title: Stride on image using Opencv C++
body: <p>I am on windows and use opencv 2.4.2 on C++.
  I read an image with <code>imread</code> and put it in a Mat object. 
  After that, i get a pointer on the raw data using the function <code>ptr</code> of the Mat class.
  I would like to know how works <code>imread</code> when the image contains stride. Is there stride in the data of the Mat or only data of pixels ? </p>
  
  <p>Additional information: I need the raw data because I am using a code written with array and I don't want to change it for the Mat class.</p>