In many vision problems, instead of having fully labeled training data, it is easier to obtain the input in small groups, where the data in each group is constrained to be from the same class but the actual class label is not known. Such constraints give rise to partial equivalence relations. The absence of class labels prevents the use of standard discriminative methods in this scenario. On the other hand, the state-of-the-art techniques that use partial equivalence relations, e.g., Relevant Component Analysis, learn projections that are optimal for data representation, but not discrimination. We show that this leads to poor performance in several real-world applications, especially those with highdimensional data. In this paper, we present a novel discriminative technique for the classification of weakly-labeled data which exploits the null-space of data scatter matrices to achieve good classification accuracy. We demonstrate the superior performance of both linear and nonlinear ver...
Sanjiv Kumar, Henry A. Rowley