www.pudn.com > Ms_segmenter.rar > Cut_boundary_reg.m

function [Boundary1, Inner1, Boundary2, Inner2] = ... 
   Cut_boundary(Region, Dense_pts) 
 
Min_x = min([Region.Shifts(1, 1), Dense_pts(1, :)]); 
Min_y = min([Region.Shifts(2, 1), Dense_pts(2, :)]); 
Max_x = max([Region.Shifts(1, 2), Dense_pts(1, :)]); 
Max_y = max([Region.Shifts(2, 2), Dense_pts(2, :)]); 
Image = zeros(Max_x-Min_x+1, Max_y-Min_y+1); 
 
Image(sub2ind(size(Image), ... 
	Region.Boundary(1, :)-Min_x+1, Region.Boundary(2, :)-Min_y+1)) = 1; 
Image(sub2ind(size(Image), Dense_pts(1,:)-Min_x+1, Dense_pts(2,:)-Min_y+1)) = 1; 
 
% take the inner points to be close to midpoint of the line, on both sides 
Ldp = size(Dense_pts, 2); 
Midpt = Dense_pts(:, floor(Ldp/2)) + [1-Min_x; 1-Min_y]; 
Normal = [Dense_pts(2, Ldp)-Dense_pts(2, 1); Dense_pts(1, 1)-Dense_pts(1, Ldp)]; 
Normal = Normal/norm(Normal); 
Inner1 = Midpt + floor(5*Normal); 
Inner2 = Midpt - floor(5*Normal); 
 
Image1 = double(bwfill(Image, Inner1(2), Inner1(1))); 
Image2 = bwfill(Image, Inner2(2), Inner2(1)); 
% not Image has zeros at the position of boundary and cutting line. 
% thickening nearly restores the original image boundary 
Boundary1 = Extract_region_reg(bwmorph(Image1¬(Image),'thicken'), 1); 
Boundary2 = Extract_region_reg(bwmorph(Image2¬(Image),'thicken'), 1); 
 
Boundary1 = Boundary1 + [Min_x-1; Min_y-1]*ones(1, size(Boundary1, 2)); 
Boundary2 = Boundary2 + [Min_x-1; Min_y-1]*ones(1, size(Boundary2, 2)); 
Inner1 = Inner1 + [Min_x-1; Min_y-1]; 
Inner2 = Inner2 + [Min_x-1; Min_y-1];