adaptive local filter

meanfilteredimage = filter2( ones([convwindowsize, convwindowsize]), noiseimage) / prod([convwindowsize, convwindowsize]); localVar = filter2( ones([convwindowsize,convwindowsize]), noiseimage.^2) / prod([convwindowsize, convwindowsize]) - meanfilteredimage.^2; noiseintensity = mean2(localVar); diff = noiseimage - meanfilteredimage; numerator = localVar - noiseintensity; numerator = max(0, numerator); denominator = max(localVar, noiseintensity); fractionalvalue = diff ./ denominator; Adaptivenoisefilter = meanfilteredimage + fractionalvalue .* numerator; plz explain the concept of adaptive local filter here