Title:
IMAGE IMPROVING METHOD USING QUANTIZED AVERAGE SEPARATION HISTOGRAM EQUALIZATION, AND CIRCUIT THEREFOR
Document Type and Number:
Japanese Patent JP2858742
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To improve contrast and to maintain the overall brightness of an applied picture by executing histogram equalizing processing in each sub-picture, based on an accumulated density function value stored in each sub-picture.
SOLUTION: A 1st quantizer 102 quantizes an input picture signal and a frame histogram calculator 104 calculates the average level of the quantized signal in each face unit. A frame average calculator 106 calculates the average level of the input picture signal and a 2nd quantizer 108 quantizes the average level and outputs the quantized average level. A divider 110 and 1st and 2nd CDF calculators 112, 114 are used for dividing gray level distribution into the prescribed number of quantized sub-pictures in accordance with the quantized average level and calculating an accumulated density function value. Each of interpolators 118, 122 outputs an accumulated density function value interpolated in each sub-picture. A selector 128 outputs any one of samples mapped to a gray level in each sub-picture in accordance with a selected control signal from a comparator 126.
Inventors:
KIN EITAKU
Application Number:
JP5187297A
Publication Date:
February 17, 1999
Filing Date:
March 06, 1997
Export Citation:
Assignee:
SANSEI DENSHI KK
International Classes:
G06T5/00; G06T5/20; H04N5/57; G06T5/40; H04N7/24; (IPC1-7): G06T5/00; H04N5/57
Domestic Patent References:
| JP9331486A |
Attorney, Agent or Firm:
Tadahiko Ito (1 outside)