In this work, we present the problem of automatic appearance-based facial analysis with machine learning techniques and describe common specific sub-problems like face detection, facial feature detection and face recognition which are the crucial parts of many applications in the context of indexation, surveillance, access-control or human-computer interaction.
To tackle this problem, we particularly focus on a technique called Convolutional Neural Network (CNN) which is inspired by biological evidence found in the visual cortex of mammalian brains and which has already been applied to many different classi
fication problems. Existing CNN-based methods, like the
face detection system proposed by Garcia and Delakis, show that this can be a very effective, efficient and robust approach to non-linear image processing tasks.
An important step in many automatic facial analysis applications, e.g. face recognition, is face alignment which tries to translate, scale and rotate the face image such that specific facial features are roughly at predefined positions in the image. We propose an efficient approach to this problem using CNNs and experimentally show its very good performance on difficult test images.
We further present a CNN-based method for automatic facial feature detection. The proposed system employs a hierarchical procedure which first roughly localizes the eyes, the nose and the mouth and then refines the result by detecting 10 different facial feature points. The detection rate of this method is 96%
for the AR database and 87% for the BioID database tolerating an error of 10% of the inter-ocular distance.
Finally, we propose a novel face recognition approach based on a specific CNN architecture learning a non-linear mapping of the image space into a lower-dimensional sub-space where the different classes are more easily separable.
We applied this method to several public face databases and obtained better recognition rates than with classical face recognition approaches based on PCA or LDA.
We also present a CNN-based method for the binary classification problem of gender recognition with face images and achieve a state-of-the-art accuracy.
The results presented in this work show that CNNs perform very well on various facial image processing tasks, such as face alignment, facial feature detection and face recognition and clearly demonstrate that the CNN technique is a versatile, efficient and robust approach for facial image analysis.
Table of Contents
- 1 Introduction
- 1.1 Context
- 1.2 Applications
- 1.3 Difficulties
- 1.3.1 Illumination
- 1.3.2 Pose
- 1.3.3 Facial Expressions
- 1.3.4 Partial Occlusions
- 1.3.5 Other types of variations
- 1.4 Objectives
- 1.5 Outline
- 2 Machine Learning Techniques for Object Detection and Recognition
- 3 Convolutional Neural Networks
- 4 Face detection and normalization
- 4.1 Introduction
- 4.2 Face detection
- 4.3 Illumination Normalization
- 4.4 Pose Estimation
- 4.5 Face Alignment
- 4.6 Conclusion
- 5 Facial Feature Detection
- 5.1 Introduction
- 5.2 State-of-the-art
- 5.3 Facial Feature Detection with Convolutional Neural Networks
- 5.4 Conclusion
- 6 Face and Gender Recognition
- 6.1 Introduction
- 6.2 State-of-the-art in Face Recognition
- 6.3 Face Recognition with Convolutional Neural Networks
- 6.4 Gender Recognition
- 6.5 Conclusion
Objectives and Key Themes
This dissertation aims to evaluate the performance of Convolutional Neural Networks (CNNs) in various facial image processing tasks. It investigates the robustness of CNNs against common sources of noise in facial analysis and proposes novel CNN architectures for specific problems.
- Evaluation of CNNs for appearance-based facial analysis.
- Investigation of CNN robustness against noise (illumination, pose, expression, occlusion).
- Development of CNN architectures for face alignment, feature detection, and recognition.
- Improvement of state-of-the-art performance in facial feature detection, alignment, and recognition.
- Exploration of solutions to enhance automatic face recognition.
Chapter Summaries
1 Introduction: This chapter introduces the context of automatic image processing, focusing on the importance of face image analysis in applications such as indexing, surveillance, access control, and human-computer interaction. It highlights the challenges posed by variations in illumination, pose, facial expressions, and occlusions. The chapter outlines the dissertation's objectives and structure.
2 Machine Learning Techniques for Object Detection and Recognition: This chapter reviews various machine learning techniques relevant to object detection and recognition, including statistical projection methods (PCA, LDA), Active Appearance Models (AAMs), Hidden Markov Models (HMMs), Adaboost, Support Vector Machines (SVMs), and Neural Networks (including MLPs, RBF networks, and SOMs). The chapter provides a foundation for understanding the convolutional neural networks used in the dissertation.
3 Convolutional Neural Networks: This chapter delves into the theory and application of Convolutional Neural Networks (CNNs), highlighting their advantages over traditional MLPs for image processing tasks. The chapter explores the background of CNNs, including the Neocognitron and LeCun's models, and details the training process using error backpropagation. Various extensions and variants of CNNs are also discussed.
