement signal to the noise reduction video signal to output a processed video signal. The apparatus may further comprise an input terminal for receiving the video signal, wherein the edge enhancement signal generation circuit and the noise reduction circuit coupled to the input terminal are in parallel. This apparatus may further comprise a first delay circuit for delaying the video signal by one horizontal line period to generate a 1-H delayed video signal and a second delay circuit responsive to the video signal for generating a 2-H delayed video signal, wherein the edge enhancement signal generation circuit generates the edge enhanced signal from the video signal, the 1-H delayed video signal, and the 2-H delayed video signal and the noise reduction circuit generates the noise reduced video signal from the video signal, the 1-H delayed video signal, and the 2-H-delayed video signal.

Video signal processing apparatus with noise reduction and edge

An image contour enhancing apparatus capable of minimizing excessive enhancement of the image contour in an image area where both a horizontal contour enhancing signal and a vertical contour enhancing signal are generated in overlapping relation. In the image contour enhancing apparatus, an image contour enhancing signal produced by deriving a horizontal contour enhancing signal from a video input signal by a high-pass filter, deriving a vertical contour enhancing signal from the video input signal by another high-pass filter and by adding these contour enhancing signals is added by an adder to the video input signal to improve the sharpness of the image contour, and circuits are provided for making variable the signal level of the image contour enhancing signal in the image area where both the horizontal and vertical contour enhancing signals are generated in overlapping relation.

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Yokohama, Japan

Misa Kasahara