%?This?Matlab?program?demomstrates?the?level?set?algorithm?in?paper:
%????“Active?contours?with?selective?local?or?global?segmentation:?a?new?variational?approach?and?level?set?method“?
%????to?appear?in?Image?and?Vision?Computing?2010.?
%?Authors:?Kaihua?Zhang?Lei?Zhang?Huihui?Song?and?Wengang?Zhou
%?E-mail:?zhkhua@mail.ustc.edu.cn?cslzhang@comp.polyu.edu.hk?
%?URL:?http://www4.comp.polyu.edu.hk/~cslzhang/

%?Notes:Some?parameters?may?need?to?be?modified?for?different?types?of?images.?
%?Please?contact?the?authors?if?any?problem?regarding?the?choice?of?parameters.
%?Date:?5/11/2009

clc;clear?all;close?all;

Img?=?imread（‘twocells.bmp‘）;

Img?=?Img（::1）;
Img?=?double（Img）;
%?Img?=?200*ones（100）;
%?Img（20:8010:30）=?140;
%?Img（20:8040:70）=?180;
%?Img（20:8080:90）=50;
[rowcol]?=?size（Img）;
phi?=?ones（rowcol）;
phi（10:row-1010:col-10）?=?-1;
u?=?-?phi;
[c?h]?=?contour（u?[0?0]?‘r‘）;
title（‘Initial?contour‘）;
%?hold?off;

sigma?=?1;
G?=?fspecial（‘gaussian‘?5?sigma）;

delt?=?1;
Iter?=?80;
mu?=?25;%this?parameter?needs?to?be?tuned?according?to?the?images

for?n?=?1:Iter
????[ux?uy]?=?gradient（u）;
???
????c1?=?sum（sum（Img.*（u<0）））/（sum（sum（u<0）））;%?we?use?the?standard?Heaviside?function?which?yields?similar?results?to?regularized?one.
????c2?=?sum（sum（Img.*（u>=0）））/（sum（sum（u>=0）））;
????
????spf?=?Img?-?（c1?+?c2）/2;
????spf?=?spf/（max（abs（spf（:））））;
????
????u?=?u?+?delt*（mu*spf.*sqrt（ux.^2?+?uy.^2））;
????
????if?mod（n10）==0
????imagesc（Img[0?255]）;?colormap（gray）;hold?on;
????[c?h]?=?contour（u?[0?0]?‘r‘）;
????iterNum?=?[num2str（n）?‘iterations‘];
????title（iterNum）;
????pause（0.02）;
????end
????u?=?（u?>=?0）?-?（?u????u?=?conv2（u?G?‘same‘）;
end
imagesc（Img[0?255]）;colormap（gray）;hold?on;
[c?h]?=?contour（u?[0?0]?‘b‘）;



????

?屬性????????????大小?????日期????時間???名稱
-----------?---------??----------?-----??----
?????文件???????27512??2009-09-07?17:15??brain1.bmp
?????文件???????53910??2008-03-07?16:42??d.bmp
?????文件????????1862??2009-11-05?13:59??Demo.m
?????文件???????59014??2008-03-07?16:44??e.bmp
?????文件???????15120??2008-06-21?16:16??fin1.bmp
?????文件???????49186??2009-08-06?21:44??galaxy.jpg
?????文件???????26840??2008-03-26?18:54??h.bmp
?????文件???????47001??2009-08-06?20:23??lv1.JPG
?????文件???????68166??2009-08-06?21:17??lvmr1.bmp
?????文件???????34798??2009-08-06?19:11??narrow.bmp
?????文件???????34798??2009-08-09?10:12??nn.bmp
?????文件??????121976??2009-08-08?10:43??plane2.bmp
?????文件???????28173??2007-10-31?15:54??plane4.jpg
?????文件???????16434??2004-07-23?19:36??twocells.bmp