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Investigating Acrobat and PDF
Tom Arah investigates the design potential of the latest Acrobat 6.
When the first release of Adobe Acrobat was launched on June 15th 1993 its introduction was hardly noticed. Now, almost exactly a decade later, the launch of Acrobat 6 is a major event. Adobe has claimed that this latest release is the most significant yet, but what exactly does it mean for the designer?
To appreciate Acrobat's importance you first have to realise that Acrobat isn't so much an application as a platform built upon the Acrobat file format: PDF (Portable Document Format). And to understand what makes PDF special you have to understand what it is and where it came from. PDF developed out of Adobe's work on PostScript. PostScript is a Page Description Language (PDL) which programmatically describes the contents of any page including all vectors, bitmaps and fonts so that running the same code on any PostScript-enabled device produces exactly the same resolution-independent output. It's PostScript's programmatic nature that ensures that designers can proof exactly the same page layout on their PostScript laser printer as will eventually be output on the imagesetter.
Ten years ago PostScript and its standalone EPS (Encapsulated PostScript) file format were already well established as the underlying architecture for commercial print, but Adobe realized that a PDL could be useful for more than just print. However they had a major problem: look at a PostScript file and all you'll see is reams of code (or at best, in the case of EPS, a crude bitmapped preview). To fulfill its potential Adobe had to make PostScript viewable onscreen. In fact that was always the intention, but the financial and processing overheads involved meant that Adobe failed to persuade the OS developers to license its DisplayPostScript technology (with the notable exception of Steve Jobs' ill-fated NeXT project).
Adobe's stroke of genius was to rework the inherently print-oriented PostScript. What they came up with was a format based on a superset of PostScript functionality optimized to onscreen viewing and then compressed to within an inch of its life. Effectively PDF was a "distilled" version of PostScript. And that's exactly how the PDF files themselves were originally created. Central to the early Acrobat was - and still is - the Distiller utility that takes a PostScript print-to-disk file and converts it to PDF. In other words the PDF is created by printing the document to a viewable file (these days Distiller can be bypassed but the process is still built on print-based output).
The viewable PDF format is based on the PostScript PDL.
It's an awkward and roundabout way to go about producing files but it's the secret of Acrobat's success: all applications can print and so all applications can produce PDFs - exact electronic replicas of their printed output. This PDL-based universality is unique and was especially important in the early days of Acrobat when incompatibility between platforms and applications was strangling the development of business computing. Acrobat's initial raison d'etre was therefore to act as computing's lingua franca. In plain English it acted as a universal middleman - embodied in Acrobat's juggler logo - enabling office users to collaborate, whatever their platform and application. It was the heady days of the imagined "paperless office".
As it turned out the arrival of the Internet and the ever-increasing dominance of Microsoft and the PC combined to remove most of the problems that Acrobat was designed to solve and the technology might well have struggled if it wasn't for the release of the free Acrobat Reader program. At a stroke PDF was transformed into a capable publishing format as it meant that authors could provide free-to-view electronic versions of previously printed material - and at virtually no cost to themselves! The PDF software manual was born, encouraging more users to install the Acrobat Reader which in turn encouraged more PDF publishing and so on.
The free Acrobat Reader application turned PDF into a publishing medium.
PDF became an important publishing medium in its own right but of course it never actually cut down on the need for traditional paper-based publishing. And here PDF had another obvious role to play. As a universal single file format containing all images and fonts and, crucially, based on PostScript, it's the natural medium for designers to deliver their commercial print for output. And it's ideal for the bureaux too as they only need to support one master application rather than every release of every possible publishing application.
The possibilities are enormous and it's almost impossible to over-estimate the potential of PDF for the designer during the proofing/review process, as the final published electronic product and as the digital master for commercial print. But there's a big difference between the drawing board and the real world and the early Acrobat needed to change radically to begin delivering on the dream. That's exactly what it's done with each release and update of the PDF file format.
For collaborative working, the breakthrough version was Acrobat 3 which bundled the previously separate Exchange and Distiller and provided everything needed to take full advantage of the PDF format including the sticky-note style commenting capabilities that we've all grown used to. Version 4 added a host of new commenting tools and the Annotations panel for easier review, but its main advance was the introduction of encryption ensuring secure collaboration. Version 5 rethought the whole workgroup review process by enabling efficient browser-based access to a single centrally-held master.
Acrobat's page-based review is tailor-made for proofing for print.
