Terrain Height Tool

I have been playing with the terrain height import using a 256x256xRGB png. In the past I remember seeing information about R,G, and B having different weights for height. So I made a bitmap that took a median greyscale height using 127,127,127 as the major height. I put a 255,255,255 color in one corner and a 0,0,0 color in another corner to get the import to put 127,127,127 right in the middle of height range of 0 to 300. Then I made some 1 pixel sized points with the following values:
130,130,0 - no blue
0,130,130 - no red
130,0,130 - no green

From this I found that the height is affected as follows:
blue - least significant
red - mid significant
green - most significant

The main question I have, is there any export scripts, tools, etc that take advantage of this information? I imagine that the internal functions in torque make use of the fact that you can vary the height of a level with immensely fine level of detail. I am trying to brain storm using the GIMP in such a way to come out with extremely well smoothed surfaces before I ever get to torque. Right now I am exploring the ability to manipulate each color separately.

If anybody has additional information on tools and such please let me know.