Attention-Based Generative Neural Image Compression on Solar Dynamics Observatory Ali Zafariy Atefeh Khoshkhahtinaty Piyush M. Mehtaz Nasser M. Nasrabadiy Barbara J. Thompsonx

2025-04-27 0 0 1.22MB 8 页 10玖币
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Attention-Based Generative Neural Image
Compression on Solar Dynamics Observatory
Ali Zafari, Atefeh Khoshkhahtinat, Piyush M. Mehta, Nasser M. Nasrabadi, Barbara J. Thompson§,
Daniel da Silva§, Michael S. F. Kirk§
Dept. of Computer Science & Electrical Engineering, West Virginia University, WV USA
Dept. of Mechanical & Aerospace Engineering, West Virginia University, WV USA
§NASA Goddard Space Flight Center, MD USA
{az00004,ak00043}@mix.wvu.edu,{piyush.mehta,nasser.nasrabadi}@mail.wvu.edu
{barbara.j.thompson,daniel.e.dasilva,michael.s.kirk}@nasa.gov
Abstract—NASAs Solar Dynamics Observatory (SDO) mission
gathers 1.4 terabytes of data each day from its geosynchronous
orbit in space. SDO data includes images of the Sun captured at
different wavelengths, with the primary scientific goal of under-
standing the dynamic processes governing the Sun. Recently, end-
to-end optimized artificial neural networks (ANN) have shown
great potential in performing image compression. ANN-based
compression schemes have outperformed conventional hand-
engineered algorithms for lossy and lossless image compression.
We have designed an ad-hoc ANN-based image compression
scheme to reduce the amount of data needed to be stored and
retrieved on space missions studying solar dynamics. In this
work, we propose an attention module to make use of both local
and non-local attention mechanisms in an adversarially trained
neural image compression network. We have also demonstrated
the superior perceptual quality of this neural image compressor.
Our proposed algorithm for compressing images downloaded
from the SDO spacecraft performs better in rate-distortion trade-
off than the popular currently-in-use image compression codecs
such as JPEG and JPEG2000. In addition we have shown that
the proposed method outperforms state-of-the art lossy transform
coding compression codec, i.e., BPG.
Index Terms—Learned lossy image compression, solar dynam-
ics observatory, generative adversarial network, attention
I. INTRODUCTION
Image compression using artificial neural networks (ANN)
has shown great potential to be applied on a wide variety
of different areas since their first appearance [1]. In the
past couple of years, they have outperformed most of the
hand-engineered codecs such as JPEG [2] and JPEG2000
[3] in terms of rate-distortion (RD) performance [4]. One
major advantage of ANN-based compression algorithms is
that they can be developed on any ad-hoc dataset to do better
compression than general codecs [4].
Although it is believed that the ultimate trade-off in im-
age compression is between the rate and distortion, recent
studies have shown that there is a third role governing the
This research is based upon work supported by the National Aeronautics
and Space Administration (NASA), via award number 80NSSC21M0322
under the title of Adaptive and Scalable Data Compression for Deep Space
Data Transfer Applications using Deep Learning.
visual quality of compressed images known as perception [5].
Generative Adversarial Networks (GANs) are known for their
high-quality reconstructed images by enforcing the ANN to
capture the distribution of their input image. Hence, to improve
the perceptual quality of reconstructed image at the receiver,
GANs have been applied to image compression networks in
the literature [6].
Another venue of works to improve the performance of Con-
volutional Neural Networks (CNNs) is attention mechanism.
With its unprecedented influence in natural language process-
ing [7], attention has found its way in computer vision and
object detection/classification tasks [8], [9]. We have utilized
both of these improvements in learned image compression net-
works to enhance the performance in terms of rate-distortion-
perception trade-off [5]. As shown in Figure 1, although the
attention mechanism can reach better performance compared
with other compression standards, augmenting it with a GAN
will lead to better perceptual quality.
Contributions of This Work. In this work we have inves-
tigated the application of recently successful learned image
compression methods in the field of solar imaging. We have
shown that these neural compression schemes could easily
outperform traditional and currently-in-use image codecs. In
addition, we have proposed a curated attention module to
improve the RD tradeoff performance in state-of-the art neural
compression architectures. We have also utilized adversarial
training to encourage the decoder of our neural network
to preserve the distribution of the solar images during the
reconstruction process.
The remainder of the paper is organized as follows. Sec-
tion II reviews the neural-based compression methods and
the importance of compression on SDO mission. Section III
describes our proposed method. The experiments and ablation
studies are discussed in section IV with a conclusion at section
