Recent advances in sign language research have benefited from CNN-based backbones, which are primarily transferred from traditional computer vision tasks (\eg object detection, image recognition). However, these CNN-based backbones usually excel at extracting features like contours and texture, but may struggle with capturing sign-related features. To capture such sign-related features, SignGraph model extracts the cross-region sign features by building the Local Sign Graph (LSG) module and the Temporal Sign Graph (TSG) module. However, we emphasize that although capturing cross-region dependencies can improve sign language performance, it may degrade the representation quality of local regions. To mitigate this, we introduce MixSignGraph, which represents sign sequences as a group of mixed graphs for feature extraction. Specifically, besides the LSG module and TSG module that model the intra-frame and inter-frame cross-regions features, we design a simple yet effective Hierarchical Sign Graph (HSG) module, which enhances local region representations following the extraction of cross-region features, by aggregating the same-region features from different-granularity feature maps of a frame, \ie to boost discriminative local features. In addition, to further improve the performance of gloss-free sign language task, we propose a simple yet counter-intuitive Text-based CTC Pre-training (TCTC) method, which generates pseudo gloss labels from text sequences for model pre-training. Extensive experiments conducted on the current five sign language datasets demonstrate that MixSignGraph surpasses the most current models on multiple sign language tasks across several datasets, without relying on any additional cues. Code and models are available at: \href{https://github.com/gswycf/SignLanguage}{\textcolor{blue}{https://github.com/gswycf/SignLanguage}}.

Sign Language Video Generation (SLVG) seeks to generate identity-preserving sign language videos from spoken language texts. Existing methods primarily rely on the single coarse condition (e.g., skeleton sequences) as the intermediary to bridge the translation model and the video generation model, which limits both the naturalness and expressiveness of the generated videos. To overcome these limitations, we propose SignViP, a novel SLVG framework that incorporate multiple fine-grained conditions for improved generation fidelity. Rather than directly translating error-prone high-dimensional conditions, SignViP adopts a discrete tokenization paradigm to integrate and represent fine-grained conditions (i.e., fine-grained poses and 3D hands). SignViP contains three core components. (1) Sign Video Diffusion Model is jointly trained with a multi-condition encoder to learn continuous embeddings that encapsulate fine-grained motion and appearance. (2) Finite Scalar Quantization (FSQ) Autoencoder is further trained to compress and quantize these embeddings into discrete tokens for compact representation of the conditions. (3) Multi-Condition Token Translator is trained to translate spoken language text to discrete multi-condition tokens. During inference, Multi-Condition Token Translator first translates the spoken language text into discrete multi-condition tokens. These tokens are then decoded to continuous embeddings by FSQ Autoencoder, which are subsequently injected into Sign Video Diffusion Model to guide video generation. Experimental results show that SignViP achieves state-of-the-art performance across metrics, including video quality, temporal coherence, and semantic fidelity. The code is available at https://github.com/umnooob/signvip/.

Despite the recent success of sign language research, the widely adopted CNN-based backbones are mainly migrated from other computer vision tasks, in which the contours and texture of objects are crucial for identifying objects. They usually treat sign frames as grids and may fail to capture effective cross-region features. In fact, sign language tasks need to focus on the correlation of different regions in one frame and the interaction of different regions among adjacent frames for identifying a sign sequence. In this paper, we propose to represent a sign sequence as graphs and introduce a simple yet effective graph-based sign language processing architecture named SignGraph, to extract crossregion features at the graph level. SignGraph consists of two basic modules: Local Sign Graph (LSG) module for learning the correlation of intra-frame cross-region features in one frame and Temporal Sign Graph (TSG) module for tracking the interaction of inter-frame cross-region features among adjacent frames. With LSG and TSG, we build our model in a multiscale manner to ensure that the representation of nodes can capture cross-region features at different granularities. Extensive experiments on current public sign language datasets demonstrate the superiority of our SignGraph model. Our model achieves very competitive performances with the SOTA model, while not using any extra cues. Code and models are available at: https://github.com/gswycf/SignGraph.

There are two problems that widely exist in current end-to-end sign language processing architecture. One is the CTC spike phenomenon which weakens the visual representational ability in Continuous Sign Language Recognition (CSLR). The other one is the exposure bias problem which leads to the accumulation of translation errors during inference in Sign Language Translation (SLT). In this paper, we tackle these issues by introducing contrast learning, aiming to enhance both visual-level feature representation and semantic-level error tolerance. Specifically, to alleviate CTC spike phenomenon and enhance visual-level representation, we design a visual contrastive loss by minimizing visual feature distance between different augmented samples of frames in one sign video, so that the model can further explore features by utilizing numerous unlabeled frames in an unsupervised way. To alleviate exposure bias problem and improve semantic-level error tolerance, we design a semantic contrastive loss by re-inputting the predicted sentence into semantic module and comparing features of ground-truth sequence and predicted sequence, for exposing model to its own mistakes. Besides, we propose two new metrics, i.e., Blank Rate and Consecutive Wrong Word Rate to directly reflect our improvement on the two problems. Extensive experimental results on current sign language datasets demonstrate the effectiveness of our approach, which achieves state-of-the-art performance.

To provide instant communication for hearing-impaired people, it is essential to achieve real-time sign language processing anytime anywhere. Therefore, in this paper, we propose a Region-aware Temporal Graph based neural Network (RTG-Net), aiming to achieve real-time Sign Language Recognition (SLR) and Translation (SLT) on edge devices. To reduce the computation overhead, we first construct a shallow graph convolution network to reduce model size by decreasing model depth. Besides, we apply structural re-parameterization to fuse the convolutional layer, batch normalization layer and all branches to simplify model complexity by reducing model width. To achieve the high performance in sign language processing as well, we extract key regions based on keypoints in skeleton from each frame, and design a region-aware temporal graph to combine key regions and full frame for feature representation. In RTG-Net, we design a multi-stage training strategy to optimize keypoint selection, SLR and SLT step by step. Experimental results demonstrate that RTG-Net achieves comparable performance with existing methods in SLR or SLT, while greatly reducing the computation overhead and achieving real-time sign language processing on edge devices. Our code is available at https://github.com/SignLanguageCode/realtimeSLRT.

As an essential communication way for deaf-mutes, sign languages are expressed by human actions. To distinguish human actions for sign language understanding, the skeleton which contains position information of human pose can provide an important cue, since different actions usually correspond to different poses/skeletons. However, skeleton has not been fully studied for Sign Language Translation (SLT), especially for end-to-end SLT. Therefore, in this paper, we propose a novel end-to-end Skeleton-Aware neural Network (SANet) for video-based SLT. Specifically, to achieve end-to-end SLT, we design a self-contained branch for skeleton extraction. To efficiently guide the feature extraction from video with skeletons, we concatenate the skeleton channel and RGB channels of each frame for feature extraction. To distinguish the importance of clips, we construct a skeleton-based Graph Convolutional Network (GCN) for feature scaling, i.e., giving importance weight for each clip. The scaled features of each clip are then sent to a decoder module to generate spoken language. In our SANet, a joint training strategy is designed to optimize skeleton extraction and sign language translation jointly. Experimental results on two large scale SLT datasets demonstrate the effectiveness of our approach, which outperforms the state-of-the-art methods. Our code is available at https://github.com/SignLanguageCode/SANet.