matlab呼叫攝像頭運用差幀法實作雙物體跟蹤

差幀法是在靜止背景下實作運動物體追蹤的一種簡單的方法，主要利用兩張二值影像的差值來實作對運動物體的追蹤，本文基于插幀法，通過適當的處理得到兩個運動物體分布的區域，從而實作對雙運動物體的追蹤，

vid = videoinput('winvideo', 1, 'YUY2_640x480');
set(vid, 'TriggerRepeat', 1000);
                          % 設定攝像頭的屬性（具體引數可以查閱百度）
set(vid, 'FramesPerTrigger', 1);
set(vid, 'ReturnedColorspace', 'rgb');
vid.FrameGrabInterval =2;                            %抓取時間間隔
vid_src=getselectedsource(vid);                      %add
set(vid,'Tag','motion ');                            %add
set(gcf,'doublebuffer','on');                        %add
 
%set(vid, 'FrameGrabInterval', 5);%also OK
%start the video aquisition here
start(vid)；

若不知電腦攝像頭的引數可用下列代碼查詢：

% win_info=imaqhwinfo('winvideo');
% d_win_info=imaqhwinfo('winvideo',1);
% d_win_info.SupportedFormats

%初始化，為作出運動軌跡做準備
i=1;
t=1;
while(vid.FramesAcquired<=100)        %100為拍攝的總幀數，可根據需要自行調整
    % Get the snapshot of the current frame
             %data = getsnapshot(vid);
    data=getdata(vid,2);%從攝像頭中截取2張圖片
    diff_im=imabsdiff(data(:,:,:,2),data(:,:,:,1));%將兩張圖片做差
    
    
    % Convert the resulting grayscale image into a binary image.
    diff_im = im2bw(diff_im,0.18);
    if sum(diff_im(:,:))==0                        %若無運動物體則繼續while回圈
        continue;
    end
    % Remove all those pixels less than 300px
    bw = bwareaopen(diff_im,300);       %從二值影像中洗掉小于300個像素點的連通區域
    rows = size(bw, 1);                 %pixels的第1維即為視頻畫面的行數
    cols = size(bw, 2);
   
    
    %尋找兩個上下左右邊界

    for row=1:rows                  %上部分邊界
        for col=1:cols
            if diff_im(row,col)>0.5
                top1=row;
                break;
            end
        end
        if diff_im(row,col)>0.5
          break;      
        end
    end
    
    for row=top1:rows
        for col=1:cols
            if row==rows
                button1=row;
                break;
                break;
            else
                if diff_im(row,col)>0.5&&(sum(diff_im(row+1,:))==0)
                    button1=row;
                    break;
                end
            end
        end
        if row==480||diff_im(row,col)>0.5&&sum(diff_im(row+1,:))==0
            break;
        end
    end
    for col=1:cols 
        for row=top1:button1       
            if diff_im(row,col)>0.5
                right1=col;
            end
        end
    end
    
     for col=cols:-1:1 
        for row=top1:button1       
            if diff_im(row,col)>0.5
                left1=col;
            end
        end
     end
     
                                    %下部分邊界
   top2=0;                                 
    for row=button1+1:rows
        for col=1:cols
            if diff_im(row,col)>0.5
                top2=row;
                break;
            end
        end
        if diff_im(row,col)>0.5
            break;
        end
    end
    if top2
        for row=top2:rows
            for col=1:cols
                if row==rows
                    button2=row;
                else if diff_im(row,col)>0.5&&sum(diff_im(row+1,:))==0
                        button2=row;
                        break;
                        break;
                    end
                end
            end
        end
        for col=1:cols
            for row=top2:button2
                if diff_im(row,col)>0.5
                    right2=col;
                end
            end
        end
        
        for col=cols:-1:1
            for row=top2:button2
                if diff_im(row,col)>0.5
                    left2=col;
                end
            end
        end
    end



   
    
    
    
    wd1 = right1-left1;
    hg1 = button1-top1;
    widt = wd1/2;
    heit = hg1/2;
    cenx1 = left1+widt;
    ceny1 = top1+heit;
    

    % 顯示并標記
    figure(1);
    % Display the image
    imshow(data(:,:,:,2))%add(:,:,:,2)
    hold on
    if wd1>0&&hg1>0
         rectangle('Position',[left1 top1 wd1 hg1], 'EdgeColor', 'r', 'LineWidth', 2);
         plot(cenx1,ceny1, 'm-.s','MarkerSize',7, 'LineWidth', 1) 
        if cenx1>0&&ceny1>0
             x(i)=cenx1;
             y(i)=ceny1;
             i=i+1;
        end
    end
   if ~isempty(top2)&&top2      %經實驗可知若影像不動，top2為空，以下操作會出現語法錯誤
    
        wd2 = right2-left2;
        hg2 = button2-top2;
        widt = wd2/2;
        heit = hg2/2;
        cenx2 = left2+widt;
        ceny2 = top2+heit;
   
        % 顯示并標記
        figure(1);
        % Display the image
        imshow(data(:,:,:,2))%add(:,:,:,2)
        hold on
        if wd2>0&&hg2>0
             rectangle('Position',[left2 top2 wd2 hg2], 'EdgeColor', 'r', 'LineWidth', 2);
             plot(cenx2,ceny2, 'm-.s','MarkerSize',7, 'LineWidth', 1) 
            if cenx2>0&&ceny2>0
                 m(t)=cenx2;
                 n(t)=ceny2;
                 t=t+1;
            end
        end

   end
   






end

hold on
plot(x,y);
plot(m,n);

hold off
% 關閉攝像頭
stop(vid);

% Flush all the image data stored in the memory buffer.
flushdata(vid);

最后配上一張簡陋的效果圖：