Settings
Last updated on
Sep 23, 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.
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Description |
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Downsample |
Reduces file size by lowering image resolution by merging the colors of original pixels into larger pixels. |
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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. |
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Quality |
Applies only to JPEG and JPEG2000 formats. Optimization removes some pixel data permanently. |
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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. |
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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.
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Settings |
Description |
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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 without changing their look and feel. Form data is merged with the page to become page content. |
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Discard all JavaScript actions |
Removes any actions in the PDF that use JavaScript. |
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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. |
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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. |
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Discard document tags |
Removes tags from the document, which also removes the accessibility and reflow capabilities for the text. |
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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. |
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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. |
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Discard embedded print settings |
Removes embedded print settings, such as page scaling and duplex mode, from the document. |
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Discard embedded search index |
Removes embedded search indexes, which reduces the file size. |
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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.
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Settings |
Description |
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Discard all comments, forms and multimedia |
Removes all comments, forms, form fields, and multimedia from the PDF. |
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Discard document information and metadata |
Removes information in the document information dictionary and all metadata streams. |
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Discard all object data |
Removes all objects from the PDF. |
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Discard file attachments |
Removes all file attachments, including attachments added to the PDF as comments. |
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Discard external cross references |
Removes links to other documents. Links that jump to other locations within the PDF aren't 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. It doesn't affect the functionality of the PDF, but it does decrease the file size. |
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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.
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Settings |
Description |
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Object compression options |
Specifies how to apply Flate compression in the file. |
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Use Flate to encode streams that are not encoded |
Applies Flate compression to all streams that aren’t encoded. |
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In streams that use LZW Encoding, use Flate instead |
Applies Flate compression to all content streams and images that use LZW encoding. |
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Discard invalid bookmarks |
Removes bookmarks that point to pages in the document that have been deleted. |
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Discard invalid links |
Removes links that jump to invalid destinations. |
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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. |
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Optimize page content |
Converts all the end-of-line characters to spaces, which improves Flate compression. |
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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.
