Compensating for darkening that occurs during lamination

Question

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?

Answer 1

This kind of three-times-removed situation is becoming more and more common, and renders the standard "talk to your printer" and "get a contract proof" null much of the time.

Here's how I would proceed in this situation.

For Photoshop files placed in AI, as opposed to embedded, a Curves or Levels adjustment would be your best bet. You don't want to affect the blacks or the extreme highlights, so it's really the mid-to-light tones you're most interested in.

Alternatively, a neutral gray layer at roughly RGB 135, 135, 135 (CMYK 120, 120, 120, 120) and set to Overlay would similarly lighten tones that are NOT fully black and shouldn't blow out any highlights. You'd need to experiment. This will work in Illustrator or Photoshop, but the BIG caveat is that anywhere you have fully transparent art you're going to get solid gray, so it's very limited.

I'd definitely try Curves first, lightening only the center point of the curve. With Levels, it would be only the mid-tone slider. You can record this as an action, then use Tools > Photoshop > Batch... from Bridge to run the action on all selected files. If the files are scattered about in different folders, make a Collection in Bridge first, then run the batch on the Collection.

If your PSDs are embedded, unembed them first (tedious, but what's a designer to do?) then proceed as above.

Any remaining art in the AI files can then be lightened using additional fills and strokes in neutral gray/overlay where you need them.

Answer 2

If I were you, I would try to profile the lamination process. The photo SE site has a good description, as well as this site. Basically, what you do is as follows:

1. Find a service which will allow you to profile your printer.
2. Print a test photo of some kind as they recommend, and then laminate it as you normally would.
3. Send in the test print to said service. They give you a profile of your print out.
4. Use the profile they send you when you do your prints.

This will require no change to your design, only a change to your printing profile.

If you aren't wanting to profile your printer, you can look for profiles that have been generated by other people. These won't be quite as high of fidelity, but should be good enough for your purposes. In particular, see if there is a profile provided by the maker of your laminator.