title: Java library to compare image similarity
body: <p>I spent quite some time researching for a library that allows me to compare images to one another in Java.</p>
  
  <p>I didn't really find anything useful, maybe my GoogleSearch-skill isn't high enough so I thought I'd ask you guys if you could point me into a direction of where I could find something like this.</p>
  
  <p>Basically what I want to do is to compare two images with each other and get a value of how much the two are similar. Like a percentage or so.</p>
  
  <p>I hope you guys have something I can use, I wouldn't know how to write something like that myself...</p>
  
  <p>PS: It doesn't necessarily has to be in Java, that's just the environment my app will be running.</p>