Abstract: A method of decoding a bitstream by an electronic device is provided. A block unit having a block height and a block width is determined from an image frame according to the bitstream. A mode list including a plurality of intra modes is determined for reconstructing the block unit. At least one of the intra modes is selected from the mode list based on a comparison between the block height and the block width, and removed from the mode list to generate an adjusted list including a plurality of unselected modes. The block unit included in the image frame is reconstructed based on the adjusted list.