Sketch Re-identification (Sketch Re-ID), which aims to retrieve target person from an image gallery based on a sketch query, is crucial for criminal investigation, law enforcement, and missing person searches. Existing methods aim to alleviate the modality gap by employing semantic metrics constraints or auxiliary modal guidance. However, they incur expensive labor costs and inevitably omit fine-grained modality-consistent information due to the abstraction of sketches. To address this issue, this paper proposes a novel $\textit{Optimal Transport-based Labor-free Text Prompt Modeling}$ (OLTM) network, which hierarchically extracts coarse- and fine-grained similarity representations guided by textual semantic information without any additional annotations. Specifically, multiple target attributes are flexibly obtained by a pre-trained visual question answering (VQA) model. Subsequently, a text prompt reasoning module employs learnable prompt strategy and optimal transport algorithm to extract discriminative global and local text representations, which serve as a bridge for hierarchical and multi-granularity modal alignment between sketch and image modalities. Additionally, instead of measuring the similarity of two samples by only computing their distance, a novel triplet assignment loss is further proposed, in which the whole data distribution also contributes to optimizing the inter/intra-class distances. Extensive experiments conducted on two public benchmarks consistently demonstrate the robustness and superiority of our OLTM over state-of-the-art methods.

For deployment on an embedded processor for distracted driver classification, the model should satisfy the demand for both high accuracy, real-time inference, and limited storage resources. Conventional deep CNN models such as VGG, ResNet, DenseNet, often aim for high accuracy, making their model heavy for an embedded system with limited memory space and computing resources. In contrast, lightweight models are greatly compressed but at a significant sacrifice of accuracy. To bridge this gap, we propose an instance-specific multi-teacher knowledge distillation model (IsMt-KD) to learn more accurate, speedy, and lightweight CNNs for distracted driver posture classification. Specifically, in multi-teacher knowledge distillation, most of the current approaches either randomly select a teacher model and apply the prediction of such teacher model as the soft-label or allocate an equal weight to every teacher model and average all the predictions of the teachers as the soft label. In this paper, we observe that, when facing the same instance, the outputs of different teachers vary greatly, in which some teachers can predict it right whereas the others may give pretty high probabilities to the irrelevant classes. Thus, it is inappropriate to set fixed weights or the same weights for teachers. To this end, a simple yet effective instance-specific teacher grading module is designed to dynamically assign weights to teacher models based on individual instances. In this way, we can dynamically distill the knowledge from multiple teachers by considering both instance-specific high-level and instance-specific intermediate-level information. Our extensive experimental results on AUC and StateFarm datasets, and our implementation on edge hardware platforms including HUAWEI MediaPad c5 and Nvidia Jetson TX2, verify the effectiveness and feasibility of our approach.

Label distribution learning (LDL) is a novel machine learning paradigm to deal with label ambiguity issues by placing more emphasis on how relevant each label is to a particular instance. Many LDL algorithms have been proposed and most of them concentrate on the learning models, while few of them focus on the feature selection problem. All existing LDL models are built on a simple feature space in which all features are shared by all the class labels. However, this kind of traditional data representation strategy tends to select features that are distinguishable for all labels, but ignores label-specific features that are pertinent and discriminative for each class label. In this paper, we propose a novel LDL algorithm by leveraging label-specific features. The common features for all labels and specific features for each label are simultaneously learned to enhance the LDL model. Moreover, we also exploit the label correlations in the proposed LDL model. The experimental results on several real-world data sets validate the effectiveness of our method.

Label distribution learning (LDL) can be viewed as the generalization of multi-label learning. This novel paradigm focuses on the relative importance of different labels to a particular instance. Most previous LDL methods either ignore the correlation among labels, or only exploit the label correlations in a global way. In this paper, we utilize both the global and local relevance among labels to provide more information for training model and propose a novel label distribution learning algorithm. In particular, a label correlation matrix based on low-rank approximation is applied to capture the global label correlations. In addition, the label correlation among local samples are adopted to modify the label correlation matrix. The experimental results on real-world data sets show that the proposed algorithm outperforms state-of-the-art LDL methods.