Why Are PDF Files Unreadable?

by Filonia LeChat

The PDF, or portable document format, file bridges the gaps between many software programs. Someone using one program to create a file need not worry that his intended recipient have that same program, because PDFs just require a free software program to open. On occasion, it may seem like a PDF is just as hard to open as a native file created in that proprietary software, but one of a variety of factors may contribute to the unreadability problem.


One of the most common reasons a PDF is unreadable -- and the easiest to fix -- is that the person trying to open the PDF doesn't have the software to do so. To open a PDF requires the free downloadable program Reader, created and distributed by Adobe, which also makes the PDF-creation software Acrobat. A person who doesn't have Reader installed won't see the familiar red-and-black PDF icon; they'll see a white box symbolizing that the computer doesn't know how to read the file.


Although it seems quite obvious, a person's screen resolution may have everything to do with why a PDF appears unreadable. Since PDFs are often scans or saved files of standard 8.5-by-11-inch paper, small fonts and occasionally handwriting can get be scaled to tiny dimensions when the sheet is viewed full size. Zoomed out, a heavily typed or scrawled PDF may appear as a bunch of jumbled black dots and lines instead of the clear text it would be when zoomed in.


Even if you have the Reader software installed, trying to open a PDF in a program that doesn't allow it will cause problems. For example, the Reader software doesn't let you edit a PDF -- you need Acrobat for that -- but you can still use other programs to do things such as redacting, or making black lines to obscure information. You can open a PDF in a program such as Adobe Photoshop and have the PDF be completely readable. On the other hand, if you try to open a PDF in Windows Paint, the operating system's native graphics tool, it will be unreadable because Paint does not accept PDF files.

Missing Elements

Something that appears perfectly readable on one person's screen may look entirely unreadable on another, solely because of what's missing from the file. In some cases, a PDF that looks jumbled is a result of missing fonts. While it may seem simple to just create a PDF from whatever document you're working on, if the person who receives your PDF doesn't have those fonts installed, the PDF may be unreadable. You can combat this one of two ways -- try to use universal fonts, such as Helvetica; or take the extra steps to embed the fonts into the PDF. This requires use of Distiller, also an Adobe product. An unreadable PDF may also be missing the password or certificate to render the document readable. Contact the person who created the PDF to inquire whether he locked it with an encryption. Encryption is removable with a key or password.

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