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Note: Masked images and images with a size less than 16-by-16 pixels are not downsampled.
Compression
Reduces file size by eliminating unnecessary pixel data. In general, JPEG and JPEG 2000 compression
give better results on images like photographs with gradual transitions from color to color. ZIP is the better choice for
illustrations with large areas of solid, flat color, or patterns made up of flat colors. For monochrome images, JBIG2
compression, which is available in PDF Optimizer but not in Distiller, and it is superior to CCITT.
Quality
Available only for JPEG and JPEG 2000 formats. JPEG and JPEG 2000 compression methods are typically lossy,
a process that permanently removes some pixel data. You can apply lossy JPEG or JPEG 2000 compression to color
images at various levels (Minimum, Low, Medium, High, Maximum). For JPEG 2000 compression, you can also specify
lossless so that no pixel data is removed. Compression for monochrome images is lossless, except for JBIG2
compression, which provides both Lossy and Lossless modes of compression.
Tile Size
Available only for JPEG 2000 format. Divides the image being compressed into tiles of the given size. (If the
image height or width is not an even multiple of the tile size, partial tiles are used on the edges.) Image data for each
tile is individually compressed and can be individually decompressed. The default value of 256 is recommended.
Optimize Images Only If There Is A Reduction In Size
When selected, if the image setting will cause an increase in file
size, the optimization for that image is skipped.
Fonts panel
To ensure an exact match to the source document, it’s a good idea to embed all fonts used in the document. If you don’t
need an exact match and you prefer a smaller file, you can choose not to embed fonts for roman text and East Asian
text (Traditional Chinese, Simplified Chinese, Korean, and Japanese). Text in these languages is replaced with a
substitution font when viewed on a system that does not have the original fonts. The Fonts panel of the PDF Optimizer
contains two lists for fonts: fonts that are available for unembedding, and fonts to unembed. Certain fonts aren’t
available for unembedding and don’t appear in the Fonts panel. To unembed fonts in a document, select one or more
fonts in the Embedded Fonts list, and click the Unembed button. If you don’t want to embed subsets of the embedded
fonts, deselect Subset All Embedded Fonts. To prevent unembedding for all fonts in the document, select Do Not
Unembed Any Font.
Transparency panel
If your PDF includes artwork that contains transparency, you can use presets in the Transparency panel of PDF
Optimizer to flatten transparency and reduce file size. (Flattening incorporates transparency into corresponding
artwork by sectioning it into vector-based areas and rasterized areas.) PDF Optimizer applies transparency options to
all pages in the document before applying other optimization options.
If you select the Acrobat 4.0 And Later compatibility setting, the Transparency panel is enabled and all transparency
in the file is flattened during optimization. This ensures compatibility with Acrobat 4.0 and earlier, which doesn’t
support transparency.
When you create flattening presets, they appear with the default presets in the Transparency panel.
Note: Transparency flattening cannot be undone after the file is saved.
Discard Objects panel
The Discard Objects panel lets you specify objects to remove from the PDF and lets you optimize curved lines in CAD
drawings. You can discard objects created in Acrobat DC and in other applications. Selecting an object removes all
occurrences of that object within the PDF.
In the Discard Objects area, you can select from these and other options:
Discard All Form Submission, Import And Reset Actions
Disables all actions related to submitting or importing form
data, and resets form fields. This option retains form objects to which actions are linked.
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Flatten Form Fields
Makes form fields unusable with no change to their appearance. Form data is merged with the page
to become page content.
Discard All JavaScript Actions
Removes any actions in the PDF that use JavaScript.
Discard All Alternate Images
Removes all versions of an image except the one destined for on-screen viewing. Some
PDFs include multiple versions of the same image for different purposes, such as low-resolution on-screen viewing and
high-resolution printing.
Discard Embedded Page Thumbnails
Removes embedded page thumbnails. This is useful for large documents, which
can take a long time to draw page thumbnails after you click the Page Thumbnails button.
Discard Document Tags
Removes tags from the document, which also removes the accessibility and reflow capabilities
for the text.
Convert Smooth Lines To Curves
Reduces the number of control points used to build curves in CAD drawings, which
results in smaller PDF files and faster on-screen rendering.
Detect And Merge Image Fragments
Looks for images or masks that are fragmented into thin slices and tries to merge
the slices into a single image or mask.
Discard Embedded Print Settings
Removes embedded print settings, such as page scaling and duplex mode, from the
document.
Discard Embedded Search Index
Removes embedded search indexes, which reduces the file size.
Discard Bookmarks
Removes all bookmarks from the document.
Discard User Data panel
Use the Discard User Data panel to remove any personal information that you don’t want to distribute or share with
others. If you’re unable to find personal information, it may be hidden. You can locate hidden text and user-related
information by using the Examine Documentcommand (Tools > Redact > Remove Hidden Information).
