1. A region dividing method of a target image, the region dividing method comprising: generating a plurality of primary region groups, wherein each primary region group includes a plurality of primary regions, which are produced by dividing the target image in such a manner that each primary region of the primary region group is characterized by a measured value of at least one common corresponding feature value, wherein the at least one common corresponding feature value is common to the plurality of primary regions of the primary region group; generating a single basic region group that includes a plurality of basic regions, which are produced by dividing the target image, wherein each basic region has the measured value of the at least one corresponding feature value of each overlapping one of the plurality of primary regions of each primary region group, which overlaps with the basic region, so that each basic region has the measured values of the feature values of the overlapping primary regions of the plurality of primary region groups, which overlap with the basic region; and integrating similar adjacent ones of the plurality of basic regions into a corresponding integrated region, wherein a similarity of the similar adjacent ones of the plurality of basic regions satisfies a predetermined similarity with respect to the measured values of the feature values of the similar adjacent ones of the plurality of basic regions.