Hypergraph-Enhanced Hashing for Unsupervised Cross-Modal Retrieval via Robust Similarity Guidance

Unsupervised cross-modal hashing retrieval across image and text modality is a challenging task because of the suboptimality of similarity guidance, i.e., the joint similarity matrix constructed by existing methods does not possess clear enough guiding significance. How to construct more robust similarity matrix is the key to solve this problem. The unsupervised cross-modal retrieval methods based on graph have a good performance in mining semantic information of input samples, but the graph hashing based on traditional affinity graph cannot capture the high-order semantic information of input samples effectively. In order to overcome the aforementioned limitations, this paper presents a novel hypergraph-based approach for unsupervised cross-modal retrieval that differs from previous works in two significant ways. Firstly, to address the ubiquitous redundant information present in current methods, this paper introduces a robust similarity matrix constructing method. Secondly, we propose a novel hypergraph enhanced module that produces embedding vectors by hypergraph convolution and attention mechanism for input data, capturing important high-order semantics. Our approach is evaluated on the NUS-WIDE and MIRFlickr datasets, and yields state-of-the-art performance for unsupervised cross-modal retrieval.