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Short-Time Fourier Transform for deblurring Variational Autoencoders
Jan 06, 2024
Variational Autoencoders (VAEs) are powerful generative models, however their generated samples are known to suffer from a characteristic blurriness, as compared to the outputs of alternative generating techniques. Extensive research efforts have been made to tackle this problem, and several works have focused on modifying the reconstruction term of the evidence lower bound (ELBO). In particular, many have experimented with augmenting the reconstruction loss with losses in the frequency domain. Such loss functions usually employ the Fourier transform to explicitly penalise the lack of higher frequency components in the generated samples, which are responsible for sharp visual features. In this paper, we explore the aspects of previous such approaches which aren't well understood, and we propose an augmentation to the reconstruction term in response to them. Our reasoning leads us to use the short-time Fourier transform and to emphasise on local phase coherence between the input and output samples. We illustrate the potential of our proposed loss on the MNIST dataset by providing both qualitative and quantitative results.
Dataset Distillation via the Wasserstein Metric
Nov 30, 2023Dataset distillation (DD) offers a compelling approach in computer vision, with the goal of condensing extensive datasets into smaller synthetic versions without sacrificing much of the model performance. In this paper, we continue to study the methods for DD, by addressing its conceptually core objective: how to capture the essential representation of extensive datasets in smaller, synthetic forms. We propose a novel approach utilizing the Wasserstein distance, a metric rooted in optimal transport theory, to enhance distribution matching in DD. Our method leverages the Wasserstein barycenter, offering a geometrically meaningful way to quantify distribution differences and effectively capture the centroid of a set of distributions. Our approach retains the computational benefits of distribution matching-based methods while achieving new state-of-the-art performance on several benchmarks. To provide useful prior for learning the images, we embed the synthetic data into the feature space of pretrained classification models to conduct distribution matching. Extensive testing on various high-resolution datasets confirms the effectiveness and adaptability of our method, indicating the promising yet unexplored capabilities of Wasserstein metrics in dataset distillation.