参考文献：Chum, Ondřej, Mikulík, Andrej, Perdoch M , et al. Total recall II: Query expansion revisited[C]// Computer Vision & Pattern Recognition. IEEE, 2011.原文链接
Query Expansion (QE). We select the top K images after retrieval and aggregate their features and query feature by average . We use the aggregated feature as a new query and perform the retrieval again to obtain the final ranking list.
拓展查询(QE, Query Expansion): 指对返回的前top@K个结果,包括查询样本本身,对它们的特征求和取平均,以此为检索特征，再做一次查询。目的是为了提高召回率。