I have a mapoverlay in a custom projection which I need to add as a layer to an Openstreet map within a website. Since I was not able to change the projection earlier, I decided to manipulate the raster image in Photoshop in order to make it "fit" onto the Openstreet base map.
Now I have a png file with the "correct" projection. My problem is that I now have to make tiles from this image which can be used as overlay and thus need to set the correct coordinates. I can find out the exact lat/lon values using OSM but how can I tell
gdal2tiles where the top-left or bottom-right position of my image is?
My command line so far is:
$gdal2tiles.py -p 'raster' myimage.png
What I am missing is an idea on how to set coordinates. Do I have to use another tool prior to tile-making?