I further realised that an Iphone, with a nice colour screen and the zoomy inny outy stuff, would be a good way of showing it. But gphoto2 seemed unable to send the photo to the Iphone over MTP ("operation not supported"); transferring the photo to the only PC with Itunes on (which is the laptop, outside the firewall), only to wrestle with the Itunes UI to work out how to send a photo, didn't seem appealing; and though t'internet alleged it was possible to store photos without Itunes, it seemed like a big hassle.