title: Cannot edit images in wordpress 3.8.1 in backend
body: <p>I cannot edit (crop, rotate, scale, ...) images in the back-end of WordPress, on my local machine with Apache it works fine. I checked the permissions of the image, they are set to 777.</p>
  <p>Is there a library which I need to install on the webserver?</p>
  <p>My WordPress version is 3.8.1.</p>