图像分离处理matlab,数字图像处理-图像分割：Snake主动轮廓模型 Matlab代码及运行结果...

% =========================================================================

% Snakes：Active Contour Models

% =========================================================================

% By gujinjin 2012/12/10-12 Sunny

% 基于KASS等的论文思想

% 参考文献：

% [1] KASS etc.Snakes：Active Contour Models

% [2] CSDN 博客 - Author：乐不思蜀Tone

% [3] Ritwik Kumar(Harvard University),D.Kroon(Twente University)的程序

% [4] 《数学建模与数学实验》

% ------

clc;clf;clear all;

% =========================================================================

% 获取手动取点坐标

% =========================================================================

% 读取显示图像

%I = imread('Coronary_MPR.jpg');

I = imread('test1.png');

% 转化为双精度型

%I = im2double(I);

% 若为彩色，转化为灰度

%if(size(I,3)==3), I=rgb2gray(I); end

figure(1),imshow(I);

%---------------------------

% 高斯滤波

%---------------------------

sigma=1;

% 创建特定形式的二维高斯滤波器H

H = fspecial('gaussian',ceil(3*sigma), sigma);

% 对图像进行高斯滤波,返回和I等大小矩阵

Igs = filter2(H,I,'same');

%---------------------------

% 获取Snake的点坐标

%---------------------------

figure(2),imshow(Igs);

x=[];y=[];c=1;N=100; %定义取点个数c,上限N

% 获取User手动取点的坐标

% [x,y]=getpts

while c

[xi,yi,button]=ginput(1);

% 获取坐标向量

x=[x xi];

y=[y yi];

hold on

% text(xi,yi,'o','FontSize',10,'Color','red');

plot(xi,yi,'ro');

% 若为右击，则停止循环

if(button==3), break; end

c=c+1;

end

% 将第一个点复制到矩阵最后，构成Snake环

xy = [x;y];

c=c+1;

xy(:,c)=xy(:,1);

% 样条曲线差值

t=1:c;

ts = 1:0.1:c;

xys = spline(t,xy,ts);

xs = xys(1,:);

ys = xys(2,:);

% 样条差值效果

hold on

temp=plot(x(1),y(1),'ro',xs,ys,'b.');

legend(temp,'原点','插值点');

% =========================================================================

% Snakes算法实现部分

% =========================================================================

NIter =1000; % 迭代次数

alpha=0.2; beta=0.2; gamma = 1; kappa = 0.1;

wl = 0; we=0.4; wt=0;

[row col] = size(Igs);

% 图像力-线函数

Eline = Igs;

% 图像力-边函数

[gx,gy]=gradient(Igs);

Eedge = -1*sqrt((gx.*gx+gy.*gy));

% 图像力-终点函数

% 卷积是为了求解偏导数，而离散点的偏导即差分求解

m1 = [-1 1];

m2 = [-1;1];

m3 = [1 -2 1];

m4 = [1;-2;1];

m5 = [1 -1;-1 1];

cx = conv2(Igs,m1,'same');

cy = conv2(Igs,m2,'same');

cxx = conv2(Igs,m3,'same');

cyy = conv2(Igs,m4,'same');

cxy = conv2(Igs,m5,'same');

for i = 1:row

for j= 1:col

Eterm(i,j) = (cyy(i,j)*cx(i,j)*cx(i,j) -2 *cxy(i,j)*cx(i,j)*cy(i,j) + cxx(i,j)*cy(i,j)*cy(i,j))/((1+cx(i,j)*cx(i,j) + cy(i,j)*cy(i,j))^1.5);

end

end

%figure(3),imshow(Eterm);

%figure(4),imshow(abs(Eedge));

% 外部力 Eext = Eimage + Econ

Eext = wl*Eline + we*Eedge + wt*Eterm;

% 计算梯度

[fx,fy]=gradient(Eext);

xs=xs';

ys=ys';

[m n] = size(xs);

[mm nn] = size(fx);

% 计算五对角状矩阵

% 附录: 公式(14) b(i)表示vi系数(i=i-2 到 i+2)

b(1)=beta;

b(2)=-(alpha + 4*beta);

b(3)=(2*alpha + 6 *beta);

b(4)=b(2);

b(5)=b(1);

A=b(1)*circshift(eye(m),2);

A=A+b(2)*circshift(eye(m),1);

A=A+b(3)*circshift(eye(m),0);

A=A+b(4)*circshift(eye(m),-1);

A=A+b(5)*circshift(eye(m),-2);

% 计算矩阵的逆

[L U] = lu(A + gamma.* eye(m));

Ainv = inv(U) * inv(L);

% =========================================================================

% 画图部分

% =========================================================================

%text(10,10,'+','FontName','Time','FontSize',20,'Color','red');

% 迭代计算

figure(3)

for i=1:NIter;

ssx = gamma*xs - kappa*interp2(fx,xs,ys);

ssy = gamma*ys - kappa*interp2(fy,xs,ys);

% 计算snake的新位置

xs = Ainv * ssx;

ys = Ainv * ssy;

% 显示snake的新位置

imshow(I);

hold on;

plot([xs; xs(1)], [ys; ys(1)], 'r-');

hold off;

pause(0.001)

end