How to find width and height of bounding box after using vision.blobanalysis?

For example, after this code,

    hsrc = vision.VideoFileReader('mv2_001.avi');

    hfg = vision.ForegroundDetector(...
       'NumTrainingFrames', 10, ... % 5 because of short video
       'InitialVariance', 30*30); % initial standard deviation of 30

   hblob = vision.BlobAnalysis(...
       'CentroidOutputPort', false, 'AreaOutputPort', false, ...
       'BoundingBoxOutputPort', true, ...
       'MinimumBlobAreaSource', 'Property', 'MinimumBlobArea', 250);

   hsi = vision.ShapeInserter('BorderColor', 'White');

   hsnk = vision.VideoPlayer();

     while ~isDone(hsrc)

     frame  = step(hsrc);
     fgMask = step(hfg, frame);

     bbox   = step(hblob, fgMask);

     out    = step(hsi, frame, bbox); % draw bounding boxes around cars

     step(hsnk, out);
      % view results in the video player
    end
release(hsnk);
release(hsrc);

I want to track objects whose bounding box width is less than certain threshold. Pease help.

Answer 1

[Dima Lisin]

In your example bbox is an M-by-4 matrix containing the bounding boxes represented as [x y w h]. First, you should delete the rows in which 3-rd element (the width) is less then your threshold. To learn how to track the blobs from frame to frame take a look at this example .