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PDF History

 

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Introduction
The paperless office. Remember that buzz word that never seems to vanish completely even though history has proven that the use of computers has until now only lead to an increase in the use of paper?
PDF started off on the dream of a paperless office, as the pet project of one of Adobe’s founders, John Warnock. Initially it was an internal project at Adobe to create a file format so documents could be spread throughout the company and displayed on any computer using any operating system. In his paper which led to the development of PDF, John Warnock wrote: ‘Imagine being able to send full text and graphics documents (newspapers, magazine articles, technical manuals etc.) over electronic mail distribution networks. These documents could be viewed on any machine and any selected document could be printed locally. This capability would truly change the way information is managed.’
Adobe already had two more-or-less fitting technologies: PostScript as a device and platform independent technology to describe documents and Adobe Illustrator as an example of an application that ran on several platforms (OK, actually on 2: Windows and Mac but that is 99 percent of all computers) and could open and visualize fairly simple PostScript files, even if they were created using other applications. The engineers at Adobe enhanced these two technologies and created both a new file format (PDF, which is really a kind of optimized PostScript) and a set of applications to create and visualize these files.

PDF 1.0
The first time Adobe actually talked about this technology was at a Seybold conference in San Jose in 1991. At that time, it was referred to as ‘IPS’ which stood for ‘Interchange PostScript.’ Version 1.0 of PDF was announced at Comdex Fall in 1992 where the technology won a ‘best of Comdex’ award. The tools to create and view PDF-files, Acrobat, were released in on 15 June 1993. This first version was of no use for the prepress community. It already featured internal links and bookmarks and fonts could be embedded but the only color space supported was RGB.
The original code name for what later became the Acrobat software was ‘Camelot’, later renamed to ‘Carousel’. That is why the file type of a PDF file on Macintosh was ‘CARO’.
Adobe asked a steep price for the tools to create PDF files. Acrobat Distiller was available in personal and network versions, priced at $695 and $2,495 respectively. You even had to pay 50 dollar for Acrobat Reader. This approach didn’t exactly turn PDF into a popular format overnight. Later on, Adobe dropped the price of Acrobat and launched the free version of Acrobat Reader

PDF 1.1
Acrobat 2 became available in November 1994. It supported the new PDF 1.1 file format which added support for:
• external links
• article threads
• security features
• device independent color
• notes
Acrobat 2.0 itself also got some nice enhancements, including a new architecture of Acrobat Exchange to support plug-ins in and the possibility to search PDF files.
Adobe themselves were one of the first big users of PDF. They distributed all documents for developers as PDF files. Another early adopter of PDF were the US tax authorities who distributed tax forms as PDF files.
Acrobat 2.1 added multimedia support with the possibility of adding audio or video data to a PDF document.
In those days, PDF was not the only attempt at creating a portable device and operating system independent file format. Its biggest competitor was a product called Common Ground. Envoy and DejaVu were two other competing products.
In 1995, Adobe began shipping Acrobat Capture for a rather steep 4000 US dollar. At the same time, Adobe also started adding PDF support to many of its own applications, including FrameMaker 5.0 and PageMaker 6.

