How can I stretch a PNG raster coming from GMT (Generic Mapping Tools 4.5.6) in such a way that does align with google satellite or bing? such raster is in wgs84 and crosses two UTM zones (17 and 18 south). I think this is the problem of the misalignment. I use gdalwarp to convert the PNG to GeoTiff. The raster is served by mapserver 5.6.7 and displayed by openlayers 2.11 as WMS over google or bing. I use epsg:4326 and epsg:3857.
Other WMS in wgs84 (ie. epsg:4326) are served by mapserver, they don't have this misalignment problem with google or bing, but only with the GeoTiff.
I appreciate some support with this please, thanks!!