Adobe Illustrator for Windows - CMYK Black values keep changing from computer to computer

Author

CMYK Black values keep changing from computer to computer

Dean_Daniels@adobeforums.com

2007-06-19, 10:23 pm

Greetings:

I puzzeling problem has developed when my clients, my vendors and me exchange native Illustrator files (often between platforms MACs and PCs). We deal with CMYK output for linotronic and plate outputs. If a file sent at one end reads Black as (C-0% M-0% Y
-0% K-100%) it often appears at another end reading Black as a CMYK blend - in other words it has values for CMY other than 0%. A vendor at one end wants to charge for changing all the values - and some clients say thier files were sent at 100% K and all
CMY at 0%. I have seen this myself - having changed a file's Black setting myself and watched the vendor open it to a different set of CMYK values. This has appeared across Illustrator versions 9-CS2.3. Clues?

Scott Falkner

2007-06-20, 3:18 am

If the file is RGB, then the 0,0,0,100 entered in the CMYK fields will be stored as RGB, according the the document's profile, if it has one, or the computer's default RGB profile if not.

Dean_Daniels@adobeforums.com

2007-06-20, 3:18 am

So in determination:
A file must be

a) "created" with which application set preferences?

OR -

b) "opened" - with which application set preferences?

THANKS!

Scott Falkner

2007-06-20, 3:18 am

Use the same Document Color Mode (CMYK) and profiles for each file.

Dean_Daniels@adobeforums.com

2007-06-20, 3:18 am

Is there a way to STRIP the RGB information and copy the file and paste into a new CMYK based file?

Brett Dalton

2007-06-20, 6:22 pm

Set the Doc mode to CMYK, however if colour are specified as RGB you can still force out of gamut numbers. Best advice is spend some time reading up on colour management, being careful about using the same working space at both ends will help as will.

There is also options relating to how Rich blacks are handled, look up "rich blacks" in the help files. It's possible that some of pure blacks(100% k) are being output as rich black (100%k +CMY at some value) which is blacker than black but the creators a
rn't aware of this happening.

BRETT