PDF 1.2 – the prepress world wakes up !!
In November 1996, Adobe launched Acrobat 3.0 (code name: Amber) and the matching PDF 1.2 specifications. PDF 1.2 was the first version of PDF that was really usable in a prepress environment. Besides forms, the following prepress related options were included:
• support for OPI 1.3 specifications
• support for the CMYK colour space
• spot colors could be maintained in a PDF
• halftone functions could be included as well as overprint instructions.
The release of a plug-in to view PDF files in the Netscape browser increased the popularity of PDF file on the booming Internet. Adobe also added the possibility to link PDF files to HTML pages and vice versa. PDF also slowly began to get accepted by the graphic arts industry. Initially the black-and-white digital printing market began using PDF for output on fast Xerox digital presses.
In Acrobat 3, the open architecture of Acrobat Exchange finally began to pay off and a lot of interesting prepress xtensions appeared in ‘97 and ‘98, including several essential prepress tools.
• PitStop and CheckUp from Enfocus software and CrackerJack from Lantanarips were some of the early Acrobat plug-ins.
• Global Graphics had already added native PDF support to their Jaws RIP in 1993. In 1997 they added the same capability to their much more popular Harlequin RIP.
• Agfa was the first major company that promoted the use of PDF for full color commercial printing with their Apogee system, launched in 1998. Other manufacturers followed soon after.
Although vendors pushed hard to get PDF of the ground, the market was a bit slow to react. This was mainly due to the fact that the use of PDF required additional tools as well as some know-how on the file format, its limitations and curiosities. People also got disappointed of PDF when they discovered that it is a very open standard. Although the PDF standard was usable in a prepress environment, there were simply to many ways in which a perfectly valid but unusable PDF-file could be created.
PDF/X-1 – a (very) slowly emerging standard
To solve the reliability issue, a consortium of prepress companies got together and released the PDF/X-1 standard in 1998. PDF/X-1 is based on the PDF 1.2 file specifications but it is a very well defined description on what a PDF file should look like to allow for blind transfers. A PDF/X-1 file is a file in which you are sure that all fonts are included, all highres images are embedded and so on.
Although PDF/X-1 is based on PDF 1.2, a number of extra operators were added. They are described in Adobe technote 5188 and include:
• the possibility to embed extra data like copydot files
• support for ICC based colors
• the definition of a bleed, trim and art-box
• a key that documents whether the file has already been trapped.
You can find more information on PDF/X on this page and this one.

PDF 1.3 – Listening to prepress needs
Acrobat 4, internally known as ‘Stout’ within Adobe, was launched in April 1999. It brought us PDF 1.3. The new PDF specs included support for:
• 2-byte CID fonts
• OPI 2.0 specifications
• a new color space called DeviceN to improve support for spot colors
• smooth shading, a technology that allows for efficient and very smooth blends (transitions from one color or tint to another).
• annotations
Acrobat itself also had its fair share of novelties, including:
• support for page sizes up to 5080 x 5080 mm, up from 1143 x 1143 mm
• Webcapture
• a series of preset configurations in Acrobat Distiller, making it easier to create valid PDF-files.
• a very confusion change of names: the former Acrobat Exchange was renamed to Acrobat, which also happens to be the name of the entire software suite.
• easy integration in Microsoft Office.
The initial version of Acrobat 4, aptly numbered 4.0, contained quite a lot of bugs that limited the usefulness of the software for prepress purposes. Users got quite upset when Adobe tried to charge for the bugfix, Acrobat 4.05. Luckily Adobe listened to its users and send a free copy to registered users (We did have to wait 4 months or so for it in Europe).
By the time Acrobat 4.05 was released, it could hardly be disputed that PDF had become an accepted file format for information exchange. More that 100 million copies of Acrobat Reader had been downloaded from the web. In prepress, few people still doubted the usefulness of PDF for file exchange, troubleshooting and/or softproofing.

llustrator 9 and PDF 1.4 – Acrobat will have to wait
Mid 2000, Adobe did something weird: they released Illustrator 9. Although launching a new version of a drawing application is not that bizarre, Illustrator 9 did have one amazing feature: it was the first application to support PDF 1.4 and its transparency feature. This was the first time Adobe did not accompany a new version of PDF with a new version of Acrobat. They also did not release the full specs of PDF 1.4, although technote 5407 documented the transparency support in PDF 1.4.
Acrobat 5 (codename: Brazil)
In May 2001 Acrobat 5 did finally show up and PDF 1.4 became a reality. The file format itself had not changed that much. For prepress, the things worth mentioning included:
• the addition of transparency support, which allows an object like text or an image to see through.
• improved security, including 128-bit encryption and the option of setting the quality of printing (you can define that a PDF can be printed but only in low resolution)
For non-prepress users, Adobe also added some goodies to the PDF 1.4 file format:
• There was improved support for JavaScript, including JavaScript 1.5 and better integration with databases.
• “Tagged PDFs” are PDF files that also contain structural information about the data that are representated by the PDF document. This means that meta-information like defining titles, blocks of text,… can be part of a PDF-document.
• This makes it easier to create PDF-files that can adapt themselves to the device they will be used upon. This new feature is mainly meant for the emerging market of ebooks, since it allows PDF files to be repurposed so they can be used on a wider variety of systems. Adobe has started shipping a version of Acrobat Reader that runs on PalmOS PDA’s.
• It will also make it easier to repurpose content
Most users were more pleased with all of the new features that Acrobat 5 itself offered. Prepress users enjoyed the following enhancements:
• Acrobat 5 itself can correctly display overprints. So if a user puts a yellow box in overprint on a cyan background, Acrobat 5 can display the resulting green box. Please note that this option is switched off by default.
• Acrobat 5 can also perform batch operations which can be used, among others, to export folders full of PDF files to EPS-es.
• Distiller 5 can compress images that use DeviceN colors. This means that PDF files containing multitones will be a lot smaller.
• Acrobat and Distiller 5 also use an improved color management engine, known as ‘ACE’, which provides finer control.
• Annotating PDF-files is more flexible in Acrobat 5 and can also happen across the internet.
Acrobat 5 was a more significant upgrade for non-prepress users:
• The forms-functionality was enhanced a lot.
• The user interface of Acrobat resembled Microsoft Office applications a lot more. The integration of Acrobat within Office had also improved.
• You could start Distiller or Catalog from within Acrobat.
• Thumbnails are created automatically when a PDF file is opened in Acrobat 5.
• There are more and improved export-filters, including an option to export data from a PDF to the RTF file format. This made it easier to maintain the appearance of files when exporting them to word processors.
• Interestingly enough, Acrobat 5 was also a downgrade for some users: Adobe replaced the ‘Paper capture’ plug-in that could OCR scanned pages to create a true text-based PDF by a fairly limited Web service.


