主动轮廓模型基于GVF和VFC应用

使用GVF域和VFC域进行图片分割 % Vector field convolution (VFC) external force field example. % % See also AMT, EXAMPLE_PIG, AM_VFC, AM_VFK, AC_DISPLAY. % % Reference % [1] Bing Li and Scott T. Acton, "Active contour external force using % vector field convolution for image segmentation," Image Processing, % IEEE Trans. on, vol. 16, pp. 2096-2106, 2007. % [2] Bing Li and Scott T. Acton, "Automatic Active Model % Initialization via Poisson Inverse Gradient," Image Processing, % IEEE Trans. on, vol. 17, pp. 1406-1420, 2008. % % (c) Copyright Bing Li 2005 - 2009. clear all disp('======================================') disp('Vector field convolution (VFC) example') %% parameter settings disp('Initializing parameters ...') SAVE_AVI = 0; % set it to 1 if you want to save the process as .avi movie DISPLAY_STREAMLINE = 0; % set it to 1 if you want to plot streamlines, note that it takes a while mu = .2; GVF_ITER = 100; normalize = 1; alpha = .5; beta = 0; tau = .5; SNAKE_ITER = 5; SNAKE_ITER1 = 60; RES = .5; clr = {'b' 'b' 'r'}; %% Read images disp('Reading images ...') U = imread('im_U.bmp'); noisyU=imread('im_Unoisy.bmp'); figure(1) %% compare 3 different cases for cs = 1:3, %% compute external force fields switch cs, case 1, % traditional GVF with Gaussian filter disp('--------------------------------------------------') disp('Case 1: GVF snake with initial circle close to FOI') disp('Computing the external force field ...') h = fspecial('gaussian',[5 5],5); f = imfilter(double(noisyU),h); titl = 'GVF'; Fext = AM_GVF(f, mu, GVF_ITER, normalize); R = 20; case 2, % traditional GVF with Gaussian filter disp('--------------------------------------------------') disp('Case 2: GVF snake with initial circle far away from FOI') disp('Computing the external force field ...

function vertex = AC_deform（vertexalphabetatauFextITERtype）
% AC_DEFORM     Deform an active contour （AC） also known as snake.
%     vertex1 = AC_DEFORM（vertex0alphabetatauFextiter）
%     vertex1 = AC_DEFORM（vertex0alphabetatauFextitertype）
%   
%     Inputs
%     vertex0     position of the vertices n-by-2 matrix each row of 
%                 which is [x y]. n is the number of vertices.
%     alpha       AC elasticity （1st order） parameter ranges from 0 to 1.
%     beta        AC rigidity （2nd order） parameter ranges from 0 to 1.
%     tau         time step of each iteration.
%     Fext        the external force fieldd1-by-d2-by-2 matrix 
%                 the force at （xy） is [Fext（yx1） Fext（yx2）].
%     iter        number of iterations usually ranges from 1 to 5.
%     type        ‘close‘ - close contour （default） the last vertex and
%                           first vertex are connected 
%                 ‘open‘  - open contour  the last vertex and first vertex
%                           are not connected 
%               
%     Outputs
%     vertex1     position of the vertices after deformation n-by-2 matrix
%     
%     Note that if the vertices are outside the valid range i.e. y>d1 ||
%     y<1 || x>d2 || x<1 they will be pulled inside the valid range. 
% 
%     Example
%         See EXAMPLE_VFC EXAMPLE_PIG.
%
%     See also AMT AM_VFC AM_VFK AM_PIG AC_INITIAL AC_REMESH
%     AC_DISPLAY AM_GVF EXAMPLE_VFC EXAMPLE_PIG. 
% 
%     Reference
%     [1] Bing Li and Scott T. Acton “Active contour external force using
%     vector field convolution for image segmentation“ Image Processing
%     IEEE Trans. on vol. 16 pp. 2096-2106 2007.  
%     [2] Bing Li and Scott T. Acton “Automatic Active Model
%     Initialization via Poisson Inverse Gradient“ Image Processing
%     IEEE Trans. on vol. 17 pp. 1406-1420 2008.   
% 
% （c） Copyright Bing Li 2005 - 2009.

