PDF notes
PDF is a file format to store published versions of documents.
It is mot often seen for manuals, articles (alongside PostScript), and such.
Like PS, A PDF should render the same everywhere.
From a functional point of view, the PDF language combines
- layout and graphics in much in the same way as PostScript does (which is why the two are fairly directly and accurately convertible), though PDF is not a full language as PS is.
- Font embedding in documents
- Other file embedding
Graphical advantages over Postscript include transparency, embedded raster images
But like Postscript, it is a rendering format more than it is a document format.
Versions
The internal format versions often went with major Acrobat releases.
- PDF 1.0 with Acrobat 1.0 (1993)
- PDF 1.1 with Acrobat 2.0 (1996)
- Introduced links, some color features, passwords
- PDF 1.2 with Acrobat 3.0 (1996)
- Introduced Unicode, some interactivity, media, some more color and image features
- PDF 1.3 with Acrobat 4.0 (2000)
- Introduced digital signatures, some color features, JavaScript actions
- PDF 1.4 with Acrobat 5.0 (2001)
- introduced transparency, JBIG2 images, OCR text layers
- PDF 1.5 with Acrobat 6.0 (2003)
- some more stream features, JPEG2000 raster
- PDF 1.6 with Acrobat 7.0 (2004)
- Inroduced option of OpenType fonts
- XML forms
- AES encryption
- Embedded multimedia
- PDF 1.7 with Acrobat 8.0 (2006)
Since here, PDF specs were handed over to ISO. This means Adobe no longer releases PDF specs, but publishes extensions that initially only their products support, but which it tries to get into the ISO standard.
- PDF 1.7 plus Adobe Extension Level 3 with Acrobat 9.0 (2008)
- PDF 2.0 (2017), ISO 32000-2
Most viewers support all 1.4 features, and not necessarily all features since that time. (verify)
From a quick and likely-skewed sampling of PDF files, it seems that typical versions lag a decade behind what's available - which is probably great for compatibility. And is partly intentional, as saving PDFs for backwards compatibility often went a few versions/years back.
PDF/A
For long-term preservation of documents it is a good idea to restrict a PDF to a subset of features to ensure that
- it can be fully rendered anywhere, e.g.
- requiring font information be embedded rather than linked
- require a lack of encryption
- disallow audio, video
- it does not use any more recent features that are potentially exploitable
- disallow scripting, executable launching
PDF/A-1 (2005) is a specification based on PDF (1.4) of such a set of restrictions.
- It refers to ISO 19005-1:2005, "Document Management - Electronic document file format for long term preservation - Part 1: Use of PDF 1.4 (PDF/A-1)"
- PDF/A-1a and PDF/A-1b refer to a specific levels of compliance.
PDF/A-2 (2011) considers features from 1.5, 1.6 and 1.7 and decided to include JPEG 2000, OpenType fonts, transparency effects and layers, digital signatures
PDF/A-3 (2012) allows embedding of arbitrary files
PDF/A-4 is expected in 2019, and based on PDF 2.0
See also:
PDF/UA
Things that output to PDF that are somewhat more specific-purpose (but sometimes quite controllable):
- Various reporting systems
- Jasper ()
- BIRT (Java, free, part of eclipse(verify))
- G2 Report Engine (Java, free)
- Pentaho
Technical notes
Sizes
MediaBox - size of the media
CropBox - box that is expected to be shown or printed
- usually a li
BleedBox -
TrimBox
ArtBox -
Broadly, this is about professional printing, and cutting. Very roughly:
- Mediabox should be the size of the media we're printing on,
- Cropbox, BleedBox and TrimBox are about the area you end up
- it seems that TrimBox is most used when printing many copies / pages onto a single sheet (see terms like press sheet)
- ...and it may just be the same as CropBox
- it seems that TrimBox is most used when printing many copies / pages onto a single sheet (see terms like press sheet)