@powersoffour However, that doesn't tell the *entire* story, because the PIC data is already a way more efficient format than the raw 320×190 4-bit images they represent. If you squash two 4-bit pixels into each byte, then it takes 30,400 bytes for each full background.
So, on *average* the savings is closer to a compression ratio of 6.6∶1 (or around a 84.8% reduction) over totally uncompressed EGA screens. Which is pretty impressive overall.