So I have a black and white map of my world and wanted to make a relief map.

The problem I'm running into is that all the tutorials I'm finding rely on generating clouds, using that to make your landmass and then going from there for a realistic relief. This is of course impossible, since I already have my map drawn out.

Does anyone have any advice on making a nice relief map without creating the terrain with clouds?

Using GIMP btw, tho I do have Photoshop installed. And Wilbur (no clue how to use that one).