% Revision Log
%   11-30-2005  original 
%   01-30-2006  external force interpolation outside the image 
%   02-18-2006  add open contour codes
%   01-30-2009  minor bug fix

%% inputs check
if ~ismember（nargin 6:7） || ndims（Fext） ~= 3 || size（Fext3） ~= 2
    error（‘Invalid inputs to AC_DEFORM!‘）    
end
if nargin == 6
    type = ‘close‘;
end

N = size（vertex1）;
if size（vertex2） ~= 2
    error（‘Invalid vertex matrix!‘）
end

if N < 3
    return
end

%% compute T = （I + tao*A） of equation （9） in reference [1]
Lap = sparse（1:N 1:N -2） + sparse（1:N [N 1:N-1] 1） + sparse（1:N [2:N 1] 1）;

if strcmp（type‘open‘） % offset tau for boundary vertices    
    tau = sparse（1:N 1:N tau）;
    tau（1） = 0;
    tau（end） = 0;
    offset = sparse（1:N 1:N 1）;
    offset（11）=0;      offset（NN） = 0;
    offset（12）=1;      offset（NN-1） = 1;
    Lap = offset*Lap;
end

T =sparse（1:N1:N1）+ tau*（beta*Lap*Lap-alpha*Lap）;

%% Another way to compute T for close AC
% a

 属性            大小     日期    时间   名称
----------- ---------  ---------- -----  ----
     目录           0  2010-06-17 17:31  AMT\
     文件        4014  2009-02-01 05:48  AMT\AC_deform.m
     文件        2223  2009-01-31 08:05  AMT\AC_display.m
     文件        2391  2009-01-31 06:13  AMT\AC_initial.m
     文件        3651  2009-01-31 08:09  AMT\AC_isoLine.m
     文件        1813  2009-02-01 05:13  AMT\AC_quiver.m
     文件        4108  2009-01-31 08:08  AMT\AC_remesh.m
     文件        3777  2009-01-31 08:43  AMT\AM_CoD.m
     文件       11139  2009-02-01 05:50  AMT\AM_FFS.m
     文件        3629  2009-02-03 02:49  AMT\AM_gradient.m
     文件        3063  2009-01-31 09:07  AMT\AM_gradient_c.c
     文件        3157  2009-02-03 02:49  AMT\AM_GVF.m
     文件       11490  2009-01-31 09:07  AMT\AM_GVF_c.c
     文件        1979  2009-02-03 02:49  AMT\AM_laplacian.m
     文件        7321  2009-01-31 09:07  AMT\AM_laplacian_c.c
     文件        5122  2009-02-01 02:22  AMT\AM_PIG.m
     文件        4755  2009-02-01 04:42  AMT\AM_VFC.m
     文件        3033  2009-02-01 04:34  AMT\AM_VFK.m
     文件        2538  2009-02-01 05:28  AMT\Contents.m
     文件        5500  2010-02-26 16:34  AMT\example_pig.asv
     文件        5488  2009-02-01 05:50  AMT\example_pig.m
     文件        4888  2010-02-26 14:39  AMT\example_vfc.asv
     文件        4921  2010-07-03 20:19  AMT\example_vfc.m
     文件       41554  2010-06-18 12:46  AMT\Fext.mat
     文件       78520  2009-01-23 22:03  AMT\im_lung.png
     文件         574  2006-01-10 05:52  AMT\im_U.bmp
     文件         574  2006-01-10 09:27  AMT\im_Unoisy.bmp
     文件       18011  2006-03-08 22:33  AMT\licence.txt
     文件        1174  2009-02-01 05:34  AMT\readme.txt
     文件     2290146  2008-04-18 21:50  AMT\TIP.07.VFC.pdf
     文件     2672665  2010-07-14 18:58  AMT\TIP.08.PIG.pdf
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