Variable data printing

As the digital production sector has matured it has, unsurprisingly, diversified into multiple sectors, from direct marketing to books, to print on demand, to photo finishing, to newsprint, to a complementary service for offset that can handle shorter run-lengths more efficiently. And each of those sectors, in turn, has split again; direct marketing has garnered more terminology for its subsectors than any other, from 1:1 to personalization to transpromo.

And yet the principles of VDP still persist across many of these sectors.

Those principles boil down to the identification of shared graphical elements at the sub-page level and then special treatment of those elements in such a way that they do not need to be completely processed every time they are used within a job, or a series of jobs.

Thus each page is typically built from a set of components, some of which are shared with other pages, and some of which are unique to that page.

In direct marketing the value is obvious; a mailing may be a personalized postcard in which the address information and greeting differs between recipients but the rest: images, maps, the body of the text, is the same for everyone.

The proportion of the content that's different for each recipient may vary; in some cases each recipient may see one image picked from a set of a dozen or so that was selected based on market information held by the agency running the promotion.

In general that proportion is rising with time as the sophistication of creation tools increases, and the amount of information about recipients held by the commissioning organization grows.

But the same approach is also used for personalized catalogs and for transpromo (one or more of a set of advertising elements printed in the white space on a credit card or phone bill as an onsert, or packaged with a transactional piece as an insert).

Perhaps surprisingly it can extend to photobooks as well, where one image is often chosen as the common background for a photobook, such as a bouquet or confetti for a wedding album, for instance.

Thus many digital print solutions must be able to process such jobs as efficiently as possible, to ensure that the digital press runs at rated speed without the bill of materials (BoM) for the DFE being disproportionately high in comparison to the cost of the press itself.

Digital presses range from light production (< 100 thousand pages/month duty cycle; pp/mon) to ultra-high volume (> 15 million pp/mon).

Some vendors include specialized hardware to assist with aggregation of rasters for shared and unique page elements after the RIP, while others rely on software aggregation, either within or after the RIP. An efficient VDP solution needs to scale with the cost of the press to ensure that the DFE BoM remains proportionate, and the RIP chosen for use within a DFE must be able to work with the other components of the solution.

For light and medium-volume production it may be possible to remove the need to include other components if that would make the whole more cost effective for both vendor and users.

Going back to the early days of digital presses, the identification of shared graphical elements was often the responsibility of the creation application, reducing the load on the DFE at the expense of a little more work in creation, but more importantly at the cost of making a specialized and proprietary format with very few tools for proofing and validation.

Over the last year or so PDF has emerged as a strong contender for variable data print.

This is partly because of the very broad base of powerful tools to manipulate PDF files, and partly because of an increasing demand to handle various forms of transparency in VDP jobs, from drop shadows to advanced graphical effects.

Transparency is just one more weapon in the arsenal used by designers to make a specific direct marketing piece stand out from the rest of your mailbox and therefore stand a better chance of being read before it’s recycled.

Live transparency

The introduction of live transparency has disrupted the VDP marketplace, as many older solutions cannot be efficiently extended to support all variations of PDF element blending.

It also complicates the identification of which page elements can be processed separately to reduce the overall computing load in a DFE.

PDF/VT

The PDF/VT standard (ISO 16612-2:2010) is designed to help make both creation and consumption of PDF-based variable data print jobs as efficient as possible.

It does this by allowing creation tools to associate usage hints with graphical elements; to include a hierarchical metadata structure that can be used to inform decisions around imposition, finishing and fulfillment; and to bundle a series of related file ‘chunks’ into a single data stream.

Thus a modern DFE built for a press that will be used with any form of variable data print is likely to need to be able to handle PDF/VT.