V.
II. RELATED WORK
A. Neural Image Compression
Transform coding based image compression algorithms
share four main steps to compress an image [10]. First,
978-1-6654-6283-9/22/$31.00 ©2022 IEEE
DOI 10.1109/ICMLA55696.2022.00035
arXiv:2210.06478v2 [eess.IV] 4 May 2023
0.367/33.27
JPEG
BPG
0.362/35.07
Original
8/
0.361/34.10.360/35.2
Attention
JPEG2000
0.361/34.17
Attention+GAN
Fig. 1. Visual comparison of proposed compression schemes (Attention only
and GAN+Attention) to other standard codecs. Reported performance in terms
of bit-rate/distortion [bpp/PSNR]. GAN outputs are visually closer to the
original input unless their lower performance in terms of PSNR. Best viewed
on screen.
encoding the images from their input space (e.g., RGB) to an
uncorrelated space. Second, quantizing to discard less signifi-
cant information from the data in its uncorrelated domain. At
the third step, an entropy coding will be utilized to losslessly
encode the quantized samples into a stream of ones and zeros.
This bitstream will be the compressed image. Final step occurs
at the receiving end (or at reconstructing step), which is
responsible to decode the quantized values to the original
space of the input image. The first and most widely used
architecture to mimic this scenario in deep neural networks, is
the convolutional autoencoder, which has shown its superiority
in the literature [11]. Both the encoding and decoding part
of the traditional transform coding, could be imitated by an
autoencoder [12].
End-to-end optimizing of the neural networks are capable
of handling various tasks [13], [14], [15], [16] if the learning
objective chosen to be differentiable. In an end-to-end opti-
misation of an autoencoder, problems arise when we want
to do quantization on its bottleneck. It is worth mentioning
that quantization is the essential part of compression. Merely
doing dimensionality reduction cannot necessarily result in
discarding the redundant information, which is necessary to
attain high compression ratios [17].
ANNs are optimized using gradient descent algorithms
which update the parameters of the network by back-
propagating the gradients of the loss function. Thus, all the
operations performed in it must be differentiable. As a result,
we need to approximate hard discrete quantization with a soft
continuous operation. To do so, several approaches have been
proposed in the literature. [1] used recurrent neural networks
to directly binarize the latent code stochastically, while [17]
used an approach similar to straight through estimator [18]
by back-propagating the gradients of identity function and
rounding to the nearest integer in the forward pass. By this
continuous approximation, the network parameters can be
successfully learned with backpropagating the gradient of the
loss function. The most widely used approach is proposed by
[19], inherited from [20], they showed that adding independent
and identically distributed uniform noise in the range of scalar
quantization can be interpreted equivalently as doing scalar
quantization on the bottleneck. By doing so, we can optimize
the differential entropy of the continuous approximation as
a variational upper bound [21] to reduce the entropy of
the bottleneck. Low entropy messages are compressed more
efficiently into bitstreams [22], [23].
In classical image compression schemes, to get the best
out of the quantization process, the first step was to apply
an invertible linear transform and translate the image into
decorrelated coefficients using Discrete Cosine Transform
(DCT). By doing so, scalar quantization could reach a rea-
sonable performance close to vector quantization [10]. The
application of vector quantization in ANN-based compression
has been investigated by [24], with the cost of complicated
training procedure. On the other hand, it has been shown [11],
[12] that a joint-optimized learned nonlinear transform, i.e.,
neural network, followed by scalar quantization can ideally
approximate a parametric form of vector quantization.
Replacing the actual quantization with uniform noise ap-
proximation in the bottleneck of a vanilla autoencoder during
training of the network [25], will transform it to a Variational
Aueoencoder (VAE) [26]. The only difference is on the chosen
prior. In autoencoder-based image compression, the Gaussian
prior of the VAE is replaced with unit uniform distribution
centered on integer numbers.
B. Solar Dynamics Observatory (SDO) Mission
1) Image Compression on SDO Data:Advances in sensor
technology and an increasing desire for a deeper understanding
of the space environment (Sun to Earth and beyond) have led
to an explosion of data volume in recent years (unprecedented
spatial and/or temporal resolution as well as multi-spectral
摘要:

Attention-BasedGenerativeNeuralImageCompressiononSolarDynamicsObservatoryAliZafariy,AtefehKhoshkhahtinaty,PiyushM.Mehtaz,NasserM.Nasrabadiy,BarbaraJ.Thompsonx,DanieldaSilvax,MichaelS.F.KirkxyDept.ofComputerScience&ElectricalEngineering,WestVirginiaUniversity,WVUSAzDept.ofMechanical&AerospaceEngineer...

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