Contextual SVM Using Hilbert Space Embedding for Hyperspectral Classification

In this letter, a kernel-based contextual classification approach built on the principle of a newly introduced mapping technique, called Hilbert space embedding, is proposed. The proposed technique, called contextual support vector machine (SVM), is aimed at jointly exploiting both local spectral and spatial information in a reproducing kernel Hilbert space (RKHS) by collectively embedding a set of spectral signatures within a confined local region into a single point in the RKHS that can uniquely represent the corresponding local hyperspectral pixels. Embedding is conducted by calculating the weighted empirical mean of the mapped points in the RKHS to exploit the similarities and variations in the local spectral and spatial information. The weights are adaptively estimated based on the distance between the mapped point in consideration and its neighbors in the RKHS. An SVM separating hyperplane is built to maximize the margin between classes formed by weighted empirical means. The proposed technique showed significant improvement over the composite kernel-based SVM on several hyperspectral images.