A method for decoding a current block of a digital image. The method includes: decoding coefficients of the current block; and transforming the current block into a decoded block, by implementing a first sub step to produce an intermediate block, that applies to the column and row vectors of the current block, and a second substep to produce a block of pixels that applies to the row and column vectors of the intermediate block, resulting from the first substep; and rebuilding the image from the decoded block. At least one of the first and second substeps includes, for an input row or column vector: forming a first subvector of size K