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The algorithm is the basis for the JPEG-LS lossless/near-lossless
compression standard for continuous-tone images.
But NASA didn't use JPEG-LS; scientists "went
right to the source," says Gadiel Seroussi,
director of the Information Theory Research group
at HP Labs.
"This lossless compression is mandatory
in cases where the images are very precious, as
in the case of space imagery, where data is very
costly to obtain and must be accurately preserved
for scientific exploration," he says.
Scientists at the Jet Propulsion Laboratory (managed for NASA by the California Institute of Technology), who modified LOCO for their purposes,
credit HP Labs researchers Marcelo Weinberger,
Gadiel Seroussi and
Guillermo Sapiro
(now with the University of Minnesota) in their technical papers,
saying that LOCO-I helps to "maximize data
return within stringent mission download links."
"NASA and the Jet Propulsion Laboratory
have traditionally been strongholds in imaging
technologies," Seroussi says. "In this
case, they chose LOCO-I for its superior compression
performance and low complexity implementability."
Together with LOCO-I, NASA used the JPL-developed ICER, a lossy image compression scheme. The mission uses a mixture of lossless and lossy image compression to optimize bandwidth, human visual perception, and scientific precision requirements.
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Printable version
An HP Labs image-compression algorithm is partly to thank
for some of the spectacular, high-resolution images of Mars now
being transmitted by NASA's roving spacecraft.
The method is used in cases where images must be transmitted without quality loss.