Access to well-labeled recordings of facial expression is critical to progress in automated facial expression recognition. With few exceptions, publicly available databases are limited to posed facial behavior that can differ markedly in conformation, intensity, and timing from what occurs spontaneously. To meet the need for publicly available corpora of well-labeled video, we collected, ground-truthed, and prepared for distribution the Denver intensity of spontaneous facial action database. Twenty-seven young adults were video recorded by a stereo camera while they viewed video clips intended to elicit spontaneous emotion expression. Each video frame was manually coded for presence, absence, and intensity of facial action units according to the facial action unit coding system. Action units are the smallest visibly discriminable changes in facial action; they may occur individually and in combinations to comprise more molar facial expressions. To provide a baseline for use in future research, protocols and benchmarks for automated action unit intensity measurement are reported. Details are given for accessing the database for research in computer vision, machine learning, and affective and behavioral science.

DISFA: A Spontaneous Facial Action Intensity Database

Automatic affect analysis has attracted great interest in various contexts including the recognition of action units and basic or non-basic emotions In spite of major efforts, there are several open questions on what the important cues to interpret facial expressions are and how to encode them In this paper, we review the progress across a range of affect recognition applications to shed light on these fundamental questions We analyse the state-of-the-art solutions by decomposing their pipelines into fundamental components, namely face registration, representation, dimensionality reduction and recognition We discuss the role of these components and highlight the models and new trends that are followed in their design Moreover, we provide a comprehensive analysis of facial representations by uncovering their advantages and limitations; we elaborate on the type of information they encode and discuss how they deal with the key challenges of illumination variations, registration errors, head-pose variations, occlusions, and identity bias This survey allows us to identify open issues and to define future directions for designing real-world affect recognition systems

Automatic Analysis of Facial Affect: A Survey of Registration, Representation, and Recognition

The face is one of the most powerful channels of nonverbal communication. Facial expression provides cues about emotion, intention, alertness, pain, personality, regulates interpersonal behavior, and communicates psychiatric and biomedical status among other functions. Within the past 15 years, there has been increasing interest in automated facial expression analysis within the computer vision and machine learning communities. This chapter reviews fundamental approaches to facial measurement by behavioral scientists and current efforts in automated facial expression recognition. We consider challenges, review databases available to the research community, approaches to feature detection, tracking, and representation, and both supervised and unsupervised learning. keywords : Facial expression analysis, Action unit recognition, Active Appearance Models, temporal clustering.

Facial Expression Analysis.

A major factor hindering the deployment of a fully functional automatic facial expression detection system is the lack of representative data. A solution to this is to narrow the context of the target application, so enough data is available to build robust models so high performance can be gained. Automatic pain detection from a patient's face represents one such application. To facilitate this work, researchers at McMaster University and University of Northern British Columbia captured video of participant's faces (who were suffering from shoulder pain) while they were performing a series of active and passive range-of-motion tests to their affected and unaffected limbs on two separate occasions. Each frame of this data was AU coded by certified FACS coders, and self-report and observer measures at the sequence level were taken as well. This database is called the UNBC-McMaster Shoulder Pain Expression Archive Database. To promote and facilitate research into pain and augment current datasets, we have publicly made available a portion of this database which includes: 1) 200 video sequences containing spontaneous facial expressions, 2) 48,398 FACS coded frames, 3) associated pain frame-by-frame scores and sequence-level self-report and observer measures, and 4) 66-point AAM landmarks. This paper documents this data distribution in addition to describing baseline results of our AAM/SVM system. This data will be available for distribution in March 2011.

Painful data: The UNBC-McMaster shoulder pain expression archive database

Research in face perception and emotion theory requires very large annotated databases of images of facial expressions of emotion. Annotations should include Action Units (AUs) and their intensities as well as emotion category. This goal cannot be readily achieved manually. Herein, we present a novel computer vision algorithm to annotate a large database of one million images of facial expressions of emotion in the wild (i.e., face images downloaded from the Internet). First, we show that this newly proposed algorithm can recognize AUs and their intensities reliably across databases. To our knowledge, this is the first published algorithm to achieve highly-accurate results in the recognition of AUs and their intensities across multiple databases. Our algorithm also runs in real-time (>30 images/second), allowing it to work with large numbers of images and video sequences. Second, we use WordNet to download 1,000,000 images of facial expressions with associated emotion keywords from the Internet. These images are then automatically annotated with AUs, AU intensities and emotion categories by our algorithm. The result is a highly useful database that can be readily queried using semantic descriptions for applications in computer vision, affective computing, social and cognitive psychology and neuroscience, e.g., "show me all the images with happy faces" or "all images with AU 1 at intensity c."

/pdf/emotionet-an-accurate-real-time-algorithm-for-the-automatic-52las2mzrk.pdf

EmotioNet: An Accurate, Real-Time Algorithm for the Automatic Annotation of a Million Facial Expressions in the Wild

In a clinical setting, pain is reported either through patient self-report or via an observer. Such measures are problematic as they are: 1) subjective, and 2) give no specific timing information. Coding pain as a series of facial action units (AUs) can avoid these issues as it can be used to gain an objective measure of pain on a frame-by-frame basis. Using video data from patients with shoulder injuries, in this paper, we describe an active appearance model (AAM)-based system that can automatically detect the frames in video in which a patient is in pain. This pain data set highlights the many challenges associated with spontaneous emotion detection, particularly that of expression and head movement due to the patient's reaction to pain. In this paper, we show that the AAM can deal with these movements and can achieve significant improvements in both the AU and pain detection performance compared to the current-state-of-the-art approaches which utilize similarity-normalized appearance features only.

/pdf/automatically-detecting-pain-in-video-through-facial-action-59sj4iym7m.pdf

Automatically Detecting Pain in Video Through Facial Action Units

Automatically detecting pain in video through facial action units

Automatically recognizing pain from video is a very useful application as it has the potential to alert carers to patients that are in discomfort who would otherwise not be able to communicate such emotion (i.e young children, patients in postoperative care etc.). In previous work [1], a “pain-no pain” system was developed which used an AAM-SVM approach to good effect. However, as with any task involving a large amount of video data, there are memory constraints that need to be adhered to and in the previous work this was compressing the temporal signal using K-means clustering in the training phase. In visual speech recognition, it is well known that the dynamics of the signal play a vital role in recognition. As pain recognition is very similar to the task of visual speech recognition (i.e. recognising visual facial actions), it is our belief that compressing the temporal signal reduces the likelihood of accurately recognising pain. In this paper, we show that by compressing the spatial signal instead of the temporal signal, we achieve better pain recognition. Our results show the importance of the temporal signal in recognizing pain, however, we do highlight some problems associated with doing this due to the randomness of a patient’s facial actions. Index Terms: facial expression, pain, action units (AUs), visual speech recognition, active appearance models (AAM)

Jessica M. Howlett

Papers

Automatically Detecting Pain in Video Through Facial Action Units

Automatically detecting pain in video through facial action units

Improving Pain Recognition Through Better Utilisation of Temporal Information.