So I have a ton of 825×1125 images ( (>300, in png format but I can make jpegs). I need to create a printable PDF with them (to print playing card prototypes). They have to be in a 3×3 grid pattern in the Letter format (they're meant for 300dpi).
I'm pretty sure I can batch resize them beforehand if it helps.
I'm guessing you can do this with convert or something but for the life of me I can't figure it out.