Discard All Comments, Forms And Multimedia
Removes all comments, forms, form fields, and multimedia from the PDF.
Discard Document Information And Metadata
Removes information in the document information dictionary and all metadata streams. (Use the Save As command
to restore metadata streams to a copy of the PDF.)
Discard All Object Data
Removes all objects from the PDF.
Discard File Attachments
Removes all file attachments, including attachments added to the PDF as comments. (PDF Optimizer doesn’t optimize
attached files.)
Discard External Cross References
Removes links to other documents. Links that jump to other locations within the PDF are not removed.
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Discard Private Data Of Other Applications
Strips information from a PDF document that is useful only to the application that created the document. This does
not affect the functionality of the PDF, but it does decrease the file size.
Discard Hidden Layer Content And Flatten Visible Layers
Decreases file size. The optimized document looks like the original PDF but doesn’t contain any layer information.
Clean Up panel
The options in the Clean Up panel of the PDF Optimizer dialog box allow you to remove useless items from the
document. These items include elements that are obsolete or unnecessary for your intended use of the document.
Removing certain elements can seriously affect the functionality of the PDF. By default, only elements that do not affect
functionality are selected. If you are unsure of the implications of removing other options, use the default selections.
Object Compression Options
Specifies how to apply Flate compression in the file.
Use Flate To Encode Streams That Are Not Encoded
Applies Flate compression to all streams that aren’t encoded.
In Streams That Use LZW Encoding, Use Flate Instead
Applies Flate compression to all content streams and images that
use LZW encoding.
Discard Invalid Bookmarks
Removes bookmarks that point to pages in the document that have been deleted.
Discard Invalid Links
Removes links that jump to invalid destinations.
Discard Unreferenced Named Destinations
Removes named destinations that are not being referenced internally from
within the PDF document. Because this option does not check for links from other PDF files or websites, it does not fit
in some workflows.
Optimize Page Content
Converts all end-of-line characters to space characters, which improves Flate compression.
Optimize The PDF For Fast Web View
Restructures a PDF document for page-at-a-time downloading (byte-serving)
from web servers.
Enable Fast Web View in a PDF
Fast Web View restructures a PDF document for page-at-a-time downloading (byte-serving) from web servers. With
Fast Web View, the web server sends only the requested page, rather than the entire PDF. This option is especially
important with large documents that can take a long time to download from a server.
Check with your webmaster to make sure that the web server software you use supports page-at-a-time downloading.
To ensure that the PDF documents on your website appear in older browsers, you can also create HTML links (versus
ASP scripts or the POST method) to the PDF documents and use relatively short path names (256 characters or fewer).
Verify that an existing PDF is enabled for Fast Web View
Open the PDF in Acrobat DC, and choose File > Properties. Look in the lower-right area of the Description panel
of the dialog box for the Fast Web View setting (Yes or No).
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Verify the Fast Web View Preferences setting
Follow this procedure to make sure that you have Acrobat DC set up to enable Fast Web View during the PDF creation
process.
1 In the Preferences dialog box under Categories, select Documents.
2 On the right side of the dialog box, under Save Settings, make sure that Save As Optimizes For Fast Web View is
selected, and click OK.
Enable Fast Web View for an existing PDF
Use this procedure after you have verified your Fast Web View Preferences setting and checked the PDF properties to
be sure that the file is not already enabled for Fast Web View.
1 Open the PDF.
2 Choose File > Save As. Select the same filename and location.
3 When a message appears asking if you want to overwrite the existing file, click OK.
In Acrobat Pro, you can also quickly enable Fast Web View in entire folders of Adobe PDF files by using the Prepare for
Web Publishing action. See Run an action.
More Help topics
Reduce file size by saving
Action wizard
Transparency flattening
Edit a flattener preset in the PDF Optimizer
Examine a PDF for hidden content
PDF properties and metadata
View document properties
When you view a PDF, you can get information about it, such as the title, the fonts used, and security settings. Some of
this information is set by the person who created the document, and some is generated automatically.
In Acrobat DC, you can change any information that can be set by the document creator, unless the file has been saved
with security settings that prevent changes.
1 Choose File > Properties.
2 Click a tab in the Document Properties dialog box.
Document Properties
Description
Shows basic information about the document. The title, author, subject, and keywords may have been set
by the person who created the document in the source application, such as Word or InDesign, or by the person who
created the PDF. You can search for these description items to find particular documents. The Keywords section can
be particularly useful for narrowing searches.
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Note that many search engines use the title to describe the document in their search results list. If a PDF does not have
a title, the filename appears in the results list instead. A file’s title is not necessarily the same as its filename.
