METHOD AND APPARATUS FOR DECODING AND METHOD AND APPARATUS FOR ENCODING

A method and apparatus for decoding and a method and apparatus for encoding are disclosed. The method for decoding includes detecting a short data code indicating a most probable mode and applying a luma intra prediction decoding mode of a previous image region to a sample of a current region, and if the mode to be applied is not the most probable mode: determining a luma intra prediction decoding mode for the current sample according to a pattern of a given image region; applying one of two or more different sets of candidate prediction directions to a given image region, the pattern being one or more of: the region shape and location of the given image region; and selecting a prediction direction of the sample from a set of candidate prediction directions that can be applied to a given image region; wherein, depending on the size of the non-square block, a smaller set of candidate prediction directions is applied for the non-square block to reflect a larger number of potential reference samples on the left