A semiconductor-inspection tool scans a semiconductor die using a plurality of optical modes. A plurality of defects on the semiconductor die are identified based on results of the scanning. Respective defects of the plurality of defects correspond to respective pixel sets of the semiconductor-inspection tool. The scanning fails to resolve the respective defects. The results include multi-dimensional data based on pixel intensity for the respective pixel sets, wherein each dimension of the multi-dimensional data corresponds to a distinct mode of the plurality of optical modes. A discriminant function is applied to the results to transform the multi-dimensional data for the respective pixel sets into respective scores. Based at least in part on the respective scores, the respective defects are divided into distinct classes.