Serendipity
b8a8ff2bc6
实现内容： - 网格划分：投影分析 + 自相关估周期 + 白顶帽去背景 + 质心提取 - 三种阈值分割：人工阈值、Otsu自动阈值、迭代阈值 - TV去噪（Chambolle投影算法） - 后处理：去小连通域 + 保留最大连通域 - 完整可视化：网格叠加、阈值对比、收敛曲线、分割结果 参考MATLAB代码：NewGridAndCV/demo_GriddingAndCV.m
408 lines
14 KiB
Matlab
408 lines
14 KiB
Matlab
%==========================================================================
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%
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% Active contour with Chen-Vese Method
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% for image segementation
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%
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% Implemented by Yue Wu (yue.wu@tufts.edu)
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% Tufts University
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% Feb 2009
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% http://sites.google.com/site/rexstribeofimageprocessing/
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%
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% all rights reserved
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% Last update 02/26/2009
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%--------------------------------------------------------------------------
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% Usage of varibles:
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% input:
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% I = any gray/double/RGB input image
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% mask = initial mask, either customerlized or built-in
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% num_iter = total number of iterations
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% mu = weight of length term
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% method = submethods pick from ('chen','vector','multiphase')
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%
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% Types of built-in mask functions
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% 'small' = create a small circular mask
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% 'medium' = create a medium circular mask
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% 'large' = create a large circular mask
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% 'whole' = create a mask with holes around
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% 'whole+small' = create a two layer mask with one layer small
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% circular mask and the other layer with holes around
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% (only work for method 'multiphase')
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% Types of methods
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% 'chen' = general CV method
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% 'vector' = CV method for vector image
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% 'multiphase'= CV method for multiphase (2 phases applied here)
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%
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% output:
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% phi0 = updated level set function
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%
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%--------------------------------------------------------------------------
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%
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% Description: This code implements the paper: "Active Contours Without
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% Edges" by Chan and Vese for method 'chen', the paper:"Active Contours Without
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% Edges for vector image" by Chan and Vese for method 'vector', and the paper
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% "A Multiphase Level Set Framework for Image Segmentation Using the
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% Mumford and Shah Model" by Chan and Vese.
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%
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%--------------------------------------------------------------------------
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% Deomo: Please see HELP file for details
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%==========================================================================
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function seg = chenvese(I,mask,num_iter,mu,method)
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%%
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%-- Default settings
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% length term mu = 0.2 and default method = 'chan'
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if(~exist('mu','var'))
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mu=0.2;
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end
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if(~exist('method','var'))
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method = 'chan';
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end
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%-- End default settings
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%%
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%-- Initializations on input image I and mask
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% resize original image
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s = 200./min(size(I,1),size(I,2)); % resize scale
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if s<1
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I = imresize(I,s);
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end
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% auto mask settings
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if ischar(mask)
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switch lower (mask)
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case 'small'
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mask = maskcircle2(I,'small');
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case 'medium'
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mask = maskcircle2(I,'medium');
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case 'large'
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mask = maskcircle2(I,'large');
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case 'whole'
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mask = maskcircle2(I,'whole');
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%mask = init_mask(I,30);
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case 'whole+small'
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m1 = maskcircle2(I,'whole');
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m2 = maskcircle2(I,'small');
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mask = zeros(size(I,1),size(I,2),2);
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mask(:,:,1) = m1(:,:,1);
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mask(:,:,2) = m2(:,:,2);
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otherwise
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error('unrecognized mask shape name (MASK).');
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end
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else
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if s<1
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mask = imresize(mask,s);
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end
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if size(mask,1)>size(I,1) || size(mask,2)>size(I,2)
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error('dimensions of mask unmathch those of the image.')
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end
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switch lower(method)
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case 'multiphase'
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if (size(mask,3) == 1)
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error('multiphase requires two masks but only gets one.')
