Turn files into images and back. Lossy image compression will of course render the image useless.
imagify <file> <outputfile>
Imagify will encode if file does not have a .png extension, and will decode if it does. Hence imagify image.png doc.pdf will decode, and imagify doc.pdf image.png will encode.
Run make.
Or alternatively run gcc -I . main.c stb_image/stb_image.h stb_image/stb_image_write.h -lm -o imagify