运动目标检测|单高斯背景建模

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%Author：Ziheng H. Shen @Tsinghua Univ.
%Date:20170308  @Digital Image Process Practice
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clear all  
%% 读入视频，并记录帧率
fileName = '768x576.avi';   
Video = VideoReader(fileName);  
numFrames = Video.NumberOfFrames;  
frame = read(Video,1);  
%% 用第一帧图像数据初始化背景模型
alpha   = 0.03;     %背景建模alpha值  
stdInit = 20;       %初始化标准差  
varInit = stdInit * stdInit ;    %初始化方差  
lamda   = 2.5*1.2 ; %背景更新参数   
[h,w] = size(frame);%提取第一帧图像的高度和宽度  
w = w/3;  %彩色图像RGB，所以需要除以3  
for i=1:h  
    for j=1:w  
        pixel_R = frame(i,j,1); pixel_G = frame(i,j,2);  pixel_B = frame(i,j,3);  
        %期望图像为原图,背景
        pixel_uR = pixel_R;  pixel_ug = pixel_G;  pixel_ub = pixel_B;  
        %前景图像初始化为0  
        pixel_dr = 0;  pixel_dg = 0;  pixel_db = 0;  
        %标准差 
        pixel_stdr = stdInit;  pixel_stdg = stdInit;  pixel_stdb = stdInit; 
        %方差
        pixel_varr = varInit;  pixel_varg = varInit;  pixel_varb = varInit;  
          
        frame_u(i,j,1:3)   = [pixel_uR pixel_ug pixel_ub];  
        frame_d(i,j,1:3)   = [pixel_dr pixel_dg pixel_db];  
        fram_std(i,j,1:3)  = [pixel_stdr pixel_stdg pixel_stdb];  
        frame_var(i,j,1:3) = [pixel_varr pixel_varg pixel_varb];       
    end  
end   
%% 单高斯背景更新  
 for k = 1 : 5%numFrames % 读取帧数据  
     frame = read(Video,k);  
     for i=1:h   
         for j=1:w  
              pixel_R = frame(i,j,1);   pixel_G = frame(i,j,2);  pixel_B = frame(i,j,3);  
              %期望图像(背景),初始化为第一帧图  
              pixel_uR = frame_u(i,j,1);  pixel_ug = frame_u(i,j,2);  pixel_ub = frame_u(i,j,3);  
              %前景图像，初始为0 
              pixel_dr =  frame_d(i,j,1);  pixel_dg =  frame_d(i,j,2);  pixel_db =  frame_d(i,j,3); 
              %标准差  
              pixel_stdr =  fram_std(i,j,1);  pixel_stdg =  fram_std(i,j,2);  pixel_stdb =  fram_std(i,j,3);  
              %方差   
              pixel_varr = frame_var(i,j,1);  pixel_varg = frame_var(i,j,2);  pixel_varb = frame_var(i,j,3); 
              %|I-u|<lamda*std时认为是背景，进行背景更新  
              if(  (abs(pixel_R-pixel_uR)<lamda*pixel_stdr) &&...
                   (abs(pixel_G-pixel_ug)<lamda*pixel_stdg) &&...
                   (abs(pixel_B-pixel_ub)<lamda*pixel_stdb)      )  
  
                  %更新期望，u=(1-alpha)*u+alpha*1  
                  pixel_uR = (1-alpha)* pixel_uR + alpha * pixel_R;  
                  pixel_ug = (1-alpha)* pixel_ug + alpha * pixel_G;  
                  pixel_ub = (1-alpha)* pixel_ub + alpha * pixel_B;     
                  %更新方差var=(1-alpha)*var+alpha*(I-u)^2  
                  pixel_varr = (1-alpha)*pixel_varr + alpha*(pixel_R-pixel_uR)^2;  
                  pixel_varg = (1-alpha)*pixel_varg + alpha*(pixel_G-pixel_ug)^2;  
                  pixel_varb = (1-alpha)*pixel_varb + alpha*(pixel_B-pixel_ub)^2;    
                  %更新标准差  
                  pixel_stdr = sqrt(double(pixel_varr));  
                  pixel_stdg = sqrt(double(pixel_varg));  
                  pixel_stdb = sqrt(double(pixel_varb));  
                  %图像内容更新  
                  frame_u(i,j,1:3) = [pixel_uR pixel_ug pixel_ub];   
                  fram_std(i,j,1:3) = [pixel_stdr pixel_stdg pixel_stdb];  
                  frame_var(i,j,1:3) = [pixel_varr pixel_varg pixel_varb];         
              else  
                pixel_dr =  pixel_R -  pixel_uR;  
                pixel_dg =  pixel_G -  pixel_ug;  
                pixel_db =  pixel_B -  pixel_ub;  
                frame_d(i,j,1:3) = [pixel_dr pixel_dg pixel_db];  
              end  
         end  
     end  
     figure(2*k-2)  %查看每一帧循环下来的结果 
     imshow(frame_u); %背景
     figure(3*k-1)
     imshow(frame_d); %前景
     figure(3*k)  %先腐蚀后膨胀
     disk = strel('disk',1); 
     frame_d = imdilate(imerode(frame_d,disk),disk),disk;
     imshow(frame_d); %前景
 end