title: Creating black/white squares using matlab
body: <p>I'have to create these three simple squares in Matlab:</p>
  
  <p><img src="https://i.stack.imgur.com/uSF6q.png" alt=""></p>
  
  <p>Can anyone give me a hand? I know how to use images by openning them (imread) but I dont know how to create them on matlab from 0.</p>