function cc = chain_code(matrix, i, j)
%matrix: array
%i, j: initial pixel

[M,N] = size(matrix);

d_i = [0 -1 -1 -1 0 1 1 1];
d_j = [1 1 0 -1 -1 -1 0 1];

firstVal = matrix(i, j);
k = 0;
w = i;  y = j; %Current pixel coordinates
index = 4;

while ((w ~= i) || (y ~= j))
    proper_neighbor = false;
    d = -1;

    for ii = index+1:index+7 %Pixel neighbors
        jj = mod(ii, 8);
        if ((d_i(jj + 1) + w) <= M) && ((d_j(jj + 1) + y) <= N) && (d_i(jj + 1) + w > 0) && ((d_j(jj + 1) + y) > 0)
            if (matrix(d_i(jj + 1) + w, d_j(jj + 1) + y) == firstVal)
                d = jj;
				proper_neighbor = true;
                break;
            end;
        end;
    end;

    if proper_neighbor
        if k < 200
            k = k+1;
            c(k) = d;
            w = w + d_i(d+1); y = y + d_j(d+1);
            index = mod(d+4, 8);
        end;
        else break;
    end;

	if k >= 200
	    break;
    end;
end;

cc = c;