Xanadu Halkias

Beyond SIFT for Image Categorization by Bag-of-Scenes Analysis

In this paper, we address the general problem of image/object categorization with a novel approach referred to as Bag-of-Scenes (BoS). Our approach is efficient for both low semantic applications, such as texture classification and higher semantic tasks such as natural scenes recognition. It is based on the widely used combination of (i) Sparse coding (Sc), (ii) Max-pooling and (iii) Spatial Pyramid Matching (SPM) techniques applied to histograms of multi-scale Local Binary/Ternary Patterns (LBP/LTP) as local features. This approach can be considered as a two-layer hierarchical architecture. The first layer encodes quickly the local spatial patch structure via histograms of LBP/LTP, while the second layer encodes the relationships between pre-analyzed LBP/LTP-scenes/objects. In order to provide comparative results, we also introduce an alternate 2-layer architecture. For this latter, the first layer is encoding directly the multi-scale Differential Vectors (DV) local patches instead of histograms of LBP/LTP. Our method outperforms SIFT-based approaches using Sc techniques and can be trained efficiently with a simple linear SVM. Our BoS method achieves \(87.46\,\%\), and \(90.35\,\%\) of accuracy for Scene-15, UIUC-Sport datasets respectively.