1. An image processing device comprising: an image sensor array including a plurality of image sensors configured to take a plurality of images of a first object and a second object; an image pre-processing circuit coupled to the image sensor array and configured to receive the images and process the images to generate a first shift image and a second shift image associated with the first object and the second object; a depth information generator coupled to the image pre-processing circuit and configured to generate depth information according to the first shift image and the second shift image, wherein the depth information includes first distance information associated with the first object; a focusing circuit coupled to the image pre-processing circuit and the depth information generator and configured to generate a first pair of focused images according to the depth information, the first shift image, and the second shift image, wherein the first pair of focused images have the first object focused thereon; a three-dimensional image synthesizer coupled to the focusing circuit and configured to generate a three-dimensional image according to the first pair of focused images and an occlusion location information; a two-dimensional image synthesizer coupled to the focusing circuit and configured to generate a two-dimensional image according to the first pair of focused images; an occlusion detector coupled to the depth information generator, the focusing circuit and the three-dimensional image synthesizer and configured to generate the occlusion location information corresponding to the first pair of focused images according to the depth information and the first pair of focused images; and a display unit coupled to the three-dimensional image synthesizer and configured to display the three-dimensional age in a stereoscopic three-dimensional way.