PDF 1.5 & Acrobat 6 – More choice for already confused users
• In April 2003, Adobe announced Acrobat 6 which started shipping late May. The internal codename for Acrobat 6 was ‘Newport’. As usual, the new version of Acrobat also brought along a new version of PDF, version 1.5.
• PDF 1.5 brings along a number of new features to will probably take a pretty long time before they get implemented or supported in applications. The new stuff includes.
• Improved compression techniques including object streams & JPEG 2000 compression
• Support for layers
• Improved support for tagged PDF
• The Acrobat software itself actually offers far more immediate advantages than the new PDF file format.
• Acrobat Reader got renamed Adobe Reader and now also includes the functions of the Adobe eBook Reader. Unfortunately this application has also grown and now has a file size that is perhaps over 1000 times larger than most office type PDF documents that people want to look at.
• Acrobat Professional is the high-end version of Acrobat 6, geared towards prepress use. It offers a plethora of new features.
• Integrated preflighting
• PDF Optimizer
• Rulers and guides
• Job tickets
• PDF/X support
• Separation output & a separation preview
• Transparency flattener
• Layers
• Measurement tool & loup tool
• A new user interfaces which closer resembles other Adobe applications

2005: another year, another PDF revision
• In January 2005 Adobe started shipping Acrobat 7 (original code name: Vegas). Of course it offered support for a new PDF flavor. PDF 1.6 offers the following improvements:
• NChannel is an extension of the DeviceN mechanism for defining spot colors in a PDF document. It is backwards compatible with DeviceN and enable more accurate handling of color blending by including additional dot gain and color mixing information.
• Improved encryption algorithms
• Some minor enhancements to annotations and tagging
• OpenType fonts can be embedded directly into the PDF, they no longer have to be embedded as either TrueType or PostScript Type 1 fonts.
• PDF 1.6 files can be used as a kind of ‘container’ file format by offering the possibility to embed files into a PDF.
• The major new feature is the ability to embed 3D data. At first I though this feature would only be interesting for architects or the CAD-CAM crowd. Then a colleague showed me a PDF he had created using ArtiosCAD, a design application for packaging. Within a PDF you can look at a box from all angles, check the graphic design and the positioning of images or bar codes. That’s when I understood that this technique can also be useful for graphic arts, specifically for people working in packaging or display.

PDF 1.7 – Adobe goes ISO
• Probably the most ‘unexciting’ PDF-version to ever be released, PDF 1.7 contained improved support for commenting and security. Support for 3D also got improved, with the possibility to add comments to 3D-objects and more elaborate control over 3D animations. A PDF 1.7 file can include default printer settings such as paper selection, number of copies and scaling.
• Adobe Acrobat 8, code name Atlas and made available in October 2006, introduced one interesting new feature: instead of using PDF 1.7 as its default file format, it sticks to PDF 1.6. It has also become easier to save documents as an older PDF version. This is probably Adobe’s acknowledgment that most people don’t need the latest PDF release to get things done. For printing and prepress, PDF 1.3 or PDF 1.4 are just fine. Other new features include improved support for PDF/A, better organized menus & toolbars and the ability to save forms in Adobe Reader 8. The fact that the preflight engine can also handle a number of corrections (called fix-ups) is another nice touch. Most people seem to think the enhanced performance, especially on Intel Macs is the biggest advantage. Some people don’t like the new interface
• One interesting development with PDF 1.7 is the fact that it became an official ISO-standard (ISO 32000-1:2008) in January 2008. The official specs were released on 1 July.


