Images in a DokuWiki entry is by default aligned to th e left. Here’s the tag to insert image in a DokuWiki entry;

{{.:center-image/dokuwiki-admin-configuration-manager-anti-spam-settings.png|}}

To align the image to the center, add space to both left and right of the image tag in DokuWiki syntax as the following;

{{ .:center-image/dokuwiki-admin-configuration-manager-anti-spam-settings.png |}}