When was the last time you heard “too flexible” as a criticism? Well, that’s exactly what concerned the printing and publishing industries about PDF. As the use of PDF for transferring graphic arts content files between sites, publishers, and printers has grown, so have the anomalies, idiosyncrasies and plain old incompatibilities when it comes to reliable sharing of pre-press data using various PDF software.
So a group of intrepid publishers and printers took it upon themselves to work with standards bodies to develop versions of PDF that suit the varied output requirements of all manner of diverse workflow methods and production techniques.
What is ?
The family of standards was developed to address the many diverse needs of the printing and publishing industries. As such, it offers several versions, each designed for a specialized result.
- -1a is for exchanges in which all files are to be delivered in CMYK (and/or spot colors), with no RGB or color-managed data.
- PDF/X-3 is used for sharing when all files are based on device independent (color-managed) data.
- PDF/X-4 supports transparencies, so PDF-X/4 contains all data required for output without flattening.
- PDF/X-5 is based on PDF/X-4, adding support for external graphics via reference XObjects, as well as external n-colorant profiles for rendering intent. Use it for partial exchange of printing data using PDF version 1.6
(Note that the absence of PDF/X-2 is not an oversight. This standard was for partial data exchange but never saw the light of day.)
The purpose of PDF/X is to facilitate graphics exchange via , and it therefore has a series of printing related requirements that do not apply to standard PDF files. For example, in PDF/X-1a all fonts need to be embedded and all images need to be CMYK or spot colors. PDF/X-3 accepts calibrated RGB and CIELAB colors, while retaining most of the other restrictions of PDF/X-1a.
PDF/X files must not only follow certain restrictions, they also must contain a special file identification inside the PDF software file that says which PDF/X version they are. Meaning, the printing conditions or output intent need to be specified in the file. This restricts a file to only conforming to a single specific PDF/X standard, even if all other requirements are met. So once you choose which PDF/X standard you’re going to use, that’s the one your file is compatible with. Period.
When should you use PDF/X?
All these PDF/X requirements and restrictions can seem like overload, but the whole point of the ISO 15930 series is to actually simplify the sharing of pre-press digital data within PDFs by ensuring that they adhere to necessary standards to ensure flawless output. Because nothing makes a designer less happy than having to redo print jobs endlessly due to inferior output. (Your numbers people don’t love what that does to budgets either.)
So if you’re in the printing or publishing industries, it definitely pays to be familiar with the different PDF/X standards available in PDF software, especially the ones that can improve processing efficiency in your workflow, as you’ll surely see it in shorter project timeframes and lower costs.