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

function [Svd_dist_bdry, Svd_dist_reg] = Svd_dist (Region1, Region2) 
% first represent the two boundaries as matrices where ones stand for 
% boundary pixels and zeros elsewhere, next use SVD decomposition to 
% find eigenvalues, and finally adjust those (take shorter array and 
% multiply it by the lengths ratio) - observed from resizing the same 
% image 
 
Subints = 8; 
 
  
if length(Region1.Boundary) < length(Region2.Boundary)	% rotate 1 is quicker 
	Temp = Region1; 
	Region1 = Region2; 
	Region2 = Temp; 
end 
 
 
% finding the first region boundary and filled 
Max_x1 = Region1.Shifts(1, 2); Min_x1 = Region1.Shifts(1, 1); 
Max_y1 = Region1.Shifts(2, 2); Min_y1 = Region1.Shifts(2, 1); 
Mb1 = zeros(Max_x1-Min_x1+1, Max_y1-Min_y1+1); 
Mb1(sub2ind(size(Mb1), Region1.Boundary(1, :)-Min_x1+1, ... 
	Region1.Boundary(2, :)-Min_y1+1)) = 1; 
	 
Bdry_diag1 = svd(Mb1); 
To_start_fill = [Region1.Inner_pts(2, :)-Min_y1+1; ... 
	Region1.Inner_pts(1, :)-Min_x1+1]; 
Mb1 = bwfill(Mb1, To_start_fill(1, :), To_start_fill(2, :)); 
 
% global Mb1f; 
% Mb1f = Mb1; 
% global Mb2f; 
 
Reg_diag1 = svd(double(Mb1)); 
Ld1 = length(Reg_diag1); 
[Rows1, Cols1] = size(Mb1); 
 
% finding the second region filled 
Max_x2 = Region2.Shifts(1, 2); Min_x2 = Region2.Shifts(1, 1); 
Max_y2 = Region2.Shifts(2, 2); Min_y2 = Region2.Shifts(2, 1); 
Mb2_orig = zeros(Max_x2-Min_x2+1, Max_y2-Min_y2+1); 
Mb2_orig(sub2ind(size(Mb2_orig), Region2.Boundary(1, :)-Min_x2+1, ... 
	Region2.Boundary(2, :)-Min_y2+1)) = 1; 
To_start_fill = [Region2.Inner_pts(2, :)-Min_y2+1; ... 
	Region2.Inner_pts(1, :)-Min_x2+1]; 
Mb2_orig = bwfill(Mb2_orig, To_start_fill(1, :), To_start_fill(2, :)); 
 
% Mb2f = Mb2_orig; 
 
[Rows, Cols] = find(Mb2_orig); 
Mb2_orig = [Rows'; Cols']; 
 
for i=1:Subints+1 
	% obtaining rotated second filled and extracting boundary next 
	Theta = (i-1)*(pi/2)/(Subints+1); 
	Matrix = [cos(Theta), sin(Theta); -sin(Theta), cos(Theta)]; 
	Mb2_ind = Matrix * Mb2_orig; 
	Mb2_ind = [round(Mb2_ind), floor(Mb2_ind), ceil(Mb2_ind)]; 
	Max_x2 = max(Mb2_ind(1, :)); Min_x2 = min(Mb2_ind(1, :)); 
	Max_y2 = max(Mb2_ind(2, :)); Min_y2 = min(Mb2_ind(2, :)); 
	Mb2 = zeros(Max_x2-Min_x2+1, Max_y2-Min_y2+1); 
	Mb2(sub2ind(size(Mb2), Mb2_ind(1, :)-Min_x2+1, Mb2_ind(2, :)-Min_y2+1)) = 1; 
	Reg_diag2 = svd(Mb2); 
	Ld2 = length(Reg_diag2); 
	Mb2 = double(bwperim(Mb2)); 
	Bdry_diag2 = svd(Mb2); 
	[Rows2, Cols2] = size(Mb2); 
 
	if Ld1 > Ld2 
		Bdry_diag_1 = Bdry_diag1(1:Ld2); 
		Reg_diag_1 = Reg_diag1(1:Ld2); 
	else 
		Bdry_diag_1 = Bdry_diag1; 
		Reg_diag_1 = Reg_diag1; 
		Bdry_diag2 = Bdry_diag2(1:Ld1); 
		Reg_diag2 = Reg_diag2(1:Ld1); 
	end 
 
	Factor = sqrt((Rows1*Cols1)/(Rows2*Cols2)); 
	if Factor > 1 
		Bdry_diag2 = Bdry_diag2*Factor; 
		Reg_diag2 = Reg_diag2*Factor; 
	 else 
		Bdry_diag1 = Bdry_diag1/Factor; 
		Reg_diag1 = Reg_diag1/Factor; 
	end 
 
	Svd_dist_bdry(i) = norm(Bdry_diag_1-Bdry_diag2); 
	Svd_dist_reg(i) = norm(Reg_diag_1-Reg_diag2); 
end 
 
Svd_dist_bdry = min(Svd_dist_bdry); 
Svd_dist_reg = min(Svd_dist_reg);