Exports all 15 of the detail maps from legends mode. Extract the zip into your hack/scripts directory, start a world in legends mode, run exportmaps from dfhack console and then go grab a sandwich or two (large worlds can take a while).

Alternatively, register a keybinding in dfhack.init such as
When all is done, find your maps in the dwarf fortress directory. They will be named something like world_graphic-MAPTYPE-region1-###.bmp



(written for DFHack r3)