Word confidence versus symbol confidence

[farhad khalafi]

I am totally puzzled with how the confidence reported at Word level relates to the confidences assigned to the characters of the same word. 

I used the attached TIFF image to recognize a simple MICR line of a check. 

The recognized text had two words:

495096 700000b01b205xX0eL00007010717

The confidence percentiles for the words were 59% and 38% respectively.

The confidence percentiles for the characters of the first word were (rounded):

4    97%

9    99%

5    100%

0    100%

9    99%

6    96%

I would like to know how with such high confidence scores for individual characters, one can compute the word level confidence at 59%.

I ran this test using fast training data for English with no training of my own. I am not worried about the accuracy, just curious about how to interpret confidence scores.

Thanks!

[Soumik Ranjan Dasgupta]

Could you tell how did you get the confidence percentiles? I would like to know that. :)

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Regards,

Soumik Ranjan Dasgupta

[farhad khalafi]

        /// <summary>
        /// Gets the confidence percentile for the current element at the specified level.
        /// </summary>
        public float GetConfidence(PageIteratorLevel level)
        {
            return TessApi.TessResultIteratorConfidence(Handle, level);
        }



I use a custom .NET layer somewhat similar to Tesseract.net. 

The Handle is returned from TessBaseAPIGetIterator() after a page is recognized, and level defines the element type (PageIteratorLevel.Symbol for characters, PageIteratorLevel.Word for words)