I.R.I.S. Readiris 14 for Mac User Guide - Manual (Page 87)

Section 8: Saving Documents
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Below you find an overview of the supported output formats.
 PDF
PDF stands for "Portable Document Format". It is a format
developed by Adobe Systems Inc. to facilitate document
exchange. PDF files are device-independent and resolution-
independent, and can be opened on any Operating System
(Windows, Mac OS, Linux, iOS, Android, etc.) PDF files are
mostly used for storage purposes. Note that the content of
PDF files cannot be edited (easily).
With Readiris you can generate 4 types of PDF files:
o PDF Image-Text. This file type is most commonly used.
It contains two layers: the recognized text, and the original
image on top of the text. This way, you have both access to
the recognized text and you still see the original image.
Note: since the image covers the text, any recognition mistakes
will not be visible.
o PDF Text-Image. This file type is the opposite of PDF
Image-Text. It contains the original image in the
background, and the recognized text on top of the image.
Note: any recognition mistakes will be visible in this format.
o PDF Text. This file type contains the recognized text, but
does not contain the original image of your document. Any
images in the original document are included as graphics in
the PDF file.
o PDF Image. When you select this file type, Readiris
doesn't execute the text recognition on your document.
Your PDF file will not be text-searchable, it only contains
the image of your original document.