I.R.I.S. Readiris 14 for Mac User Guide - Manual (Page 39)

Section 4: Scanning and Opening Documents
34
The options you set here are applied as default to all the documents
you'll open or scan.
Preprocessing Options.
Smoothen color and grayscale images
This option is activated by default. It renders grayscale and color
images more homogeneous by smoothening out differences in
intensity. As a result, a stronger contrast is created between the
foreground (text) and background (artwork). Sometimes
smoothening is the only way to separate text from a colored
background.
Process as 300 dpi
Select the option Process as 300 dpi when you are processing
images of an incorrect or unknown resolution. The images will be
processed as if they had a 300 dpi resolution.
Automatic despeckling
Sometimes documents contain a lot of "noise" - little black spots
that occur when scanning low-quality documents or using bad
scanner settings.
To remove these little black spots, use the Despeckle slider. The
more you move it to the right, the larger the spots that will be
removed.