[gdal-dev] Sub-optimal access to cloud optimized GeoTIFF

[Even Rouault]

Jukka,
> 
> This image http://193.166.24.122/gtk/mp_500000_7500000.tif should be
> prepared as adviced in
> https://trac.osgeo.org/gdal/wiki/CloudOptimizedGeoTIFF and the validation
> script agrees on that.
> 
> python c:\temp\validate_cloud_optimized_geotiff.py mp_500000_7500000.tif
> Result:
> mp_500000_7500000.tif is a valid cloud optimized GeoTIFF
> 
> However, it seems to me that gdal_translate is reading the whole GeoTIFF
> (from byte 0 to 3430936 ) once and then a little bit more (2850413 to
> 2984219). My command and debug info looks like this:
> 

The issue is that the file has a ColorMap and is of type UInt16. Consequently there are 65536 
entries * 3 values per entry * 2 bytes per value = 393 KO for a colormap. And as the colormap 
is put in each of the 7 resolution levels, that makes a total size for all the image file 
directories of 2.78 MB.

Even

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