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PDF: The Cure for Dawdling Digital Files

(December 1999) posted on Tue Dec 14, 1999

Learn the basics of creating PDF files.

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By Mark A. Coudray

But frequently when we attempt to image a job, we discover that one or more of the images that should be included in the electronic file are either missing or need updating. Links may be lost when design elements are modified, and relying solely on visual inspection of the final graphic on a monitor is not enough to ensure that the image is correct. The more elements the design incorporates, the greater the problem.


Even if we're careful to include all graphic elements and build the design correctly, we may still experience unexplained shifting or changing of the elements when the graphic file is sent to an imagesetter or digital-printing device. Occasionally, this may stem from using a different version of the layout program to open and output the file than was used to create it. It also occurs frequently if we rasterize vector-based images from Illustrator or Freehand into Photoshop. Any placed EPS bitmap image may move unexplainably. In all these situations, our only recourse is to measure and compare the positions of placed elements on the print or film after it is output.


Finally, we must deal with the challenges of electronic delivery via e-mail, Internet, or direct modem. We never know (especially with e-mail attachments) whether we can open a file and whether the file is correct and complete. Nothing is worse than downloading a file for 45 minutes only to find an "unexpected end of file" error when the downloading process is 98% complete.


Additionally, we are challenged by the task of compressing or decompressing files. If lossy compression is used (where apparently redundant data is omitted by the compression algorithm), we can't be sure that it hasn't damaged the original file by deleting necessary data--the results will not be visible until film separations or the final color image are output. In many cases, a sequence of compressions may have been applied to the graphic, and our only hope of opening the file correctly is to decompress it using the identical sequence in reverse order. One slip, and we have alphabet soup!



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