title: Android images for different screens
body: <p>I'm developing an Android app which uses a number of images and icons.
  In order to prevent the device to work hard and run out of memory, I want to create multiple images for each screen size.<br>
  My question is: Do I need to measure <strong>exactly</strong> what dp I want and then convert it to pixels?<br>
  Sometimes it's hard to know exactly the size of the image in dp- for instance if it's width is <code>match_parent</code> and there's margin etc.  </p>
  
  <p>How can I solve this problem?<br>
  I would be glad for guidance on how to do this the best way.</p>