I.R.I.S. Readiris Corporate 12 for Windows User Guide - Manual (Page 46)

Chapter 6 – Adjusting scanned documents
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(Binarized image. The default brightness settings yield fragmented
characters)
(The darkened image yields satisfactory recognition results)
o Use the slider to increase or decrease the Contrast.
The Contrast settings determine the contrast between darker and
lighter zones of an image. Use these settings to make character
shapes stand out against a colored background.
(Color image)
(Default contrast settings yield broken characters)
(Increased contrast settings yield satisfactory recognition results)
o Use the slider to increase or decrease the Despeckle
options.