[GRASS-dev] GRASS GIS raster files: LZW compression?

Markus Neteler neteler at osgeo.org
Thu Oct 26 09:57:10 PDT 2017


On Thu, Oct 26, 2017 at 9:25 AM, Markus Metz
<markus.metz.giswork at gmail.com> wrote:
> On Wed, Oct 25, 2017 at 10:40 PM, Markus Neteler <neteler at osgeo.org> wrote:
>>
>> Hi devs,
>>
>> while playing with the SRTM 30m world I see that there is a difference
>> of 66GB in size between LZ4 (larger) and DEFLATE (smaller). While this
>> is not a surprise I was wondering if LZW compression could be brought
>> back. AFAIK the license issue is gone for a while and indeed GRASS got
>> a special permit back in 1988 according to the old source code.
>>
>> Would that make sense?
>
> You could test with compress (LZW) and gzip (DEFLATE based on LZ77) if that
> would make sense.
>
> Implementation would be a bit of an effort: either adapt from the source
> code of compress or from GDAL's LZW compression for Tiff.

I thought to remember that the LZW compression was in libgis some
decades ago but did not find any trace so far.
At that point I happily abandon this idea - no need to waste energy here :-)

markusN


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