How to use H=lpfilter('gaussian',M,N,sigma); filter in frequency domain

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Ali 2015-11-7

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https://ww2.mathworks.cn/matlabcentral/answers/253672-how-to-use-h-lpfilter-gaussian-m-n-sigma-filter-in-frequency-domain

回答： ali ibrahim 2015-12-7

I used the following codes : [M,N]=size(f); H=lpfilter('gaussian',M,N,sig); where f is the image and sig=10. I have downloaded the lpfilter.m but it gives the following error.

Undefined function 'dftuv' for input arguments of type 'double'.

Error in lpfilter (line 10) [U,V] = dftuv(M,N);

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Answer 1

ali ibrahim 2015-12-7

1
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/253672-how-to-use-h-lpfilter-gaussian-m-n-sigma-filter-in-frequency-domain#answer_202436

在 MATLAB Online 中打开

miss function dftuv:

 function [U, V] = dftuv(M, N)
%DFTUV Computes meshgrid frequency matrices.
%   [U, V] = DFTUV(M, N) computes meshgrid frequency matrices U and
%   V.  U and V are useful for computing frequency-domain filter
%   functions that can be used with DFTFILT.  U and V are both
%   M-by-N.

% Set up range of variables. u = 0:(M - 1); v = 0:(N - 1);

% Compute the indices for use in meshgrid. idx = find(u > M/2); u(idx) = u(idx) - M; idy = find(v > N/2); v(idy) = v(idy) - N;

% Compute the meshgrid arrays. [V, U] = meshgrid(v, u);