[Freegis-list] A public alternative to MRSID?

[Frank Warmerdam]

Roger Bedell wrote:
 > Heiko,
 > This has bugged me for a while. I think that it should be possible to put
 > together an alternative using JPEG2000. JPEG2000 uses the same compression
 > technique (wavelet compression) as mrsid, and is a public format. However,
 > mrsid it ain't. Perhaps there could be the same sort of effort that gave
 > birth to SVG, a now viable alternative to FLASH, or GML vs SHP for that
 > matter. Maybe an adjunct to GML, that specifies some JPEG2000 scheme? Any
 > ideas?

Roger / Heiko,

I don't think you will see any public implmentation of MrSID due to patent
issues - and LizardTech have shown themselves to be more than willing to
litigate to "protect" their IP.

The ERMapper ECW compression is moderately more public, but ultimately I
think ERMapper has a patent and intends to control the compressor side of
the technology.

The best hope seems to be the JPEG2000 format.  There is almost-free software
available from the JasPer project (http://www.ece.ubc.ca/~mdadams/jasper/).
The only non-free aspect to the license seems to be the restriction that
the software cannot be used for formats that are not ISO standard JPEG2000.
That is, you cannot adapt the software for other purposes such as embedding
JPEG2000 style imagery in a TIFF file or something.

If we seriously want a fairly good lossy image compression capability for the
open source community I would suggest we form a group to take advantage of
the JasPer libraries, adapting them as needed so they can be used in other
applications.  I looked at JasPer a little while ago, and it seemed to me
there were some quirks about the way the library worked that would require
some adaption - I think it assumes images can be loaded into ram or something.

However, if we do this, note that the JasPer libraries restriction on using
the code for other purposes will keep the result technically non-free and
likely difficult to mix with GPL code.  Furthermore, it would preclude any
intrisive ideas like GML wrappers around JPEG2000 (though GML documents
referring to an ISO standard JPEG2000 file would still be fine).  Furthermore,
I think there are concerns about patents related to JPEG2000, and the
availability of the JasPer software does not preclude being prevented from
using it by other parties due to patent issues.

We could also try and make a fresh implementation of JPEG 2000 libraries
or even implement our own format that would hopefully be free of patent issues
but this requires a high degree of knowledge in this specialized image
processing field (as well as some legal sophistication to avoid patented
methods) that are well beyond my capability.

Best regards,

-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | Geospatial Programmer for Rent