Method and apparatus for encoding and decoding image by using large transformation unit

A method of decoding image, the method comprising:

• determining coding units having a hierarchical structure for decoding an image using split information of a coding unit, determining at least one prediction unit for predicting a coding unit among the coding units using information about a partition type, and determining at least one transformation unit for inversely transforming the coding unit using information about a depth of the at least one transformation information about a depth of the at least one transformation unit are parsed from a bitstream;
• obtaining, from the bitstream, transformation coefficients generated by transformation according to the at least one transformation unit generated by dividing the coding unit, and reconstructing a residual of the at least one transformation unit by performing inverse quantization and inverse transformation on the parsed transformation coefficients;
• and
• performing intra prediction or inter prediction on the at least one prediction unit to generate a predictor, and reconstructing the image based on the residual and the predictor,
• wherein the coding units are split hierarchically according to a depth of the coding unit, and
• wherein a size of the at least one transformation unit in the coding unit is determined without considering a size of the at least one prediction unit in the coding unit,
• the image is split into a plurality of maximum coding units, according to information about a maximum size of the coding unit,
• the maximum coding unit is hierarchically split into one or more coding units of depth including at least one of a current depth and a lower depth, according to split information,
• when the split information indicates a split for the current depth, the coding unit of the current depth is split into four rectangular coding units of a lower depth, independently from neighboring coding units, and
• when the split information indicates a non-split of the lower depth, the at least one prediction unit is obtained from the coding unit of the lower depth.