Risk Controlled Image Retrieval
Kaiwen Cai, Chris Xiaoxuan Lu, Xingyu Zhao, Xiaowei Huang
TL;DR
This work tackles the reliability gap in image retrieval by introducing Risk Controlled Image Retrieval (RCIR), which adds a probabilistic coverage guarantee to retrieved candidate sets. RCIR uses a Retrieval Set Size Adapter to scale the retrieval size based on query uncertainty and a Risk Controller to enforce a user-specified risk bound $\alpha$ with failure rate $\delta$ via a Hoeffding-based upper confidence bound. The approach yields provable guarantees regardless of data distribution or model choice, and experiments on CAR-196, CUB-200, Pittsburgh, and ChestX-Det demonstrate effective risk control with retrieval sets that adapt to query difficulty while remaining efficient. This framework enhances safety-critical retrieval applications by providing predictable coverage of true nearest neighbors and clarifies the role of uncertainty estimates in a probabilistic risk setting.
Abstract
Most image retrieval research prioritizes improving predictive performance, often overlooking situations where the reliability of predictions is equally important. The gap between model performance and reliability requirements highlights the need for a systematic approach to analyze and address the risks associated with image retrieval. Uncertainty quantification technique can be applied to mitigate this issue by assessing uncertainty for retrieval sets, but it provides only a heuristic estimate of uncertainty rather than a guarantee. To address these limitations, we present Risk Controlled Image Retrieval (RCIR), which generates retrieval sets with coverage guarantee, i.e., retrieval sets that are guaranteed to contain the true nearest neighbors with a predefined probability. RCIR can be easily integrated with existing uncertainty-aware image retrieval systems, agnostic to data distribution and model selection. To the best of our knowledge, this is the first work that provides coverage guarantees to image retrieval. The validity and efficiency of RCIR are demonstrated on four real-world datasets: CAR-196, CUB-200, Pittsburgh, and ChestX-Det.
