[Gdal-dev] Advice on Raster Formats

[Andrey Kiselev]

On Tue, Aug 30, 2005 at 08:03:26PM +0200, Bart van den Eijnden wrote:
> I *think* you would have to translate your tiff files first to
> compressed  tiff using the -co option.
> 
> COMPRESS=[JPEG/LZW/PACKBITS/DEFLATE/NONE]

I just want to add that typical compression ratio in case of LZW or
DEFLATE methods may be improved by using a predictor feature. It is
disabled by default, but can by switched on with the PREDICTOR=[2/3]
parameter. Value 2 means horisontal differencing, it should help in most
cases when we are working with integer data. Value 3 corresponds to
floating point predictor and should help when you have floating point
dataset. But be carefull: predictor 3 is a newest addition from Adobe
and supported by the limited number of software (for example it is
Photoshop CS2 and software based on latest libtiff 3.7.3). Predictor 2
must be widely supported.

Interleaving type and tile/strip size affect compression ratio as well,
but not too much (though it may be valuable when you are working with
very large datasets).

Regards,
Andrey


-- 
Andrey V. Kiselev
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