Is an camera an in put or out put device?

It accepts data, pixel information, millions of it. Input.

It displays data through the LCD. output.

Heck, it has its own processor. It's a computer by itself!

Then, if you connect it to a computer with a USB cable, it transforms to a mere storage device. Surprised? Connect one and check My Computer. The camera appears there as a Removable Storage Device or something to the tune of that. It's no longer a camera when that happens. It's only one big expensive card reader.