A method of performing depth estimation, the method comprising: estimating, at a higher spatial resolution of images, a global disparity map based on disparity between corresponding pixels of a stereo disparity map obtained from images forming a stereo image set associated with a passive depth estimation technique and an active depth map associated with an active depth estimation technique, wherein the disparity is estimated within a restricted range determined based on a disparity previously estimated between a stereo disparity map and an active depth map corresponding to a lower spatial resolution of the said images and map.