ImageGear Professional DLL for Windows
Confidence Reporting

For some applications, it may be important to know the reliability of the recognized text. These applications may require having additional confidence information for the recognized characters and/or words.

Confidence information can be retrieved directly into application memory by a call to the IG_REC_letters_get function, after issuing the IG_REC_image_recognize function call. The IG_REC_letters_get function provides the most detailed information about the recognized data: it results in a AT_REC_LETTER structure for each recognized character.

The AT_REC_LETTER structure provides character recognition confidence information via its Confidence field, which ranges between 0 and 100. A value of 100 means that the Engine recognized the character with high confidence. In some cases a word may have some or all characters that are individually suspicious but the characters are not marked as suspicious in the word bit. This is usually a result of language or user dictionary checking. It means the word was validated by the spelling module. Applications that examine the character confidence information can use a threshold value, above which the character value is treated as a suspicious result. A value of 36 is recommended for this purpose. A value greater than 36 will indicate that the character was recognized with high confidence. A value of 36 or less marks that the code is suspected. The confidence reporting system works best when all three recognition modules are used in the voting scheme (IG_REC_RM_OMNIFONT_PLUS3W recognition module). If other machine print recognition modules are used IG_REC_RM_OMNIFONT_PLUS2W, IG_REC_RM_OMNIFONT_MTX, etc.) the confidence information is still available, but the ability of the system to properly report confidence will be reduced. This will result in a higher level of false negative and false positive reporting of suspected recognition results.

Also, the AT_REC_LETTER structure has the WordUncertain field, which indicates whether the word can be considered as certain or not. The word is uncertain if this value is TRUE.

 

 


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