Version 3 was also the seminal release for those authoring PDFs as their end product as it showed that electronic publications could offer more than their paper equivalents. The Link tool made it possible to set up basic navigation while the Form tool took this interactivity further. The Sound and Movie tools even let you link to WAV audio and AVI video to give your work a multimedia edge. Version 4 added little to Acrobat's authoring capabilities, but version 5 introduced content tagging which was most obviously useful for preparing layouts that could re-flow - essential for handheld viewing on the new Pocket PC Reader. And with a push towards eBooks and its Content Server software, Adobe also provided a secure mechanism through which authors could charge for their publications.
Surprisingly, despite its obvious qualifications, Adobe hadn't originally intended PDF to be used for producing commercial print - that was PostScript's job. As such, the early Acrobat was RGB-only and it was only later that the crucial CMYK and "Device N" support for other colour models such as spot and hi-fi colour were added. Further essential improvements were Acrobat 4's support for PostScript Level 3 and ICC-based colour profiles and version 5's introduction of the shared ACE (Adobe Colour Engine) and transparency handling.
With the launch of version 5 in April 2001, Acrobat had changed out of all recognition - but still no-one could claim that it was an unqualified success. For collaborative work, the use of PDF still largely boiled down to the digital equivalent of covering a page with sticky notes and passing it on. For Acrobat-based publishing, the PDF still offered little more than an electronic replica of printed output - and with the huge drawback that no-one enjoys reading on screen. And for commercial print, the lack of essential features such as colour separations and pre-flighting, meant that the user either had to turn to expensive third-party plug-ins or cross their fingers and hope. The underlying technology might be unbeatable - and there was certainly no alternative - but the bottom line was damning: trying to make sense of an annotated PDF was a chore, trying to read a PDF computer manual was a pain and trying to produce commercial print via PDF could turn into an expensive nightmare.
Clearly there was plenty of scope for improvement and expectations were correspondingly high for Acrobat 6 - but my first impression was disappointment. This was largely down to the fact that the hard information provided amounted to a couple of skimpy press releases pushing Acrobat's office-centred credentials. And these boiled down to two cosmetic changes. Firstly the Acrobat application has been split into four variations: Adobe Reader for free viewing; Acrobat Elements for large corporates; Acrobat Professional for high-end designers and Acrobat Standard for everyone else. Secondly the creation of PDF has been made simpler with the emphasis on one-click authoring. Yes, being able to select the new Convert to PDF command from a DOC file in Windows Explorer is more convenient, but the underlying process is still fundamentally the same - the command simply opens the file into Word where the PDFMaker macro takes over to print/distill the document.
Convenience isn't to be sneered at however, as the new collaboration features in Acrobat Standard and Professional show. There's not much Adobe can do about Acrobat's essentially sticky-note based approach to annotation as the whole point of PDF is that it shows a fixed representation of the page layout, but the new tools, review management and especially the redesigned Comments panel certainly make the whole process much smoother (see full review last issue). I'm still not convinced that the office users Acrobat Standard is aimed at wouldn't be better off using Word's own review capabilities as these enable suggestions to be automatically incorporated. For designers though Acrobat's page-layout based commenting system has always been invaluable for speeding up the proofing process and Acrobat 6's major overhaul will be especially welcome when deadlines are tight.
The main benefits for the designer though come with the design-oriented Acrobat Professional. Adobe is especially targeting this version at those designers producing commercial print so my first port of call was to load up Distiller to see what new power was available. I was particularly surprised therefore to find that the top of the range "Press Quality" preset still defaults to Acrobat 5/PDF 1.4 compatibility. By forcing the compatibility setting to Acrobat 6/PDF 1.5 I was able to find a couple of new features - notably the support for greater object level compression and JPEG2000 image compression - but while slightly smaller file sizes are welcome, they are hardly revolutionary.
I thought that I might have found the new power I was looking for in the two new Acrobat Professional presets: the suitably intimidating "PDF/X1a" and "PDF/X3". There's a whole new tab in Distiller's PDF Settings dialog dedicated to handling PDF/X features such as the document's TrimBox, MediaBox, and BleedBox and trapping. In fact though none of these features are new as shown by the fact that both PDF/X presets output to the Acrobat 4/PDF 1.3 format. In fact the PDF/X1a and PDF/X3 presets are simply codified standards for CMYK and colour-managed prepress exchange respectively - ideal for example for handling adverts.
The PDF/X standards are designed for prepress exchange,
What Distiller 6's PDF/X support shows is not Acrobat's new power but its new concern for quality control. This is even more apparent in Acrobat Professional. Previously Adobe took no interest in the quality of your PDF master: if there was an RGB image mixed up with the CMYK images or a low resolution image, well that was your problem, and you'd only find out about it when your print-run arrived. Now there's a Preflight command which checks your file in exhaustive detail listing all potential problems.
