Learning local image descriptors using binary decision trees

In this paper we propose a unified framework for learning such local image descriptors that describe pixel neighborhoods using binary codes. The descriptors are constructed using binary decision trees which are learnt from a set of training image patches. Our framework generalizes several previously proposed binary descriptors, such as BRIEF, LBP and their variants, and provides a principled way to learn new constructions which have not been previously studied. Further, the proposed framework can utilize both labeled or unlabeled training data, and hence fits to both supervised and unsupervised learning scenarios. We evaluate our framework using varying levels of supervision in the learning phase. The experiments show that our descriptor constructions perform comparably to benchmark descriptors in two different applications, namely texture categorization and age group classification from facial images.