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基于二维熵阈值分割与遗传算法结合的图像分割

news 2025/10/29 19:26:28

一、算法原理框架

1. 二维熵阈值分割基础

\(p_{ij}\)：灰度值i与邻域均值j的联合概率
\(w_0,w_b\)：目标和背景的累积概率
目标：最大化总熵\(H=H_o+H_b\)

2. 遗传算法优化流程

graph TD A[初始化种群] --> B[适应度计算] B --> C[选择操作] C --> D[交叉变异] D --> E[更新种群] E -->|未收敛| C E -->|收敛| F[输出最优阈值]

二、关键算法实现（MATLAB）

1. 二维熵计算函数

function H = calc2DEntropy(I, t, s)[M,N] = size(I);hist = imhist2(I, t, s); % 计算二维直方图p = hist / (M*N);w0 = sum(p(1:t,1:s));w1 = sum(p(t+1:end,s+1:end));H0 = -sum(sum(p(1:t,1:s) .* log(p(1:t,1:s)./w0)));H1 = -sum(sum(p(t+1:end,s+1:end) .* log(p(t+1:end,s+1:end)./w1)));H = H0 + H1;
end

2. 遗传算法主程序

%% 参数设置
popSize = 50;    % 种群大小
maxGen = 100;    % 最大迭代
pc = 0.8;        % 交叉概率
pm = 0.05;       % 变异概率
tRange = [1,256];% 阈值范围%% 初始化种群
pop = randi(tRange, popSize, 2);%% 适应度计算
fitness = @(t) -calc2DEntropy(im2double(I), t(1), t(2));%% 遗传算法迭代
for gen = 1:maxGen% 计算适应度fitValues = arrayfun(fitness, pop);% 选择操作（锦标赛选择）selected = tournamentSelection(pop, fitValues);% 交叉操作（模拟二进制交叉）offspring = sbx_crossover(selected, pc);% 变异操作（多项式变异）offspring = poly_mutation(offspring, pm, tRange);% 更新种群pop = [selected; offspring];
end%% 最优解提取
[~, idx] = max(fitness(pop));
bestT = pop(idx,:);

三、关键技术优化

1. 二维直方图加速计算

function hist = imhist2(I, t, s)[M,N] = size(I);kernel = fspecial('average', [3,3]);meanImg = imfilter(I, kernel, 'replicate');% 灰度值和邻域均值联合统计hist = accumarray([I(:), round(meanImg(:))]+1, 1, [t+1, s+1]);
end

2. 自适应遗传算法改进

动态变异率：

pm = 0.05 + 0.05*(gen/maxGen); % 随迭代次数增加变异率

精英保留策略：

eliteRatio = 0.1;
eliteNum = round(eliteRatio * popSize);
[sortedFit, idx] = sort(fitValues, 'descend');
elitePop = pop(idx(1:eliteNum), :);

四、工程应用案例

1. 医学图像分割

% 加载DICOM图像
img = dicomread('CT_scan.dcm');
grayImg = im2double(rgb2gray(img));% 遗传算法参数设置
options = optimoptions('ga',...'PopulationSize',50,...'MaxGenerations',100,...'CrossoverFcn',{@crossoverarithmetic,0.8,1,2});% 执行优化
[bestT, fval] = ga(@(t) -calc2DEntropy(grayImg, t(1), t(2)), 2, [], [], [], [], [1,256], [1,256], [], options);% 显示结果
segImg = grayImg > bestT(1);
imshow(segImg); hold on;
contour(bwperim(segImg),'r');

2. 工业检测系统

% 实时视频处理
video = VideoReader('factory_inspection.mp4');
while hasFrame(video)frame = readFrame(video);gray = im2double(rgb2gray(frame));% GPU加速计算gpuImg = gpuArray(gray);parfor i=1:10t = ga(@(t) -calc2DEntropy(gpuImg, t(1), t(2)), 2);endseg = gather(gpuImg > t(1));% 显示结果imshow(seg); drawnow;
end

参考代码使用二维熵图像阈值分割法和遗传算法对图像进行分割处理 www.youwenfan.com/contentcnk/64824.html