colfilter.m

matlab做的图像检索源码

function Y = colfilter(X, h)
% function Y = colfilter(X, h)
% Filter the columns of image X using filter vector h, without decimation.
% If length(h) is odd, each output sample is aligned with each input sample
% and Y is the same size as X.
% If length(h) is even, each output sample is aligned with the mid point
% of each pair of input samples, and size(Y) = size(X) + [1 0]; 
%
% Cian Shaffrey, Nick Kingsbury
% Cambridge University, August 2000

[r,c] = size(X);
m = length(h);
m2 = fix(m/2);

if any(X(:))
   % Symmetrically extend with repeat of end samples.
   xe = reflect([(1-m2):(r+m2)], 0.5, r+0.5); % Use 'reflect' so r < m2 works OK.
   
   % Perform filtering on the columns of the extended matrix X(xe,:), keeping
   % only the 'valid' output samples, so Y is the same size as X if m is odd. 
   Y = conv2(X(xe,:),h(:),'valid'); 
else
   Y = zeros(r+1-rem(m,2),c);
end
return;