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end
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end
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end
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switch lower(method)
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case 'chan'
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if size(I,3)== 3
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P = rgb2gray(uint8(I));
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P = double(P);
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elseif size(I,3) == 2
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P = 0.5.*(double(I(:,:,1))+double(I(:,:,2)));
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else
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P = double(I);
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end
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layer = 1;
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case 'vector'
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s = 200./min(size(I,1),size(I,2)); % resize scale
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I = imresize(I,s);
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mask = imresize(mask,s);
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layer = size(I,3);
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if layer == 1
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display('only one image component for vector image')
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end
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P = double(I);
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case 'multiphase'
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layer = size(I,3);
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if size(I,1)*size(I,2)>200^2
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s = 200./min(size(I,1),size(I,2)); % resize scale
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I = imresize(I,s);
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mask = imresize(mask,s);
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end
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P = double(I); %P store the original image
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otherwise
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error('!invalid method')
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end
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%-- End Initializations on input image I and mask
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%%
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%-- Core function
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switch lower(method)
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case {'chan','vector'}
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%-- SDF
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% Get the distance map of the initial mask
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mask = mask(:,:,1);
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phi0 = bwdist(mask)-bwdist(1-mask)+im2double(mask)-.5;
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% initial force, set to eps to avoid division by zeros
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force = eps;
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%-- End Initialization
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%-- Display settings
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% figure();
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% subplot(2,2,1); imshow(I); title('Input Image');
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% subplot(2,2,2); contour(flipud(phi0), [0 0], 'r','LineWidth',1); title('initial contour');
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% subplot(2,2,3); title('Segmentation');
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% figure(1);
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% imshow(I); title('Input Image');
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% figure(2); contour(flipud(phi0), [0 0], 'r','LineWidth',1); title('initial contour');
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% figure(3);
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%-- End Display original image and mask
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%-- Main loop
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for n=1:num_iter
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inidx = find(phi0>=0); % frontground index
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outidx = find(phi0<0); % background index
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force_image = 0; % initial image force for each layer
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for i=1:layer
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L = im2double(P(:,:,i)); % get one image component
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c1 = sum(sum(L.*Heaviside(phi0)))/(length(inidx)+eps); % average inside of Phi0
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c2 = sum(sum(L.*(1-Heaviside(phi0))))/(length(outidx)+eps); % verage outside of Phi0
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force_image=-(L-c1).^2+(L-c2).^2+force_image;
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% sum Image Force on all components (used for vector image)
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% if 'chan' is applied, this loop become one sigle code as a
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% result of layer = 1
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end
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% calculate the external force of the image
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force = mu*kappa(phi0)./max(max(abs(kappa(phi0))))+1/layer.*force_image;
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% normalized the force
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force = force./(max(max(abs(force))));
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% get stepsize dt
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dt=0.5;
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% get parameters for checking whether to stop
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old = phi0;
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phi0 = phi0+dt.*force;
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new = phi0;
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indicator = checkstop(old,new,dt);
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% intermediate output
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if(mod(n,20) == 0)
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% showphi(I,phi0,n);
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end;
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if indicator % decide to stop or continue
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% showphi(I,phi0,n);
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%make mask from SDF
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seg = phi0<=0; %-- Get mask from levelset
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% figure(4); imshow(seg); title('Global Region-Based Segmentation');
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return;
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end
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end;
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% showphi(I,phi0,n);
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%make mask from SDF
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seg = phi0<=0; %-- Get mask from levelset
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% figure(4);; imshow(seg); title('Global Region-Based Segmentation');
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case 'multiphase'
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%-- Initializations
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% Get the distance map of the initial masks
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mask1 = mask(:,:,1);
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mask2 = mask(:,:,2);
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phi1=bwdist(mask1)-bwdist(1-mask1)+im2double(mask1)-.5;%Get phi1 from the initial mask 1
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phi2=bwdist(mask2)-bwdist(1-mask2)+im2double(mask2)-.5;%Get phi1 from the initial mask 2
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%-- Display settings
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figure();
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subplot(2,2,1);
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if layer ~= 1
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imshow(I); title('Input Image');
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else
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imagesc(P); axis image; colormap(gray);title('Input Image');
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end
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subplot(2,2,2);
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hold on
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contour(flipud(mask1),[0,0],'r','LineWidth',2.5);
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contour(flipud(mask1),[0,0],'x','LineWidth',1);
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contour(flipud(mask2),[0,0],'g','LineWidth',2.5);
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contour(flipud(mask2),[0,0],'x','LineWidth',1);
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title('initial contour');
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hold off
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subplot(2,2,3); title('Segmentation');
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%-- End display settings
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%Main loop
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for n=1:num_iter
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%-- Narrow band for each phase
