faded cmyk files

[kagamushu]

Hello,
i sent 3 poster files to my print shop for laser ouput. I converted 2 of my files to cmyk before sending them in pdf. The third one i sent in rgb, also sent as a pdf. Surprisingly, the 2 cmyk documents came out faded, (especially noticable on the black areas) and the rgb was fine. On screen in ps and acrobat all 3 look great. I then noticed that when previewing the 2 cmyk images by pressing spacebar (i'm on mac), they were indeed faded, the rgb looked fine.
Ok, first question: how come the preview in osx detected the faded quality of my images but not ps or acrobat? #2 why were they faded in the first place?
thanks,

[Lukas Engqvist]

You are probably thinking that the faded is that you have less saturation. Remember CMYK is device dependant. You have probably converted from RGB to CMYK with a CMYK profile that is set to an uncoated or newspaper quality, where colours are limited. Your laser printout is then trying to simulate how the job would look like if printed on that kind of output deice.
CMYK is not device independant, you need to know what CMYK you should convert to.
If you want colour predictability the advice is to spend some time learning colour management.

[michaelejahn]

Lukas is correct in that perhaps you might have some 'default' setting in you PS application that is converting you RGB files to CMYK inappropriately for the device they are using "print shop for laser ouput" - what ever that is (please share, as that would be helpful!)

But while Lukas suggests you might "spend some time learning colour management." - while I would never discourage investing time in that, you might FIRST start with learning a little more about that device and perhaps ask them what the "print shop" folks suggest - learn what they do when they process your files.

It may be that the "print shop" folks discovered that the one PDF was in RGB, and they converted it, using different setting than you did -- or, it may be that they imported an ICC file (or better, an output intent) - into the PDF -- or -- they may indeed even prefer that they do the conversion,(that is, they simply have some nice RGB to CMYK "print" settings, and may even prefer that you continue to send them RGB, as the device "print shop for laser output" has a bigger gamut and is not set up to 'simulate' SWOP ( a standard print condition used in color publishing) but to print in a larger gamut (more color than is possible in SWOP)

Without knowing how you are set up in your applications color settings (look under Edit) - or knowing how you generate the PDF (PS--> Distiller - or -- export to PDF (what application?) using (What PDF Export settings?) - I can begin to explain what is happening -- BUT -- I will guess that the ColorSync and the Apple Macintosh Preview application is not simulating CMYK output - (what version of the Mac OSX?)

PS - by the way - means PostScript to many peope, but I will guess that you use PS to mean Photoshop. Both Photoshop and Acrobat use ACE (Adobe Color Engine) and again, depending on you color setting policies, they will render your pixels differently than the Preview application - again, depending on the version of the Mac OSX, and how ColorSync is set up, this can prove rather tricky getting them "In SYnc".

To quickly "jump start" - you might want to invest into something like the X-Rite ColorMunki, where this is "Color Management Kit" that can help you get you computer, the computer OS color management policies and your Photoshop and Acrobat color management policies more inline - and you can even create an output intent profile for that "print shop for laser output" device, so it will then help Photoshop and certainly Acrobat 'simulate" how a Photoshop or PDF file 'will look like when printed'

Hope this helps.

-
Michael Jahn
Jahn & Associates
PDF Color Conversion Specialist
1824 North Garvin Avenue
Simi Valley
California 93065
Office: (805) 527 8130
Cell: (805) 217 6741
Email: michaelejahn@gmail.com
Skype: michaelejahn
Twitter: Twitter / michaelejahn

[Lukas Engqvist]

thank you Michael, I was too lazy to write all that ;P

[kagamushu]

thanks alot for all the info guys,
i will check my settings and report back.