As an example I will take the following tile
http://a.tile.openstreetmap.org/3/4/2.png and save it as
"4_2.png". The WGS84 coordinates of this tile can be calculated
or read there by clicking the corresponding tile: 0
66.51326044311185 45 40.97989806962013 (West North East South)
How to georeference the tile correctly (using gdal to generate a
geotiff or another georeferenced format) so that: - The bitmap
don't need to be stretched (= the pixels in the geotiff are
exactly the same as in the original bitmap) - The resulting
image will be opened at the right place in a GIS viewer/editor
(like for example in TatukGIS Free Viewer)? (Edited at Sept 19
2011 to make my question clearer and include my conclusions) I
first though that the third idea (see below) was the right one.
I opened the geotiff in a GIS Viewer and compared the displayed
coordinates with what I expected. The geotiff out of the second
idea seems to be shifted 2 pixels towards north. That is why I
considered idea 3 (or 4) as the right one. But if y