Optimizing a PDF by removing unnecessary objects

Qoppa’s 100% Java PDF optimizer library, jPDFOptimizer, allows, among other things, to remove unnecessary objects in a PDF document in order to reduce the file size.

This is done using the OptSettings class.

OptSettings options = new OptSettings();
// Options to remove objects
options.setDiscardAltImages(true);
options.setDiscardAnnotations(true);
options.setDiscardBookmarks(true);
options.setDiscardDocumentInfo(true);
options.setDiscardFileAttachments(true);
options.setDiscardFormFields(true);
options.setDiscardJSActions(true);
options.setDiscardLinks(true);
options.setDiscardPageThumbnails(true);
options.setDiscardUnusedResources(true);
options.setDiscardXMPData(true);
Method Description
Alternate Images

OptSettings.discardAltImages()

 Removes alternate embedded image dictionaries that are used for high resolution printing to reduce file size. Only visible images displayed on the PDF while viewing will be kept in the document.
Bookmarks

OptSettings.discardBookmarks()

 Removes all bookmarks from the PDF document
Document Info

OptSettings.setDiscardDocumentInfo()

 Removes any document information located in the document properties (Document->Document Properties) that would include the following:

  • Title
  • Author
  • Subject
  • Keywords
  • Producer
JavaScript Actions

OptSettings.setJSActions()

 This will remove all JavaScript actions from the PDF document but retain any objects that may have had JavaScript actions such as form fields, push buttons, etc…
Embedded Thumbnails

OptSettings.setDiscardPageThumbnails()

 Removes page thumbnails that are stored in the PDF document. Once removed the page thumbnails will just be rendered each time the document is loaded.
Comments

OptSettings.setDiscardComments()

 Removes all annotations and comments from the PDF document
Links

OptSettings.setDiscardLinks()

 Removes all links from the PDF document
Attachments

OptSettings.setDiscardFileAttachments()

 Removes any attachments that are stored within the document
Form Fields

OptSettings.setDiscardFormFields()

 Removes all form fields that are on the PDF document
Metadata

OptSettings.setDiscardXMPData()

 Removes all additional or extra Metadata from the PDF Document
Unused Resources

OptSettings.setDiscardUnusedResources()

 Removes resources that are located within the document but are never referenced by any objects in the PDF document.
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