A communication apparatus measures a received signal strength indicator of a communication network and transmits the measured received signal strength indicator to an image pickup apparatus. The image pickup apparatus transmits, to the communication apparatus, any one of a thumbnail of selected image data, data obtained by compressing the selected image data, and the selected image data in a raw state in accordance with the received signal strength indicator of the received data of the communication network. The communication apparatus transfers the received image data for transfer to the communication network.