researching how to generate art with a computer quickly in text form (pbm) and save it in a better format (webp/png/jpg):

This is what I landed on, using the magick command, my_program outputs to stdout, magick reads from stdin using the -:

my_program | magick - output.webp

https://imagemagick.org/script/formats.php

I plan to use this in further weeks to draw rectangles, circles and other things in different configurations on bitmaps using only integer-based math.