Tesseract with Grayscale

[Mayce Al]

Hi Guys,

I am using Tesseract default model for German Fraktur. I found out, it gave bad recognition for grayscale.

I was thinking of binarize them before recognize them with Tesseract, but i found out that Tesseract is already used Otsu Binarization through the recognition process.

Does anyone have an idea about any parameter to turn the thresholding inside Tesseract to have good results?,


Cheers, Mayce

[Max Cantor]

Try a sauvola binarization first. Factors between 0.15 and 3 are usually good. Lower factor - more speckles and noise. Higher factor - more washed out image

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[Mayce Al]

Thanks a lot Max,

The question is that does Tesseract provide sauvola binarization through the command line?

I used the: tesseract image output -l lang -psm, but there is no way to call the binarization. 

So i guess it is provided through leptonica and I should write few lines of code to call it! right ?

Cheers, Mayce

[Max Cantor]

You'd. Need to call it yourself. BUT, the code for the tesseract executable does exactly that so you could just hack up your own execrable. On my phone now so can't give you line numbers but shouldn't be too hard to find. Look for PIX* types in the cpp files. 

Max

[Mayce Al]

Thanks Max, exactly I found something like "pixSauvolaBinarize"
I appreciate your support
Cheers, Mayce