Optimizing PDF files
This content is taken from WebSiteOptimaation.com at
http://www.websiteoptimization.com/speed/tweak/pdf/optimizer.html
PDF’s have become quite popular on the Web but most are designed for high quality print output and are not
optimized for the Web. Even PDFs designed for Web use can have problems with excess fonts and unoptimized
images and forms. By optimizing your PDF files for the Web you can significantly shrink their size and boost
the display speed, saving bandwidth and user frustration.
What Is a PDF?
Portable Document Format (PDF) files allow one to display the content of a document on or off the Web
independently of any specific software except the Adobe Acrobat Reader. The reader is included in current Web
browsers.
To create PDF files and optimize the files for Web delivery, one must purchase the Adobe Acrobat Professional
software program. The software includes settings to compress and optimize the PDF file.
It is in how well you use these compression techniques, how efficiently the data is described (including image
resolution) and the complexity of the document (read number of fonts, forms, images, and multimedia) that
ultimately determines how large your resulting PDF file will be.
Creating Small PDFs
The main factors in creating small PDFs are image resolution, image type (bitmap or vector), the number of
fonts used and how they are embedded, PDF version, and the level of compression. In general the higher the
PDF version number, the smaller the file. Acrobat will usually display (with a warning) a more recent PDF
version, but new compression schemes will spawn an error when opened in older versions of Acrobat.
To create the smallest possible PDFs for the Web minimize the number of fonts, bitmapped images, and
substitute vector based-graphics instead. Minimize the number and complexity of forms in your PDF document
and flatten form fields, and avoid the use of multimedia.
Graphics
Use the best quality images that you can at the output resolution of the PDF. Inserting compressed JPEGs into
PDFs and Distilling them may recompress JPEGs, which can create noticeable artifacts. Use black and white
images and text instead of color images for the best quality in compression. Be sure to turn off thumbnails
when saving PDFs for the Web.
Minimize Fonts
How you use fonts, especially in smaller PDFs, can have a significant impact on file size. Minimize the number
of fonts you use in your documents to minimize their impact on file size. Each additional fully embedded font
can easily take 40K in file size.
Flatten Fat Forms
Acrobat forms can take up a lot of space in your PDFs. New in Acrobat 8 Pro you can flatten form fields in the
Advanced -> PDF Optimizer -> Discard Objects dialog. Flattening forms makes form fields unusable and
form data is merged with the page.