4 Face detection and normalization: This chapter examines face detection methods, comparing template-based and feature-based approaches. It focuses on the Convolutional Face Finder (CFF), a high-performing CNN-based face detector, detailing its architecture, training, and performance evaluation. The chapter also explores illumination normalization, pose estimation, and face alignment techniques.
5 Facial Feature Detection: This chapter reviews existing facial feature detection methods, categorized into local and iterative approaches. The author then proposes a hierarchical CNN-based system for precise and robust facial feature detection, describing its architecture, training methodology, and performance evaluation on various datasets. The chapter also analyzes the system's robustness to noise and occlusions.
6 Face and Gender Recognition: This chapter surveys existing face and gender recognition methods, classifying them into global and local approaches. A novel CNN-based face recognition method is proposed, utilizing image reconstruction to learn a robust, non-linear mapping for classification. The chapter presents experimental results and a comparison with traditional methods. A CNN-based gender recognition system is also detailed, along with its performance evaluation.
Keywords
Face image analysis, Convolutional Neural Networks (CNNs), face detection, face alignment, facial feature detection, face recognition, gender recognition, machine learning, image processing, pattern recognition, robustness, BioID database, AR database, FERET database.
Frequently Asked Questions: A Comprehensive Language Preview on Convolutional Neural Networks for Facial Image Processing
What is the main topic of this dissertation?
This dissertation focuses on evaluating the performance of Convolutional Neural Networks (CNNs) in various facial image processing tasks. It investigates the robustness of CNNs against common sources of noise and proposes novel CNN architectures for specific problems, including face detection, alignment, feature detection, and recognition, as well as gender recognition.
What are the key objectives of this research?
The key objectives include evaluating CNNs for appearance-based facial analysis; investigating CNN robustness against noise (illumination, pose, expression, occlusion); developing CNN architectures for face alignment, feature detection, and recognition; improving state-of-the-art performance in facial feature detection, alignment, and recognition; and exploring solutions to enhance automatic face recognition.
What are the main challenges addressed in facial image processing?
The dissertation highlights common challenges in facial image analysis, such as variations in illumination, pose, facial expressions, and partial occlusions. These factors significantly impact the accuracy and reliability of automated facial recognition systems.
What machine learning techniques are reviewed in this work?
The dissertation reviews various machine learning techniques relevant to object detection and recognition, including statistical projection methods (PCA, LDA), Active Appearance Models (AAMs), Hidden Markov Models (HMMs), Adaboost, Support Vector Machines (SVMs), and Neural Networks (including MLPs, RBF networks, and SOMs). The focus then shifts to Convolutional Neural Networks (CNNs) due to their superior performance in image processing.
What is the role of Convolutional Neural Networks (CNNs) in this research?
CNNs are central to this dissertation. The research explores their theoretical background, application in various facial image processing tasks, and proposes novel CNN architectures for improved performance in face detection, normalization, feature detection, and recognition, including gender recognition. The dissertation compares CNNs to traditional methods and highlights their advantages.
What specific facial processing tasks are addressed?
The dissertation covers several key facial processing tasks: face detection and normalization (including illumination normalization, pose estimation, and face alignment); facial feature detection; and face and gender recognition. For each task, the research reviews existing methods and proposes novel CNN-based approaches.
What datasets are used in the experiments?
The dissertation mentions the use of several well-known databases for evaluating the performance of the proposed methods, including BioID, AR, and FERET databases.
What are the main contributions of this dissertation?
The main contributions include a comprehensive evaluation of CNNs for facial image processing, the development of novel CNN architectures for specific tasks, and the improvement of state-of-the-art performance in face detection, alignment, feature detection, and recognition, including gender recognition. The research also contributes to a deeper understanding of the robustness of CNNs against common noise sources in facial images.
How are the findings presented?
The dissertation presents its findings through a structured format including an introduction, detailed literature review, theoretical background of CNNs, chapter-wise summaries of the different facial processing tasks addressed, experimental results, and a concluding chapter summarizing the contributions and potential future research directions.
What are the key words associated with this research?
Key words include: Face image analysis, Convolutional Neural Networks (CNNs), face detection, face alignment, facial feature detection, face recognition, gender recognition, machine learning, image processing, pattern recognition, robustness, BioID database, AR database, FERET database.
- Citar trabajo
- Dr. Stefan Duffner (Autor), 2008, Face Image Analysis with Convolutional Neural Networks, Múnich, GRIN Verlag, https://www.grin.com/document/133318
