1. An apparatus configured to decode an image, the apparatus comprising: an entropy decoder which extracts an intra prediction mode of a current block from a bitstream, the intra prediction mode indicating a particular direction among a plurality of directions, wherein the particular direction is indicated by using one of a dx number in a horizontal direction and a fixed number in a vertical direction, or a dy number in the vertical direction and a fixed number in the horizontal direction, wherein dx and dy are integers; and an intra prediction performer which determines a number of neighboring pixels located on a left side of the current block or an upper side of the current block, determines a location of one or more neighboring pixels among the neighboring pixels located on the left side of the current block or the upper side of the current block using a bitwise shift operation based on a position of a current pixel (j, i) and one of the dx or dy numbers indicating the particular direction, where j and i are integers; and performs intra prediction on the current block using the number of neighboring pixels and the location of the one or more neighboring pixels, wherein the intra prediction performer obtains a value of the current pixel using the number of neighboring pixels, and the location of the one or more neighboring pixels, wherein: the location of the one or more neighboring pixels located on the upper side of the current block is determined based on i*dx>>m, where i is a position of the current pixel in the vertical direction, dx is the dx number in the horizontal direction, m is related to the fixed number in the vertical direction, and >> is the bitwise shift operation, and the location of the one or more neighboring pixels located on the left side of the current block is determined based on j*dy>>n, where j is a position of the current pixel in the horizontal direction, dy is the dy number in the vertical direction, and n is related to the fixed number in the horizontal direction, wherein the bitwise shift operation operates on a binary representation of i*dx and j*dy.