A method of coding and transmitting moving pictures includes the steps of coding an extended background image, coding parameters indicative of an image area within the extended background image, coding a foreground picture that is to be composed with a background picture corresponding to the image area indicated by the parameters, coding a defocus value indicative of an extent to which the background picture should blur, and transmitting the coded extended background image, the coded parameters, the coded foreground picture, and the coded defocus value as a data stream to a decoder side. Coding and transmitting of the defocus value makes it possible to defocus the background picture at the decoder end, thereby producing a composed image of the background picture and the foreground picture having natural appearance.