[Gdal-dev] Ecw and Overviews

[Frank Warmerdam]

On Wed, 2 Feb 2005 15:17:18 +0100, Nacho <brodin_ign at gva.es> wrote:
> Hi,
> I need to read a full Ecw image with a smaller resolution than the total size.
> In other formats (MrSID) I select the overview that I want but with Ecw image
> I don't know how to do it. Somebody can help me?

Nacho, 

The ECW raster bands will return TRUE to a HasArbitraryOverviews() call.
This means you can do a RasterIO() call at any resolution and overviews
will effectively be used. 

Really MrSID should have been done that way too, but in practice many
apps work better with apparent descrete overviews.  At some point I may
engineer this into ECW as well. 

Best regards,
-- 
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