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Title:
ADAPTIVE PICTURE EMPHASIS CIRCUIT
Document Type and Number:
Japanese Patent JPH04321379
Kind Code:
A
Abstract:

PURPOSE: To sharpen an input picture by deciding an optimum characteristic of a weighting circuit in response to the local characteristic of the input picture.

CONSTITUTION: A low frequency spatial filter 2 obtains an average local intensity signal with respect to an input picture signal and subtracts the signal from the input picture signal to obtain a high frequency picture signal. A detail signal spatial density calculation circuit 4 is used to select a picture element to be amplified from the high frequency picture signal to obtain a detailed signal spatial density. Moreover, a 1st conversion circuit 5 is used to obtain an amplification factor with respect to each picture element signal and the high frequency picture signal is amplified by using a multiplier 6 based on the amplification factor. On the other hand, the amplitude difference of the output of the low frequency spatial filter 2 is reduced by using a 2nd conversion circuit 7 to amplify the component with a small amplitude and to attenuate the component with a large amplitude. Finally, an adder 8 adds the amplified high frequency picture signal and the average local intensity signal whose amplitude difference is reduced to obtain a picture without increased dynamic range from an output terminal 9.


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Inventors:
KURODA ICHIRO
Application Number:
JP1991000000531
Publication Date:
November 11, 1992
Filing Date:
January 08, 1991
Export Citation:
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Assignee:
NEC CORP
International Classes:
H04N5/208; G06T5/20; (IPC1-7): H04N5/208; G06F15/68



 
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