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Subspace Learning from Image Gradient Orientations
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ISSN: 0162-8828
Georgios Tzimiropoulos, University of Lincoln, London and Imperial College London, London
Stefanos Zafeiriou, Imperial College London, London
Maja Pantic, Imperial College, London and University of Twente, Enschede
We introduce the notion of subspace learning from image gradient orientations for appearance-based object recognition. As image data is typically noisy and noise is substantially different from Gaussian, traditional subspace learning from pixel intensities fails very often to estimate reliably the low-dimensional subspace of a given data population. We show that replacing pixel intensities with gradient orientations and the $\ell_2$ norm with a cosine-based distance measure offers, to some extend, a remedy to this problem. Within this framework, which we coin IGO (Image Gradient Orientations) subspace learning, we first formulate and study the properties of Principal Component Analysis of image gradient orientations (IGO-PCA). We then show its connection to previously proposed robust PCA techniques both theoretically and experimentally. Finally, we derive a number of other popular subspace learning techniques, namely Linear Discriminant Analysis (LDA), Locally Linear Embedding (LLE) and Laplacian Eigenmaps (LE). Experimental results show that our algorithms outperform significantly popular methods such as Gabor features and Local Binary Patterns and achieve state-of-the-art performance for difficult problems such as illumination- and occlusion-robust face recognition. In addition to this, the proposed IGO-methods require the eigen-decomposition of simple covariance matrices and are as computationally efficient as their corresponding $\ell_2$ norm intensity-based counterparts.
Index Terms:
Face recognition, Subspace learning
Citation:
Georgios Tzimiropoulos, Stefanos Zafeiriou, Maja Pantic, "Subspace Learning from Image Gradient Orientations," IEEE Transactions on Pattern Analysis and Machine Intelligence, 19 Jan. 2012. IEEE computer Society Digital Library. IEEE Computer Society, <http://doi.ieeecomputersociety.org/10.1109/TPAMI.2012.40>
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