It is not possible to download a SmartFrame to a computer, tablet or mobile device.
Conventional images are files that you can save to your computer or send by email. This makes them vulnerable to theft, as the moment the image is displayed online, it’s very easy to download it.
By contrast, SmartFrames are not files. The original image file you upload is kept safe behind the firewall, and the SmartFrame counterpart is streamed to the user, quickly and always in the correct resolution. This is why you cannot download SmartFrames, and have to embed them instead.