Bump Maps
When using a bump map, you've got a full 8-bits of luma within the bitmap
itself (shades of 0-255) to use to set the bumpiness. This is before you
even start thinking about the percentage slider in Medit. It's important
to use as much bandwidth in the bitmap as possible, and then the slide just
will affect the amount of the map that's mixed in to the rest of the
material. Note that when you use an sxp as a bumpmap (like dents or
noise), the slider's full 0-100 range is very effective, but when you use a
bitmap as a bumpmap, the truly useful range is more like 0-20.
– G