1. A shrimp-processing system comprising: a conveyor conveying shrimps along a processing line; an off-line QC station having a vision system capturing digital images of sample shrimps collected from the shrimps on the conveyor; a processor determining the number of tail segments present in each of the sample shrimps or estimating the percentage of full weight of each of the sample shrimps from the digital image and classifying each of the sample shrimps into one of a plurality of classes according to the number of tail segments present in or the percentage of full weight of each of the sample shrimps.