조명변화에 강인한 얼굴인식을 위한 개선된 전처리 방법

학위논문(석사) - 한국과학기술원 : 전산학전공, 2007.2, [ vi, 50 p. ]Illumination Variation is one of the main obstacles in automatic face recognition systems. In the past few years, many approaches to coping with illumination variations have been proposed which can be categorized into model based and preprocessing based. Although the model-based approaches seem more perfect in theory, they commonly introduce more constraints and computational time is very prohibitive in most cases. On the other hand, the preprocessing approaches commonly exploit simple and efficient image processing techniques. The typical approaches based on image processing include histogram equalization (HE), histogram specification (HS), derivatives of the gray-level images by Laplacian of Gaussian filter (LOG), wavelet based method, and quotient image bases methods like self quotient image (SQI). In this thesis, I propose some improved methods based on the LOG and wavelet based method. The main idea is to apply image de-noising to suppress noises and Gamma Adjustment to alleviate the uneven illumination conditions. After that we extract and enhance facial features using LOG and wavelet decomposition so as to facilitate our recognition task. By comparing proposed methods with previous methods on the CAS-Peal Face database and Extended Yale Face Database B, proposed methods showed an obvious improvement on both databases compared with previous major methods which showed excellent performance. Experimental results proved the effectiveness of the proposed methods. Our proposed methods do not need any training or time consuming optimization procedure, so they are suitable for real time applications.한국과학기술원 : 전산학전공

Preprocessing apparatus and method for illumination-invariant face recognition

이 발명은 얼굴인식 기술에 관한 것으로서, 조명 변화에 따른 얼굴 왜곡을 보상하기 위한 얼굴인식 전처리장치 및 방법과, 이를 이용한 얼굴인식 시스템에 관한 것이다.이 발명에 따른 얼굴인식 전처리장치는, 입력 영상의 히스토그램을 균등분포로 변환하는 히스토그램 평활화기와, 상기 히스토그램 평활화기에서 히스토그램 평활화된 영상의 불균일한 조명 조건을 완화시키는 감마보정기와, 상기 감마보정기에서 감마보정된 영상의 잡음을 제거하는 비너필터와, 상기 비너필터에서 잡음이 제거된 영상의 얼굴특징을 추출하는 로그(LoG; Laplacian of Gaussian)필터와, 상기 로그필터에서 추출된 얼굴특징의 대비를 향상시키는 대비보정기를 포함한다