The Advanced area shows the PDF version, the page size, number of pages, whether the document is tagged, and if it’s
enabled for Fast Web View. (The size of the first page is reported in PDFs or PDF Portfolios that contain multiple page
sizes.) This information is generated automatically and cannot be modified.
Security
Describes what changes and functionality are allowed within the PDF. If a password, certificate, or security
policy has been applied to the PDF, the method is listed here.
Fonts
Lists the fonts and the font types used in the original document, and the fonts, font types, and encoding used to
display the original fonts.
If substitute fonts are used and you aren’t satisfied with their appearance, you may want to install the original fonts on
your system or ask the document creator to re-create the document with the original fonts embedded in it.
Initial View (Acrobat only)
Describes how the PDF appears when it’s opened. This includes the initial window size, the
opening page number and magnification level, and whether bookmarks, thumbnails, the toolbar, and the menu bar are
displayed. You can change any of these settings to control how the document appears the next time it is opened. You
can also create JavaScript that runs when a page is viewed, a document is opened, and more.
Custom (Acrobat only)
Lets you add document properties to your document.
Advanced
Lists PDF settings, print dialog presets, and reading options for the document.
In the PDF settings for Acrobat, you can set a base Uniform Resource Locator (URL) for web links in the document.
Specifying a base URL makes it easy for you to manage web links to other websites. If the URL to the other site changes,
you can simply edit the base URL and not have to edit each individual web link that refers to that site. The base URL is
not used if a link contains a complete URL address.
You can also associate a catalog index file (PDX) with the PDF. When the PDF is searched with the Search PDF window,
all of the PDFs that are indexed by the specified PDX file are also searched.
You can include prepress information, such as trapping, for the document. You can define print presets for a document,
which prepopulate the Print dialog box with document-specific values. You can also set reading options that determine
how the PDF is read by a screen reader or other assistive device.
Add a description to Document Properties
You can add keywords to the document properties of a PDF that other people might use in a search utility to locate the
PDF.
1 Choose File > Properties.
2 Click the Description tab, and type the author’s name, subject, and keywords.
3 (Optional) Click Additional Metadata to add other descriptive information, such as copyright information.
Create document properties
You can add custom document properties that store specific types of metadata, such as the version number or company
name, in a PDF. Properties you create appear in the Document Properties dialog box. Properties you create must have
unique names that do not appear in the other tabs in the Document Properties dialog box.
1 Choose File > Properties, and then select Custom.
2 To add a property, type the name and value, and then click Add.
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3 To change the properties, do any of the following, and then click OK:
• To edit a property, select it, change the Value, and then click Change.
• To delete a property, select it and click Delete.
To change the name of a custom property, delete the property and create a new custom property with the name you
want.
Edit document metadata
PDF documents created in Acrobat 5.0 or later contain document metadata in XML format. Metadata includes
information about the document and its contents, such as the author’s name, keywords, and copyright information, that
can be used by search utilities. The document metadata contains (but is not limited to) information that also appears
in the Description tab of the Document Properties dialog box. Document metadata can be extended and modified
using third-party products.
The Extensible Metadata Platform (XMP) provides Adobe applications with a common XML framework that
standardizes the creation, processing, and interchange of document metadata across publishing workflows. You can
save and import the document metadata XML source code in XMP format, making it easy to share metadata among
different documents. You can also save document metadata to a metadata template that you can reuse in Acrobat.
View document metadata
1 Choose File > Properties, and click the Additional Metadata button in the Description tab.
2 Click Advanced to display all the metadata embedded in the document. (Metadata is displayed by schema—that is,
in predefined groups of related information.) Display or hide the information in schemas by schema name. If a
schema doesn’t have a recognized name, it is listed as Unknown. The XML name space is contained in parentheses
after the schema name.
Edit or append document metadata
1 Choose File > Properties, click the Description tab, and then click Additional Metadata.
2 Select Advanced from the list on the left.
3 To edit the metadata, do any of the following, and then click OK.
• To add previously saved information, click Append, select an XMP or FFO file, and click Open.
• To add new information and replace the current metadata with information stored in an XMP file, click Replace,
select a saved XMP or FFO file, and click Open. New properties are added, existing properties that are also
specified in the new file are replaced, and existing properties that are not in the replacement file remain in the
metadata.
• To delete an XML schema, select it and click Delete.
• To append the current metadata with metadata from a template, hold down Ctrl (Windows) or Command (Mac
OS) and choose a template name from the dialog box menu in the upper right corner.
Note: You must save a metadata template before you can import metadata from a template.
To replace the current metadata with a template of metadata, choose a template file (XMP) from the dialog box
menu in the upper right corner.
Save metadata as a template or file
1 Choose File > Properties, click the Description tab, and then click Additional Metadata.
2 Select Advanced from the list on the left.
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