Image Relevance Prediction Using Query-Context Bag-of-Object Retrieval Model

摘要

Image search reranking and image research result summarization are two effective approaches which enhance text-based image search results using visual information. Since the existing approaches optimize search relevance in terms of average performance, they usually cannot achieve satisfactory results for some particular classes of queries, like “object queries,” which is defined as the queries with the intent of searching for some kinds of objects. One possible reason is that the generic approaches such as , , are mostly built based on the global statistics of images as features while ignoring the fact that the relevance between the image and the query sometimes depends on an image patch instead of the whole image. In this paper, we therefore design a novel bag-of-object retrieval model to predict image relevance, which is particularly effective for object queries. First, we construct an object vocabulary containing query-relative objects by mining frequent object patches from the result image collection of the expanded query set. After representing each image as a bag of objects, our retrieval model can be derived from a risk-minimization framework for language modeling. To demonstrate the effectiveness of the proposed model, this paper also present two related applications: for image search reranking, we adopt a supervised framework to combine multiple ranking features from different assumptions; for image search result summarization, we propose a two-step ranking process which optimizes not only representativeness but also image attractiveness. The experimental results show that the proposed methods can significantly outperform the existing approaches.