It has to be 8 bit 256 colors to show up.
The way I make my clipboard maps is to get my terrain posistion in Ogres mapmaker utility then I make a screen capture with Irfanview to edit in Photoshop.
I scale and colorize the greyscale then add the appropriate gridline provided in the editors "maps" subdirectory.
Then you need to divide the 512x512 image into 4 sections of 256x256 working from the top left to right,and bottom left to right and name them map0,map1,map2,map3. Then place them in yout terrains folder.