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nb1 = find(phi1<1.2 & phi1>=-1.2); %narrow band of phi1
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inidx1 = find(phi1>=0); %phi1 frontground index
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outidx1 = find(phi1<0); %phi1 background index
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nb2 = find(phi2<1.2 & phi2>=-1.2); %narrow band of phi2
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inidx2 = find(phi2>=0); %phi2 frontground index
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outidx2 = find(phi2<0); %phi2 background index
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%-- End initiliazaions on narrow band
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%-- Mean calculations for different partitions
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%c11 = mean (phi1>0 & phi2>0)
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%c12 = mean (phi1>0 & phi2<0)
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%c21 = mean (phi1<0 & phi2>0)
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%c22 = mean (phi1<0 & phi2<0)
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cc11 = intersect(inidx1,inidx2); %index belong to (phi1>0 & phi2>0)
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cc12 = intersect(inidx1,outidx2); %index belong to (phi1>0 & phi2<0)
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cc21 = intersect(outidx1,inidx2); %index belong to (phi1<0 & phi2>0)
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cc22 = intersect(outidx1,outidx2); %index belong to (phi1<0 & phi2<0)
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f_image11 = 0;
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f_image12 = 0;
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f_image21 = 0;
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f_image22 = 0; % initial image force for each layer
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for i=1:layer
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L = im2double(P(:,:,i)); % get one image component
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if isempty(cc11)
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c11 = eps;
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else
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c11 = mean(L(cc11));
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end
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if isempty(cc12)
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c12 = eps;
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else
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c12 = mean(L(cc12));
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end
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if isempty(cc21)
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c21 = eps;
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else
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c21 = mean(L(cc21));
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end
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if isempty(cc22)
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c22 = eps;
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else
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c22 = mean(L(cc22));
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end
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%-- End mean calculation
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%-- Force calculation and normalization
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% force on each partition
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f_image11=(L-c11).^2.*Heaviside(phi1).*Heaviside(phi2)+f_image11;
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f_image12=(L-c12).^2.*Heaviside(phi1).*(1-Heaviside(phi2))+f_image12;
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f_image21=(L-c21).^2.*(1-Heaviside(phi1)).*Heaviside(phi2)+f_image21;
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f_image22=(L-c22).^2.*(1-Heaviside(phi1)).*(1-Heaviside(phi2))+f_image22;
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end
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% sum Image Force on all components (used for vector image)
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% if 'chan' is applied, this loop become one sigle code as a
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% result of layer = 1
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% calculate the external force of the image
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% curvature on phi1
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curvature1 = mu*kappa(phi1);
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curvature1 = curvature1(nb1);
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% image force on phi1
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fim1 = 1/layer.*(-f_image11(nb1)+f_image21(nb1)-f_image12(nb1)+f_image22(nb1));
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fim1 = fim1./max(abs(fim1)+eps);
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% curvature on phi2
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curvature2 = mu*kappa(phi2);
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curvature2 = curvature2(nb2);
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% image force on phi2
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fim2 = 1/layer.*(-f_image11(nb2)+f_image12(nb2)-f_image21(nb2)+f_image22(nb2));
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fim2 = fim2./max(abs(fim2)+eps);
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% force on phi1 and phi2
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force1 = curvature1+fim1;
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force2 = curvature2+fim2;
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%-- End force calculation
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% detal t
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dt = 1.5;
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old(:,:,1) = phi1;
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old(:,:,2) = phi2;
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%update of phi1 and phi2
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phi1(nb1) = phi1(nb1)+dt.*force1;
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phi2(nb2) = phi2(nb2)+dt.*force2;
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new(:,:,1) = phi1;
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new(:,:,2) = phi2;
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indicator = checkstop(old,new,dt);
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if indicator
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showphi(I, new, n);
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%make mask from SDF
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seg11 = (phi1>0 & phi2>0); %-- Get mask from levelset
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seg12 = (phi1>0 & phi2<0);
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seg21 = (phi1<0 & phi2>0);
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seg22 = (phi1<0 & phi2<0);
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se = strel('disk',1);
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aa1 = imerode(seg11,se);
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aa2 = imerode(seg12,se);
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aa3 = imerode(seg21,se);
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aa4 = imerode(seg22,se);
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seg = aa1+2*aa2+3*aa3+4*aa4;
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subplot(2,2,4); imagesc(seg);axis image;title('Global Region-Based Segmentation');
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return
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end
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% re-initializations
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phi1 = reinitialization(phi1, 0.6);%sussman(phi1, 0.6);%
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phi2 = reinitialization(phi2, 0.6);%sussman(phi2,0.6);
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%intermediate output
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if(mod(n,20) == 0)
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phi(:,:,1) = phi1;
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phi(:,:,2) = phi2;
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showphi(I, phi, n);
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end;
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end;
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phi(:,:,1) = phi1;
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phi(:,:,2) = phi2;
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showphi(I, phi, n);
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%make mask from SDF
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seg11 = (phi1>0 & phi2>0); %-- Get mask from levelset
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seg12 = (phi1>0 & phi2<0);
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seg21 = (phi1<0 & phi2>0);
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seg22 = (phi1<0 & phi2<0);
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se = strel('disk',1);
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aa1 = imerode(seg11,se);
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aa2 = imerode(seg12,se);
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aa3 = imerode(seg21,se);
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aa4 = imerode(seg22,se);
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seg = aa1+2*aa2+3*aa3+4*aa4;
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%seg = bwlabel(seg);
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subplot(2,2,4); imagesc(seg);axis image;title('Global Region-Based Segmentation');
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end
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