Apparatus for encoding and decoding image by skip encoding and method for same

An image decoding method performed by a decoding apparatus, comprising:

• determining whether to perform filtering on signals to be used in generating intra prediction signals of decoding object signals, the signals being reconstructed earlier than the decoding object signals, the signals being adjacent to the decoding object signals;
• determining a strength of a filter used in the filtering based on a flag transmitted from an encoding apparatus in response to the determination that the filtering is performed;
• performing the filtering on the signals based on the determined strength of the filter;
• and
• generating the intra prediction signals of the decoding object signals using the filtered signals,
• wherein the determination of whether to perform the filtering is based on a block size of the decoding object signals and an intra prediction mode of the decoding object signals.