Adobe Acrobat and PDF

PDF is considered a "portable" document because:

• Standard Format: it is a standard file format which can be viewed across multiple computer platforms.
• Embedded content: All fonts and images are embedded into the document, therefore all computers will view the document identically, and will print the document as it appeared when created.
• Compression: .PDF files are compressed files ... all content (images and text) is converted to either .zip or .jpg format. Therefore, a typical 1500 KB file will often compress into a .pdf file under 150 KB. This makes for speedy transmission of documents over networks, through email and on web pages.
• Security: .PDF files can be password protected.

Most file formats open inconsistently on different computers because:

• Many programs use a computer's default printer drivers while formatting a document. Therefore, two computers which are attached to two different types of printers will typically view a document differently.
• Different platforms view documents differently, i.e. Windows, OS/2, Sun Solaris, Macintosh, etc.
• If a computer does not have installed on it the program that a file was originally created in, often it cannot open that file, or will open it improperly.

UWRF Use:

• Collecting and disseminating information: Used for creating forms or material for printing from the web or within the office. Registration forms, handouts, brochures, etc. Some departments use a .pdf file as an email web form by entering data in fields and submitting the data electronically.
• Student web portfolios: Creating .PDF files from student materials is the fastest and easiest way to make their hardcopy or disk files of job-related materials available on the web for viewing by potential employers.

Special Office Use:

• Editing: A single document may be routed through an organization and each individual may "scribble" their comments regarding the document's content "on" the document and have them stored within the document.

Tips for use:

• If creating a document to be converted to .pdf, set Adobe PDFWriter as the default printer.
• If documents are already complete, set Adobe PDFWriter as the default printer, then reformat the document as necessary so it appears in .pdf format as intended.

Drawbacks:

• Content of a .PDF file cannot be changed. To make a change, one must first change the original document in its native format, then convert that document to a .pdf file.
• Viewing on screen: .PDF files often appear blurry or fuzzy on screen; however, .pdf files print crisp and clear.
• The compression of images when converting to .pdf format often reduces image quality. This may be remedied by adjusting settings within the PDFWriter or Acrobat Distiller.

Adobe Acrobat Distiller Settings:

To utilize the Adobe Acrobat Distiller settings, one must first create a PostScript file (do so by checking the print box "Print to file". Now open the PostScript file using Distiller to convert it to .pdf format with the assigned settings:

Acrobat Distiller Compression Settings

JPEG: Attempts to reduce file size by removing image data. This may result in lower quality images. Much lower file size may be achieved by using the JPEG setting vs. the ZIP setting. Quality may be set from Minimum to Maximum.

ZIP: Also called "Flate" compression. This is a lossless compression which doesn't reduce the quality of images, yet compresses images by saving them in .zip format. Keep in mind that if images are 8-bit, you will want to select 8-bit compression to maintain image quality (the 4-bit setting reduces 8-bit image quality to 4-bit quality).

Automatic: Adobe Acrobat determines when to use JPEG or ZIP compression. If Distiller finds sharp color changes in 8-bits-per-component images, it uses Flate compression. If the image has smooth color changes, Distiller uses JPEG.

Bicubic downsampling: Slowest but most precise method, resulting in the smoothest tonal gradations of images.

Average downsampling: Reduces image size and quality by averaging pixels across an entire image.

Subsampling: Significantly reduces the distilling time compared with downsampling but results in images that are less smooth and continuous.

* Keep in mind that a typical screen resolution is approximately 72 dpi, while a typical printer resolution is 300 dpi or more. If an image is intended for on-screen use rather than for printed use, then reducing images to 72 dpi may greatly improve speed when downloading and viewing.

**Thanks to Matt Fitzgerald of Career Services for the development of this document.

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