I.R.I.S. Readiris 14 for Windows User Guide - Manual (Page 119)

Section 9: Saving Documents
126
PDF Version
In this drop-down list you can select which PDF version you want
to generate. Behind each version, the Acrobat version required to
open the PDF's is mentioned.
PDF - intelligent High-Quality Compression
In Readiris you also have the possibility to compress your PDF
documents. Refer to the separate section Compressing PDF
documents for more information.
Tip: also see the section Password-protecting PDF documents and
Digitally signing PDF documents.
C
OMPRESSING
PDF
DOCUMENTS
The PDF documents you generate with Readiris can be hyper-
compressed by means of iHQC. iHQC stands for intelligent High-
Quality Compression, I.R.I.S.' proprietary, efficient compression
technology. iHQC is to images what MP3 is to music and what
DivX is to movies.
To generate compressed PDF documents:

Click the Format button in the Output group.