Codebook-Centric Deep Hashing: End-to-End Joint Learning of Semantic Hash Centers and Neural Hash Function

TL;DR

This paper introduces CRH, an end-to-end deep hashing framework that dynamically reassigns hash centers from a codebook during training, improving semantic alignment and retrieval performance without multi-stage optimization.

Contribution

The paper proposes CRH, a novel end-to-end deep hashing method that dynamically reassigns hash centers from a codebook, integrating semantic relationships directly into the learning process.

Findings

CRH outperforms state-of-the-art methods on three benchmarks.

CRH learns semantically meaningful hash centers.

The multi-head mechanism enhances semantic capture.

Abstract

Hash center-based deep hashing methods improve upon pairwise or triplet-based approaches by assigning fixed hash centers to each class as learning targets, thereby avoiding the inefficiency of local similarity optimization. However, random center initialization often disregards inter-class semantic relationships. While existing two-stage methods mitigate this by first refining hash centers with semantics and then training the hash function, they introduce additional complexity, computational overhead, and suboptimal performance due to stage-wise discrepancies. To address these limitations, we propose $\textbf{Center-Reassigned Hashing (CRH)}$, an end-to-end framework that $\textbf{dynamically reassigns hash centers}$ from a preset codebook while jointly optimizing the hash function. Unlike previous methods, CRH adapts hash centers to the data distribution $\textbf{without explicit center optimization phases}$, enabling seamless integration of semantic relationships into the learning process. Furthermore, $\textbf{a multi-head mechanism}$ enhances the representational capacity of hash centers, capturing richer semantic structures. Extensive experiments on three benchmarks demonstrate that CRH learns semantically meaningful hash centers and outperforms state-of-the-art deep hashing methods in retrieval tasks.