TIP 138: Optimizing Your PDF Documents
Some projects are quite involved. You may have had a few rounds of reviewing, and dozens of comments have been applied. You may have received a document from a user less skillful in the construction of source documents and the resolutions of images may be too high for your intended use of the document. You may have embedded a movie in several renditions and then changed your mind and deleted most of them… the list can be almost endless.
Save It Again
One of the simplest ways to reduce file size is to save a file as itself. If you have been working with a documentfor example, adding and removing pagesthe file is saved on top of itself each time you save it, and these iterations can really add up to a huge file size. Choose File > Save As. In the Save As dialog, leave the name as is and click Save. A prompt asks if you want to overwrite the file; click Yes. The file is resaved, and content is consolidated. You may be surprised how much smaller the file becomes! |
You don't have to try to remember all the different elements that can bloat your files' size and then manually clean them up. Instead, use two tools in Acrobat to take care of the problem areas for you. The PDF Optimizer (which you can customize) checks all aspects of a document for unnecessary content, and then removes it. Beware: Optimizing a signed document will invalidate the signature. (Read about signatures in Chapter 18.) First, analyze the document. Choose Advanced > PDF Optimizer to open the dialog. Click Audit space usage at the upper right of the dialog. Acrobat examines the document and displays a report (Figure 138a). Depending on the type of contents in the document, you see listings for such elements as fonts, comments, and images; each is defined both in percentages of the entire document size and in bytes. Click OK to close the audit report.
Figure 138a. Test your document first to see how its elements contribute to the file size.
The default settings in the PDF Optimizer are for Acrobat 5.0 compatibility. If you click the Make compatible with pull-down arrow and choose another program version, the Preset in the upper left of the dialog changes from Standard to Custom. The options available in the different panes of the dialog vary according to the selected program version.
Easy Optimizing
Do you need to apply the same optimization settings to a number of files? Once in a while or on a regular basis? Do you have a number of files that need optimizing right now? Customize a collection of settings in the PDF Optimizer and click Save on the dialog to name and save the settings. The next time you need to optimize a file using the same settings, click the Preset pull-down menu, and your custom settings are included in the list for you to select. You can remove your custom settings as wellselect the settings' name from the Preset pull-down menu, and click Delete. If you find you are optimizing files on a regular basis, include Output Options in a batch sequence instead. Read about batch sequences in Tip 135. |
Click a label in the left column on the dialog to display settings (Figure 138b). As you look through the list, deselect items that you don't want to optimize; look for optimizing in these areas: Images
Define settings for color, grayscale, and monochrome images. Choose compression types, quality, and downsampling values. Scanned Pages
Activate the compression and quality check box and then apply filters to clean up a scan, such as halo removal, descreen, or despeckle. If you choose Adaptive Compression options on this pane of the dialog, the settings on the Images pane are disabled. Fonts
The fonts in the document are listed in the dialog; unembed those you don't need, such as system fonts or common fonts. If a document is intended for departmental circulation, for example, and you know everyone viewing it uses the same set of fonts, you can delete those from the list. Transparency
Choose transparency flattening and settings such as resolutions for text, line art, and gradients. Discard Objects
Decide what objects can be removed from the document, such as layers, form content, cross-references, and comments. Clean Up
Choose other cleanup details, such as removal of invalid links or bookmarks, encoding options, and a method of compressing the document's structure.
Figure 138b. You can customize dozens of settings in the PDF Optimizer to precisely balance the quality of the document against the file's size.
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Click Save to name and save the settings if you plan to reuse them at a later time. If optimizing is a one-time thing, click OK to close the dialog. The Save Optimized As dialog opens. Click Save to overwrite the original file; to be on the safe side, save the document with another name instead. Once you check the results and are satisfied, delete the original. |
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