Why can't I place annotations on a PDF?

Our extension relies on the text information that is contained in the PDF to be able to place the annotations. Depending on how the PDF was created, it may or may not contain this text information. PDFs generated from a digital document will almost always contain this text information.

However, PDFs that contain a scanned image will probably not contain it (for instance, if you scanned a printed page into a PDF on your personal scanner). Some higher-end scanners will attempt to capture the text information. Also, some publishers who have digitized their older content as scans of journals, magazines, etc., will add this text information.

The simplest way to tell is to try to select the text in the PDF as if you were going to copy and paste it. If the PDF has the text information, you will be able to select the text. PDFs without this information won't let you make the selections.

If you find that your PDF doesn’t contain text information, you can use a tool like SmallPDF's OCR feature to convert your scanned PDF into a text-based format. This process will analyze the PDF and add the missing text layer, enabling our extension to interact with the document properly. Simply upload your PDF to the OCR tool, follow the instructions, and download the converted file. Once converted, the text information should be selectable, allowing the extension to place annotations effectively. As a reminder, this is not a Scrible product and we are unable to support it.