Metric Learning with HORDE: High-Order Regularizer for Deep Embeddings
Résumé
Learning an effective similarity metric between the image
representations is key to the success of the recent advances
in visual search tasks (e.g. verification or zero shot
learning). Although the metric learning part is well addressed,
this metric is usually computed over the average
of the extracted deep features. This representation is then
trained to be discriminative, however, these deep features
tend to be scattered across the feature space. That way, the
representations are not robust for the feature outliers, object
occlusions, background variations, etc. In this paper,
we tackle this scattering problem with a distribution-aware
regularization named HORDE. This regularizer is designed
to ensure that the feature distributions from two dissimilar
images are well separated in the feature space. In the case
of similar images, the feature distributions are enforced to
be localized in the same feature space. We prove theoretically
that our regularizer upper and lower bounds wellknown
distances between distributions, such as the Maximum
Mean Discrepancy and the Wasserstein distance. Empirically,
HORDE consistently improves deep metric learning
architectures, leading to state-of-the-art results on 3 out
of 4 deep metric learning datasets.