Tis the key to the city

I love my usb keys. I managed to store a single 487mg tiff image file on my old usb key (Eurythos) while i held another 230mg worth of files on my new usb key (Argentum). ~720mg of files on something fitting in my pocket is fun.

What tiff image file could possibly be that massive? Airphotos of Ottawa (about half of the city) at 1/8th the resolution. Yes, the normal airphotos of all of Ottawa are in the 30gig range.