Question

急求中值滤波器的matlab算法代码

Answer 1

I=imread('D:\picture.jpg');
figure;
imshow(I);
K=imnoise(I,'gaussian',0.02);%加噪声
figure;
imshow(K);
g=medfilt2(K);%中值滤波
figure;
imshow(g);

Answer 2

function y = medfilt1(x,n,blksz,DIM)
%MEDFILT1 One dimensional median filter.
% Y = MEDFILT1(X,N) returns the output of the order N, one dimensional
% median filtering of X. Y is the same size as X; for the edge points,
% zeros are assumed to the left and right of X. If X is a matrix,
% then MEDFILT1 operates along the columns of X.
%
% If you do not specify N, MEDFILT1 uses a default of N = 3.
% For N odd, Y(k) is the median of X( k-(N-1)/2 : k+(N-1)/2 ).
% For N even, Y(k) is the median of X( k-N/2 : k+N/2-1 ).
%
% Y = MEDFILT1(X,N,BLKSZ) uses a for-loop to compute BLKSZ ("block size")
% output samples at a time. Use this option with BLKSZ << LENGTH(X) if
% you are low on memory (MEDFILT1 uses a working matrix of size
% N x BLKSZ). By default, BLKSZ == LENGTH(X); this is the fastest
% execution if you have the memory for it.
%
% For matrices and N-D arrays, Y = MEDFILT1(X,N,[],DIM) or
% Y = MEDFILT1(X,N,BLKSZ,DIM) operates along the dimension DIM.
%
% See also MEDIAN, FILTER, SGOLAYFILT, and MEDFILT2 in the Image
% Processing Toolbox.

% Author(s): L. Shure and T. Krauss, 8-3-93
% Copyright 1988-2004 The MathWorks, Inc.
% $Revision: 1.8.4.3 $ $Date: 2007/12/14 15:05:24 $

% Validate number of input arguments
error(nargchk(1,4,nargin,'struct'));
if nargin < 2, n = []; end
if nargin < 3, blksz = []; end
if nargin < 4, DIM = []; end

% Check if the input arguments are valid
if isempty(n)
n = 3;
end

if ~isempty(DIM) && DIM > ndims(x)
error(generatemsgid('InvalidDimensions'),'Dimension specified exceeds the dimensions of X.')
end

% Reshape x into the right dimension.
if isempty(DIM)
% Work along the first non-singleton dimension
[x, nshifts] = shiftdim(x);
else
% Put DIM in the first (row) dimension (this matches the order
% that the built-in filter function uses)
perm = [DIM,1:DIM-1,DIM+1:ndims(x)];
x = permute(x,perm);
end

% Verify that the block size is valid.
siz = size(x);
if isempty(blksz),
blksz = siz(1); % siz(1) is the number of rows of x (default)
else
blksz = blksz(:);
end

% Initialize y with the correct dimension
y = zeros(siz);

% Call medfilt1D (vector)
for i = 1:prod(siz(2:end)),
y(:,i) = medfilt1D(x(:,i),n,blksz);
end

% Convert y to the original shape of x
if isempty(DIM)
y = shiftdim(y, -nshifts);
else
y = ipermute(y,perm);
end

%-------------------------------------------------------------------
% Local Function
%-------------------------------------------------------------------
function y = medfilt1D(x,n,blksz)
%MEDFILT1D One dimensional median filter.
%
% Inputs:
% x - vector
% n - order of the filter
% blksz - block size

nx = length(x);
if rem(n,2)~=1 % n even
m = n/2;
else
m = (n-1)/2;
end
X = [zeros(m,1); x; zeros(m,1)];
y = zeros(nx,1);

% Work in chunks to save memory
indr = (0:n-1)';
indc = 1:nx;
for i=1:blksz:nx
ind = indc(ones(1,n),i:min(i+blksz-1,nx)) + ...
indr(:,ones(1,min(i+blksz-1,nx)-i+1));
xx = reshape(X(ind),n,min(i+blksz-1,nx)-i+1);
y(i:min(i+blksz-1,nx)) = median(xx,1);
end