Lots of packages that either generate or manipulate images might use ImageMagick. For example, I'm pretty sure that Gallery3, NextCloud, and Wordpress can all be configured to use ImageMagick if it is available.
You may be able to tell what package needs/wants ImageMagic using
rpm -q --whatrequires ImageMagick6-libs.x86_64
However, the apps listed above can be configured to use imagemagick without having it as a dependency for the core application. Try searching your web app locations (ibays and maybe /opt) for the string 'imagemagick' to see what pops up:
# cd /home/e-smith/files/ibays/wordpress/html
# grep -ril imagemagick *
wp-includes/class-wp-image-editor-imagick.php
The php file my search found reminded me that ImageMagick is used by the PHP module "imagick" - so you do some searches for that too.