Image analysis – Image enhancement or restoration – Image filter
Patent
1996-03-15
1999-09-28
Lee, Thomas D.
Image analysis
Image enhancement or restoration
Image filter
382266, 382270, 358448, 358466, G06K 940, H04N 140
Patent
active
059601213
ABSTRACT:
Image data scanned by a scanner in a digital scanner, a digital copying machine or a facsimile machine is processed to detect an edge despite low contrast. A first MTF compensation portion enhances an edge area of the image data. An edge detector detects edge data from the first PTF co pensation portion. A second MTF compensation portion enhances the edge data from the equalization filter. An equalization filter calculates a binary cut-off level for input data. Another edge detector functions as a device for detecting edge data from the equalization filter by a Laplacian filter. Clamp circuits clamp a highest limit and a lowest limit of the binary cut-off level of signals from the equalization filter. A first comparator compares an output signal from the MTF compensation portion to an output signal from one of the clamp circuits. A second comparator compares an output signal from the first equalization filter to an output signal from the other clamp circuit. A first selector selects data from the first comparator or data from the second comparator in response to an edge signal from the edge area detector. A third comparator compares a output signal from another edge detector to a parameter select signal. A second selector selects either data from the first selector or a null signal in response to an output signal of the second comparator. A binary filter eliminates isolated specks in the background.
REFERENCES:
patent: 4876610 (1989-10-01), Ohsawa et al.
patent: 5452107 (1995-09-01), Koike
Lee Thomas D.
Ricoh & Company, Ltd.
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