[gdal-dev] Can overviews be fiddled?

[Even Rouault]

Jukka,

Yes, I believe I have a workflow to do what you want.

Let that your full resolution be foo.tif
Put the first level of overview in foo.tif.ovr
The second level of overview in foo.tif.ovr.ovr
And so on

You can check with gdalinfo foo.tif that the overviews are
all taken into account.

If you use latest svn trunk version, you can use the new COPY_SRC_OVERVIEWS 
creation option to translate foo.tif and its existing overviews into a target 
GTiff