I was asked this question the other day and I must admit, I didn’t know the answer. So, I went looking for an easy to explain answer that I could give the person who had asked, and through looking at multiple sites and help files, I have an answer – of sorts.
Firstly, PDF stands for Portable Document Format – and it is designed to do just that – create a document that is portable. They aren’t designed to reduce file size – rather to present the file in a format that is going to be consistent across the different platforms it can be viewed on – different computers and in print form. This means that if it needs to make the file larger to create the file, it will.
Why does it make the file larger? It doesn’t always make the file size larger than the original, but if it does, it may be due to Picture & Font issues.
How can I fix these issues?
With your pictures, where possible start with the smallest & clearest image you can. Otherwise, compress the images before finalising and converting the document.
With your fonts, it gets easier. Publisher has a pre-determined (and very limited) set of fonts that it classes as “web-ready”. If another font is used, then Publisher will typically convert the text to an image when it converts it to a PDF. If it does this, then the resulting images will increase your file size.
So, what are Publisher’s “Web Ready” Fonts? Arial, Arial Black, Comic Sans MS, Courier New, Impact, Georgia, Times New Roman, Trebuchet MS, Verdana, Symbol, Wingdings, and Webdings. Not very many, and none that can allow for much personalisation and feature headings.
The problem is though, that even after doing these things, it is entirely possible to end up with a larger file than you started with anyway.
A Publisher file, containing the equivalent of 4 A5 pages, using the fonts Gulim and Calabri, and containing 5 images totalling 410KB, has a finished file size of 549KB, and a PDF size of 740KB.
If I compress the images using the Target output of Web, I can reduce the images down to a total of 349KB, but upon saving, the PDF file size is 932KB.
With the font changed to Arial, the resulting PDF file is now 723KB.
We can see that in this example, the resulting PDF is still larger than the original file, but is now slightly smaller than the original PDF.
A publisher file, containing the equivalent of 8 A4 pages, using the fonts Bookman Old Style & Rage Italic, containing 22 full colour images images totalling 18MB, has a finished file size of 343KB.
If I compress the images using the Target output of Web, I can reduce the image total down to 1052KB, but the resulting PDF has a file size of 379KB.
Converting all the text to Arial results in a larger PDF file again, this time 508KB.
Still a much smaller file size than the original file, but larger than the original PDF.
Why have these files increased in size? I don’t know. What I do know though is that whatever font we chose to use in a file and then convert to PDF, when that PDF is viewed on another computer, or printed out, the font and the placement of images and everything else will be consistent across platforms. Also, since PDF viewers are usually easy to find and usually free (Adobe has a free PDF reader), just about anyone can view a PDF, but not everyone will be able view the original file, especially if the program used is specialist in it’s nature.