2008: Acrobat 9 sticks to PDF 1.7 ‘Adobe Extension Level 3
• Since the ISO-organisation now controls the PDF-standard, Adobe couldn’t introduce a new PDF 1.8 file format with the release of Acrobat 9, code named ‘Nova’ in June 2008. The PDF file format is pretty flexible however and it allows for the use of extensions – data that might have value to a certain application but that other software can simply ignore. Acrobat 9 PDF files are enhanced with such extensions, called Adobe Extension Level 3.  This extension can be used to embed geospatial data in a PDF file, something that is useful for maps. At the moment of writing, the Acrobat 9 SDK hadn’t been released yet so I don’t know which other features Extension Level 3 has.
• It seems logical that Adobe will keep adding new features to PDF using such extensions, simply to add extra value to new releases of Acrobat. They may propose that some of them make it into new ISO-certified PDF releases. Of course other companies can do the same or may request changes to Adobe’s proposals. The PDF standard will continue to evolve but since more companies & organizations can now get involved and committees by nature work much slower, there won’t be a new PDF version every 18 months.

Acrobat 9 Professional offers good support for industry standards such as PDF/X-4 and GWG.
• The application allows you to embed multiple files and data types into a Portfolio, which is similar to a ZIP file. It is unclear if this way of bundling data will become popular.
• For a whole slew of common issues, there is no longer a need to revert to plug-ins as Acrobat 9 itself has the tools on board. A few examples:
• The Touch Up Text Tool now supports word wrap (even though using it is still a hit-and-miss affair).
• The Crop Tool lets you define the ArtBox, BleedBox, CropBox or TrimBox.
• The ‘Convert Colors’ tool is more powerful and faster. It also seems to have less issues with transparent objects.
• Using the ‘Examine Document’ menu option you can delete all objects that are completely outside the page are (CropBox) or trim area (TrimBox).
• ‘Output preview’ can simulate the effect of varying press conditions.
• The application seems to run faster on Macs.
• One small thing to keep in mind: ‘Overprint Preview’ is set for ‘Only for PDF/x files’ as default. Changing this to ‘Always’ is more reliable but slows down the application. Check out this blog for more background information.
• Of course there are also a number of features that target other markets besides print. Support for AES-256 encryption is an example of this.

2010: Acrobat X
• At the moment of writing Adobe had promised Acrobat X would start shipping on December 1st.
• The Acrobat and Reader user interface went through a major overhaul.
• The Portfolio function is been greatly extended, allowing users to embed audio, video and other rich media files in a PDF Portfolio.
• Given all the security flaws that showed up in previous releases of Acrobat and Reader, Adobe implemented a Protected Mode for version 10. This ’sandboxing’ technique should minimize the risk of opening infected PDF files by accessing them in an application that is confined to its own private execution environment.
• Adobe Acrobat X and Reader X remain 32 bit applications but running them on 64 bit systems is supported.
• The document comparison function has been enhanced, making it easier to import multiple versions of the same PDF and discover the differences.
• One odd change is that Adobe now markets a version called Acrobat X Suite which includes Photoshop CS5.
• As far as I know Adobe did not create any Acrobat X-specific proprietary extensions for the PDF file format. In 2009 they did publish the specs of extension level 5 – some new PDF functions that were used in Acrobat 9.1.

The future of PDF
• The ISO-committee is currently working on the specifications of PDF 2.0. This standard is expected to be released in early 2012. It will apparently be a minor refinement of the existing PDF 1.7 specifications. I have been told that PDF 2.0 will not incorporate any of the ideas from Mars. Mars was an Adobe project which focused on using XML as the internal data format within PDF documents. The main advantage of using XML as the internal format for PDF files would be that programmers would be able to use the incredible number of XML-tools and technologies that are available on the market to create or process PDF files.