Zero ;) . First of all, it would only work with colors, no textures, since each of those would have to be sampled individually (you can imagine how slow it would be). But even if it were possible or if you only would clamp colors it wouldn't make much sense in my opinion. You can't simply make things darker or clamp channels. You could clamp colors like "pure red" or just make every color 180 max in magnitude, but it's not what you should be doing if you're trying to achieve useful albedo. Your brighter colors would clamp to 180 max but all the colors close to 180 would stay exactly the same, probably resulting in washed out renderings. If people want to do it... well.. not very difficult via scripting, but I won't include that in the converter, sorry ;-)