Check for print and prepress related PDF 2.0 features
PDF 2.0 has been published by ISO in July 2017. In it's introduction chapter is stated that a lot has changed:
- 14 completely new features
- 26 extensions to existing features
- 22 deprecated features
All PDF 2.0 features will usually be treated as "unknown" data for older equipment. Since the PDF concept always allowed for extensibility such processors will ignore them. That means that in most cases current workflows will not crash with a PDF 2.0 file. Problems will, however, occur once PDF 2.0 features are expected to be taken into account for print production.
The Profile below checks for new PDF 2.0 features that may have relevance for such workflows. It requires pdfToolbox 9.4 or newer.
Which features are new and could require changes in present PDF based prepress workflows?
PDF 2.0 entry in the PDF header
Each PDF has in it's header the PDF version according to which it has been produced. A newer PDF creator may very well write "%PDF 2.0" without using any of the new features.
A PDF processor who reads this entry may refuse to process the file, when it expects this value to start with a '1'.
DPart metadata for PDF pages
DPart metadata is associated with PDF pages or parts. Other than XMP metadata it is organized in a tree so that it is easier for any PDF processors to identify pages or page ranges that have certain properties. It was initially invented in PDF/VT and is taken over from there into PDF 2.0. It may be used e.g. in order to mark certain pages for certain processes, e.g. for the first and last pages of a PDF to be output in 4c (to form a cover) and for the remaining page to be output in b/w (to form the inner part).
Page based Output Intents
Output Intent objects were until PDF 2.0 always associated with a PDF as a whole. PDF 2.0 makes it possible to have page based Output Intents, e.g. for the same example as before: first and last pages have a 4c Output Intent while the remaining pages have one for gray.
Black Point Compensation entry
BPC is a parameter for color conversion that takes the maximum black of source and destination color space into account. Usually results are better when applied, so most color conversion engines just use it. However, in some cases this is not desired and up until PDF 2.0 it was not possible to treat objects different in a single PDF. It was not even possible to switch BPC on or off for the whole document. Both becomes possible with PDF 2.0 and PDF creators may now mark certain objects for color conversion using BPC and other for not using it.
CxF and Mixing Hints in Output Intent dictionaries
Both entries provide data for processing of spot colors in a PDF.
Mixing Hints contain information about expected results when spot colors interact with each other in print.
This information might be used e.g. by a proofer. Until PDF 2.0 Mixing Hints could be present in an NChannel color space, in PDF 2.0 also in an Output Intent dictionary for the whole PDF. (That actually makes more sense, since such interacting spot colors are not necessarily part of an NChannel object).
SpectralData has spectral measurements for spot colors in CxF/X-4 form (ISO 17972-4).
Measurements are required for blank substrate (0% and 100%) and optional for intermediate values. In addition measurements on black preprinted substrate are possible to allow for calculating results from spot colors that interact with each other in the same object or by means of overprint or transparency.
The new HTO entry allows for specifying the halftone origin.
Requirements array in Catalog
The Requirements entry in the Catalog indicates which requirements a PDF file has.