Introduction to the special issue on face analysis applications

At the core of human social interactions is our ability to communicate information in multiple ways, implicitly and explicitly, and the human face is one of the most powerful carriers of information, about identity, gender, age, ethnicity, health, emotional state, and physical wellness, to name a few. This motivated several studies, addressed within a broad range of disciplines, with the aim to analyze the appearance, 3D structure, and dynamics of the face to extract useful information for recognition, classification, prediction, and synthesis. The definition of a computational model to formalize the precise nature of this process remains challenging due to the high-dimensional, dynamic information space required to model the appearance and deformations of the face. Nevertheless, many research teams at the crossband of computer vision, machine learning, and social sciences have investigated the use of computational models to process still images and videos, 2D and 3D data, to enable face recognition in the wild, face learning for re-identification, age, gender, and ethnicity estimation from face images, appearance prediction across aging, expression analysis for emotional and sentiment awareness, analysis of facial expressivity impairment for neurological disorder monitoring, and micro-expression recognition for deception detection.