Face and facial expressions recognition and analysis

Face recognition and facial expression analysis are essential abilities of humans, which provide the basic visual clues during human-computer interaction. It is important to enable the virtual human/social robot such capabilities in order to achieve autonomous behavior. Local binary pattern (LBP) has been widely used in face recognition and facial expression analysis. It is popular because of robustness to illumination variation and alignment error. However, local binary pattern still has some limitations, e.g. it is sensitive to image noise. Local ternary pattern (LTP), fuzzy LBP and many other LBP variants partially solve this problem. However, these approaches treat the corrupted image patterns as they are, and do not have an mechanism to recover the underlying patterns. In view of this, we develop a noiseresistant LBP to preserve the image micro-structures in presence of noise.We encode the small pixel difference as an uncertain state first, and then determine its value based on the other bits of the LBP code. Most image micro-structures are represented by uniform codes and non-uniform codes mainly represent noise patterns. Therefore, we assign the value of uncertain bit so as to form possible uniform codes. In such a way, we develop an error-correctionmechanism to recover the distorted image patterns. In addition, we find that some image patterns such as lines are not captured in uniform codes. They represent a set of important local primitives for pattern recognition. We thus define an extended noise-resistant LBP (ENRLBP) to capture line patterns. NRLBPandENRLBPare validated extensively on face recognition, facial expression analysis and other recognition tasks. They are shown more resistant to image noise compared with LBP, LTP and many other variants. These two approaches greatly enhance the performance of face recognition and facial expression analysis.