We have a two-color press publication (PMS colors) that utilizes overprinting to mix the two inks. We also have a second use for the press PDFs, which are ingested into a system that creates a Flash product for web access of the same project.
Unfortunately, overprinting fails in the SWF output of this system. Instead of the darker, mixed colors, you see only the opaque top layer. We tried converting the spot-color PDFs to CMYK but there was no difference in the ingested result.
My question: Is anyone aware of a transformation that can be done to the spot PDFs to internally convert objects defined as overprinting so that they truly mix with the object below?
Our alternative is to build transparent objects (using multiply) in Indesign and Illustrator artwork, but this method has its own pitfalls.
This on a Mac using Acrobat 9.0 Pro but we also have access to Pitstop.
You're mixing three different color spaces:
* PMS colors are spot colors used with specially mixed inks on the press
* CMYK colors are using for printing process colors on a press
But when you're viewing Flash projects, you're always viewing them on a monitor with RGB color.
So converting PMS to Process will do nothing.
You'll have to do your best to simulate the visual appearance of two overprinting PMS colors (which is a very press-specific interaction) with what it looks like on-screen. Basically, you need to use a monitor (hopefully calibrated) to pick a similar color. PMS colors can be measured as Lab values and used by themselves you might be able to use Photoshop to take those Lab values and switch to RGB, but when you add in the overprinting component, I don't think Photoshop can help you.
It will probably have to be done visually.
Thanks for the reply, Steve.
This is a math publication and it will be using coloration symbolically, as in lines on graphs. Thus we have a wide tolerance of color shifts within the non-print products, as long as the chosen tints convey their function and the exhibits in the book are "consistent enough" with the screen versions.
As for my original query re transformation of objects in Acrobat, I made tests yesterday using Preflight > PDF Fixups, "Flatten Transparency" and "Flatten Overprints" and neither of them gave us what we needed, which is a PDF in which overprinting objects have been converted to transparency.
As you say, it appears that we will have to alter the art to use transparencies rather than overprinting.