流形学习方法可以有效的发现存在于高维图像空间的低维子流形并进行维数约简,近年来越来越受到生物特征识别和认知科学领域的研究者的重视。但是流形学习是一种非监督学习方法,其鉴别能力反而不如传统的维数约简方法,而且流形学习方法大多没有明晰的投影矩阵,很难直接对新样本进行维数约简。针对这两个问题,本文提出一种新的有监督的核局部线性嵌入算法(supervised kernel local linear embedding,SKLLE),并将算法应用于面部表情识别。该算法通过非线性核映射将人脸图像样本投影到高维核空间,然后将人脸图像局部流形的结构信息和样本的类别信息进行有效的结合进行维数约简,提取低维鉴别流形特征用于表情分类。SKLLE算法不仅能发现嵌入于高维人脸图像空间的低维表情子流形,而且增强了局部类间的联系,同时对新样本有较好的泛化性,实验结果表明该算法能有效的提高面部表情识别的性能。
Abstract
Manifold learning method can discover intrinsic low-dimensional submanifold embedded in the high-dimensional image space
it attracts more and more attention in the research area of biometrics and cognitive science. However
manifold learning is an unsupervised learning method
the discriminative ability of the low-dimensional feature obtained by the algorithm is often lower than those obtained by the conventional dimensionality reduction methods. Furthermore
manifold learning methods don’t have direct mapping for new example
so it’s difficult to acquire the low dimensional features of new example. To address the two problems
this paper introduces a novel supervised kernel local linear embedding (SKLLE) method for facial expression recognition
it maps face images to high dimensional kernel space through nonlinear kernel mapping
then fuses prior class-label information and nonlinear facial expression submanifold of real face images to extract discriminative features for expression classification. SKLLE can not only gains a perfect approximation of facial expression manifold
but also enhances local within-class relations. It also does well on the new samples. Experimental results show that the proposed method can improve face expression classification performance effectively.