Lane Medical Library

Many PDFs carry excessive weight; the large file size slows down PDF performance, creates email problems and printer jams, and can be a source of user frustration.

It’s a good idea to aim for the smallest possible file size, unless you are preparing a PDF for high quality print.

To create the smallest possible PDF for faster web delivery and retain a good office printing quality:

• Audit Space Usage
• Use "Save As" command not "Save"
• Optimize images, scanned pages, and transparency
• Minimize the number of fonts and do not embed them
• Minimize the number of bitmapped images
• Use the RGB not CMYK Color Space
• Choose the latest possible PDF version while saving the file
• Remove unused elements and clean up the document

You can audit the PDF file first to see which elements are significantly large.

• Choose Advanced > PDF Optimizer
• Click Audit Space Usage
• The audit results list the bytes used by each element and its percentage of the document's total size

• After making changes, choose File > Save As
• By default, it removes changes that are appended to PDFs by the Save command, and unused objects
• Save the file with the same name to overwrite the original one

• Choose Advanced > PDF Optimizer > Images to select compression options for color, grayscale, and monochrome images
• Compression eliminates unnecessary data
• Downsampling lowers the resolution of bitmaps (photographic) images
• Use JPEG for photographs and other images with continuous tone. You can select a quality level to determine how much pixel data is removed (lower quality means smaller file but you need to watch out image quality)
• ZIP is good for illustrations with large areas of solid color
• Use JBIG2 for monochrome images

Later versions of Acrobat allow you to reduce PDF size by simply choosing Document > Optimize Scanned PDF

• Fonts can have a big impact on PDF file size. Minimizing the number of fonts you use will make the pdf smaller
• If you use a common (system) font, unembed it. Each additional fully embedded font can easily add up to 40K to file size
• Be aware that if the font is not available on other machines, Acrobat will display a substitute

• Go to Advanced > PDF Optimizer > Fonts. Choose the fonts to be unembedded

• For bitmap graphics, prepare them in a graphics program (such as Adobe Photoshop)
• Do not insert the large images into PDF — resize them to the dimensions needed while still within the graphics application
• Lower image resolution. 72-100 dpi is enough for web PDF and should be enough for office printing
• Use the best quality images. Inserting already compressed JPEGs into PDFs can create noticeable pixelation
• Use black and white images and text instead of color images if you can
• Be sure to turn off thumbnails when saving PDFs for the Web
• Use vector-based graphics if possible. They scale better, and usually take up less space. Wikipedia about vector graphics »
• Acrobat Reader version 5 and 6 also support the SVG standard. SVG format helps reduce the file size

• For web PDFs use the RGB color space, not CMYK. RGB has one less data channel than CMYK, so files are that much smaller in size
• For office printing, when color accuracy is not critical, it is also ok to use RGB space
• Go to Advanced > Print Production > Convert Colors
• Check the Output intent box. Choose sRGB profile

• In general, the later the PDF version, the smaller the file
• Since over 90% of Acrobat users have version 5.0 or greater, using PDF 1.4 is safe

• Go to Advanced > PDF Optimizer > Discard Objects

• Select  the version of Acrobat that you want to make the document compatible with, and then any additional items that you don’t use

• On the Clean Up panel, choose a compression option and then select which items to remove
• The Clean Up panel lets you remove elements from the PDF document that you don’t need. The options that are selected by default don’t affect functionality, but other options may, so be careful when selecting unfamiliar options
• Save the optimized PDF file under a new name so that you leave the original PDF document unchanged