Because I am working on porting pdfsizeopt to windows, so I am also keeping an eye on other solution about how to optimize and reduce PDF file size, and now I like to introduce an article written by the Creative Team at Adobe.
Distributing documents as Adobe? PDF files can reduce the problems that may occur when you exchange large presentation or page-layout files. In many cases, you can make your Adobe PDF file even more compact without compromising the document’s integrity. The PDF Optimizer in Adobe Acrobat? 7.0 Professional gives you easy access to several options that can help you reduce the file’s size, including compression options that are comparable to the ones available when you create an original Adobe PDF file by using Adobe Acrobat Distiller?.
Use the Save As command.
After you make any final changes to the Adobe PDF document, choose File > Save As. Save the document with the same name to overwrite the original with your changes.
When you choose Save As, Acrobat rewrites the entire PDF document as efficiently as possible. When you choose Save, changes are appended to the file, meaning the file size might be increased. By default, Acrobat also optimizes a PDF document for faster web viewing when you choose Save As. Documents optimized in this way can be downloaded one page at a time from a web server or network, reducing the time it takes to access and view them.
Audit the use of space in the file.
Choose Advanced > PDF Optimizer. Click the Audit Space Usage button. The audit results list the bytes used by each element and its percentage of the document’s total size.
The audit results can help you identify the most effective ways to reduce the file’s size by showing which elements are significantly large. The audit reports the total number of bytes used by fonts, images, bookmarks, forms, and comments, as well as the total file size.
Optimize images, scanned pages, and transparency.
If you created your PDF document with a scanner, use the adaptive compression slider in the Scanned Pages panel to balance file size and quality based on the color values in the document. For all other documents, use the Images panel to select compression options for color, grayscale, and monochrome images. (Selecting adaptive compression disables options in the Images panel.)
Downsampling lowers the resolution of images. Compression eliminates unnecessary pixel data. In general, you should use JPEG for photographs and other images in which color changes gradually. ZIP is good for illustrations with large areas of solid, flat color. JBIG2 works well for monochrome images. If you choose JPEG compression, select a quality level to determine how much pixel data is removed.
If your file contains artwork with transparency, you can further reduce file size by flattening transparency in the Transparency panel. Transparent areas are divided into rasterized or vector regions.
Unembed fonts, when appropriate.
On the Fonts panel, select the fonts you want to unembed. Ctrl-click (Windows) or Shift-click (Mac OS) to select multiple fonts. Then click the Unembed button. To remove a font from the list of those to be unembedded, select it and click the Retain button.
Fonts often account for a large percentage of a PDF document’s file size. You can safely unembed fonts if you know that they are already installed on the computers of the people who will read your PDF document. If you unembed a font that isn’t available to someone reading your PDF document, Acrobat will display a substitute font when the document is opened on their computer.
Remove unused elements and clean up the document.
On the Discard Objects panel, select the version of Acrobat that you want to make the document compatible with, and then remove any additional items that you don’t use.
On the Clean Up panel, choose a compression option and then select which items to remove or discard from the file. 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. Use caution when selecting unfamiliar options. If you choose to experiment, save the optimized PDF file with a new name so that you leave the original PDF document unchanged.
Save the optimized file.
After you select the options you want, click OK. Then save the optimized PDF document with the same name to overwrite the original—or, if you want to compare the optimized document with the original, save it with a new name or to a new location.
Acrobat retains the settings in the PDF Optimizer dialog box. They appear as default settings the next time you use PDF Optimizer.
Optimize files in batches.
If you want to optimize multiple documents at once, consider using a batch processing sequence. For more information, see “Processing Adobe PDF documents in batches” in Acrobat Help for information.