% This Matlab code demomstrates an improved algorithm based on the local binary fitting (LBF) model
% in Chunming Li et al's paper:
%    "Implicit Active Contours Driven By Local Binary Fitting Energy" in Proceedings of CVPR'07
%
% Author: Chunming Li, all rights reserved
% E-mail: li_chunming@hotmail.com
% URL:  http://vuiis.vanderbilt.edu/~licm/
%       http://www.engr.uconn.edu/~cmli/
%
%  Notes:
%    1. Some parameters are set to default values for the demos in this package. They may need to be
%       modified for different types of images. 
%    2. The current version does not work for images with multiple junctions, due to its two-phase
%       formulation (i.e. using only one level set function). For example, an image has 3 objects/regions, 
%       and each object/region is directly contiguous to all the other two objects/regions. This code will be 
%       extended to multiphase in the future version, which will be available at the author's webpage.
%    3. The image intensities may need to be rescaled to the range of [0, 255], if the intensities are much lower
%       or much higher than 255. Alternatively, you can change the parameters lambda1 and lambda2, and nu (the 
%       coefficient of lenght term) accordingly.

close all;
clear all;
iterNum = 400;   % the number of iterations depend on the location of the initial contour.
                 % 

Img=imread('k.jpg');
Img=double(Img(:,:,1));


lambda1 = 1.0;
lambda2 = 1.0;
nu = 0.004*255*255;   

figure;imagesc(Img, [0, 255]);colormap(gray);hold on; axis off;
text(6,6,'Left click to get points, right click to get end point','FontSize',[12],'Color', 'r');
BW=roipoly;
c0=2;
initialLSF=c0*2*(0.5-BW);
u=initialLSF;
hold on;
[c,h] = contour(u,[0 0],'r');

pause(0.1);
timestep = 0.1;
mu = 1;

epsilon = 1.0;
sigma=2.0;    % scale parameter in Gaussian kernel
K=fspecial('gaussian',round(2*sigma)*2+1,sigma); % Gaussian kernel
Img;
KI=conv2(Img,K,'same');  
KONE=conv2(ones(size(Img)),K,'same');
% start level set evolution
time = cputime;
for n=1:iterNum
    method='ChunmingLi2005'; % this parameter specifies the method published in CVPR07 (developed in 2006).
    DiracFunction='global'; % this parameter specifies the Dirac function that is defined by the
                            % equation (12) in the CVPR07 paper. Do NOT change this parameter for this version. 
    Iter=1;
    % LSE: level set evolution.  
    u=LSE(u,Img,K,KI,KONE, nu,timestep,mu,lambda1,lambda2,epsilon,Iter,1,DiracFunction,method,2004);
    % The input '2004' represents the internal energy term used in my CVPR'05 and 07 papers (developed in 2004).
    % Do NOT change this parameter for this version.  
    if mod(n,10)==0
        pause(0.001);
        imagesc(Img, [0, 255]);colormap(gray);hold on; axis off;
        contour(u,[0 0],'r');
        iterNum=[num2str(n), ' iterations'];
        title(iterNum);
        hold off;
    end   
end
totaltime = cputime - time
imagesc(Img, [0, 255]);colormap(gray);hold on; axis off;
contour(u,[0 0],'r');
iterNum=[num2str(n), ' iterations'];
title(iterNum);