The superimposition unit 125 superimposes the display data generated by the display data generation unit 124 over the moving image data input to the image data input unit 122. In this case, the superimposition unit 125 performs processing for enhancing the visibility of the description 203 superimposed and displayed over the image, for example, processing of reducing the resolution of moving image data, processing on the display data so that each of portions determined to be a description portion is to be bordered and displayed, processing of changing the color of display data so that the color of each of portions determined to be a description portion is differentiated from the color of the background image (image based on moving image data), or the like.

The moving image data over which the display data is superimposed is supplied from the superimposition unit 125 to the image compression processing unit 126. The image compression processing unit 126 performs data compression encoding processing using the MPEG method, for example, on moving image data over which display data is superimposed, thereby generating encoded image data.

The encoded image data is directly supplied to the network interface 127 or is once recorded in the recording unit 128, reproduced at an appropriate timing, and supplied to the network interface 127. The network interface 127 transmits the encoded image data to the display devices 103-1 to 103-N through a wireless or wired network.