Yet you picked a specialized tool "imagemagick" (made for working with images), and want to drive it by another specialized tool (the shell, made for file and process management).
Since you want "mindset oblivious" tools why not write everything from scratch, in C?
Because imagemagick, julia and other specialized programs already provide the advanced algorithms that I need. Unfortunately, julia is not a good team player.
What it excels at is rapidly solving the same problem many times within one REPL/interpreter (since after the first time the code will be compiled), or for longer computations where the overhead of the initial compilation does not matter.
It would be great if it could also get fast at the use case you are interested in, but this isn’t currently what it excels at.
Or, you know, Julia is not specialized for your use case.