Three things everyone should know to improve object retrieval

--------Relja Arandjelović and Andrew Zisserman (CVPR 2012)

1. RootSIFT:
 Improves performance in every single experiment (not just retrieval);
 Every system which uses SIFT is ready to use RootSIFT;
 Easy to implement, no added computational or storage cost;
2. Discriminative query expansion:
 Consistently outperforms average query expansion;
 At least as efficient as average QE;
 No arguments against it except for slightly increased implementation ;
complexity
3. Database-size feature augmentation:
 Useful for increasing recall;
 Our extension improves precision but increases storage requirements; this trade-off should be considered when deciding whether to use it or not;