The Dempster-Shafer theory (DST) is particularly interesting to deal with imprecise information. However, it is known for its high computational cost, as dealing with a frame of discernment Ω involves the manipulation of up to 2^|Ω| elements. Hence, classification problems where the number of classes is too large cannot be considered. In this paper, we propose to take advantage of a context of ensemble classification to construct a frame of discernment where only a subset of classes is considered. We apply this method to script recognition problems, which by nature involve a tremendous number of classes.