1. An image synthesis and communication apparatus comprising: imaging means for inputting images in time series; image storing means for storing the images inputted from the imaging means; feature point extracting means for extracting a point of a large luminance change from an image of a current frame, as a feature point; search range determining means for determining a predetermined region of an image of a subsequent frame, as a search range for a correlation calculation; correlation calculating means for obtaining correlations between the feature point and pixels in the search range; image synthesizing means for synthesizing an image on the basis of a motion amount obtained from the correlation calculating means; image transmitting means for transmitting an image obtained from the image synthesizing means; and image receiving means for receiving the image transmitted from the image transmitting means.