1. A block matching method for estimating a motion vector of an estimation block of an image frame, comprising: comparing the estimation block with at least one reference block corresponding to a first object to obtain a plurality of pixel difference values; determining a mask area corresponding to the first object and a calculation area corresponding to a second object in the estimation block according to the plurality of pixel difference values; and performing block matching operations on the calculation area to determine a motion vector of the second object to be used as the motion vector of the estimation block.