www.pudn.com > MATLAB.zip > PLSE_demo3.m, change:2006-08-04,size:2029b


%  **********   Do not distribute this file  *********** 
% This Matlab program implements the level set method in Li et al's paper 
%    "Level Set Evolution Without Re-initialization: A New Variational Formulation" 
%    in Proceedings of CVPR'05, vol. 1, pp. 430-436. 
% Copyright (c) 2004--2007 by Chunming Li 
% Author: Chunming Li 
% Revision by Chunming Li 4/25/2006 
% e-mail: li_chunming@hotmail.com 
% http://vuiis.vanderbilt.edu/~licm/ 
 
clear all; 
close all; 
% Img = imread('twocells.bmp');  % The same cell image in the paper is used 
 
[X,Y,Img]=peaks(100); 
 
[Ix,Iy]=gradient(Img); 
imshow(uint8(Img)); 
figure; 
f=Ix.^2+Iy.^2; 
% g = max(max(f))-f; 
g=1./(1+f);  % edge indicator function. 
imshow(g); 
 
lambda=5; % coefficient of the weighted length term L(\phi) 
mu=0.04;  % coefficient of the internal (penalizing) energy term P(\phi) 
alf=1.5;  % coefficient of the weighted area term A(\phi) 
epsilon=0.5; % the papramater in the definition of smooth Dirac function 
timestep=2;  % time step 
 
% define initial level set function (LSF) as -c, 0, c at points outside, on 
% the boundary, and inside of a region R, respectively. 
[nrow, ncol]=size(Img);   
c=3; 
initialLSF=c*ones(nrow,ncol); 
d=8; 
initialLSF(d+1:end-d, d+1:end-d)=0;  % zero level set on the boundary of R 
initialLSF(d+2:end-d-1, d+2: end-d-1)=-c; % negative constant inside of R 
u=initialLSF; 
figure;imagesc(Img);colormap(gray);hold on; 
[c,h] = contour(u,[0 0],'g'); 
                           
title('Initial contour'); 
% start level set evolution 
for n=1:500 
    u=EVOLUTION_PLSE(u, g ,lambda, mu, alf, epsilon, timestep, 1);   
    pause(0.05); 
    if mod(n,20)==0 
        imagesc(Img);colormap(gray);hold on; 
        [c,h] = contour(u,[0 0],'r');  
        iterNum=[num2str(n), ' iterations'];         
        title(iterNum); 
        hold off; 
    end 
end 
imagesc(Img);colormap(gray);hold on; 
[c,h] = contour(u,[0 0],'r');  
totalIterNum=[num2str(n), ' iterations'];   
title(['Final contour, ', totalIterNum]);