An electronic apparatus performs a method for video decoding. The method comprises: receiving, from a bitstream, a coding unit and determining a mode type condition of the coding unit; if the coding unit is encoded in a first chroma format, setting the mode type condition of the coding unit to a first mode type condition; if the coding unit is encoded in a second chroma format and the coding unit is a smallest chroma intra prediction unit, setting the mode type condition of the coding unit to a second mode type condition if a luma block of the coding unit and the splitting method satisfy a first criterion; setting the mode type condition of the coding unit to a third mode type condition if the luma block of the coding unit and the splitting method satisfy a second criterion, and decoding the coding unit based on the mode type condition.