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Proceedings Paper

Improving multispectral satellite image compression using onboard subpixel registration
Author(s): Mathieu Albinet; Roberto Camarero; Maxime Isnard; Christophe Poulet; Jokin Perret
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Paper Abstract

Future CNES earth observation missions will have to deal with an ever increasing telemetry data rate due to improvements in resolution and addition of spectral bands. Current CNES image compressors implement a discrete wavelet transform (DWT) followed by a bit plane encoding (BPE) but only on a mono spectral basis and do not profit from the multispectral redundancy of the observed scenes. Recent CNES studies have proven a substantial gain on the achievable compression ratio, +20% to +40% on selected scenarios, by implementing a multispectral compression scheme based on a Karhunen Loeve transform (KLT) followed by the classical DWT+BPE. But such results can be achieved only on perfectly registered bands; a default of registration as low as 0.5 pixel ruins all the benefits of multispectral compression.

In this work, we first study the possibility to implement a multi-bands subpixel onboard registration based on registration grids generated on-the-fly by the satellite attitude control system and simplified resampling and interpolation techniques. Indeed bands registration is usually performed on ground using sophisticated techniques too computationally intensive for onboard use. This fully quantized algorithm is tuned to meet acceptable registration performances within stringent image quality criteria, with the objective of onboard real-time processing. In a second part, we describe a FPGA implementation developed to evaluate the design complexity and, by extrapolation, the data rate achievable on a spacequalified ASIC. Finally, we present the impact of this approach on the processing chain not only onboard but also on ground and the impacts on the design of the instrument.

Paper Details

Date Published: 24 September 2013
PDF: 10 pages
Proc. SPIE 8871, Satellite Data Compression, Communications, and Processing IX, 887106 (24 September 2013); doi: 10.1117/12.2024066
Show Author Affiliations
Mathieu Albinet, Ctr. National d'Études Spatiales (France)
Roberto Camarero, Ctr. National d'Études Spatiales (France)
Maxime Isnard, Thales Services (France)
Christophe Poulet, EREMS (France)
Jokin Perret, EREMS (France)


Published in SPIE Proceedings Vol. 8871:
Satellite Data Compression, Communications, and Processing IX
Bormin Huang; Antonio J. Plaza; Chein-I Chang, Editor(s)

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