[Geowanking] downsampling large rasters from HD

[viktoras]

hi friends ;-),

just wanted to ask for any practical hints (algorithms) on downsampling 
very large raw binary (32 bit integer) raster file from disk. Looking 
for an algorithm or library that could be implemented or used in Ada, 
C/C++, Fortran, Assembly, Perl, Python or whatever else. The simpler the 
better :-). My aim is to subsample 2-4 gigabyte raster data file without 
loading it into RAM within 10 seconds on an "ordinary" PC with Intel 
processor (Windows, Linux, MacOSX on Intel). Wishing to explore as many 
options as possible... If you know any paper or website dealing with 
this kind of algorithms, I would appreciate the url.

For example I have 50000x50000 raster and I need a portion of it resized 
to 700x700...

Thanks in advance
All the best!
Viktoras