lpfilter.m

实现对小孔的高斯滤波

function[H,D]=lpfilter(type,M,N,D0,n)
[U,V]=dftuv(M,N);
D=sqrt(U.^2+V.^2);
switch type
    case 'btw'
        if nargin==4
            n=1;
        end
        H=1./(1+(D./D0).^(2*n));
    case 'gaussian'
        H=exp(-(D.^2)./(2*(D0^2)));
    otherwise
        error('Unknown filter type.')
end