Portable Document Format (PDF) is the standard file format for documents to be printed or transmitted through the web. These documents retain their settings no matter what the operating system or the settings is. For the purposes of transmission through e-mails or downloading, it is convenient to reduce PDF file sizes by compressing them. Transmitting compressed PDF files is time-saving, and consequently also money-saving.
There are several factors that play a role in reduction of pdf file sizes: compression level, image format (vector or bitmap), number of used fonts, image resolution, and Acrobat version ( later versions compress files more efficiently). Here are some ways to reduce PDF file sizes:
Fonts: use the least possible number of fonts. Dont embed them. Use subsetted fonts instead, that only include those glyphs actually used in the document. This can reduce PDF file sizes by as much as 40K per font.
Images: use vector images wherever possible. Vectors are perfectly scalable, and can be compressed into ZIP files, which will reduce PDF file sizes. If you must use bitmap, use compressed and distilled jpegs, using grayscale or at least RGB rather than CYMK. Turn off the thumbnail option when exporting the files. RGB has one channel less than CYMK, and compresses pdf files better.
Acrobat Version: Later versions of Acrobat will reduce pdf file sizes more efficiently and produce smaller files. Version 5 was launched in 2001 and version 7 is more than 2 years old. So there is no question of their non-availability. Versions 5 and later are especially ideal for monochrome images since they use JBIG2 (Joint Bi-level Image Experts Group) that can significantly reduce pdf image data. CVISIONTECH pdf compressors can also reduce pdf file sizes. They use the OCR technique. However, these efficient softwares are best suited for textual pdf files.