Probabilistic Filtered Soft Labels for Domain Adaptation

Many domain adaptation (DA) methods aim to project the source and target domains into a common feature space, where the inter-domain distributional differences are reduced and some intra-domain properties preserved. Recent research obtains their respective new representations using some predefined statistics. However, they usually formulate the class-wise statistics using the pseudo hard labels due to no labeled target data, such as class-wise MMD and class scatter matrice. The probabilities of data points belonging to each class given by the hard labels are either 0 or 1, while the soft labels could relax the strong constraint of hard labels and provide a random value between them. Although existing work have noticed the advantage of soft labels, they either deal with thoes class-wise statistics inadequately or introduce those small irrelevant probabilities in soft labels. Therefore, we propose the filtered soft labels to discard thoes confusing probabilities, then both of the class-wise MMD and class scatter matrice are modeled in this way. In order to obtain more accurate filtered soft labels, we take advantage of a well-designed Graph-based Label Propagation (GLP) method, and incorporate it into the DA procedure to formulate a unified framework.