车道线的线方程

Question

我必须在二进制iamge中找到每个通道的中点，我写了一个代码，但这太长了，当我改变道路的图片时它会给出错误。我必须保存每个车道的中点，然后通过找到斜率和截距，我必须在该二进制图像上绘制线条。  这是代码

    x=imread('C:\users\guest\documents\matlab\1.png');
    [q,r]= size(x);
    n4=zeros(q,r);
    midpoint= zeros (720,2); % Array to store midlle points of road lane.

    % finding mid points of both lanes.
     for n3=540:720
       s=x(n3,:);
       startIndex =1;                                                                                    
       lastIndex =1280;                                                                                 
       pixelsRow =s;  
       FirstWhiteStart=0; FirstWhiteEnd=0; SecondWhiteStart=0; SecondWhiteEnd=0;

       for k=1:1280
            if (pixelsRow(k) == 1)&&(FirstWhiteStart == 0)                                         
            FirstWhiteStart =k;
            elseif (pixelsRow(k)==0)&&(FirstWhiteStart>0)&&(FirstWhiteEnd==0)             
            FirstWhiteEnd=k-1;
            elseif (pixelsRow(k)== 1)&&(FirstWhiteEnd>0)&&(SecondWhiteStart==0)
            SecondWhiteStart=k;
            elseif (pixelsRow(k)==0)&&(SecondWhiteStart>0)&&(SecondWhiteEnd==0)          
            SecondWhiteEnd=k-1;
            end
            end
            m1=(FirstWhiteStart + FirstWhiteEnd)./2;  % first lanes middle point
            m1r = round(m1);
            if (m1r <= 1)

             mp= sub2ind(size(midpoint),n3,1);
             midpoint(mp) = 0;

              elseif (m1r > 1)
              indices = sub2ind(size(n4),n3,m1r);
              n4(indices) = 1;
              if (m1r >=640)
              mp= sub2ind(size(midpoint),n3,2);
              midpoint(mp) =  m1r;
              elseif (m1r <= 640)
              mp= sub2ind(size(midpoint),n3,1);
              midpoint(mp) = m1r;
              end 
          end  

          m2=(SecondWhiteStart + SecondWhiteEnd+1)./2;  % second lane middle point.
          m2r = round(m2);

           if (m2r <= 1)
            indices = sub2ind(size(n4),n3,m2r);
           n4(indices) = 0;
           mp= sub2ind(size(midpoint),n3,1);
           midpoint(mp) = 0;


            elseif (m2r > 1)
            indices = sub2ind(size(n4),n3,m2r);
            n4(indices) = 1;
            if (m2r >=640)
            mp= sub2ind(size(midpoint),n3,2);
            midpoint(mp) =  m2r;
            elseif (m2r <=640)
            mp= sub2ind(size(midpoint),n3,1);
            midpoint(mp) =  m2r;
            end 
              end
              end

           pairpoints = nchoosek([540:720],2);

           var1 = zeros (16290,2);                        % array to store variables a and b of first lane. 
           var2 = zeros (16290,2);                        % array to stote variables a and b of second lane.

          % calling middle points previously stored in array,putting in equation.
           for n = 1 : 16290

            x1 = pairpoints(n,1);                           %value of frst row
            x2 = pairpoints(n,2);                           %value of 2nd row 
            y1 = midpoint (pairpoints(n,1), 1);             %rows of midpoint matrix are                   specified from pairpoints location martix
            y2 = midpoint (pairpoints(n,2), 1);
            z1 = midpoint (pairpoints(n,1), 2);
            z2 = midpoint (pairpoints(n,2), 2);

            a1 = (y2 - y1) ./ (x2 - x1);
            a2 = (z2 - z1) ./ (x2 - x1);


             b1=(((x2)*(y1)) - (x1)*(y2)) ./ (x2 - x1);
             b2=(((x2)*(z1)) - (x1)*(z2)) ./ (x2 - x1);

                  % variables a and b of first lane.
             line = sub2ind(size(var1),n,1);
             var1(line) = a1;
                line = sub2ind(size(var1),n,2);
                  var1(line) = b1;

              % variables A and b of second lane.
             line = sub2ind(size(var2),n,1);
             var2(line) = a2;
              line = sub2ind(size(var2),n,2);
              var2(line) = b2;

              end

              v11=round(var1);
              v22=round(var2);

              % eleminating zeros from array. 
             [i,j] = find(v11);

             a1 = v11(i,1);
             a1= a1(a1~=0);
             b1 = v11(i,2);
             b1= b1(b1~=0);

             a11=median(a1)
             b11=median(b1)

            % eleminating zeros from array. 
            [k,l] = find(v22);

             row = i;
             a2 = v22(k,1);
             a2= a2(a2~=0);
             b2 = v22(k,2);
             b2= b2(b2~=0);

              a22=median(a2)
              b22=median(b2)

                %assign variables
             lin=zeros(720,2);

              % implementation of final line equation.
            for x1 = 1:720   

            % equation becomes (w = eh + f) as actual was (y = ax + b)
           y1 = (a11 * x1) + b11;
           y2 = (a22 * x1) + b22;


           col = sub2ind( size(lin),x1,1);         % equation for first lane.
           lin(col)= y1;

           col = sub2ind( size(lin),x1,2);         % equation for second lane.
          lin(col)= y2;

            end

          array=lin;

          r= 1:720;
          c= 1:1280;
           x(r,c)= 0;
          imshow(x);
         imwrite(x,'a.png');

          image =imread('C:\users\guest\documents\matlab\a.png');

         for r1 = 1:720
            for  c = 1:2;
                 if array(r1,c) < 0;
                  lin(r1,c) = abs (array(r1,c));
                   image(r1,lin(r1,c))= 0;

                 elseif array(r1,c) > 0;
                    image(r1,lin(r1,c))= 1;

                 end
            end
        end
        imshow(image)