Optical Character Recognition, or OCR, is a software process which enables images of printed text to be translated into machine-readable text. OCR is most commonly used when scanning paper documents to create electronic copies, but can also be performed on existing electronic documents (e.g. PDF).
The OCR edition of Nitro Pro 7 includes the OCR plugin as part of the installer. You can purchase an upgrade for your current version of Nitro PDF Professional if it does not include the OCR button from the Nitro website.