%??This?Matlab?code?demonstrates?an?edge-based?active?contour?model?as?an?application?of?
%??the?Distance?Regularized?Level?Set?Evolution?（DRLSE）?formulation?in?the?following?paper:
%
%??C.?Li?C.?Xu?C.?Gui?M.?D.?Fox?“Distance?Regularized?Level?Set?Evolution?and?Its?Application?to?Image?Segmentation“?
%?????IEEE?Trans.?Image?Processing?vol.?19?（12）?pp.?3243-3254?2010.
%
%?Author:?Chunming?Li?all?rights?reserved
%?E-mail:?lchunming@gmail.com???
%?????????li_chunming@hotmail.com?
%?URL:??http://www.engr.uconn.edu/~cmli/

clear?all;
close?all;

Img=imread（‘gourd.bmp‘）;
Img=double（Img（::1））;
%%?parameter?setting
timestep=1;??%?time?step
mu=0.2/timestep;??%?coefficient?of?the?distance?regularization?term?R（phi）
iter_inner=5;
iter_outer=20;
lambda=5;?%?coefficient?of?the?weighted?length?term?L（phi）
alfa=-3;??%?coefficient?of?the?weighted?area?term?A（phi）
epsilon=1.5;?%?papramater?that?specifies?the?width?of?the?DiracDelta?function

sigma=.8;????%?scale?parameter?in?Gaussian?kernel
G=fspecial（‘gaussian‘15sigma）;?%?Caussian?kernel
Img_smooth=conv2（ImgG‘same‘）;??%?smooth?image?by?Gaussiin?convolution
[IxIy]=gradient（Img_smooth）;
f=Ix.^2+Iy.^2;
g=1./（1+f）;??%?edge?indicator?function.

%?initialize?LSF?as?binary?step?function
c0=2;
initialLSF?=?c0*ones（size（Img））;
%?generate?the?initial?region?R0?as?two?rectangles
initialLSF（25:3520:25）=-c0;?
initialLSF（25:3540:50）=-c0;
phi=initialLSF;

figure（1）;
mesh（-phi）;???%?for?a?better?view?the?LSF?is?displayed?upside?down
hold?on;??contour（phi?[00]?‘r‘‘LineWidth‘2）;
title（‘Initial?level?set?function‘）;
view（[-80?35]）;

figure（2）;
imagesc（Img[0?255]）;?axis?off;?axis?equal;?colormap（gray）;?hold?on;??contour（phi?[00]?‘r‘）;
title（‘Initial?zero?level?contour‘）;
pause（0.5）;

potential=2;??
if?potential?==1
????potentialFunction?=?‘single-well‘;??%?use?single?well?potential?p1（s）=0.5*（s-1）^2?which?is?good?for?region-based?model?
elseif?potential?==?2
????potentialFunction?=?‘double-well‘;??%?use?double-well?potential?in?Eq.?（16）?which?is?good?for?both?edge?and?region?based?models
else
????potentialFunction?=?‘double-well‘;??%?default?choice?of?potential?function
end??

%?start?level?set?evolution
for?n=1:iter_outer
????phi?=?drlse_edge（phi?g?lambda?mu?alfa?epsilon?timestep?iter_inner?potentialFunction）;????
????if?mod（n2）==0
????????figure（2）;
????????imagesc（Img[0?255]）;?axis?off;?axis?equal;?colormap（gray）;?hold?on;??contour（phi?[00]?‘r‘）;
????end
end

%?refine?the?zero?level?contour?by?further?level?set?evolution?with?alfa=0
alfa=0;
iter_refine?=?10;
phi?=?drlse_edge（phi?g?lambda?mu?alfa?epsilon?timestep?iter_inner?potentialFunction）;

finalLSF=phi;
figure（2）;
imagesc（Img[0?255]）;?axis?off;?axis?equal;?colormap（gray）;?hold?on;??contour（phi?[00]?‘r‘）;
hold?on;??contour（phi?[00]?‘r‘）;
str=[‘Final?zero?level?contour?‘?num2str（iter_outer*iter_inner+iter_refine）?‘?iterations‘];
title（str）;

figure;
mesh（-finalLSF）;?%?for?a?better?view?the?LSF?is?displayed?upside

?屬性????????????大小?????日期????時間???名稱
-----------?---------??----------?-----??----

?????文件???????3291??2018-05-14?07:53??DRLSE（Li）\demo_1.m

?????文件???????3171??2018-05-14?07:53??DRLSE（Li）\demo_2.m

?????文件????1966604??2020-01-06?21:12??DRLSE（Li）\DRLSE.pdf

?????文件???????3517??2018-05-14?07:53??DRLSE（Li）\drlse_edge.m

?????文件???????5798??2018-05-14?07:53??DRLSE（Li）\gourd.bmp

?????文件???????3123??2018-05-14?07:53??DRLSE（Li）\improved-drlse.m

?????文件??????16434??2018-05-14?07:53??DRLSE（Li）\twocells.bmp

?????文件??????14286??2018-05-14?07:53??DRLSE（Li）\vessel.bmp

?????目錄??????????0??2020-01-06?16:26??DRLSE（Li）

-----------?---------??----------?-----??----

??????????????2016224????????????????????9