Sorry for the confusion, I use poser native units as my default display units, The .0096 is default 1" in poser 6.
You are welcome to use any node you wish as long as the end result is around 2" or as far away as required or desired, I think the subtract node is the most usefull math function so I tend to use it instead of add, multiply, divide or any other fixed value node.
There are many other ways of getting similar results, but this is the simplest and most effective way I could think of.
Thank you GBREAL for another good question.

Gain is a math function.

I think all the value inputs (with numbers) desaturate, only the color inputs pass the color data, so just plug the image into the bump input and adjust the value. If you want a negative image use a math or colormath node, set to subract your image from one or white.
The gain function is the easiest way to adjust the contrast. .5 is no change, zero results in .5 gray, 1 is on or off if the input is greater, or less than .5 (on or off instead of white and black because the colormath node handles red, green and blue independantly).
You can adjust an exploding displacement map with a subtract node.
Be sure to open the previews the results can be easily viewed.

You would set the blending  the same as value 2. You would also need to plug the result into a value input, to grey the output.

The blender node blends the two inputs by the ratio of the blending input. The add will add the two values if value 1 plus value 2 equals 1 then you could get the same result with a blender. A blender also uses more resources.

If you use an add node, you can control the quantity of each by adjusting the value inputs. If you use a multiply the values effect the output not the ratio of the inputs.

Attached Link: http://market.renderosity.com/mod/forumpro/showthread.php?thread_id=2716398

This one is not simple although I did try and simlplify it.

I posted another image at the end of this thread, it is very dynamic.

You can reverse the normals of the offending polys, using the grouping tool, but this will make them invisible from behind.

Those are backfacing polys. You can reverse the normals of the offending polys with the grouping tool.