Facsimile and static presentation processing – Facsimile – Specific signal processing circuitry
Patent
1990-01-25
1991-11-26
Peng, John K.
Facsimile and static presentation processing
Facsimile
Specific signal processing circuitry
368136, 368105, H04N 712, H04N 718
Patent
active
050687255
ABSTRACT:
In a band compression apparatus, an input signal is separated into high- and low-frequency components H and L by an LPF and an adder. The component H is in-frame-averaged by an in-frame average circuit. The component L is output as a signal S.sub.3 having a large energy via a field delay circuit and a switch circuit. An in-frame difference of the low-frequency component L is obtained by a field delay circuit and an adder. This in-frame differential signal S.sub.2 is added to an in-frame average signal S.sub.1 by an adder. A signal S.sub.4 having a small energy is obtained by this addition. In a band restoration apparatus the signals S.sub.3 and S.sub.4 are separated into signals of two fields by an adder and a switch circuit. A signal S.sub.5 consisting of the components L and H is obtained in one field. A signal S.sub.2 consisting of only the component L is obtained in the other field. The signal S.sub.5 is output via a switch circuit. The signal S.sub.2 is added to the signal S.sub.5 in an immediately preceding field by an adder. A signal S.sub.6 consisting of the components L and H is obtained by this addition. The signal S.sub.6 is output via the switch circuit at a timing delayed by one field with respect to the signal S.sub.5.
REFERENCES:
patent: 4546386 (1985-10-01), Matsumoto et al.
patent: 4924305 (1990-05-01), Nakagawa et al.
patent: 4984077 (1991-01-01), Uchida
Kawai Kiyoyuki
Ogawa Yoshihiko
Yasuki Seijiro
Kabushiki Kaisha Toshiba
Peng John K.
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