Hi Gregor,
[...] > Now I'm wondering if changing the runtime dependency to "graphicsmagick-imagemagick-compat | imagemagick" would achieve the same while allowing the user to choose (or keep) one of the two implementations?
good point! I noticed that imagemagick contains mogrify-im6.q16, but missed that it makes that available as mogrify via the alternatives system.
Since graphicsmagick uses "gm" and ...-compat is "just" a compatiblity package, I'm even considering using "imagemagick | imagemagick-6.q16hdri | graphicsmagick-imagemagick-compat" (different order plus ...hdri variant).
Best regards, Joachim