Matlab text skelecton extraction

gistfile1.matlab

function im = thinning(img)
% 	THINNING   Short description
% 		[IM] = THINNING(IMG)
	im = img;
	
	repeat = 1;
	is_even = 0;
	
	while repeat
		repeat = 0;
		boundaries = im * 0;
		is_even = 1-is_even;
        
		
		for i = 1:size(im,1)
		    for j = 1:size(im,2)
				if im(i,j) == 1
					if is_even
						if fst_condition(im, i, j)
							boundaries(i,j) = 1;
							repeat = repeat + 1;
						end
					else
						if snd_condition(im, i, j)
							boundaries(i,j) = 1;
							repeat = repeat + 1;
						end
					end
				end
			end
		end
		im = im - boundaries;
	end
end %  function


function b = shared_condition(im, i, j)
	P = neighbors(im, i, j);
	B = size(find(P>0),2);
	b = 2 <= B && B <= 6;
	b = b && size(findstr([P P(1)], [0 1]),2) == 1;
end %  function

function b = fst_condition(im, i, j)
	b = shared_condition(im, i, j);
	
	P = [ -1 neighbors(im, i, j)];
	b = b && P(2)*P(4)*P(6) == 0;
	b = b && P(4)*P(6)*P(8) == 0;
end % function

function b = snd_condition(im, i, j)
	b = shared_condition(im, i, j);
	
	P = [ -1 neighbors(im, i, j)];
	b = b && P(2)*P(4)*P(8) == 0;
	b = b && P(2)*P(6)*P(8) == 0;
end % function

function nei = neighbors(im, i, j)
	P = [];
	for k = -1:1
		for l = -1:1
			if k ~= 0 || l ~= 0
				try 
					P = [P im(i+l, j+k)];	
				catch 
					P = [P 0];	
				end
			end
		end
	end
	nei = [ P(4) P(6:8) P(5) P(3) P(2) P(1) ];
end %  function