My printer has requested that a batch of graphic files be lightened by 5% to compensate for darkening that happens when the print is laminated.
That would have been easy, until I asked, "What about the true black. If we're lightening everything so details still show up in the shadows, presumably we want the darkest stuff to still be fully dark as it can be." And they said that was correct: Black should still be black, but otherwise, nudging everything 5% lighter will keep the shaded areas showing up properly.
How would you accomplish this? As best I can figure, ideally it would even be a step more complicated: We wouldn't want a sudden break from pure tonal black to lightened shadows, so the stuff that's very nearly black, we want to lighten less than the rest. How would you generate this curve? And for bonus points, how would you automate it, since I'm going to be doing this to over 100 files?