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PDF/VT format is expected to improve predictability
of variable-data output
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August 12, 2008 — PDF/VT is a new, PDF-based
document-description format that is optimized for production of
variable-data documents, including transactional documents.
Known as ISO 16612-2, the PDF/VT standard is under development by
a committee of the International Organization for Standardization (ISO).
The goal is to define a PDF-based format for describing
variable-data documents in a way that will allow fast and efficient
production of
predictable output for variable-document content.
The "VT" in PDF/VT stands for "Variable Transactional."
(Transactional documents are invoices, statements, etc.)
Builds on existing standards
The PDF/VT format builds on two other ISO standards:
- PDF/X-4 (ISO 15930-7)
- PDF/X-5 (ISO 15930-8)
Conversion to PostScript not required
In a PDF/VT workflow, variable-data-printing software will generate
output in PDF/VT format, and a Raster Image Processor (RIP)
or Digital Front End (DFE) that is capable of interpreting
the PDF/VT format will be used for print production.
Variable-data-printing workflows based on PDF/VT are expected to
be able to produce output that is more predictable than output
generated by variable-data-printing workflows that are in use
currently. The main reason for this is that a RIP that's used
in a pure PDF/VT workflow is able to interpret the PDF/VT code
directly; in contrast, current workflows require that PDF files
be converted to PostScript format before being processed by the
RIP, because most RIPs in use today are not capable of interpreting
the code in PDF files. Converting to PostScript compromises the predictability
of the output, mainly because the PDF imaging model is richer
than the PostScript imaging model — so, when converting from
PDF to PostSctipt, transparency must be flattened,
fonts might be converted to outlines, device-independent colors
are converted to device-dependent colors, spot colors are
converted to process colors, and so on. Often, a file's contents
are converted multiple times to prepare it for output to
a specific device, and every conversion compromises the
integrity of the original design. For example, the RGB
color gamut is larger than that of CMYK; therefore,
converting an RGB digital photograph to CMYK constrains
the color for output to a particular device.
PDF/VT will support the full graphics model of PDF 1.6,
which includes transparency, ICC-based color management,
and layers.
Caching of static elements
Of course, like other print technologies that are optimized for
variable-data printing
(VPS,
FreeForm,
VIPP, etc.), PDF/VT
will provide for one-time rendering and caching of the
static text & graphics in a variable-data print run.
This allows documents to be produced faster than would be possible
if the code for the static text & graphics were sent to the RIP/DFE
over and over, once for each document in the print run.
Industry stakeholders involved
Committee members involved in development of the PDF/VT standard
include hardware and software vendors, commercial printers,
and other industry stakeholders. A number of leading solution
providers have committed to supporting the PDF/VT standard; the
list includes DirectSmile, GMC, Bitstream/Pageflex, and XMPie.
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