Attached Link: http://www.soft-rabbit.com/

It actually is neither brightness nor contrast - Poser is using the "Value" (as in HSV) which is a very unlikely and non-intuitive choice. For example, all plain primary colours (like 100% red, green or blue) are seen as 100% white. If you convert the colour template into greyscale, the primary colours will turn into some shade of grey (darker than white) and consequently change the "bump" effect - colour to grey typically uses the "Luminance" (as in HSL) and not the "Value". I wrote a set of filters for GraphicConverter (May only, sorry) which include a function to remove colour from a template without changing the "bump" effect.