A method for encoding luma intra mode using context adaptive entropy processing determines a current luma intra mode for a current block and determines whether a neighboring block of the current block within a region of an independently coded slice is on a different side of a boundary of the region from the current block. The method replaces prediction mode information associated with the neighboring block by DC mode if the neighboring block is on the different side of the boundary of the region from the current block, and forms data for processing a current syntax element associated with the current luma intra mode based on the prediction mode information associated with the neighboring block. In addition, the method performs context adaptive entropy encoding processing on the current syntax element according to the formed data.