One of the biggest barriers to PDF accessibility occurs with “image-only” documents. An image-only PDF contains no actual text, just an image of text. This type of PDF is created by scanning a printed page. Lacking any real text, an image-only PDF does not support useful features such as searching, highlighting, text copy, and text reflow; nor will it allow the use of Adobe’s magnification and reading tools.
Software such as Adobe Acrobat Professional can take an image-only PDF and convert it to "Searchable" using a process called Text Recognition, or Optical Character Recognition (OCR). The resulting document has text that you can interact with using a variety of technologies.
Benefits of a searchable PDF include the ability to:
- Search text
- Select text
- Highlight text
- Create a Table of Contents
- Listen to text