Novel illumination-normalization method based on region information

Ching-Chun Huang, Cheng-Yi Liu

Abstract: A region based illumination-normalization method which only uses gray level values in an image as information is proposed in this paper. The general purpose of illumination normalization is to reduce lighting effect when the testing images are captured in different environment and supplies useful and uniform data. We apply the algorithm in our face recognition system. The algorithm first divides the testing face images into two parts using homomorphic filtering method. One is the face feature, <i>F</i>₀, and the other one is the illumination information, <i>I</i>₀. Next, an illumination reference model is constructed from a set of normal face images. The illumination information of the testing face image is then adjusted according to the illumination reference model. The modified illumination information, <i>I</i>_&alpha;, and original face feature, <i>F</i>₀, are at last combined to make up the normalized face image. The face recognition result is improved after the algorithm is applied.