I received an excellent answer to my question of how to get the lat/lon coordinates of the corners of a geotiff file. I used gdalinfo. The lat/lon info comes out into a file. Similarly I turned the geotiff file into a bmp file using gdal_translate thanks to work colleague in another city who is hard to get hold of. It would be much better for me if I could get the bmp file directly into memory, and the lat/lon coordinates directly into C++ variables. Can anyone give me advice on how to do that?