Object classification using a local texture descriptor and a support vector machine

Abstract

Objects classification or object detection is one of the most challenging tasks in computer vision. Digital images taken of real-life scenes capture objects at different positions, rotations and scales. Furthermore, variations in lighting, shape, color and texture within the same class make object classification a huge obstacle for computer vision algorithms. The most robust methodologies related to variations in lighting, rotation, color and scale, are based on “key points” localization, followed by applying a local descriptor to each surrounding region. Researchers have used various methods for detecting key points and have applied various local descriptors. Of these, the Scale-Invariant Feature Transform (SIFT), Speeded Up Robust Features (SURF) and Center-Symmetric Local Binary Pattern (CS-LBP) methods have obtained good performance and are associated with clustering algorithms or histogram representation based on independent features (Bag of Features (BoF)). In the BoF approach, the visual codebook extracted around the “key points” regions can effectively describe objects by their appearance based on local texture analysis. Recently, we proposed two new texture descriptors for object detection based on the Local Mapped Pattern (LMP) approach. The Mean-Local Mapped Pattern (M-LMP) and the Center Symmetric Local Mapped Pattern (CS-LMP) exhibit better performance than SIFT and CS-LBP, but prior results have shown that the size of descriptors could be reduced without loss of sensitivity. In this paper, we investigated reducing the size of the M-LMP descriptor and then evaluating its performance for object classification by a Support Vector Machine (SVM) classifier. In our experiments, we implemented an object recognition system based on the M-LMP reduced descriptor, and compared our results against the SIFT, Local Intensity Order Pattern (LIOP) and CS-LMP descriptors. The object classification results were analyzed using a BoF model and a SVM classifier, with the result that performance using the reduced descriptor is better than the other three well-known methods tested and also requires less processing time.