IIIF Server Fatal Error Out of memory

First time user of the IIIF server. The installation worked like a charm.

But when adding a 12 MB jpeg media file via the Tiler uploader, I received the following error:

Fatal error: Out of memory (allocated 618659840) (tried to allocate 49152 bytes)
in (…)/modules/IiifServer/vendor/daniel-km/deepzoom/src/Deepzoom.php on line 572

upload_max_filesize is allready set to 64 MB
Omeka 1.3.0 with IIIF Server 3.5.14 and PHP 7.3

I have some 100MB+ digitized map that works fine. Can you set imagemagick (cli) as processor in the config of the module?

Changed the Image processor to ImageMagick (command line).

Received an indefinite Jobs Status In Progress with a [no log] entry.