Text-based person search aims to retrieve the corresponding persons in an image database by virtue of a describing sentence about the person, which poses great potential for various applications such as video surveillance. Extracting visual contents corresponding to the human description is the key to this cross-modal matching problem. Moreover, correlated images and descriptions involve different levels of semantic relevance. To exploit the multilevel relevances between human description and corresponding visual contents, we propose a pose-guided joint global and attentive local matching network (GALM), which includes global, uni-local and bi-local matching. The global matching network aims to learn global cross-modal representations. To further capture the meaningful local relations, we propose an uni-local matching network to compute the local similarities between image regions and textual description and then utilize a similarity-based hard attention to select the description-related image regions. In addition to sentence-level matching, the fine-grained phrase-level matching is captured by the bi-local matching network, which employs pose information to learn latent semantic alignment between visual body part and textual noun phrase. To verify the effectiveness of our model, we perform extensive experiments on the CUHK Person Description Dataset (CUHK-PEDES) which is currently the only available dataset for text-based person search. Experimental results show that our approach outperforms the state-of-the-art methods by 15 in terms of top-1 metric.
The key point of image-text matching is how to accurately measure the similarity between visual and textual inputs. Despite the great progress of associating the deep cross-modal embeddings with the bi-directional ranking loss, developing the strategies for mining useful triplets and selecting appropriate margins remains a challenge in real applications. In this paper, we propose a cross-modal projection matching (CMPM) loss and a cross-modal projection classification (CMPC) loss for learning discriminative image-text embeddings. The CMPM loss minimizes the KL divergence between the projection compatibility distributions and the normalized matching distributions defined with all the positive and negative samples in a mini-batch. The CMPC loss attempts to categorize the vector projection of representations from one modality onto another with the improved norm-softmax loss, for further enhancing the feature compactness of each class. Extensive analysis and experiments on multiple datasets demonstrate the superiority of the proposed approach. As an important complement to person re-identification, text-based person search in large-scale database is concerned greatly for person search applications. Given language description of a person, existing frameworks search the images in the dataset that describe the same person, by computing the affinity score between the description and each image. In this paper, we first propose an efficient patch-word matching model, which can accurately capture the local matching details between image and text. In particular, it computes the affinity between an image and a word as the affinity of the best matching patch of the image toward the word. Compared with the state-of-the-art framework, it achieves competitive performance, but yields lowcomplexity structure. In addition, we put forward a significant limitation of affinity-based model, it is overly sensitive to the matching degree of a corresponding image-word pair. For this limitation, we feed a creative adaptive threshold mechanism into the model, it automatically learns an adaptive threshold for each word, and effectively “compress” the affinity score between a word and an image when the score exceeds the words threshold. Extensive experiments on the benchmark dataset demonstrate the effectiveness of the proposed framework, which outperforms other approaches for text-based person search. To provide a deeper insight into the proposed model, we visualize the matching details between spatial patches of images and words of texts on typical examples, and illustrate how adaptive threshold mechanism compresses the affinity score and benefits the final rank of different images toward a text description. Textual-visual matching aims at measuring similarities between sentence descriptions and images. Most existing methods tackle this problem without effectively utilizing identity-level annotations. In this paper, we propose an identity-aware two-stage framework for the textual-visual matching problem. Our stage-1 CNN-LSTM network learns to embed cross-modal features with a novel Cross-Modal Cross-Entropy (CMCE) loss. The stage-1 network is able to efficiently screen easy incorrect matchings and also provide initial training point for the stage-2 training. The stage-2 CNN-LSTM network refines the matching results with a latent co-attention mechanism. The spatial attention relates each word with corresponding image regions while the latent semantic attention aligns different sentence structures to make the matching results more robust to sentence structure variations. Extensive experiments on three datasets with identity-level annotations show that our framework outperforms state-of-the-art approaches by large margins. Searching persons in large-scale image databases with the query of natural language description has important applications in video surveillance. Existing methods mainly focused on searching persons with image-based or attribute-based queries, which have major limitations for a practical usage. In this paper, we study the problem of person search with natural language description. Given the textual description of a person, the algorithm of the person search is required to rank all the samples in the person database then retrieve the most relevant sample corresponding to the queried description. Since there is no person dataset or benchmark with textual description available, we collect a large-scale person description dataset with detailed natural language annotations and person samples from various sources, termed as CUHK Person Description Dataset (CUHK-PEDES). A wide range of possible models and baselines have been evaluated and compared on the person search benchmark. An Recurrent Neural Network with Gated Neural Attention mechanism (GNA-RNN) is proposed to establish the state-of-the art performance on person search. This paper considers the task of matching images and sentences. The challenge consists in discriminatively embedding the two modalities onto a shared visual-textual space. Existing work in this field largely uses Recurrent Neural Networks (RNN) for text feature learning and employs off-the-shelf Convolutional Neural Networks (CNN) for image feature extraction. Our system, in comparison, differs in two key aspects. Firstly, we build a convolutional network amenable for fine-tuning the visual and textual representations, where the entire network only contains four components, i.e., convolution layer, pooling layer, rectified linear unit function (ReLU), and batch normalisation. End-to-end learning allows the system to directly learn from the data and fully utilise the supervisions. Secondly, we propose instance loss according to viewing each multimodal data pair as a class. This works with a large margin objective to learn the inter-modal correspondence between images and their textual descriptions. Experiments on two generic retrieval datasets (Flickr30k and MSCOCO) demonstrate that our method yields competitive accuracy compared to state-of-the-art methods. Moreover, in language person retrieval, we improve the state of the art by a large margin. Code is available at this https URL com layumi Image-Text-Embedding