Title: FMix: Enhancing Mixed Sample Data Augmentation. Abstract: Mixed Sample Data Augmentation (MSDA) has received increasing attention in recent years, with many successful variants such as MixUp and CutMix. We analyse MSDA from an information theoretic perspective, characterising learned models in terms of how they impact the models’ perception of the data.  Ultimately, our analyses allow us to decouple two complementary properties of augmentations that are useful for reasoning about MSDA. From insight on the efficacy of CutMix in particular, we subsequently propose FMix, an MSDA that uses binary masks obtained by applying a threshold to low frequency images sampled from Fourier space.  FMix improves performance over MixUp and CutMix for a number of models across a range of data sets and problem settings,  obtaining new state-of-the-art results on CIFAR-10 and Fashion-MNIST.