MATLAB >> code for Gaussian Pyramid in matlab file

by Simo » Wed, 06 Apr 2005 03:00:30 GMT

there is a code for Gaussian Pyramid in matlab file exchange. I want
to twst it but i do not understand what is input parameter. it is not
describe. Coulsd somebody tell be about Wt.
thanks

% Expand an image as per the Gaussian Pyramid.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
function IResult = expand(I, Wt)

[h w]= size(I);

hnew = ceil(h * 2);
wnew = ceil(w * 2);

%% Pad the boundaries.

I = [ I(1,:) ; I ; I(h,:) ]; % Pad the top and bottom rows.
I = [ I(:,1) I I(:,w) ]; % Pad the left and right columns.

I = double(I);

IResult = zeros(hnew, wnew); % Initialize the array in the beginning
..
for i = 0 : hnew - 1
% fprintf('\n %d', i);
for j = 0 : wnew - 1
A = [];
for m = -2 : 2
for n = -2 : 2
pixeli = (i - m)/2 ;
pixelj = (j - n)/2 ;
if ( (floor(pixeli) == pixeli) & (floor(pixelj) ==
pixelj ) & pixeli >= 0 & pixelj >= 0 )
pixeli = pixeli + 1;
pixelj = pixelj + 1;
tmpval = I (pixeli, pixelj) * Wt(m + 3) * Wt(n +
3);
A = [A, tmpval] ;
end
end
end
IResult(i + 1, j + 1)= 4 * sum(A);
% Bad array arithmetic - Matlab array indices start at 1.
% and the algorithm assumes 0. Hence got to do it.
end
end

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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Expand an image as per the Gaussian Pyramid.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
function IResult = expand(I, Wt)

[h w]= size(I);

hnew = ceil(h * 2);
wnew = ceil(w * 2);

%% Pad the boundaries.

I = [ I(1,:) ;  I ;  I(h,:) ];  % Pad the top and bottom rows.
I = [ I(:,1)    I    I(:,w) ];  % Pad the left and right columns.

I = double(I);

IResult = zeros(hnew, wnew); % Initialize the array in the beginning ..
for i = 0 : hnew - 1
%   fprintf('\n %d', i);
     for j = 0 : wnew - 1
         A = [];
         for m = -2 : 2
             for n = -2 : 2
                 pixeli = (i - m)/2 ;
                 pixelj = (j - n)/2 ;
                 if ( \
              (floor(pixeli) == pixeli) & (floor(pixelj) == pixelj )
  			       & pixeli >= 0 & pixelj >= 0 )
                     pixeli = pixeli + 1;
                     pixelj = pixelj + 1;
                     tmpval =  I (pixeli, pixelj) * Wt(m + 3)
						* Wt(n + 3);
                     A =  [A,  tmpval] ;
                 end
             end
         end
         IResult(i + 1, j + 1)= 4 * sum(A);
         % Bad array arithmetic - Matlab array indices start at 1.
         % and the algorithm assumes 0. Hence got to do it.
     end
end

-- 
  Karthik.
  Humans please 'removeme_' for my real email.

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-- 
  Karthik.
  Humans please 'removeme_' for my real email.

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