Reply by bakoguz ●December 7, 20012001-12-07
I have a problem of for loops.
I saw the messages about them but it did not help me.
I want to filter my matrix(actually an image) by a filter
and I want to convolve(2D) my filter with my image. If I use
for loops, I need two of them, but the execution is too slow.

Can you suggest something about it ?

Thank you...

burak Example Problem :

% 3x3 mean filter
mask = [ 1/9 1/9 1/9 ; 1/9 1/9 1/9 ; 1/9 1/9 1/9] ;

[row_mask, col_mask] = size(mask) ;

[row_im , col_im , rgb_ ] = size(image) ;

image = im2double(image,'indexed');

result_image = image ;

for k = 1 : (row_im + 1 - row_mask),
for m = 1 : (col_im + 1 - col_mask),
part_of_im=image(k:row_mask+k-1,m:col_mask+m-1);
temp_matrix = times(part_of_im , mask) ;
sum_temp = round( sum(sum(temp_matrix)) ) ;
temp_index_row = k-1 +(row_mask+1)/2 ;
temp_index_col = m-1 +(col_mask+1)/2 ;
result_image(temp_index_row , temp_index_col) = sum_temp ;

end;
end;