The task of face verification is made more difficult when the illumination conditions of image capture are not constrained. The differences in illumination conditions between the stored images of the client and the probe image can be lessened by the application of photometric normalisation. Photometric normalisation is the method of pre-processing an image to a representation that is robust to the illumination conditions of image capture. This thesis presents experiments comparing several photometric normalisation methods. The results demonstrate that the anisotropic smoothing pre-processing algorithm of Gross and Brajovic [35] yields the best results of the photometric normalisations tested. The thesis presents an investigation into the behaviour of the anisotropic smoothing method, showing that performance is sensitive to the selection of its parameter. A method of optimising this parameter is suggested and experimental results show that it offers an improvement in verification rates. The variation of illumination across regions of the face is smaller than across the whole face. A novel component-based approach to face verification is presented to take advantage

For an image, texture unit (TU) is a small complete unit which characterizes the local texture of a given pixel and its neighborhood. Recently, TU-based approaches have been widely used in face recognition. This paper proposes a novel face representation and recognition approach based on TU. We make three major contributions: (1) we introduce a novel TU feature, Local Gabor Quarternary Pattern (LGQP), which incorporates both Gabor magnitude and phase information in a single TU code; (2) similarity measure of two TU images is treated as a tracking problem between two images, and we present a novel point-to-point matching (PPM) approach for TU similarity measure; (3) based on an integral histogram technique, the PPM similarity can be computed very rapidly. Experimental results on CMU-PIE and FERET data sets show that our method is able to reach very promising results.