Face recognition for images of persons against a general background using approximate parameter estimation of affine transform

A method for face recognition of acquaintance in a given people image with general background is proposed. We assume that the face pattern to be recognized in the input image is perturbed approximately by affine transform (rotated, enlarged or reduced, and translated) from a registered original one and also by a lighting variation. In order to estimate the parameters of the affine transform, the method uses a Karhunen–Loeve (KL) expansion, spatial correlation, and a correction equation based on Taylor's expansion of the transform. Moreover, in order to be insensitive to the lighting variations, we deal with a normalized gradient vector field (NGVF) pattern representation. The experimental result shows that the method using NGVF representation and approximate parameter estimation is considerably effective. © 2009 Wiley Periodicals, Inc. Electron Comm Jpn, 92(11): 1–8, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10152