We are a printing company that transfers RGB to CMYK. However when printing CMYK White comes out as transparent (which makes a lot of our art look...not great). We are handling thousands of designs so we need a way to batch process pdfs in photoshop, changing CMYK (0 0 0 0), to (0 0 0 1%) to prevent unwanted elements suddenly becoming transparent.

What is the best way to achieve this?

  • are you printing on atransparent medium? – joojaa Sep 3 '19 at 17:00
  • 3
    There is no white ink used in CMYK printing. You'd have to print something with opaque white ink before overprinting in CMYK to achieve what you want. – Billy Kerr Sep 3 '19 at 17:01
  • Can you explain a bit why you want to do that? White will still be transparent. – Rafael Sep 4 '19 at 14:46
  • Confusing question. "White" in the prepress world means "NO ink," also known as the paper stock on which you are printing showing through. I don't understand at all how adding 1 percent black changes anything. Most presses won't hold a 1 % black screen anyway. Just what are you trying to achieve. Also, a picture would be worth a thousand characters in this case. – user8356 Sep 9 '19 at 18:45

Are you aware that if you're processing the pdfs in Photoshop you'll lose all vector information?

Anyway, if that doesn't bother you, you could just make an action which adds a Solid Color layer with CMYK(0, 0, 0, 1) and set the Blend Mode of the Solid Color layer to Multiply.

This will pollute all colors of the artwork with 1% black ink, but it's probably not noticeable. You could even enter the layer's Layer Style and set the Blend If options to preserve dark tones.

(This seems like a hacky way to operate your printer - there must be some other way to do this.)

  • Press Cmd + L Mac or Ctrl + L Win to open the Levels Window
  • Click twice the White Eyedropper to set the CMYK to 0 0 0 1%:

enter image description here

  • Click OK and OK to Save the new target colors as defaults?
  • Make an action with automatic levels

  • Batch all the images using this action.

Actually the levels for printing images are:

  • Black Eyedropper: H=0, S=0, B=96 to don't get areas pasted with ink
  • White Eyedropper: H=0, S=0, B=4 to don't get areas free of ink: ink holes (the problem described in the question)

Using just CMYK = 0 0 0 1%, this hole is filled with black ink while setting the white levels eyedropper to 96% brightness get distributed among the printing inks.

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