Using ezp5, and ImageMagick, attempting to apply a watermark through eZImageEditor will yield a server error. Looking at the traffic through Firebug or the Chrome developer tools, the response for the POST request for the operation is the following:

Request: POST
http://ezp5.filipe/ezwebin_site_admin/ezie/tool_watermark?ezxform_token=af999d80a961a15fabc7ad6a2bfd6eff&history_version=0&image_id=227&image_version=3&key=14%2F227-3&module_url=%2Fezwebin_site_admin%2Fezie&selection%5Bh%5D=65&selection%5Bw%5D=101&selection%5Bx%5D=10&selection%5By%5D=669&watermark_image=elephpant.png

Response: 500 Internal Server Error
TwigBundle:Exception:error500.html.twig

At this point, the editor displays an error message and quits back to the object edit form. This issue is not present using GD, or if I bypass Symfony's routing with a host pointing directly to my legacy directory.

Steps to reproduce

1. Setup an ezp5 installation with ImageEditor using ImageMagick
2. Create a new Image object
3. Edit it through the image editor, and attempt to place a watermark