Detección de Rostro en matlab

vid = videoinput('winvideo',1,'YUY2_640x480');
 set(vid, 'FramesPerTrigger', Inf);
  set(vid, 'ReturnedColorspace', 'rgb')
    vid.FrameGrabInterval = 5;
     start(vid)
while(vid.FramesAcquired<=100)
   data = getsnapshot(vid);
     diff_im = imsubtract(data(:,:,1), rgb2gray(data));  
           diff_im = medfilt2(diff_im, [3 3]);
        diff_im = imadju  st(diff_im);
     level = graythresh(diff_im);
   bw = im2bw(diff_im,level);
 BW5 = imfill(bw,'holes');
bw6 = bwlabel(BW5, 8);
 stats = regionprops(bw6,['basic']);
   [N,M]=size(stats);
if (bw==0)
        break;
else
     tmp = stats(1);
for i = 2 : N
      if stats(i).Area > tmp.Area
        tmp = stats(i);
      end
end
  bb = tmp.BoundingBox;
   bc = tmp.Centroid;
    imshow(data)
     hold on
   rectangle('Position',bb,'EdgeColor','r','LineWidth',2)
 hold off
end
end
 stop(vid);
  flushdata(vid);