How to set in Liberator 3 the reverse color scale? I would like to have stars black and the surroundings white. Or could you recommend me another program that has this ability?
I would suggest you check out SAOimage DS9, which is one of the most commonly used FITS viewers (probably the most commonly used one) among professional astronomers. It allows you to display images with a variety of different scalings and color maps (and, yes, there is an "Invert Colormap" setting under the "Color" menu).