Reacting to Zero Matches

A search that reveals zero matches may not be valid. Image resolution will affect the accuracy of ImageGear Recognition engine OCR, and consequently auto-redact.

Consider an attempt to redact the text “football” from the 96 DPI page depicted below:

A search for the pattern “football” fails to recover any matches. The OCR text recovered from the 96-dpi page, used as the search domain, is not accurate:

eApefscp :sainmscins ON Jalial u :seinffisqns oivki suogwetrio :amffiscins auo
necnooi. :seielep ON Jouids :selelep omi illy° :alelep au°
sseuiseeivks :spesu! ON wndpuei]eizi :spesu! oftni
19(1981701e :pasu! auo

For this particular example, using the ImageGear function IG_image_resolution_set to change the page’s reported resolution from 96 DPI to 128 DPI is sufficient to coerce the expected OCR text:

One insert: alph4abet Two inserts: refe[rendpum No inserts: sweetness
One delete: crittr Two deletes: spiner No deletes: football
One substitute: chambions Two substitutes: n telfer No substitutes: objective

Repeating the search for the pattern “football” locates a single match that is subsequently redacted, as depicted below:

The page OCR Performance Issues offers some additional suggestions that may improve the accuracy of ImageGear’s recognition engine for some images.