function [p,z] = direction(image,blocksize,noShow)
%	DIRECTION cacluates the local flow orientation in each local window
%  with size (blocksize x blocksize)
%  direction(grayScaleFingerprintImage,blocksize,graphicalShowDisableFlag)
%  return p ROI bound
%  return z ROI area
%Honors Project 2001~2002
%wuzhili 99050056
%comp sci HKBU
%last update 19/April/2002

%image=adaptiveThres(image,16,0);

[w,h] = size(image);
direct = zeros(w,h);
gradient_times_value = zeros(w,h);
gradient_sq_minus_value = zeros(w,h);
gradient_for_bg_under = zeros(w,h);

W = blocksize;
theta = 0;
sum_value = 1;
bg_certainty = 0;

blockIndex = zeros(ceil(w/W),ceil(h/W));
%directionIndex = zeros(ceil(w/W),ceil(h/W));


times_value = 0;
minus_value = 0;

center = [];

%Note that the image coordinate system is
%x axis towards bottom and y axis towards right

filter_gradient = fspecial('sobel');
%to get x gradient
I_horizontal = filter2(filter_gradient,image);

%to get y gradient
filter_gradient = transpose(filter_gradient);
I_vertical = filter2(filter_gradient,image);


gradient_times_value=I_horizontal.*I_vertical;
gradient_sq_minus_value=(I_vertical-I_horizontal).*(I_vertical+I_horizontal);
gradient_for_bg_under = (I_horizontal.*I_horizontal) + (I_vertical.*I_vertical);


for i=1:W:w
    for j=1:W:h
      if j+W-1 < h & i+W-1 < w
		    times_value = sum(sum(gradient_times_value(i:i+W-1, j:j+W-1)));
          minus_value = sum(sum(gradient_sq_minus_value(i:i+W-1, j:j+W-1)));
          sum_value = sum(sum(gradient_for_bg_under(i:i+W-1, j:j+W-1)));
          
          bg_certainty = 0;
          theta = 0;
          
          if sum_value ~= 0 & times_value ~=0
             %if sum_value ~= 0 & minus_value ~= 0 & times_value ~= 0
             bg_certainty = (times_value*times_value + minus_value*minus_value)/(W*W*sum_value);
             
            if bg_certainty > 0.05 
             blockIndex(ceil(i/W),ceil(j/W)) = 1;
             
             %tan_value = atan2(minus_value,2*times_value);
             tan_value = atan2(2*times_value,minus_value);
             

				theta = (tan_value)/2 ;
				theta = theta+pi/2;
            %now the theta is within [0,pi]
            
            %directionIndex(ceil(i/W),ceil(j/W)) = theta;
            %center = [center;[round(i + (W-1)/2),round(j + (W-1)/2),theta,bg_certainty]];
             center = [center;[round(i + (W-1)/2),round(j + (W-1)/2),theta]];
        		end;
        end;
    end;
 			 times_value = 0;
          minus_value = 0;
          sum_value = 0;
          
   end;
end;



if nargin == 2
	imagesc(direct);

	hold on;
	[u,v] = pol2cart(center(:,3),8);
   quiver(center(:,2),center(:,1),u,v,0,'g');
   hold off;
end;


x = bwlabel(blockIndex,4);
%map = [0 0 0;jet(3)];
%figure
%imshow(x+1,map,'notruesize')

y = bwmorph(x,'close');
%figure
%imshow(y,map,'notruesize');

%z is the region of interest (ROI)
%with the index format 

z = bwmorph(y,'open');
%figure
%imshow(z,map,'notruesize');

%p is the bound of ROI

p = bwperim(z);
%figure,
%imshow(p,map,'notruesize');

%directMap = directionIndex;