removing, say, 10% global Magenta from a print-ready PDF. Can I?

Question

Here's my situation. My dark blues are printing purple. Several printers, all high-speed online vendors who gang print. This would not apply of course if I was using a local commercial printer for just my job, as I could have them tweak the press to get the exact blue I wanted.

However, this is when I'm sending files out to online printers. They are telling me my Cyan and Magentas are too close, I need a 30% (one printer says) and 40% (another) difference between Cyan and Magenta to not have the dark blues shift to purple. This is a HUGE jump. I already have 100% Cyan, and 75% magenta, and it's purpleee, if that's a word. The only solution I'm told is to make a bigger gap between the two colors.

Now, I'm no novice at prepress and printing. Been doing this 30+ years. And until last summer, this has never, ever been a problem. Now it is.

So I'm looking at a way to reduce my magenta, across the whole document, before sending it to a printer. I don't want to just adjust the cmyk values in InDesign, as all the PDFs and self-office-printed colors will then be way too light in the magenta.

Is there a way? A plugin? I'm looking for something that I can simply tell the PDF to hold back on the magenta by, say 15%, or whatever number I determine to be close to what I need.

Extensions for Acrobat? Something in between InDesign and Acrobat when I'm exporting to PDF?

Anyone have any ideas on this one? My goal is to keep the cmyk values in Indesign as they should be, and simply adjust the PDF before sending it off to print.

Help!

Dov Isaacs · Answer

There is no built-in method for doing this in Acrobat and I don't know of any of the “standard” plug-ins that provide for something like this, either!

Sounds like a nasty color management problem that originates in content creation in InDesign. Are you using ICC color management for your colors? Which RGB color space? What is your target CMYK color space? Modern day workflows call for most color work, other that perhaps colors that must be in process CMYK (such as black text) or true spot colors (for use in print devices supporting same) to be done in ICC color-managed workspaces such sRGB and Adobe RGB. PDF should be exported as PDF/X-4 with color conversion being done at the RIP. Trying to guess at the actual color space of the output device, especially those of “high-speed online vendors who gang print” is dicey at best.

You are probably not going to like this, but trying to fix the PDF file's colors in Acrobat is really like closing the barn doors after the horses have escaped. ICC color managment (in device independent RGB color spaces) in InDesign (or earlier if placing content from elsewhere) would probably alleviate your problems.

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