GSC Sentinel-2 PDGS OCD - Emits - ESA

GSC Sentinel-2 PDGS OCD
Issue 1 Revision 2 (draft) - 25.07.2010
GMES-GSEG-EOPG-TN-09-0008
page 146 of 350
UTM Tile
Tile overlaps
across UTM zone
boundaries
MSI footprint
4.5.4.5.4.4 Image Compression
Figure 4-28 Tile Processing
At the term of the processing, the Level-1C image data will be compressed via JPEG2000 to
reduce the volumes to be transported. The standard JPEG2000 compression algorithm
features:
o Image compression capabilities with adequate control over the compressed image
quality (in lossless mode or quality controlled mode) with possibility of internal tiling;
o Compression / decompression times compatible with customer requirements, and
long-term availability as standardised through ISO/IEC 15444-1:2004
According to preliminary tests performed on a simulated Sentinel-2 dataset and reported in
[RD-30], an average compression of the 12bpp image to a 5.2 bpp image can be obtained in
lossless mode (corresponding to a compression ratio of about 2.3)
Compression in lossy mode will still be acceptable from an image quality point of view by
setting a compression-rate slightly superior to the 4 bpp data-rate used by the on-board
WICOM, hence resulting into a equivalent compression-ratio slightly inferior than 3.
The JPEG2000 compression rate will be configurable via a configuration parameter to be
evaluated during the commissioning phase. For sizing purposes, a compression-rate of
4.2bpp will be assumed (corresponding to a ratio of about 2.8 from the 12bpp radiometry
coding).
4.5.4.5.4.5 Preview and True-Colour Images Generation
The Level-1C processing will include the systematic generation of reduced-resolution preview
images (PVI) as well as full-resolution True-Colour Images (TCI), the latter being optionally
activated:
ESA UNCLASSIFIED – For Official Use
© ESA
The copyright of this document is the property of ESA. It is supplied in confidence and shall not be reproduced, copied or
communicated to any third party without written permission from ESA.