function dilated_image = dilate2( source_image, neighborhood );
% DILATE2 dilate a greyscale image.
%   dilated_image = dilate2( source_image, neighborhood );
% dilates the image to make white objects larger, black cracks smaller.
% (The MatLab function "dilate.m"
% does the same thing, but only accepts binary black-and-white image).
% Assumes source_image is a array of 0 = black, max(source_image)=white pixels;
% Assumes neighborhood is a array of
% 1 = neighbor pixels, 0 = non-neighbor pixels.
% See also ERODE2, OPEN2, CLOSE2, DILATE.

% Change log:
% 1999-05-06:DAV: merged Scott Acton's bug fix.
% 1998-03-26:DAV: updated to grayscale version.
% 1998-02-04:DAV: David Cary wrote binary version

elements = nnz(neighborhood);
% Rotate halfway around
% to make "dilate2" consistent with MatLab's "dilate" command.
% This obviously makes no difference with
% symmetrical structuring elements such as circle(11),
% but if I forget to rotate, then
% "open2" and "close2" don't work right
% for non-symmetrical neighborhoods,
% or for even-sized neighborhoods such as circle(10),
source_rotate = rot90(source_image,2);
dilated_rotate = ordfilt2(source_rotate, elements, neighborhood);
dilated_image = rot90(dilated_rotate,2);

% the following version gives correct results, but according to profile
% it is exactly the same speed as the above.
%if(1),
%[y,x] = size(neighborhood);
%rotated_neighborhood = rot90(neighborhood,2);
%if( 0 == mod( x, 2 ) ),
%    % even widths cause unwanted shift of edges, so make it odd:
%    rotated_neighborhood(y,x+1) = 0;
%end
%if( 0 == mod( x, 2 ) ),
%    % even heights cause unwanted shift of edges, so make it odd:
%    rotated_neighborhood(y+1,x) = 0;
%end
%dilated_image = ordfilt2(source_image, elements, rotated_neighborhood);
%end;

% end dilate2.m