PDF optimizer settings

Last updated on Aug 16, 2025

Learn about Adobe Acrobat settings to reduce file size, compress images, manage fonts, and remove elements from PDFs.

PDF Optimizer helps you balance file size while maintaining document quality. You can easily adjust the settings for images, fonts, and objects to create PDFs for web distribution or print production.

Images settings

The Images panel of the PDF Optimizer lets you set options for color, grayscale, and monochrome image compression and image downsampling.

Settings

Description

Downsample

Reduces file size by lowering image resolution by merging the colors of original pixels into larger pixels.

Compression

Reduces file size by removing unnecessary pixel data. JPEG and JPEG2000 compressions yield better results on images with gradual color transitions, while ZIP is suitable for illustrations with solid or flat color areas.

Quality

Applies only to JPEG and JPEG2000 formats. Optimization removes some pixel data permanently.

Tile size

Applies only to JPEG2000 format. The image is divided into tiles of the specified size. If the image height or width isn't an even multiple of the tile size, partial tiles are used on the edges.

Optimize images only if there is a reduction in size

Optimizes images only when the resulting file size is smaller. If the setting increases the file size, optimization is paused.

Font Unembedding settings

You can embed all fonts in the PDF to ensure they match the source document exactly. If you don’t require an exact match and prefer a smaller file, skip embedding fonts for Roman and East Asian text, such as Traditional Chinese, Simplified Chinese, Korean, and Japanese. Text in these languages is replaced with a substitution font when viewed on a system without the original fonts.

Transparency settings

If your PDF includes artwork with transparency, use presets in the Transparency panel of PDF Optimizer to flatten transparency and reduce file size. PDF Optimizer applies transparency options to all pages in the document before applying other optimization options.

If you select Acrobat 4.0 and later compatibility settings, the Transparency panel is turned on, and all transparency in the file is flattened during optimization. It 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.

Discard Objects settings

The Discard Objects panel allows you to specify objects to remove from the PDF and simplify curved lines in CAD drawings. You can discard objects created in Acrobat and other applications. Selecting an object removes all occurrences of that object within the PDF.

Settings

Description

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.

Flatten form fields

Makes form fields unusable without changing their look and feel. 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 onscreen viewing. Some PDFs include multiple versions of the same image for different purposes, such as low-resolution onscreen viewing and high-resolution printing.

Discard embedded page thumbnails

Removes embedded page thumbnails. It's useful for large documents, which can take a long time to draw page thumbnails after you select 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 onscreen 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 settings

Use the Discard User Data panel to remove any personal information that you don’t want to distribute or share with others. If you cannot find personal details, it may be hidden by the document creator.

Settings

Description

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.

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.

Discard external cross references

Removes links to other documents. Links that jump to other locations within the PDF aren't removed.

Discard private data of other applications

Strips information from a PDF document that is useful only to the application that created the document. It doesn't 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 contains no layer information.

Clean Up settings

The options in the Clean Up panel of the PDF Optimizer dialog allow you to remove redundant items from the document. It includes obsolete or unnecessary elements for your intended use of the document. By default, only elements that don't affect functionality are selected. Use the default selections if you are unsure of the implications of removing other options.

Settings

Description

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 not referenced internally from within the PDF document. Because this option doesn't check for links from other PDF files or websites, it doesn't fit in some workflows.

Optimize page content

Converts all the end-of-line characters to spaces, 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.

Learn how to use PDF Optimizer to compress PDFs in Acrobat.