Facsimile and static presentation processing – Facsimile – Specific signal processing circuitry
Patent
1990-11-27
1991-12-03
Hix, L. T.
Facsimile and static presentation processing
Facsimile
Specific signal processing circuitry
358227, G03B 1300
Patent
active
050703536
ABSTRACT:
An automatic focusing apparatus comprises a photographic optical system for forming an optical image of an object, an optical system driving circuit for moving the photographic optical system in a direction of its optical axis, a storage circuit for prestoring a plurality of MTF ratios corresponding to a plurality of focusing states of the photographic optical system, an image sensor for detecting the optical image, a spatial frequency component extracting circuit for extracting a plurality of spatial frequency components from image signals output from the image sensor, a calculating circuit for calculating a ratio between spatial frequency components representing different focusing states at every common frequency from the spatial frequency components extracted by the spatial frequency extracting circuit, a defocus detecting circuit for detecting a defocus amount and a focusing direction from the spatial frequency component ratios calculated by the calculating circuit and the MTF ratios stored in the storage circuit, and a driving control circuit for calculating an amount and a direction of movement of the photographic optical system from the detection result from the defocus circuit, and outputting the calculation result to the optical system driving circuit.
REFERENCES:
patent: 4561749 (1985-12-01), Utagawa
patent: 4812636 (1989-03-01), Kusaka et al.
patent: 4990947 (1991-02-01), Komiya et al.
Komiya Yasuhiro
Nagasaki Tatsuo
Gray David M.
Hix L. T,.
Olympus Optical Co,. Ltd.
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