PDF/X-1a:2001 is designed to provide the most robust and, to some extent, least flexible delivery of PDF content data. It requires that the color of all objects be expressed in CMYK or spot colors, prepared for the intended printing conditions. Elements in RGB or Lab color spaces or tagged with ICC profiles are prohibited. It also requires that all fonts used in the job be embedded in the supplied PDF file.

PDF/X-3:2002 allows slightly more flexibility in that color managed workflows are also supported. Elements in Lab and with attached ICC source profiles may also be used.

PDF/X-4:2008 supports color-managed, CMYK, gray, RGB or spot color data as well as optional content and PDF transparency.


Optional ICC Profile Support
PDF/X files all include data describing the characterized printing conditions for which the job was prepared. That data is collectively described as the output intent. It includes an identifier that may refer to a characterization held in a registry maintained by the ICC (International Color Consortium). In many cases the output intent will also include an embedded profile to support accurate color proofing, both on screen and on hard copy. The Harlequin ColorPro™ option can be used to perform in-RIP color management with the Harlequin RIP. Please note this option is included with all Digital Proofing (Epson & HP) Plugins. It can be used for many purposes, including color proofing, or for adjusting plates to enable a press to better match a characterized printing condition such as SWOP.