An imaging device for transmitting a still image file includes an interface unit and a conversion unit. The interface unit receives, from an external device via a connection between the imaging device and the external device, a control command including first data designating a still image file to be transmitted, second data designating a file type, and third data designating a resolution. The conversion unit converts the still image file designated by the first data into a still image file having the resolution designated by the third data if the file type designated by the second data is a predetermined file type. If the file type designated by the second data is not the predetermined file type, the interface unit transmits, to the external device via the connection between the imaging device and the external device, the still image file at its original resolution.