Facsimile and static presentation processing – Facsimile – Recording apparatus
Patent
1991-11-26
1993-06-29
Chin, Tommy
Facsimile and static presentation processing
Facsimile
Recording apparatus
358330, 358327, 358328, 358167, 358 36, 360 91, 360 331, H04N 980, H04N 5213
Patent
active
052239470
ABSTRACT:
A video noise reduction system is incorporated with a video recorder for the elimination of high frequency noise from only the gray level portions of a video signal being retrieved from magnetic tape. The frequency modulated video signal retrieved from the tape is directed through a demodulator into a voltage dependent low pass filter having a cutoff frequency which is normally sufficiently high to pass the unmodulated video signal from the demodulator without attenuation. The frequency modulated video signal is also fed into a band elimination filter having an attenuation band corresponding to the gray level of brightness. The output from the band elimination filter is detected, and a variable voltage is impressed to the low pass filter for lowering its cutoff frequency whenever the frequency modulated video signal has gray frequencies. Alternate embodiments are disclosed in which the cutoff frequency is lowered to different preselected values for different levels of brightness.
REFERENCES:
patent: 4825289 (1989-04-01), Ohta
patent: 5060078 (1991-10-01), Mitsuhashi
patent: 5067026 (1991-11-01), Kaneko
patent: 5079633 (1992-01-01), Hagino et al.
Chin Tommy
Teac Corporation
Truong Khoi
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