Context-Aware Multi-instance Learning Based on Hierarchical Sparse Representation

Multi-instance learning (MIL), a variant of supervised learning framework, has been applied in many applications. More recently, researchers focus on two important issues for MIL: Instances' contextual structures representation in the same bag and online MIL schemes. In this paper, we present an effective context-aware multi-instance learning technique using a hierarchical sparse representation (HSR-MIL) that addresses the two challenges simultaneously. We firstly construct the inner contextual structure among instances in the same bag based on a novel sparse $\varepsilon$-graph. We then propose a graph kernel based sparse bag classifier through a modified kernel sparse coding in higher-dimension feature space. At last, the HSR-MIL approach is extended to achieve online learning manner with an incremental kernel matrix update scheme. The experiments on several data sets demonstrate that our method has better performances and online learning ability.