The Face Recognition Problem. Is a single image database sufficient for face recognition? A Psychological Experiment

Transcription

1 The Face Recognition Problem Is a single image database sufficient for face recognition? A Psychological Experiment Introduction to Computational and Biological Vision Liron Michaely Alon Grubshtein Introduction In recent years facial recognition has become a very popular area of research in computer vision. Progress in the field of computer vision may require deep physiological understanding, and in turn may advance certain theories in the field of neuroscience. The Face Recognition Problem: Given an image of a scene, identify or verify the person in the scene using a stored database of faces. 1

2 Introduction (contd.) There are different approaches to understanding the way we see things, which in turn inspire different algorithms. Global Approach - a single feature vector that represents the whole face image is used as input to a classifier. Works well for classifying frontal views of faces. Corresponds with the psychological theory known as the Template Theory. Component-Based approach This approach classifies local facial component. Corresponds with the psychological Feature theory. Introduction (contd.) Since both solutions are based on comparisons, efficiency is based on both the time required for computation but also on the size of the database required. In our experiment we want to examine the minimum size of database required for successful face recognition 2

3 Our assumption: The human visual system is capable of successful facial recognition based on a single image, even under extreme conditions. Experimental Procedure The experiment we conducted was based upon an application we wrote. Subjects were exposed to a single frontal image of a face (the target), and were tested on their ability to distinguish the target from different other faces (the distracters). Our target was a young man, Chen Michaely. As distracters we used a group of eight young men with more or less similar prominent facial features 3

4 Experiment (contd.) In the first stage of the experiment we presented the target to our test subjects a written description of him (his habits, details about his lifestyle, etc ), and then his 0 degree image. Second stage was a series of seemingly random pictures of both target and distracters from different angles. Subjects were asked to press a Yes button upon identifying the target. Response time was also kept. 4

5 Experiment (contd.) Implemented as a C++ program. Results saved as a CSV file. Experiment (contd.) Consistency precautions: Angle accuracy Increased Similarity Control image Image Order 5

6 Results Several definitions: A correct yes answer is called a Hit (H). A correct no answer is called a Correct Rejection (CR). A wrong yes answer is called a False Alarm (FA). A wrong no answer is called a Miss (M). Results from 40 people were analyzed. Results (contd.) Answer Distribution 4% 96% % Correct Answers % Wrong Ansers 6

7 Results (contd.) No wrong answers in Control Image. Most FA mistakes occurred in two specific images of the same distracter. Results (contd.) Distribution of Wrong Answers 7% 93% %M %FA Normalized 34% 66% %M %FA 7

8 Results (contd.) Number of Mistakes as a function of Angle deg -45 deg 0 deg 45 deg 90 deg Num M Num FA Results (contd.) Average Time per number of Mistakes >7 8

9 Results (contd.) Average Time Per Angle Results (contd.) If we consider mistakes and response time as indicators to difficult images, then the direction of face does not necessarily predict the difficulty level of the required analysis. 9

10 Conclusions The HVS is capable of processing an image, in such a way that allows it to identify a face from a new point of view, not previously in its database, and relying on a single frontal image. Discussion Main question: how is this done? A Computer Science approach: Create a 3D morphable model from three pictures. Use model to calculate new synthetic images, and compare using component based algorithm. 90% accuracy. Is this also what we do? non existing relation between the performance level and the angle of the face. The HVS produces significantly lower results in the case of upside down faces. 10

11 Bibliography [1]. Bernd Heisele, Purdy Ho, Jane Wu, and Tomaso Poggio (2003) Face recognition: component-based versus global approaches. Computer Vision and Image Understanding 91 (2003) [2]. Karl Haberlandt. Cognitive Psychology, 2nd Ed, Trinity college. [3]. Jennifer Huang, Bernd Heisele, and Volker Blanz (2003). Component-based Face Recognition with 3D Morphable Models. [4]. Yin, R.K. (1969) Looking at upside-down down faces. J. Exp. Psychology 81, [5]. Pawan Sinha, Benjamin Balas, Yuri Ostrovsky, Richard Russell. l. Face Recognition by Humans: 20 Results all Computer Vision Researchers Should Know About. Acknowledgment 11