There are many ways in which a PDF file can be edited, using a wide range of editor tools that are on the market. This page focuses on the typical editing needs in a prepress environment. The following types of changes are discussed:
- Text manipulations: how to edit the text in a PDF.
- Image editing: how to edit an image in a PDF file or replace it.
- Page related changes: how to delete pages, change their order, or rotate them.
- Altering a PDF file: how to merge pages from separate PDF files, edit password-protected files, or add bleed.
- Color editing: how to convert a PDF from color to black&white.
At the bottom is also a small overview of PDF editing applications.
Always keep in mind that PDF files are an accurate representation of a document. They are meant for output or on-screen viewing. They are not intended to be intermediate files that can still be edited. There are programs on the market that allow you to change the content of a PDF file and there are applications or plug-ins that can extract the content of a PDF so that you can insert this data into a new document. Altering PDF files is a last resort – whenever possible the original source file should be corrected and a new PDF generated. This is especially true for documents that will be reused at a later date!
How to edit the text in a PDF
Within a PDF file text is essentially stored as single lines. The concept of text flowing from one line to another within a column does not exist. This makes it fairly difficult to edit text unless you rely on special tools that somehow manage to intelligently predict how text flows within a document
- Adobe Acrobat & Acrobat Professional have a TouchUp Text tool for small text modifications. When you add or delete text, it will not reflow the text in the entire column. Some releases of Acrobat have a pretty bad reputation when it comes to the TouchUp Text tool, with users reporting weird behavior of the edited or remaining text once the tool is used. Use this tool only if there is no way to edit the original source file and recreate a PDF.
- Even though Adobe Illustrator can open a surprisingly large range of PDF files, it is a bad choice if you want to edit text. Illustrator automatically uses its own fonts instead of fonts embedded in a PDF. This can lead to text reflows even if you leave text untouched.
- For extensive text editing, Infix PDF Editor is an interesting product. I used it to add text to a book and found the reflow capabilities of the application quite impressive.
One thing to keep in mind is that there is a mechanism in PDF to store a copy of the text in its logical reading order. If you edit the text in such a so-called ‘tagged PDF’ you are only modifying the visible copy, not the hidden duplicate. That means that even after removing part of the text, it still may show up in search results!
How to edit an image in a PDF file
There are several high-end tools on the market that are optimized for this type of task. It is however surprising how much you can already achieve with Adobe Acrobat, provided you also have applications like Photoshop and Illustrator. In the ‘Touchup’ Preferences of Acrobat you can define which image and object editor you want to use from within Acrobat. Once this has been defined, you can use the Touchup Object Tool to select an object, context-click it and select the Edit option. In the case of an image, the default application (Photoshop on my set-up) opens the image. After changing the image, it is re-embedded in the PDF file.
How to replace an image in a PDF file
The above procedure for editing images can also be used to replace graphics. Use the Touchup Object Tool to open an image or artwork in Photoshop or Illustrator. Replace the content with the new image or artwork that you want to insert. In the case of images, it is best to maintain the resolution of the image you originally opened. Once the content is swapped use Save to reinsert it back into the PDF. There are other ways of swapping images that get discussed in this b4print thread.
How to delete pages, swap or rotate them
Adobe Acrobat can do all of this but there are most likely cheaper solutions around. I never bothered to check.
How to reverse the page order
If you need to swap the order of all the pages in a PDF so that the last page becomes the first one,…. check out this thread in the Adobe forums. It discusses a script for Acrobat 9 and Acrobat X. I tried the latter version on both Mac & PC and it worked fine.
How to convert a PDF from color to grayscale
Most recent versions of Acrobat Professional can be used to convert a PDF to greyscale. In Acrobat X Pro go to the Print Production tools in the Tools panel. In Preflight select the Convert to grayscale fixup. Click the Analyze and Fix button and the file will be converted.
A similiar function exists in older versions of Acrobat Pro. Check my separate page on converting a color PDF to grayscale for more information. It also discusses some other tools to do this.
Another alternative that some people suggest is printing the PDF to a new PDF and selecting Black&White in the output properties tab. I’ve never tried this myself.
Changing the entire PDF file
How to merge pages from separate PDF files
There is a separate page on this site dedicated to this topic.
How to edit a password protected PDF file
The PDF standard supports an extensive set of security features to prevent users from accessing certain features of a PDF file. One of these is the ability to edit PDF files. When you get such a protected file, the correct procedure is obviously to contact its creator and ask for the password to unlock the file. Unfortunately, it is sometimes difficult to contact that person or agency or even impossible to find out who locked the file. There are a couple of alternative solutions:
- The ColorSync utility that was included in OS X releases before version 10.5 overwrites PDF password protection. Simply open the PDF using it and do a ‘Save As’.
- PDFkey Pro is a commercial multi-platform tool that can remove the password protection from a PDF file. Another option for the online unlocker from Smallpdf.
How to add bleed to a PDF
Information on what bleed is, why it is needed and how it can be added to a PDF file is available on my page about bleed.
How to add, edit or remove metadata in a PDF
There is a separate page about working with metadata on this site.
PDF editing tools
Below is a short summary of the various types of software that are available on the market to edit PDF files.
- Adobe Acrobat (Professional) can be used to both view and manipulate PDF files. Next to the basic function discussed above, it can be used to completely repurpose PDF files (add multimedia elements like sound and video, add clickable buttons,…).
- Plug-ins can be installed in Acrobat Professional to enhance its ability to edit objects within PDF documents. The most well-known one is probably PitStop Professional from Enfocus. Another popular choice is pdfToolbox from callas software.
- Even though Adobe carefully avoids positioning Adobe Illustrator as a PDF editor, a remarkable number of PDF files can be opened and modified in Illustrator. Its major weak spot is text handling.
- Many high-end stand-alone PDF editor applications have vanished in recent years. Acrobat seems to dominate the market.
- Companies who make their money processing PDF files, such as newspapers who need to be able to make small modifications to advertisements, often use the products of OneVision to edit PDF files. These are probably the most powerful editors on the market, with a matching price tag.
- Recosoft created an interesting plug-in, named PDF2ID, which can convert a PDF file into an InDesign publication. This tool is discussed in this thread on the b4print forums.