title: Save extracted features opencv
body: <p>I have extracted the SIFT feature descriptors in OpenCV.. Next step to me is to train an SVM but before that step, I think I need to save the extracted features in a file, in order to train these features... </p>
  
  <p>So my questions are: 1- how to save these matrices?
  2- I would like to know what to do about the features, I extracted features for one image, but I need to extract features for many images in different pose for one object (e.g cola) and save them in one file...</p>
  
  <p>Do you have any idea, how to do that in opencv? </p>
  
  <p>Thank you... </p>