PDF Research

Michael Jahn's Afterword to...

PDF Printing and Publishing:
The Next Revolution After Gutenberg

As the OEM Manager at 4-Sight, I develop relationships with vendors who may use our products to enable transfer of data to and from that vendors products. For example, I spend a lot of my energy developing things like remote proofing strategies, with our goal to make it as bullet proof as faxing a document. Without a standard file format, it will be chaos. In my view, Adobe has provided us with a way to fully descibe a color document using the PDF file structure, which can at this writing, permit us to view on screen and print documents as the creator of that document intended. More importantly, we can do this without making the file as difficult to edit as a raster only page description. If you are confused about this, try correcting the spelling of a name on a bitmap image of a fax in PhotoShop. This is where we are the high end color prepress industry today.

Indeed, some of us send Quark XPress documents, others PostScript as "print to disk" files, some send proprietary Scitex CT and LW files; many believe that raster files such as TIFF/IT (similar in concept to sending bitmapped fax data) may be the most reliable method. This hodgepodge of file structures and stategies often require that the recieving end of the file do things, sometimes heroic things, to simply view the file, nevermind actually print out the file. As there are no free Macintosh or Wintel client applications that can even view a TIFF/IT file, I see the TIFF/IT file structure as the format of choise when I want to have an unscreened digital version of 4 color file, just prior to imaging it onto some high resolution media such as film or plates. Otherwise, PDF can do the job.

What the PDF file format promises is a future where we can perform a blind transfer. As an industry, we need a way to eliminate the ambiguity of exchanging color pages. We need a way for the he creator, author or originator of a color document to transfer that document while carrying all the elements and entities that are required for that document to achieve the inteneded results at the recievers end, whithout heroic intervention at that reciecers site; in essence, accomplish a reliable exchange of grapical color data between the sender and the reciever.

When I discusssed this concept with Jim Meehan, one of the Authors of the PDF specifications at Adobe, I asked him pointedly (as I think many of us would have) what the the main differences were between PostScript and PDF, and why I should be confident in PDF as the file structure that will lend itself to blind transfers of color documents. What he explained was so elegant, I simply had to give him credit for it, lest you think I was so clever; he explained to me that that a PostScript file is a "program", an actual application that is created, sent and then run inside the PostScript RIP (Raster Image Processor), and that a PDF file is more of an "object database". When a PostScript file (or PostScript application, more accurately) is run, the PostScript commands are interpreted and then rasterized into a bitmap and normally imaged to paper, film or plates. The objects that describe graphical elements and entities in PostScript are difficult to parse or otherwise find or extract. This is where we are today with PostScript. Moreover, If you want to make a simple edit, such as a spelling correction, you normally need to go back to the original application file that created it. Editing PostScript is not very straight forward. In the case of PDF, this simply is not the case. Using Adobe applications such as Exchange, one can make that spelling correction on all the popular computer platforms, and if Distiller was set up properly, without requiring you to have the fonts!

In my view, this is the very first file format that actually resolves the main problems we encounter in our industries current prepress workflow. It is compact enough to transmit efficiently, can be created, opened viewed and edited without depending on a specific computer platform, and in the case of simply viewing and printing, can be accomplished using an application that can be downloaded for free from Adobes web site (www.adobe.com). Any advertising adgency, design firm, prepress service provider, publisher or printing company can prove this to themselves by aquiring the free Adobe Acrobat reader and then downloading the facing page. Go to http://www.tool.net/friends/jahn/pdf3/cmyk.pdf, and you can view and print this documnet (it is under 600k) without a hitch. Go ahead. Open it and print it. If you have any problems, email me at mikejahn@jahn.com. I am confident that you will be suprised to learn just how easy it works.


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