1. A method for decoding a coded image on a block-by-block basis, the method comprising: decoding a reconstructed image from the coded image; and performing deblocking filtering on a reconstructed block included in the reconstructed image, wherein the deblocking filtering includes: judging whether or not to apply a deblocking filter to pixels adjacent to a first boundary between a first reconstructed block and a second reconstructed block, each of the first reconstructed block and the second reconstructed block including two half segments which are separated along a line that is perpendicular to the first boundary and having a same size as the reconstructed block in the reconstructed image, wherein, in said judging, a first judgment is performed for a pair of adjacent half segments on both sides of the first boundary using only pixels in the pair of adjacent half segments, and a second judgment is performed for the other pair of adjacent half segments on both sides of the first boundary using only pixels in the other pair of adjacent half segments.