1. A temporal smoothing apparatus for synthesizing an intermediate image from a first and a second image, the apparatus comprising: a disparity vector estimator which receives previous images and present images of the first image and the second image and generates a previous disparity vector and a present disparity vector for every image block of a predetermined size; and a temporal smoothing unit which receives the previous and present images of one image of the first image and the second image, and the previous and present disparity vectors of the one image, and generates a temporally-smoothed disparity vector of the one image, wherein the temporal smoothing unit generates the temporally-smoothed disparity vector of the one image by adjusting the previous and present disparity vectors of the one image on the basis of a mean absolute difference (MAD) between the previous image and the present image of the one image.