频域低通滤波器matlab

在MATLAB中，可以使用以下代码生成频域低通滤波器：

function H = lpfilter(type, M, N, D0, n)
    if nargin == 4
        n = 1;
    end
    
    % 计算频率域中心
    u = 0:(M-1);
    v = 0:(N-1);
    idx = find(u > M/2);
    u(idx) = u(idx) - M;
    idy = find(v > N/2);
    v(idy) = v(idy) - N;
    \[V, U\] = meshgrid(v, u);
    
    % 计算频率域距离
    D = sqrt(U.^2 + V.^2);
    
    % 根据滤波器类型生成传递函数
    switch type
        case 'ideal'
            H = double(D <= D0);
        case 'butterworth'
            H = 1 ./ (1 + (D ./ D0).^(2*n));
        case 'gaussian'
            H = exp(-(D.^2) / (2*(D0^2)));
        otherwise
            error('Invalid filter type');
    end
end

其中，`type`表示滤波器类型，可以是'ideal'、'butterworth'或'gaussian'，`M`和`N`表示图像的大小，`D0`表示截止频率，`n`表示Butterworth滤波器的阶数。函数返回的`H`即为频域低通滤波器的传递函数。
#### 引用[.reference_title]
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