1. An optical pointing system comprising: at least one reference beacon; an image sensor configured to capture an image frame containing a beacon image associated with the at least one reference beacon; a storage unit configured to save image data of at least one object image in the image frame; and a processing unit configured to sequentially process every pixel of the image frame within a scan period for identifying the at least one object image, and when a current object image is identified within the scan period and a previous object image exists in the image frame, calculate an image distance between the current object image and the previous object image to release a part of the image data associated with the at least one object image according to the calculated image distance, wherein the current object image and the previous object image are separated from each other without being connected by any object image in the image frame.