Method and device for local contrast enhancement of video signal

Details Method and device for local contrast enhancement of video signal Method and device for local contrast enhancement of video signal

1996-12-05

1999-07-27

Mancuso, Joseph

Image analysis

Image enhancement or restoration

Intensity, brightness, contrast, or shading correction

358447, 358463, 348241, 348607, 348678, G06K 940

Patent

active

059304022

ABSTRACT:
A method and a device for adaptively performing local contrast enhancement by weighing a video signal according to the magnitude of the local contrast of the video signal and by adding the weighted signal to the original video, thereby being capable of outputting the original signal intact regardless of the size of the local contrast. The device for enhancing a local contrast in a video signal processor has an M.times.N window processor for generating an M.times.N window signal calculated from an input video signal; an M.times.N lowpass filter for lowpass-filtering an M.times.N window signal generated in the M.times.N window processor; a first adder for calculating the difference between the output of the M.times.N lowpass filter and a central output of the M.times.N window processor, where the difference represents contrast which is visually perceptible to a human; an absolute circuit for converting the output of the first adder into its absolute value, thereby setting the high contrast area and the low contrast area; a weigher for outputting a weight value depending on the output of the absolute circuit; a multiplier for multiplying the output of the first adder by the output of the weigher; and a second adder for adding the central output of the M.times.N window processor to the output of the multiplier.

REFERENCES:
patent: 4825297 (1989-04-01), Fuchsberger et al.
patent: 5317427 (1994-05-01), Ichikawa

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