All 10 filters in the Map menu map an image onto an object in order to deform the image; for example, by adding relief to it, curving it, or making it seamless. The map filters often produce very dramatic effects.
Bump Map embosses an image using another image as a map. If the map is smaller than the image, some areas of the image will be left unaltered.
In the dialog, shown in Figure 17-191, the BUMP MAP menu lists all of the images open in GIMP and the images previously open in the same session. MAP TYPE can be set to one of three modes, which determine how the bump height is related to the map image luminosity: linear, spherical, or sinusoidal.
It’s generally advisable to leave the COMPENSATE FOR DARKENING box checked ...