1. A portable electronic device with 3 D image capture capability, comprising: a first image capture module and a second image capture module; a subject distance estimator, estimating a subject distance; and an image difference control mechanism, adjusting a distance between the first and second image capture modules based on the subject distance by moving at least one of the first and second image capture modules, wherein the first and second image capture modules capture a first image and a second image, respectively, to form a 3D image after the image difference control mechanism adjusts the distance between the first and second image capture modules.