求MATLAB中filter2函数的源代码。

求MATLAB中二维滤波函数filter2的编码程序。。。

急急~

若需要函数体，我可以传文件给你。下面是其代码

function y = filter2(b,x,shape)
%FILTER2 Two-dimensional digital filter.
% Y = FILTER2(B,X) filters the data in X with the 2-D FIR
% filter in the matrix B. The result, Y, is computed
% using 2-D correlation and is the same size as X.
%
% Y = FILTER2(B,X,'shape') returns Y computed via 2-D
% correlation with size specified by 'shape':
% 'same' - (default) returns the central part of the
% correlation that is the same size as X.
% 'valid' - returns only those parts of the correlation
% that are computed without the zero-padded
% edges, size(Y) < size(X).
% 'full' - returns the full 2-D correlation,
% size(Y) > size(X).
%
% FILTER2 uses CONV2 to do most of the work. 2-D correlation
% is related to 2-D convolution by a 180 degree rotation of the
% filter matrix.
%
% Class support for inputs B,X:
% float: double, single
%
% See also FILTER, CONV2.

% Copyright 1984-2004 The MathWorks, Inc.
% $Revision: 5.13.4.2 $ $Date: 2004/03/09 16:16:19 $

error(nargchk(2,3,nargin));
if nargin<3, shape = 'same'; end

if (~isa(b,'float')), b = double(b); end
if (~isa(x,'float')), x = double(x); end

code = [shape,' ']; code = code(1);
if isempty(find(code=='svf'))
error('MATLAB:filter2:InvalidParam', 'Unknown shape parameter.');
end

[mx,nx] = size(x);
stencil = rot90(b,2);
[ms,ns] = size(stencil);

% 1-D stencil?
if (ms == 1)
y = conv2(1,stencil,x,shape);
elseif (ns == 1)
y = conv2(stencil,1,x,shape);
else
if (ms*ns > mx*nx)
% The filter is bigger than the input. This is a nontypical
% case, and it may be counterproductive to check the
% separability of the stencil.
y = conv2(x,stencil,shape);
else
separable = false;
if all(isfinite(stencil(:)))
% Check rank (separability) of stencil
[u,s,v] = svd(stencil);
s = diag(s);
tol = length(stencil) * eps(max(s));
rank = sum(s > tol);
separable = (rank ==1);
end
if separable
% Separable stencil
hcol = u(:,1) * sqrt(s(1));
hrow = conj(v(:,1)) * sqrt(s(1));
if (all(all((round(stencil) == stencil))) & all(all((round(x) == x))))
% Output should be integer
y = round(conv2(hcol, hrow, x, shape));
else
y = conv2(hcol, hrow, x, shape);
end
else
% Nonseparable stencil
y = conv2(x,stencil,shape);
end
end
end

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