I ran into the missing “.exe” problem with XAMPP on Windows. To use ImageMagick on both our XAMPP development server and Linux production server, I opted to make a core change for the XAMPP installation. In file
\application\libraries\Omeka\File\Derivative\Strategy\ExternalImageMagick.php
I changed:
const IMAGEMAGICK_CONVERT_COMMAND = 'convert';
to
const IMAGEMAGICK_CONVERT_COMMAND = 'convert.exe';