Regularized Large Margin Distance Metric Learning

Distance metric learning plays an important role in many applications, such as classification and clustering. In this paper, we propose a novel distance metric learning using two hinge losses in the objective function. One is the constraint of the pairs which makes the similar pairs (the same label) closer and the dissimilar (different labels) pairs separated as far as possible. The other one is the constraint of the triplets which makes the largest distance between pairs intra the class larger than the smallest distance between pairs inter the classes. Previous works only consider one of the two kinds of constraints. Additionally, different from the triplets used in previous works, we just need a small amount of such special triplets. This improves the efficiency of our proposed method. Consider the situation in which we might not have enough labeled samples, we extend the proposed distance metric learning into a semi-supervised learning framework. Experiments are conducted on several landmark datasets and the results demonstrate the effectiveness of our proposed method.