US Patent 10484680 Method and apparatus of intra mode coding

The present disclosure describes a method of decoding a block, and the method includes receiving a flag indicating whether a current intra prediction mode is equal to any of one or more most probable modes, deriving, based on a value of the flag, the current intra prediction mode from a decoded mode index, and decoding the block according to the current intra prediction mode. The current intra prediction mode belongs to a mode set that includes a DC mode, a Planar mode, and at least one directional mode. The deriving the current intra prediction mode includes, when the mode index corresponds to a first mode index value representing the Planar mode, deriving the current intra prediction mode to be the Planar mode; and, when the mode index corresponds to a second mode index value representing the DC mode, deriving the current intra prediction mode to be the DC mode.