In addition ImageMagick, you can use the PECL ext/imagick extension (Omeka 2.2 and above) or the PHP GD extension (Omeka 2.3 and above). Instructions for configuring these options are in the linked documentation.
In addition ImageMagick, you can use the PECL ext/imagick extension (Omeka 2.2 and above) or the PHP GD extension (Omeka 2.3 and above). Instructions for configuring these options are in the linked documentation.