For a given raster image, we knew the limits of the latitude and longitude, and that the file was using Mercator projection
Location: 15 to 60 degrees North latitude, 50 to 130 degrees West longitude Orientation: North toward the top, Mercator projection Image Data: shaded and colored SRTM elevation model Original Data Resolution: SRTM 1 arcsecond (about 30 meters or 98 feet) Date Acquired: February 2000
cs2cs +proj=latlong +ellps=WGS84 +to +proj=merc +ellps=WGS84 +lat_ts=37.5 +lon_0=-90 <<EOF > -130 15 > -50 60 > EOF Output: -3537017.77 1333018.49 0.00 3537017.77 6642819.94 0.00
scale: (3537017.77 x 2) / 9600 = 736.8787021 world file contents: 736.8787021 0 0 -736.8787021 -3537017.77 6642819.94
... EXTENT -3537017.77 1333018.49 3537017.77 6642819.94 ... PROJECTION "proj=merc" "ellps=WGS84" "lat_ts=37.5" "lon_0=-90" END ...