不难看出，导向图滤波的主要步骤就两个，计算每个公式中的各种平均值，然后根据平均值计算出

计算平均值可以通过积分图高效的实现，matlab代码如下：

矩形滤波代码（计算窗口平均值）

functionimDst=boxfilter(imSrc,r)%BOXFILTERO(1)timeboxfilteringusingcumulativesum
%
%-DefinitionimDst(x,y)=sum(sum(imSrc(x-r:x r,y-r:y r)));
%-Runningtimeindependentofr;
%-Equivalenttothefunction:colfilt(imSrc,[2*r 1,2*r 1],'sliding',@sum);
%-Butmuchfaster.[hei,wid]=size(imSrc);
imDst=zeros(size(imSrc));%cumulativesumoverYaxis
imCum=cumsum(imSrc,1);
%differenceoverYaxis
imDst(1:r 1,:)=imCum(1 r:2*r 1,:);
imDst(r 2:hei-r,:)=imCum(2*r 2:hei,:)-imCum(1:hei-2*r-1,:);
imDst(hei-r 1:hei,:)=repmat(imCum(hei,:),[r,1])-imCum(hei-2*r:hei-r-1,:);%cumulativesumoverXaxis
imCum=cumsum(imDst,2);
%differenceoverYaxis
imDst(:,1:r 1)=imCum(:,1 r:2*r 1);
imDst(:,r 2:wid-r)=imCum(:,2*r 2:wid)-imCum(:,1:wid-2*r-1);
imDst(:,wid-r 1:wid)=repmat(imCum(:,wid),[1,r])-imCum(:,wid-2*r:wid-r-1);
end