Image styles: Does not work with large images The image styles, thumbnails and so on, are not created on my Drupal 7 site, when the original file is bigger than 5 MB. I did not find any error message in the log messages and the v-server, the site is hosted on, seems to have sufficient power to convert large files: I have 4 GHZ CPU and 4 GB RAM. 
The original file is uploaded correctly and I have double checked the file permissions.

Does anybody know, what to do?
I installed Imagemagick and now everything works as expected.