Fine-Grained Sketch-Based Image Retrieval (FG-SBIR) is a challenging task that focuses on retrieving relevant images based on sketch queries at the instance level. Most existing works tend to make cross-modality interactions between features at the global level and treat each feature equally when calculating similarity. However, this equal treatment may reduce the contribution of fine-grained information. To address these challenges, we propose a novel Cross-Modality Neighborhood Attention Network, named CMNA-Net. Specifically, we develop a novel CMNA mechanism in the proposed method to adjust the importance of modality-agnostic features, which not only performs neighborhood attention operation on the current modality but also performs cross-neighborhood attention on both modalities. Additionally, the edge map is innovatively introduced to reduce the modality gap. Furthermore, this work proposes a Neighborhood Weighted module that integrates the local feature weight scheme and top-k feature selection strategy, yielding more discriminative features tailored to fine-grained retrieval. Extensive experiments on three benchmark datasets demonstrate that our proposed CMNA-Net can achieve better performance compared to some existing state-of-the-art methods in FG-SBIR scenarios. The code of our method will be available at https://github.com/li1changxing/CMNA-Net.

Sketch-based 3D shape retrieval (SBSR) aims to retrieve 3D shapes using hand-drawn sketches as query inputs. Although existing SBSR methods have achieved promising results, several challenges still require further investigation. First, most existing approaches usually leverage simple aggregation schemes, often failing to capture the intrinsic relationships between views, which limits the effectiveness of 3D shape feature extraction. Second, conventional SBSR primarily focuses on instance-level alignment while ignoring multi-level alignment, which may neglect complex hierarchical relationships. To address these limitations, we propose a novel Multi-level Encoding with Hierarchical Alignment (MEHA) method for SBSR. Specifically, we adopt spatial encoding and view encoding for multiple views of 3D shapes. The proposed aggregation scheme then integrates these multi-level embedded local features to enhance the representation of 3D shape features. Considering the complexity of 3D shapes, MEHA adopts a two-stage training process: the first stage focuses on learning 3D shape features, while the second stage emphasizes modality alignment. Furthermore, we introduce a hierarchical alignment strategy that bridges the modality gap through instance-level, prototype-level, and centre-level alignment. Extensive experiments on two public benchmark datasets demonstrate the superiority of our method, showing that MEHA outperforms the state-of-the-art baselines.

In recent years, zero-shot sketch-based image retrieval (ZS-SBIR) task has attracted considerable attention. Although some ZS-SBIR approaches have been proposed, it remains challenging to handle the inherent linkages between the sketch and image domains. Moreover, how to transfer semantic knowledge from seen categories to unseen categories is still an open problem, significantly affecting retrieval performance. In this article, we propose a novel approach Modality Fused Class-Proxy with Knowledge Distillation, named MFCPKD, which develops two novel schemes to remedy the above issues. Specifically, MFCPKD leverages a Modality Fusion Model to learn modality-fused feature embeddings and class proxies. The knowledge distillation is employed for student to learn the feature from seen categories and infer the unknown category through class proxies. Furthermore, three losses constrain the student network to narrow the modality gap between sketch and image domains. Finally, we conduct extensive experiments on three benchmark datasets (Sketchy Ext, TU-Berlin Ext, and QuickDraw Ext) and demonstrate that our MFCPKD method can achieve excellent performance compared to some existing methods in ZS-SBIR scenarios. The code for our project is available athttps://github.com/li1changxing/MFCPKD.

Recently, supervised cross-modal hashing methods have gained considerable attention due to their ability to mine credible semantic relationships between multi-modal data. These methods typically rely on labels to explore semantic relationships provided that labels are always reliable, which, however, may not be true from the practical perspective. In fact, labels may be incomplete, i.e., true-label incomplete and fine-grained incomplete, which makes the performance of the existing methods deteriorated. To this end, we propose a method called Discrete Elective Hashing with Incomplete Labels (DEH-IL), which is designed to alleviate the impact of incomplete labels. Specifically, we introduce a relaxed label scheme that allows the algorithm to automatically mine potential missing information from incomplete labels, which is beneficial for exploring intra-class relationships. Moreover, we propose a novel elective loss that aggregates all estimations from incomplete labels to mine inter-class relationships. Since elective loss does not rely on any single estimation, it can effectively mitigate estimation errors arising from incomplete labels. By combining these two components, DEH-IL can effectively explore both intra-class and inter-class relationships through incomplete labels. Experimental results on benchmark datasets demonstrate the effectiveness of the proposed method.

Abstract Hyper‐spectral image (HSI) clustering has become a hot spot in remote sensing image research. However, due to the large amount and high dimension of HSI data, some traditional image clustering methods are no longer suitable, and even lead to poor clustering performance and long computing time. Therefore, this paper proposes a novel clustering method for HSI to make up for the shortcomings of traditional clustering methods. Firstly, a fuzzy similarity matrix is constructed by using the bipartite graph to obtain low‐dimensional hyper‐spectral data, which can reduce the complexity and the operation time of the algorithm. Secondly, fuzzy membership mapping is carried out through the constructed bipartite graph, and a non‐negative regularization term is added to limit ill‐conditioned problems. Thirdly, this paper uses the Geman‐McClure function to optimize Euclidean distance. Finally, in this paper, the spectral information of HSI is considered while the neighbourhood information of HSI is added to achieve the unity of space spectrum, which enhances the robustness of the algorithm and improves the clustering performance of the algorithm. Compared with existing HSI clustering algorithms, the proposed algorithm has higher clustering accuracy and efficiency.