How Do You Print K Channel Only PDF Documents?

PN
Posted By
Patrick_N_Kearns
Dec 5, 2008
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404
Replies
7
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Closed
A friend has sent to me a number of K-channel only "gray" documents. He created them using Photoshop.

"I made the files by saving as PDF from word, then opening the PDF in Photoshop (you can also open PDF in illustrator). then cleared out the CYM channels and set the K to your specification, then re-saved as PDF."

I’ve been trying to print these documents out on my MacBookPro HP C4180 printer using Preview and Adobe Acrobat Professional. In all cases what seems to happen is the K-channel only documents are somehow converted back to CYMK. The print output appears gray, but you can see the different CYMK inks used to create the gray.

What is the best way to get a K-channel only print out?

Thanks much.
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B
Buko
Dec 5, 2008
grayscale
MO
Mike_Ornellas
Dec 5, 2008
Use a rip.
PN
Patrick_N_Kearns
Dec 5, 2008
<sigh> You don’t understand.

I have a K-only PDF document. I want to print it with only the Black (K) channel active.

"Grayscale" is CYMK gray (4 channel color), a 240 – 250% ink usage. Check out your Mac printer defaults if you don’t believe me. While CYMK "gray" is similar in appearance to Black K-only "gray", there are differences.

The MacBook Pro seems to be taking a Black K-only document, and immediately converting it back to CYMK "gray" values, then trying to print out the CYMK document. What I am looking for is a way to get the K-only document to the printer as a K-only document. There does not seem t be a valid print option.
PN
Patrick_N_Kearns
Dec 5, 2008
"use a RIP"

a. Could you be a little more specific?
b. I’m looking for a way to print on my current Mac system.

Are you telling me a separate RIP package is needed to print an existing file?
B
Buko
Dec 6, 2008
If you are sending just black to an inkjet you would be better off making the file RGB and sending that. what is happening is the printer is converting the CMYK to RGB for you since it needs RGB data. the other way is to as MO suggested get a RIP.
PN
Patrick_N_Kearns
Dec 8, 2008
Buko,

Thank you for your response.

The goal is to take a black K only channel document and print it as a black only K channel document. By converting back to RGB, you end up using 2x to 3x the ink, and it is created as shades of gray based on 4 colors of ink, CYMK, vs. gray based on 1 color of ink, K.

I was hoping that somewhere in the Mac and Adobe Acrobat Pro there was a printing setting to just pass the existing file through.

The consensus answer seems to be I have to buy a RIP so that I have direct control of the CYMK channels.
NK
Neil_Keller
Dec 8, 2008
Or print to a nice black-and-white laser printer.

Neil

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