MediaM = [25, 25, 25, 25, 25;25,128,35,35,25;25,45,35,128,25;25,25,35,25,25]
[n,m]=size(M)
for i=2:n-1
for j=2:m-1
V = M(i-1:i+1,j-1)
V=[V,M(i-1:i+1,j)]
V=[V,M(i-1:i+1,j+1)]sort(V)M(i,j)=V(4)
end
end