[Gdal-dev] Default compression level...

Frank Warmerdam warmerdam at pobox.com
Thu Jul 12 12:32:42 EDT 2007


Mario Cavicchi wrote:
> Hi to all,
> I used the function GDALCreateCopy to convert some GTiff images in
> JPEG and JPEG2000, but i don't find where i can read the default
> compression level for this formats.
> Someone can help me?

Mario,

The default QUALITY for the JP2KAK driver is 20 which I believe
means the driver will attempt to make the output file 20% of the
uncompressed size or so.  I'll update the docs to indicate the
default of 20.

The default JPEG driver quality is 75 which has no correspondance
to physical file size.  It is just an arbitrary number to change to
alter the amount of compression to apply.

Best regards,
-- 
---------------------------------------+--------------------------------------
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    | President OSGeo, http://osgeo.org




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