Enhancing Image Rescaling using Dual Latent Variables in Invertible
Neural Network
- URL: http://arxiv.org/abs/2207.11844v1
- Date: Sun, 24 Jul 2022 23:12:51 GMT
- Title: Enhancing Image Rescaling using Dual Latent Variables in Invertible
Neural Network
- Authors: Min Zhang, Zhihong Pan, Xin Zhou, C.-C. Jay Kuo
- Abstract summary: A new downscaling latent variable is introduced to model variations in the image downscaling process.
It can improve image upscaling accuracy consistently without sacrificing image quality in downscaled LR images.
It is also shown to be effective in enhancing other INN-based models for image restoration applications like image hiding.
- Score: 42.18106162158025
- License: http://creativecommons.org/licenses/by-nc-sa/4.0/
- Abstract: Normalizing flow models have been used successfully for generative image
super-resolution (SR) by approximating complex distribution of natural images
to simple tractable distribution in latent space through Invertible Neural
Networks (INN). These models can generate multiple realistic SR images from one
low-resolution (LR) input using randomly sampled points in the latent space,
simulating the ill-posed nature of image upscaling where multiple
high-resolution (HR) images correspond to the same LR. Lately, the invertible
process in INN has also been used successfully by bidirectional image rescaling
models like IRN and HCFlow for joint optimization of downscaling and inverse
upscaling, resulting in significant improvements in upscaled image quality.
While they are optimized for image downscaling too, the ill-posed nature of
image downscaling, where one HR image could be downsized to multiple LR images
depending on different interpolation kernels and resampling methods, is not
considered. A new downscaling latent variable, in addition to the original one
representing uncertainties in image upscaling, is introduced to model
variations in the image downscaling process. This dual latent variable
enhancement is applicable to different image rescaling models and it is shown
in extensive experiments that it can improve image upscaling accuracy
consistently without sacrificing image quality in downscaled LR images. It is
also shown to be effective in enhancing other INN-based models for image
restoration applications like image hiding.
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