-debug <events>
enable debug printout
The events parameter specifies which events are to be logged.
It can be either None, All, or a comma-separated list consisting
of one or more of the following domains: Annotate, Blob, Cache,
Coder, Configure, Locale, Render, Resource, Transform, X11, or
User. For example, to log cache and blob events, use
convert -debug "Cache,Blob" rose: rose.png
The "User" domain is normally empty, but developers can log
"User" events in their private copy of ImageMagick.
Use the -log option to specify the format for debugging output.
Use +debug to turn off all logging.
Lass doch mal die Ausgabe davon sehen. Klingt aber irgendwie nach einer fehlerhaften (oder unzureichenden) ImageMagick Installation.