How to edit PDFs: make change to a PDF
Need to tweak or
correct a PDF? The process may not be obvious, but it can be done: here's how
PDF files are a
convenient way to distribute digital documents. As well as text and graphics,
they contain precise layout information, so a PDF is effectively a digital
representation of a printed page. Indeed, many PDF creation tools work by
setting themselves up as virtual printer drivers.
PDF isn’t a good
format for documents you intend to edit, however. It is possible to create PDFs
with editable text boxes, which you can fill in from within Adobe Reader or
another compatible tool. There’s also software that can add and remove pages
from a multi-page document, and perform other tricks such as resizing pages and
cropping away unwanted margins.
When it comes to
editing the actual content of a PDF page, however, things get tricky. It is
possible to move and edit the text and graphics within a PDF, as we’ll discuss
below. But text isn’t “live” in the way you’re probably used to: if you shorten
a line, the words below won’t jump up to close the gap – they’ll remain pinned
in place. If you can, it’s normally easier to edit or recreate the document in
Word or a similar application, rather than trying to edit a PDF directly.
Getting
hands-on with PDF
There are several
tools that can be used to edit PDFs. One is Adobe Illustrator, but a handy free
alternative is LibreOffice Draw: this isn’t distributed on its own, but you can
get it by downloading and installing the full LibreOffice suite.
LibreOffice Draw can open multi-page PDFs – use the Page Up and Page Down keys
to move around the document – and allows you to freely edit, move and add text
and graphical elements.
As I’ve mentioned,
editing text can be problematic: individual lines of text can normally be
edited with Draw’s Text tool, but you may need to move words around manually to
balance out a multi-line paragraph.
You’ll also hit
problems if the text in your PDF file uses a font that isn’t installed on your
system: in this case, LibreOffice Draw will render it in a default font, causing
the spacing to go wrong and losing the original appearance.
Just to make it interesting,
some PDFs contain text rendered as graphics: in this case, you won’t be able to
directly edit the text at all. The best you can do is select and delete
unwanted characters individually, then overlay a new text box containing the
desired replacement text.
Despite these
obstacles, hopefully you’ll be able to make the desired changes to your PDF.
When you’re happy, you can save your edited file by selecting File | Export as
a PDF… and specifying the relevant options. Note that, by default, images
embedded in a PDF will have JPEG compression applied each time you resave the
file, so picture quality can degrade if you make repeated edits.
Editing
locked PDFs
It’s worth noting
that the PDF specification includes some security features that allow a
document creator to forbid others from doing certain things, such as saving printing
or editing a PDF. Should you need to make an edit to a locked file, a quick web
search should turn up plenty of free tools and websites that will unlock PDF
files for free.
Alternatively, as
long as the document isn’t locked for printing, there’s another trick that can
be used – so long as you have both a PDF creation tool and the Microsoft XPS
Document Writer installed on your system as virtual printer drivers. All you
need to do is print the document using this latter driver, to create a copy of
it in XPS format – then open this document in Reader or another application and
reprint it as an unprotected PDF. You should then be able to tamper with it as
you choose
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