At least they did that then :) I looked at them but it was a while ago. A very basic way to do it would to use Photoshop to adjust the curves (or paint shop pro or something else, not sure what those would call it). Levels would work to some degree but curves would be more accurate. You would have to lock the curve points at 25, 50 and 75 and then adjust from there, bringing up the darks and lights. It is hard to explain without showing but it is pretty easy (if you use photoshop). Good luck.