DIY Centre:

Understanding the mysteries of PDF

PDF documents are like virtual paper, created from the software equivalent of a computer’s printer. This is not technically accurate, but thinking of them in this way helps with a practical understanding of them.

Like printed paper, the content of a PDF file can originate from many software programs, be it a letter, spreadsheet, picture, or whatever. And confusion arises from those originating software formats. For example, elsewhere in this website it has been explained how pictures to be printed need a high resolution, while web images should be of low resolution, these settings can be set in a photo editing program and then ‘printed’ to a PDF file. What you have then is two PDF files of the same image, one that is suitable for commercial printing and the other for internet download. The high resolution PDF, along with other technical settings, is what commercial printers and advertising sales staff refer to as a ‘press ready’ PDF. What they often fail to clarify is that this ‘press ready’ state largely occurs before the image is converted into a PDF document, in programs like Photoshop, QuarkXpress, etc. And this leaves the average consumer wondering why their word processor’s generated PDF file won’t be accepted or doesn’t print properly. With the reason being, that standard office programs can’t set the specifications required to print on a four colour commercial press.

As stated at the beginning, this is not a technical explanation. It’s intention is to help the average computer user understand that there is more to PDF files than meets the eye. Anyone interested in a more accurate technical understanding should consult the adobe website for more information.

And for those who have come to hate PDF for the above reason, the reader should be reminded of its great benefit of portability. Since its inception documents can be accurately reproduced on most computer and printing systems, including Windows, Mac OSX, Linux, Unix, BSD, SunSolaris, etc. which is something other software cannot do.