JPEG2000 Image Compression on Solar EUV Images
For future solar missions as well as ground-based telescopes, efficient ways to return and process data have become increasingly important. Solar Orbiter, which is the next ESA/NASA mission to explore the Sun and the heliosphere, is a deep-space mission, which implies a limited telemetry rate that makes efficient onboard data compression a necessity to achieve the mission science goals. Missions like the Solar Dynamics Observatory (SDO) and future ground-based telescopes such as the Daniel K. Inouye Solar Telescope, on the other hand, face the challenge of making petabyte-sized solar data archives accessible to the solar community. New image compression standards address these challenges by implementing efficient and flexible compression algorithms that can be tailored to user requirements. We analyse solar images from the Atmospheric Imaging Assembly (AIA) instrument onboard SDO to study the effect of lossy JPEG2000 (from the Joint Photographic Experts Group 2000) image compression at different bitrates. To assess the quality of compressed images, we use the mean structural similarity (MSSIM) index as well as the widely used peak signal-to-noise ratio (PSNR) as metrics and compare the two in the context of solar EUV images. In addition, we perform tests to validate the scientific use of the lossily compressed images by analysing examples of an on-disc and off-limb coronal-loop oscillation time-series observed by AIA/SDO.
KeywordsImage processing Image compression JPEG2000
AIA/SDO data are provided by the Joint Science Operations Center Science Data Processing. This project has received funding from the Science and Technology Facilities Council (UK) and the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No 647214). I. De Moortel and C. E. Fischer thank the ESTEC/ESA visitorship program for support. We have made use of the Coyote IDL library at www.idlcoyote.com .
Disclosure of Potential Conflicts of Interest
The authors declare that they have no conflicts of interest.
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