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.


Variable Data and Retained PDF Raster
It’s not all that surprising that a lot of companies creating Variable Data Print (VDP) jobs, and print companies who print them have elected to use PDF instead of something more specialized to the task. The ability to explain to all customers what they need to submit, to send the same file to (almost) all Digital Front Ends (DFEs), to view the final file virtually anywhere, and to create files as rich as the customer demands all go at least some way to balancing out the potential for a drop in performance in the DFE.

Variable data is now printed at more print sites than ever before, driven by an overall growth in digital printing, and by a transfer from printing customer mail in the data center to workflows that are more closely related to the graphic arts. Digital production presses and variable data print have developed greatly over the last decade or so. Presses are much faster than they were ten years ago and often running at higher resolution. The computing power available for inclusion in a controller or DFE has also been increasing, while its cost has dropped. On balance it’s now easier to render jobs fast enough to achieve full engine speed on a sheet-fed press than it used to be … as long as you print the simple VDP pages that were being processed back then. A third trend that’s occurred at the same time is that the complexity of print jobs has risen, increasing the demands on processing power in the DFE again.

PDF Retained Raster automatically analyses a PDF file to identify those pages that use shared elements. It therefore takes advantage of optimized structures in PDF files made with specialist VDP creation tools, including those saved as PDF/VT (ISO 16612-2). At the same time it works almost as well for PDF files made by general tools that are not specialized for VDP. Once a shared element has been identified it is only rendered once, while the variable data on each page is rendered separately. The benefits of the specialized VDP PDLs can therefore be achieved while using PDF.

PDF Retained Raster in the Harlequin RIP automatically recognizes combinations of graphical elements that are re-used on multiple pages in a VDP job, and delivers each as a separate raster. Post-RIP raster composition technology can be used to build each final page for print, producing maximum throughput for a minimum bill of materials.