1. An image synthesis system for a vehicle comprising: a first camera disposed on the vehicle and shooting at least a first image of at least a first portion of an outward periphery of said vehicle; a second camera disposed on the vehicle and shooting at least a second image of at least a second portion of the outward periphery of said vehicle, wherein the second image and the first image have an overlapping region; an image processing device comprising: a defining component operable to define the first image into a plurality of first points each having a first residual error, and defining the second image into a plurality of second points each having a second residual error; and, a synthesis component operable to synthesize the first image and the second image and output a third image, wherein each point of the overlapping region of the third image is selected from one of the plurality of first points and a spatially corresponding one of the plurality of second points responsive, at least in part, to a determination of which point has lower residual error to thereby be shown in the third image; and a display device for displaying at least the third image.