What is flattening a PDF? If you’ve ever wondered what choosing the “Flattened PDF” export option does to a PDF file, you’re not alone.
In fact, a Google search for “What is flattening a PDF?” comes up with over 20 million results! Here’s what it means to flatten a document and how to do it in PDFpen.
What is flattening a PDF?
When you flatten a PDF, you merge previously separated contents of your document into one. Flattening a PDF makes it so that:
- Interactive elements in PDF forms such as checkboxes, text boxes, radio buttons, drop-down lists are no longer fillable.
- Annotations become “native text”.
- Multiple layers of text, images, page numbers, and header styles turn into one single layer.
Why flatten PDFs
Document creators flatten their PDF files for different reasons:
1. To “lock” fillable form fields
In The Hidden, but Fixable Danger with PDFs, attorney and legal educator Stuart Teicher describes the following hypothetical situation: You enter your banking details in a fillable PDF form in order to receive a sum of money. Unfortunately, the form falls in the wrong hands, and because it’s still fillable, the person is able to change the information so that the money gets wired to them instead. Flattening the PDF form before sending it via email could have prevented this.*
*Note from PDFpen: Although flattening the PDF may have made it less likely for this scam to occur, it couldn’t have prevented it from happening entirely — see How to remove flattening in a PDF below. A more reliable way to secure a PDF is to password-protect it. See How to Secure a PDF Document Using PDFpen.
2. To get all the elements in print
“When you create a PDF from layered documents using software such as Adobe InDesign or Adobe Photoshop, your PDF can contain multiple layers with different content on each one. If you print your PDF as-is, you will only print the layer that is visible onscreen as opposed to all visual elements from various layers,” blogger and photographer Jackie Vlahos explains.
Flattening your PDF fixes this, which is why self-publishing ebook company Lulu asks writers to always send their books as flattened PDFs.
3. To improve the usability of a PDF
“Flattening streamlines the document to basic PDF specifications so that odd things don’t happen in the future when the document is manipulated often,” says our resident PDFpen expert Angel Vu.
Flattened PDFs are also faster to render, according to IDR Solutions developer Mark Stephens.
How to flatten a PDF in PDFpen
There are two ways to flatten a PDF using PDFpen:
- Choosing File > Print as PDF
- Choosing File > Export: Flattened PDF
How to remove flattening in a PDF
A common misconception is that once flattened, a PDF can no longer be edited. The truth is that you can still mark up and select objects in a flattened PDF, including bitmap images such as signatures, provided you have a PDF editor like PDFpen.
With PDFpen, you can edit electronically-generated PDFs directly or perform optical character recognition (OCR) on scanned files to make their contents editable – see How to Edit a Scanned PDF Document Using OCR.
A note about images in flattened PDFs
Editing bitmap images, including signatures added as images, is possible using a PDF editor like PDFpen. If you are worried about the possibility of your signature being altered, we advise against adding your signature as an image. Instead, we recommend using the Scribble tool to create a unique signature every time you need to sign a PDF document. Because a scribbled signature is an annotation and not an image, it merges with the other contents forming a single layer in a flattened PDF.
Use PDFpen to flatten and edit PDFs
With PDFpen, you can flatten PDF documents to make them printer-ready. You can also make flattened PDF documents editable.
If you upgrade to PDFpenPro, you get even more PDF editing superpowers: the ability to make flattened PDF forms fillable is one of them.