Image processing device and method for simultaneously transmitting a plurality of pieces of image data obtained from a plurality of camera modules

Provided is a surveillance system including a communication module configured to receive a plurality of pieces of image data obtained by a plurality of camera modules, receive a multiple image data request from a client terminal, and transmit a multiple image data response including multiple image data to the client terminal; and a processer configured to generate the multiple image data by scaling the plurality of pieces of image data in response to the multiple image data request and combining a plurality of pieces of scaled image data, wherein the plurality of camera modules share one internet protocol (IP) address.