The game object images are stored in individual gif files. One image per file. The default orientation of the file should be with the game object facing the 12 o'clock position.
The convention is for the image background to be black and the image foreground to be white, *breaking the convention will produce the wrong results*.
Color images are supported where the image background is black and the foreground various colors. For producing bitonal maps (white background black foreground) the conventional images are inverted by the program automatically.
The images can be any size but typically not too big. The images are scaled according to the scaling factor in the data file The images can be of any game object a ship, fighters, missiles, asteroids etc.
Please also remember that FTMAP is not limited to use with Full Thrust, and plan views of ships, tanks, aircraft etc. may also be useful. (I especially want some WW2 ships for a planned PBEM game)
You can download individual images by right clicking on them with the mouse, and selecting "Save Image As..." For some collections a .zip file of all the images in a table, is available by clicking on the title of the table.