1. A method for prediction in image encoding, comprising the steps of: receiving a plurality of candidates with respect to a current prediction target of an image, wherein the plurality of candidates are related to the current prediction target spatially or temporally; calculating a distortion-based cost of a first candidate in the plurality of candidates; and for each of the other candidates in the plurality of candidates, computing a data access availability and a data access requirement for calculating a distortion-based cost of a current candidate in the other candidates of the plurality of candidates; and if the data access requirement does not exceed the data access availability, calculating the distortion-based cost of the current candidate; otherwise, selecting the candidate with the minimum calculated distortion-based cost as a matched candidate for the current prediction target, wherein the data access availability and the data access requirement are represented respectively by the following: 
 BW Available =└CLK Available <<log 2 Bits BUS ┘>>3 
 BW Required =W curr ·H curr wherein BW Available and BW Required are respectively the data access availability and data access requirement expressed in terms of bandwidth; Bits Bus denotes a bandwidth of the system bus; and W curr and H curr are respectively a width and height of a region in the image associated with the current prediction target.