PULSE: Self-Supervised Photo Upsampling via Latent Space Exploration of
Generative Models
- URL: http://arxiv.org/abs/2003.03808v3
- Date: Mon, 20 Jul 2020 21:38:32 GMT
- Title: PULSE: Self-Supervised Photo Upsampling via Latent Space Exploration of
Generative Models
- Authors: Sachit Menon, Alexandru Damian, Shijia Hu, Nikhil Ravi, Cynthia Rudin
- Abstract summary: PULSE (Photo Upsampling via Latent Space Exploration) generates high-resolution, realistic images at resolutions previously unseen in the literature.
Our method outperforms state-of-the-art methods in perceptual quality at higher resolutions and scale factors than previously possible.
- Score: 77.32079593577821
- License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
- Abstract: The primary aim of single-image super-resolution is to construct
high-resolution (HR) images from corresponding low-resolution (LR) inputs. In
previous approaches, which have generally been supervised, the training
objective typically measures a pixel-wise average distance between the
super-resolved (SR) and HR images. Optimizing such metrics often leads to
blurring, especially in high variance (detailed) regions. We propose an
alternative formulation of the super-resolution problem based on creating
realistic SR images that downscale correctly. We present an algorithm
addressing this problem, PULSE (Photo Upsampling via Latent Space Exploration),
which generates high-resolution, realistic images at resolutions previously
unseen in the literature. It accomplishes this in an entirely self-supervised
fashion and is not confined to a specific degradation operator used during
training, unlike previous methods (which require supervised training on
databases of LR-HR image pairs). Instead of starting with the LR image and
slowly adding detail, PULSE traverses the high-resolution natural image
manifold, searching for images that downscale to the original LR image. This is
formalized through the "downscaling loss," which guides exploration through the
latent space of a generative model. By leveraging properties of
high-dimensional Gaussians, we restrict the search space to guarantee realistic
outputs. PULSE thereby generates super-resolved images that both are realistic
and downscale correctly. We show proof of concept of our approach in the domain
of face super-resolution (i.e., face hallucination). We also present a
discussion of the limitations and biases of the method as currently implemented
with an accompanying model card with relevant metrics. Our method outperforms
state-of-the-art methods in perceptual quality at higher resolutions and scale
factors than previously possible.
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