Fractional motion estimation method with adaptive mode selection

A fractional motion estimation method including the steps of categorizing search modes of the macroblock into a single mode, a reduced mode, and a full mode; determining a search mode of a to-be-process macroblock according to a predetermined condition; and conducting a fractional motion estimation of a to-be-estimated pixel according to the search mode determined in the aforesaid step. Therefore, the fractional motion estimation method can have the adaptive mode selection to spare some parts of computation for low throughput. In other words, it can effectively enhance efficiency of hardware, to lower power consumption, and to maintain consistent image quality.