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How to Flatten PDFs with ImageGear

Published: March 4, 2021 (Updated: January 11, 2023)

Although PDFs are one of the most common document types in use today, not every PDF file is identical. A document with multiple layers, annotations, or editable form fields can create significant challenges for an application, especially when it comes to viewing, printing, and OCR reading. One of the most effective ways of dealing with these PDFs is to use powerful digital tools that “flatten” the document to remove unseen or unnecessary information to reduce the overall complexity of the file.

What Is PDF Flattening?

Flattening can be used to refer to a number of different processes, but in principle, they all accomplish the same goal of merging distinct elements of the document. A few example of flattening include:

  • Making interactive form elements non-fillable and static.
  • Burning annotations into the document to make them native text.
  • Combining multiple layers of text or images into a single layer, eliminating any non-visible elements.

3 Reasons to Flatten PDFs

There are numerous reasons why an end user may wish to flatten a PDF document, but they usually fall under one of three broad categories.

1. Better Security

Forms often contain valuable information, especially when it comes to financial, insurance, or government forms. If a PDF with editable forms were to fall into the wrong hands, someone could easily alter the information contained in the form to commit fraud or falsify data. By flattening the forms, the entries become a static element of the document and cannot be altered any further. By building applications with the ability to flatten PDF forms, developers can help organizations protect themselves and their customers from the threat of falsified forms.

2. Faster Viewing

Speed is often crucial when it comes to viewing or processing documents. The more information is contained in a PDF, the longer it takes an application to render and view it. While this is sometimes a byproduct of file size, complex or poorly-designed forms can also make a PDF less responsive. Flattening a multi-layered PDF into a single, flattened layer eliminates hidden elements and makes the document much easier to read. This can also apply to forms, which often contain substantial annotation information. Eliminating forms simplifies the document, allowing it to render more quickly.

3. Easier Printing 

Many PDFs contain hidden data that is not visible on a viewing screen, but turns up on the page when the document is printed. Buttons and dropdown fields, for instance, can make a printed document look cluttered and confusing. When form fields are flattened, hidden annotation data is removed, eliminating any unpleasant surprises when the document hits the printer tray. For PDFs with multiple layers and hidden elements, flattening ensures that only the visible portions of the document will appear on the printed version.

How to Flatten a PDF Form Field Using ImageGear

With ImageGear, converting interactive form fields into static page content is a simple process that can be accomplished programmatically before documents are read by an OCR or ICR engine. It can also remove XFA form data, which often creates challenges for forms processing software.

ImageGear provides two options for flattening form fields. Although nearly identical in name, they perform somewhat different functions and should be used in different instances.

  • FlattenFormField: Flattens specified fields into the page.
  • FlattenFormFields: Flattens every field contained in the PDF into the page.

During the flattening process, a boolean can be used to indicate which fields should appear during printing, which is useful for hiding interactive elements that have no use on a printed page (such as buttons). Each field contains annotation information that determines how it should be represented on the page. Fields typically features one of three flags to dictate their representation:

  • HIDDEN: Any field with this category will not appear on the page after flattening.
  • NOVIEW: This field will only be visible on the page if “forPrinter” is specified during the flattening process.
  • PRINT: These fields will appear on the page whether or not “forPrinter” is specified. If a field does not have the PRINT flag, it will only appear when “forPrinter” is not specified.

Dealing with XFA Forms

Although officially deprecated by international open PDF standards, Adobe’s proprietary XFA forms are still found in many PDF documents. Opening and editing a PDF that contains XFA data often creates exceptions that make them difficult to manage when it comes to extracting forms information. ImageGear FlattenFormFields function will remove any XFA data from a document during the flattening process.

How to Flatten a PDF for OCR Processing with ImageGear

While flattening forms is an effective way of simplifying a document, it doesn’t change the file format itself. The document itself is still a PDF. So while ImageGear’s form flattening features are an effective solution for managing PDFs securely, another approach is often needed for OCR image processing.

Consider, for instance, an insurance solution that needs to be able to extract data from a wide variety of forms. Some of these documents are interactive PDFs with editable forms, some are static PDFs, and still others are scanned images of a document. Rather than devising multiple strategies for dealing with each document type, the solution can streamline the process by simply rasterizing every PDF it receives into an image file, which effectively flattens any form elements it contains.

Once the PDF is flattened into an image, it can easily be run through an OCR engine to match it to the correct form template and then send it to the appropriate database or extract specific form information. This process ensures that all documents coming through the solution can be handled the same way, which makes for a more streamlined and efficient workflow.

Expand Your Application’s PDF Capabilities with ImageGear

Flattening PDFs is just one of many features developers can incorporate into their applications with Accusoft’s ImageGear SDK. Other core functionality includes the ability to annotate, compress, split, and merge PDF files, as well as convert multiple file types to or from PDF format. ImageGear also provides a broad range of PDF security features like access controls, encryption settings, and digital signatures. Get a hands-on trial of ImageGear today for a closer look at what this powerful SDK can do for your application.