3 research outputs found
Positive-unlabeled learning for open set domain adaptation
Open Set Domain Adaptation (OSDA) focuses on bridging the domain gap between a labeled source domain and an unlabeled target domain, while also rejecting target classes that are not present in the source as unknown. The challenges of this task are closely related to those of Positive-Unlabeled (PU) learning where it is essential to discriminate between positive (known) and negative (unknown) class samples in the unlabeled target data. With this newly discovered connection, we leverage the theoretical framework of PU learning for OSDA and, at the same time, we extend PU learning to tackle uneven data distributions. Our method combines domain adversarial learning with a new non-negative risk estimator for PU learning based on self-supervised sample reconstruction. With experiments on digit recognition and object classification, we validate our risk estimator and demonstrate that our approach allows reducing the domain gap without suffering from negative transfer
Privacy Preserving Domain Adaptation for Semantic Segmentation of Medical Images
Convolutional neural networks (CNNs) have led to significant improvements in
tasks involving semantic segmentation of images. CNNs are vulnerable in the
area of biomedical image segmentation because of distributional gap between two
source and target domains with different data modalities which leads to domain
shift. Domain shift makes data annotations in new modalities necessary because
models must be retrained from scratch. Unsupervised domain adaptation (UDA) is
proposed to adapt a model to new modalities using solely unlabeled target
domain data. Common UDA algorithms require access to data points in the source
domain which may not be feasible in medical imaging due to privacy concerns. In
this work, we develop an algorithm for UDA in a privacy-constrained setting,
where the source domain data is inaccessible. Our idea is based on encoding the
information from the source samples into a prototypical distribution that is
used as an intermediate distribution for aligning the target domain
distribution with the source domain distribution. We demonstrate the
effectiveness of our algorithm by comparing it to state-of-the-art medical
image semantic segmentation approaches on two medical image semantic
segmentation datasets