Sign4all: a Spanish Sign Language dataset.

Sign Language Recognition (SLR) is a critical component of human-machine interaction, enabling more inclusive technologies for the deaf and hard-of-hearing community. However, current datasets often suffer from data sparsity and a bias toward right-handed signs. To support this effort, we present Sign4all, a dataset for Spanish Sign Language (LSE), specifically designed for Isolated Sign Language Recognition (ISLR). The dataset is composed of 7,756 high-resolution RGB video recordings and their corresponding skeletal keypoints, covering 24 signs related to daily activities, more specifically a vocabulary centered in the catering field. Unlike sparse lexicons, Sign4all adopts a high-density approach, providing an average of 323 samples per sign to facilitate data-intensive deep learning models. Moreover, the dataset provides a handedness balance, with equal representation of left- and right-handed signs for every sign to support handedness invariance. Each sample was manually segmented, temporally normalized and preprocessed through spatial normalization to guarantee consistency and compatibility with different deep learning pipelines. Technical validation using Transformer and skeletal models demonstrates the dataset's integrity and the need of providing pre-computed augmentation splits. All data is formatted in widely supported file types (AVI for video, HDF5 for keypoints), enabling direct use in machine learning frameworks such as TensorFlow or PyTorch.