title: SIFT, HOG and SURF c++, opencv
body: <p>I have a simple question, which I want to know, what kind of libraries are available and can give good results for implementing SIFT, HOG(Histogram Oriented Gradient) and SURF in c++ or opencv?</p>
  
  <p>Hence: 1- Give me the link for the code if you can, which I will be so appreciated.
  2- If you know one of them or any kind of information to lead me to what I want, I will be so appreciated as well. </p>
  
  <p>Thanks </p>