Preflighting is essential but by far the most important check of all is to output the colour separations yourself for proofing. Bizarrely this simply wasn't possible with Acrobat 5 without expensive third-party plug-ins - fine for the bureaux but beyond the reach of the average user. There were workarounds such as outputting each page from Acrobat as an EPS and separating those or even pre-separating your files and sending publications composed of separate cyan, magenta, yellow and black pages but clearly this went against the whole principle of the streamlined composite PDF workflow. Now at last you can output separations to any PostScript device and, even better, preview each plate onscreen.
In-built separation and preflighting boost Acrobat Professional's commercial print capability.
It's clear that Acrobat 6 represents a major step forward both in terms of collaboration and commercial print - but in each case this comes not through major new functionality at the PDF level but through exploiting the power that was already there. That's valuable in itself and a sign of Acrobat's increasing maturity as a platform, but by this stage I was beginning to wonder if there was anything new at all in the PDF 1.5 format - a feeling reinforced by just a single reference to it in the Acrobat help file.
But in a way that's the point. Trying to retrofit an existing PDF to add interactivity or multimedia or accessibility just doesn't make sense: the place to do it is in the original authoring package. And this is the real key to unlocking the direction in which Acrobat is moving and where the power in this latest version is hidden. As we've seen, the universality of Acrobat's print-to-PDF capability has been the secret of its success, but it can only go so far. The print stream is inherently only concerned with the appearance of the document, all other information is lost. But if you create the PDF directly from the application this limitation is instantly removed.
The first sign of the new richer PDFs that can be created when created directly is Acrobat 6's support for layers. At the launch the only indication of this new capability was the provision of PDFMaker macros to enable AutoCAD to produce layered drawings, but it's a safe bet to say that Adobe had other applications in mind. In particular of course, each of its three main publishing applications - Photoshop, Illustrator and InDesign - make heavy use of layers.
For InDesign and to a lesser extent Illustrator, the benefits of being able to hide and display PDF-based layers are fairly obvious with the ability to include different language versions in the same file. For Photoshop though the use of layers is really only important when editing and it's here that I think that the new PDF 1.5's richer structuring capabilities are really aimed. For many years Adobe has talked of the benefits of an all-PDF workflow and each of its publishing applications can save directly to PDF. However, users have resolutely stuck to the native file formats AI, PSD and IND to maintain maximum editability for their original work and the file standards EPS and TIFF for maximum compatibility when it comes to cross-application exchange. Gradually though all Adobe's publishing applications have been converging on a shared and increasingly editable PDF format and it's clear that Acrobat 6 will be another major step on the way.
But why stop here? The very fact that Adobe so studiously avoided mentioning Acrobat's new multimedia capabilities piques my interest. I can't imagine many users turning to Acrobat Professional's Sound and Movie tools to retrospectively add multimedia to an existing print project, but if the capability is there from the beginning in InDesign it's a different story. Forget about Acrobat's new Read Aloud command - the average user isn't going to want to listen to Microsoft Sam for long - but how about providing MP3-based narration alongside the text in a combined Talking/eBook? Or how about adding explanatory Flash animations to your projects? Or what about replacing your publication's screenshots with video walkthroughs? Maybe users will even end up groaning when their software manuals are provided on paper rather than PDF.
And why stop here even? The real beauty of Acrobat 6's new multimedia capabilities is that it doesn't provide the media player at all - it leaves that to the experts - Microsoft, Apple, Macromedia et al - and the end user. The PDF simply acts as an intelligent delivery mechanism providing the media best suited to the user's current setup. And if it's simply a wrapper what's to stop Premiere wrapping its sound and video files in a PDF? After all the whole recording industry is looking for a secure way to add chargeable value to MP3s and wouldn't you be willing to pay a premium for a PDF album that included lyrics, photos, videos and so on? Or what about DVD? These days the DVD specification looks horrendously rigid and outdated so wouldn't it give Adobe's new DVD Encore application a much-needed edge if it could also output projects to a much more modern and powerful media delivery format that automatically adapted itself to its playing setup?
PDF 1.5 can act as an intelligent wrapper for multimedia content.
By this stage I have to admit that this vision of PDF as the all-singing, all-dancing, all-encompassing creative file format is pure speculation. Moreover I don't suppose that this generation of applications will fully deliver on the Acrobat dream of universality, any more than those that went before did. Having said this though, I'm also sure that Adobe is moving strongly in the right direction. With Acrobat 6, the PDF is both building on its secure PostScript-based page description foundations and moving beyond them to become an even more powerful general-purpose design format. Perhaps even the design format.
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