I.R.I.S. Readiris Pro 12 for Windows User Guide - Manual (Page 60)

Chapter 9 – Recognizing documents
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Recognizing documents with mixed languages
Readiris also allows you to enable mixed character sets. That way
Readiris switches languages in the middle of a sentence
automatically and recognizes English words (proper names etc.)
that occur in "exotic" languages.
Click the globe button on the main toolbar and select the required
language combination in the language drop-down list.
Note: when processing Asian or Hebrew documents, mixed
characters sets are used automatically.
Speed-Accuracy
Select the right trade-off between OCR speed and OCR accuracy.
This trade-off is available for the Latin, Cyrillic and Greek alphabets.
Tip: favor accuracy over speed when the image quality is rather poor.
D EFINING THE DOCUMENT CHARACTERISTICS
Next to the document language, other document characteristics such
as the Font type and Character pitch play an important role in the
recognition process.