set3q8.m

function splitAndMerge()
    orgImg=imread('figXray.tif');
    md=input('Enter the minimum dimension of block: ');
    segImg=splitmerge(orgImg,md,@predicate);
    subplot(121);imshow(orgImg);title('Original Image');
    subplot(122);imshow(segImg);title('Segmented Image');
end

function g = splitmerge(f,mindim,fun)
    q=2^nextpow2(max(size(f)));
    [row,col]=size(f);
    f=padarray(f,[q-row,q-col],'post');
    z=qtdecomp(f,@split_test,mindim,fun);
    Lmax=full(max(z(:)));
    g=zeros(size(f));
    marker=zeros(size(f));
    for k=1:Lmax
        [vals,r,c]=qtgetblk(f,z,k);
        if ~isempty(vals)
            for i=1:length(r)
                xlow=r(i);
                ylow=c(i);
                xhigh=xlow+k-1;
                yhigh=ylow+k-1;
                region = f(xlow:xhigh,ylow:yhigh);
                flag=fun(region);
                if flag
                    g(xlow:xhigh,ylow:yhigh)=1;
                    marker(xlow,ylow)=1;
                end
            end
        end
    end
    g=bwlabel(imreconstruct(marker,g));
    g=g(1:row,1:col);
end

function flag=predicate(region)
    sd=std2(region);
    m=mean2(region);
    flag=(sd>10) & (m>0) & (m<125);
end

function v=split_test(b,mindim,fun)
    k=size(b,3);
    v(1:k)=false;
    for i=1:k
        quadregion=b(:,:,i);
        if size(quadregion,1)<=mindim
                v(i)=false;
        continue
        end
            flag=fun(quadregion);
        if flag
                v(i)=true;
        end
    end
end