PDF/X-1a
PDF/X is an ISO standard for the exchange of printing data between agency / prepress shop and printer. An important concept of PDF/X is the output intent. This is in most cases an ICC profile which describes the intended output (printing standard). In complete color management chain, the PDF/X output intent is the same icc profile which was used for sepration in photoshop, as CMYK colorspace in the Layout application and as reference for the contract proof.
The most secure version of PDF/X is PDF/X-1a
The whole content of the PDF/X file must be in CMY, Gray or Spotcolor according the final print standard. For processing the PDF/X-1a file in the printing house, there is no need for colormanagement, if the output intent is correct for the final printing process.
If the output Intent is quite different compared to the final printing process (e.g. SWOP but print on newspaper) it is possible to use a PDF colorserver to convert the whole PDF/X-1a with an optimized and controlled devicelink-profile from SWOP to newspaper.
Avoid PDF/X-3
A lot of people think, that PDF/X-3 is the PDF/X variant which should be used, if the PDF/X-file should be color converted on the printers side. This is wrong! A PDF/X-3 file is only valid for the output intent which the creator of the PDF/X-3 file has set.
Compared to PDF/X-1a PDF/X-3 has no advantages during the print productions but adds a lot of possible traps.
Avoid PDF/X-4
PDF/X-4 is based on PDF/X-3 but adds transparencies on top. From the perspective of the printer, this is not a save file format for the exchange of printing data. If PDF/X creator and printer would agree on PDF/X-4 with an additional preflight only allowing the colorspaces of PDF/X-1a, this would allow secure file exchange.
PDF/X-3 and PDF/X-4 as internal format for colorserver workflows
In a strongly controlled environment of an high end pre-press shop it may make sense to use PDF/X-3 or PDF/X-4 as an internal master-formtat for PDF colorservers. The data delivered to the printer should still remain PDF/X-1a.
November 8th, 2008 at 14:13
First of all, great blog, really interesting about color management. Congratulations !
I’m teaching near french students who prepare prepress and print diplomas in france. So, I’m really interested in color management, and about the PSO. The official website PDFX-ready, the one where you should upload the right jopoptions for the good couple paper-ink, tell us to use PDFX-3. So It’s a little beat confused for me when you give the advice to avoid PDFX-3?
Could you tell me more ?
Thank’s. Best regards.
Michel.
November 18th, 2008 at 11:08
Hello Michel,
You are right, that the situation concerning PDF/X-Ready, PDF/X-3 and PDF/X-1a is currently quite confusing…
The current available PDF/X-Ready settings are promoting a CMYK-only workflow for data exchange. Concerning PDF/X, you could either use PDF/X-1a or PDF/X-3 for CMYK-only data exchange. As PDF/X-1a allows only CMYK-objects (and spotcolor), it is in my eyes the better exchange format for CMYKonly workflows than PDF/X-3.
An ideal bunch of settings for:
- colorsettings in several applications
- PDF/X generation
- PDF/X preflight
would be the current PDF/X-Ready settings with PDF/X-1a instead of PDF/X-3.
As the PDF/X-Ready settings are open, an advanced user could edit them for internal usage.
As PDF/X-Ready was the first and only organization publishing both settings (color, PDF/X-generation and PDF/X-preflight), they are still a very educative set.
Currently, the Ghent PDF working http://www.gwg.org/group is working on integrating standard profiles into the their PDF/X preflight profiles with PDF/X-1a for CMYK only data exchange. I expect this to be the big next step in standardized data creation, -exchange and preflight.
Regards
Jan-Peter
June 25th, 2009 at 03:32
Mr. Homann,
I’ve just received the book and am really excited to dive in. I love the layout and, from my initial perusal, the book seems very practical.
In browsing the book, I noticed your vehement stand for PDF/X1a, which I thought was very rational. The thought occurred to me, however, that PDF/X1a requires files to be pre-flattened, and in today’s world, where Adobe’s PDF Print Engine rules, this struck me as counter to what the PDF Print Engine stands for. Am I misunderstanding the dangers of pre-flattening? or is it just that the benefits of PDF/X-4 etc. are out-weighed, in your mind, by the perils introduced by embedded profiles and mixed colorspace data inherent in the format?
Thanks again for another excellent color management resource,
Jay Ryder
June 25th, 2009 at 16:06
Hello Jay,
With not flattened transparencies in PDF/X-4 I´m critical about following points:
- We have currently not a test scenario, to verify, if RIP (which may has Harlequin instaed of Adobe inside) will render all kinds transparencies according the PDF/X-4 specs.
- If there is a problem with flattening during PDF/X-1a generation, this could be recognized BEFORE sending the data to the printer. Than, Only the PDF/X-1a file has to be created with new settings avoiding the problem.
If PDF/X-4 is delivered, and the problem occureres during the RIP-process, the whole job has to be reprinted.
- We currently have no control elements, that transparencies on a proof or a softproof are rendered according the PDF/X-4 specs.
Probably using Adobe Creative Suite for creation, PDF/X-4 generation and softproof and Adobe Print Engine for Proofing and CtP will avoid most potential troubles. But in my view, an ISO-Standard like PDF/X should not force users to use software only from one vendor.
February 5th, 2010 at 17:49
Dear Mr. Homann,
please, I have one question - where can I get PDF/X-1a:2003 standard? Do I have to buy it? I’m asking because I can freely get PDF 1.7 reference from Adobe site so I thought it would be possible to obtain the former spec as well.
February 7th, 2010 at 21:55
Dear Ecir Hany,
The PDF/X-1a:2003 standard is available, through http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=39938
There is no free version. Based on PDF/X-1a are the GWG specs which could be downloaded free at http://www.gwg.org/GWGversion4.phtml
If you have any questions concerning the usage of the GWG specs, I recommend the GWG forum at http://forum.gwg.org/ (currently a little bit quiet…)
Best regards
Jan-Peter Homann