how to detect door in image from vertical lines and gap of door(gap between floor and door)

like in this image

i have this code but this is not working for me

[filename, pathname] = ... uigetfile({'*.jpg';'*.bmp';'*.png';'*.*'},'File Selector'); I=imread([pathname,filename]); rotI=rgb2gray(I); %rotI = imrotate(J,33,'crop'); fig1 = imshow(rotI); BW = edge(rotI,'canny'); figure, imshow(BW); [H,theta,rho] = hough(BW); figure, imshow(imadjust(mat2gray(H)),[],'XData',theta,'YData',rho,... 'InitialMagnification','fit'); xlabel('\theta (degrees)'), ylabel('\rho'); axis on, axis normal, hold on; colormap(hot) P = houghpeaks(H,5,'threshold',ceil(0.3*max(H(:)))); x = theta(P(:,2)); y = rho(P(:,1)); plot(x,y,'s','color','black'); lines = houghlines(BW,theta,rho,P,'FillGap',5,'MinLength',7); figure, imshow(rotI), hold on max_len = 0; for k = 1:length(lines) xy = [lines(k).point1; lines(k).point2]; plot(xy(:,1),xy(:,2),'LineWidth',2,'Color','green');

   % Plot beginnings and ends of lines
   plot(xy(1,1),xy(1,2),'x','LineWidth',2,'Color','yellow');
   plot(xy(2,1),xy(2,2),'x','LineWidth',2,'Color','red');

   % Determine the endpoints of the longest line segment
   len = norm(lines(k).point1 - lines(k).point2);
   if ( len > max_len)
      max_len = len;
      xy_long = xy;
   end
end

% highlight the longest line segment plot(xy_long(:,1),xy_long(:,2),'LineWidth',2,'Color','red');

result of this code is like this i need to know how to improve this and what is further procedure