July 21, 2011, 6:50 p.m.
posted by mrthe
Unpack PDF Attachments (Even Without Acrobat)
Save attachments to your disk, where you can use them.
Authors sometimes supplement their documents with additional electronic resources. For example, a document that displays large tables of data might also provide the reader with a matching Excel spreadsheet to work with. PDF's file attachment feature is an open-ended mechanism for packing any electronic file into a PDF like this. As discussed in [Hack #54], these attachments can be associated with the overall document or with individual pages. You can unpack PDF attachments to your disk using Acrobat, Reader, or our pdftk [Hack #79] . After unpacking an attachment, you can view and manipulate it independently from the PDF document.
1 Unpack Attachments with Acrobat or Reader
In Acrobat/Reader 6, you can view and access all PDF attachments by selecting Document File Attachments . . . . Select the desired attachment and click Export . . . to save it to disk.
In Acrobat 5, you can view and access a document's page attachments using the Comments tab. Open this tab by selecting Window Comments. Select the attachments you desire to unpack, click the Comments button, and choose Export Selected . . . from the drop-down menu. View and access document attachments in Acrobat 5 by selecting File Document Properties Embedded Data Objects . . . .
Reader 5 and earlier versions do not enable you to unpack attachments.
2 Unpack Attachments with pdftk
pdftk mydoc.pdf unpack_files
If the PDF is encrypted, you must supply a password, too:
pdftk mydoc.pdf input_pw bazpass unpack_files
Unpacking a PDF's attachments does not remove them from the PDF. You can always unpack them again later.
3 Hacking the Hack
Dispense with the command line [Hack #56] to create a quick right-click action for unpacking a PDF with pdftk on Windows.