Histogramequalizationisamethodinimageprocessingofcontrastadjustmentusingtheimage'shistogram.Assumethattheoriginalimagegraylevelrnormalizedinbetween0and1,0≦r≦1.pr(r)istheprobabilitydensityfunctionoftheoriginalimagegraydistribution,thehistogramequalizationprocessingisactuallylooki