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Face Detection and Modeling for Recognition - Biometrics Research ...

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verify the face present in an image in the recognition stage.<br />

This thesis has developed<br />

a robust face detection module which is used to facilitate applications such as face<br />

tracking <strong>for</strong> surveillance, <strong>and</strong> face modeling <strong>for</strong> identification (as well as verification).<br />

We will briefly discuss the topics of face detection <strong>and</strong> recognition, face modeling as<br />

well as compression, <strong>and</strong> face-based image retrieval in the following sections.<br />

1.4 <strong>Face</strong> <strong>Detection</strong> <strong>and</strong> <strong>Recognition</strong><br />

Human activity is a major concern in a wide variety of applications such as video<br />

surveillance, human computer interface, face recognition [37], [36], [38], <strong>and</strong> face<br />

image database management [40]. Detecting faces is a crucial step <strong>and</strong> usually the<br />

first one in these identification applications.<br />

However, due to various head poses,<br />

illumination conditions, occlusion, <strong>and</strong> distances between teh sensor <strong>and</strong> the subject<br />

(which may result in a blurred face), detecting human faces is an extremely difficult<br />

task under unconstrained environments (see images in Figs. 1.13 (a) <strong>and</strong> (b)). Most<br />

face recognition algorithms assume that the problem of face detection has been solved,<br />

that is, the face location is known. Similarly, face tracking algorithms (e.g., [61])<br />

often assume the initial face location is known. Since face detection can be viewed<br />

as a two-class (face vs. non-face) classification problem, some techniques developed<br />

<strong>for</strong> face recognition (e.g., holistic/template approaches [21], [62], [63], [64], featurebased<br />

approaches [65], <strong>and</strong> their combination [66]) have been used to detect faces.<br />

However, these detection techniques are computationally very dem<strong>and</strong>ing <strong>and</strong> cannot<br />

h<strong>and</strong>le large variations in faces. In addition to the face location, a face detection<br />

15

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