I.R.I.S. Readiris 14 for Windows User Guide - Manual (Page 73)

Readiris TM 14 – User Guide
79
S
ECTION
7: A
DJUSTING THE
I
MAGE
Q
UALITY
The recognition results depend a great deal on the image quality of
your documents. If you're scanning very low-quality documents,
Readiris will not be able to recognize them properly.
The reason for this is that Readiris works by converting pictures of
text characters into actual text characters. If your documents are
too dark, the characters fade into one another and create black spots.
If your documents are too light, the text characters might be broken.
Consequently, Readiris will not be able to recognize them.
Example 1: text is too dark
Here, the letter shapes begin to fill in and become fuzzy. Letters like
a, e, and o are almost completely blurred.
Example 2: text is too bright
Here, the text characters start to show gaps and incomplete shapes.