title: Python MemoryError when not really out of memory?
body: <p>I am trying to perform mean scaling on a bunch of images (>40k).  When I read in the images, of size (3,256,256), into an np array, memory usage is at %40 (out of 60 GB, checked using htop). However, when I run arr.std(), the program crashes and gives a MemoryError, even though usage is still at %40.  </p>
  
  <p>Any thoughts on what might be wrong?</p>