A light-control unit (173) compares an average value which is input from an average-brightness measurement unit (132) with a reference brightness value, and determines the brightness of the light-control area of the acquired image information. The light-control unit (173) calculates light-emitting time of an illuminating unit (120) based on the comparison result as light-control information, and outputs the calculated light-emitting time to a timing generator (171). The calculated light-emitting time is stored as light-emitting time (191) in a register (190). A transmission-signal generator (131) generates a transmission signal to be used for wirelessly transmitting the acquired image information to an outside. A light-emitting time attachment unit (133) reads the light-emitting time (191) stored in the register (190) via a control unit 170, and attaches the light-emitting time (191) to the transmission signal generated by the transmission-signal generator (131). A transmission processing unit (140) performs a process to wirelessly transmit the transmission signal.
