A method of decoding an image, comprising steps of: determining whether to apply a Wiener filter for interpolation filtering in a first block unit by using information about whether, for encoding the first block unit, the Wiener filter has been used for the interpolation filtering or not, wherein the information is transmitted from an encoder; if it is determined that the Wiener filter has been used for the interpolation filtering, performing the interpolation filtering on the reference picture by applying the Wiener filter to the reference picture; generating predicted samples from samples within the reference picture on which the interpolation filtering has been performed; generating reconstructed samples by adding residual samples and the predicted samples together; determining whether to apply the Wiener filter for loop filtering in a second block unit based on the information and at least one of whether sizes of a first block and a second block are same, whether one of the first and second blocks includes the other of the first and second blocks, and location relation of a boundary of the first block with respect to the second block, predicted samples of the first block being generated by applying the Wiener filter for the interpolation filtering in the first block unit, the second block being a block to which the Wiener filter is to be applied for the loop filtering in the second block unit; and if it is determined to apply the Wiener filter for the loop filtering in the second block unit, performing the loop filtering on the reconstructed samples by applying the Wiener filter to the reconstructed samples. determining whether to apply a Wiener filter for interpolation filtering in a first block unit by using information about whether, for encoding the first block unit, the Wiener filter has been used for the interpolation filtering or not, wherein the information is transmitted from an encoder; if it is determined that the Wiener filter has been used for the interpolation filtering, performing the interpolation filtering on the reference picture by applying the Wiener filter to the reference picture; generating predicted samples from samples within the reference picture on which the interpolation filtering has been performed; generating reconstructed samples by adding residual samples and the predicted samples together; determining whether to apply the Wiener filter for loop filtering in a second block unit based on the information and at least one of whether sizes of a first block and a second block are same, whether one of the first and second blocks includes the other of the first and second blocks, and location relation of a boundary of the first block with respect to the second block, predicted samples of the first block being generated by applying the Wiener filter for the interpolation filtering in the first block unit, the second block being a block to which the Wiener filter is to be applied for the loop filtering in the second block unit; and if it is determined to apply the Wiener filter for the loop filtering in the second block unit, performing the loop filtering on the reconstructed samples by applying the Wiener filter to the reconstructed samples.