It has been established that active learning is effective for learning complex, subjective query concepts for image retrieval. However, active learning has been applied in a concept independent way, (i.e., the kernel-parameters and the sampling strategy are identically chosen) for learning query concepts of differing complexity. In this work, we first characterize a concept’s complexity using three measures: hitrate, isolation and diversity. We then propose a multimodal learning approach that uses images’ semantic labels to guide a concept-dependent, active-learning process. Based on the complexity of a concept, we make intelligent adjustments to the sampling strategy and the sampling pool from which images are to be selected and labeled, to improve concept learnability. Our empirical study on a 300K-image dataset shows that concept-dependent learning is highly effective for image-retrieval accuracy. Categories and Subject Descriptors I.5.1 [Pattern Recognition]: Models—stat...
Kingshy Goh, Edward Y. Chang, Wei-Cheng Lai