1. A method for Intra prediction of a block based on neighboring pixels around the block, the method comprising: utilizing a processor to perform: receiving a 2N×2N Luma block corresponding to Luma pixels of the block; if a size of the Luma block is larger than a smallest coding unit (SCU), setting a prediction block size of the Luma block to be one of: a square shape 2N×2N block size, a non-square shape 2N×N block size, or a non-square shape N×2N block size; if the size of the Luma block is equal to the SCU, setting the prediction block size of the Luma block to be one of: a square shape 2N×2N block size, a non-square shape 2N×N block size, a non-square shape N×2N block size, or a square shape N×N block size; and performing Intra prediction for the Luma block based on neighboring Luma pixels, wherein the Luma block is partitioned into one or more prediction units (PUs) according to partition mode.