Yeah that sort of thing. I didn't know you could do that with a phone. I could buy a $10 cable and copy the images to a portable hard drive. Does the S4 have enough power to spin up a 750GB USB3 hard drive?
I've not tested with a spinning disk but from what I've read online no they don't have the juice to power one.
If you used a powered usb hub then you'd get around that issue though.