Remove All Embedded Fonts
Embedding fonts in your output PDF document ensures that the document can be opened and viewed on any machine, because the fonts travel with the document. If a document needs a font that is not embedded, the font must be supplied externally whenever the document is opened for viewing. That means that the font either must be installed on the local machine where the PDF is opened, or it must be simulated using Multiple Master fonts, a special set of Type 1 fonts provided by Adobe Systems.
Datalogics recommends that clients who create PDF documents embed all of the fonts those PDF documents are likely to need within those same PDF documents. Embedding fonts is generally considered to be a best practice.
But in many PDF documents, embedded fonts can make up a large percentage of the size of the file. If a PDF file is quite large, and you want to optimize it, it might make sense to remove the embedded fonts if you know that the fonts needed by that file will be installed on machines where that file is likely to be opened for viewing or printing.
Merge Duplicate Fonts
Fonts are commonly embedded in a document to make sure that the PDF can be rendered on any platform (see "Remove all Embedded Fonts" above). The fonts travel with the PDF, so the file will open and display properly whether the same fonts are installed on the local machine or not. It is also possible to save space by including a subset of a font in a PDF document. The subset contains only those glyphs actually used in the document.
Sometimes, however, PDF documents are created with multiple copies of the same font, either as multiple subsets or multiple, fully embedded copies of a font file. When there are multiple copies of the same font, they may be merged into a single font.
Note that sometimes different versions of a font in a PDF document share the same name. When this happens, these named fonts are not merged.
Remove Embedded Base14 Fonts
The base14 fonts should be available on any machine that attempts to render or work with PDF documents. That means that there is no reason to embed base14 fonts in a PDF document any longer, but if base14 fonts are embedded in a PDF, use this option to remove them.
The Base 14 fonts are a subset of the Type 1 fonts that are installed with Adobe Acrobat and commonly used with PDF documents. These 14 fonts include five typefaces:
- Times Roman: Standard, bold, italic, bold/italic
- Helvetica: Standard, bold, italic, bold/italic
- Courier: Standard, bold, italic, bold/italic
- Symbol: which provides mathematical and special purpose characters
- ZapfDingbats: A set of small printer ornaments, like check marks and pointers
Subset all Embedded Fonts
Datalogics recommends that you set up applications to embed and subset all fonts in PDF documents wherever possible. Subsetting those fonts will reduce the space required, and thus the size of the PDF, by including only those glyphs in a font set that are actually used in the document. Subsetting is not recommended if the file may need to be edited later using Adobe Acrobat or a similar utility, since any new text introduced may need other glyphs beyond those that were provided in the font subset. But if you don’t anticipate a need to edit a PDF later, you can use this option to subset the fonts in the PDF and in the process save considerable space in the document.
Re-subset all Subset Fonts
This feature allows for already subset fonts to be re-subset if possible. Subsetting can significantly reduce the size of the PDF document if a font features thousands of glyphs, such as Mandarin. By re-subsetting a subset font in a PDF document, you are replacing it with a subset that will only contain the glyphs in currently use in the document. Suppose you have a long PDF document that uses Mandarin characters. You decide to create a summary version of this file by deleting all but the first two pages. After re-subsetting, the Mandarin characters that no longer appear in the document are removed.
Remove Unused Fonts
When processing a document PDF OPTIMIZER first lists all of the fonts found in that document. Then, the system reviews the text found on each page and looks for the fonts that are in use, and separately reviews the fonts used in annotations (such as comments) but not found in the page content.
If PDF OPTIMIZER finds font file that is embedded in the PDF document but not used in page content or in an annotation, the system removes it. After removing the font file the system also removes the name of the font file from the list of embedded fonts in the document so that the font is not included in any other processing logic for the document, such as Merge Duplicate Fonts.
This option is similar to PDFOptimizerDiscardUnusedImages and PDFOptimizerDiscardUnusedForms.