1. A display apparatus comprising: a display; a decoder which decodes an image in unit of a minimum coded unit (MCU), the MCU comprising a plurality of blocks; a scaler which scales the decoded image; a memory which stores the scaled image; and a controller which controls the display to display the scaled image, sets a random access unit (RAU) structure of the image, and further stores in the memory an RAU table corresponding to information of the RAU structure, the RAU structure comprising a plurality of MCUs, wherein the controller is configured to control the decoder to decode a first partial image of the scaled image that is to be additionally processed, by using the RAU table, when a user's input is received to additionally process the first partial image of the scaled image.