Image encoding method and apparatus, and image decoding method and apparatus

Abstract

Provided are an image encoding/decoding apparatus and method using data hiding, in which, when a difference between scan positions of a final effective transform coefficient and an initial effective transform coefficient of a sub-block of a current transform unit is greater than a threshold value, an intra-prediction direction of a current coding unit is determined using parity of the sum of transform coefficients of the sub-block corresponding to certain scan positions or a level of an effective transform coefficient among transform coefficients of the sub-block is corrected such that the parity of the sum of the transform coefficients indicates the intra-prediction direction of the current coding unit. Encoding and decoding efficiencies may be improved by reducing a bitrate by using a method of hiding data in parity of effective transform coefficients.