Tesseract's binarization

[Scott Thibault]

I want to do my own pre-processing including binarization so I can remove borders and other artifacts.  However, the performance seems to be worse.  Perhaps Tesseract has better binarization?  What algorithm does it use?

--Scott

[farhad khalafi]

I believe Tesseact uses Otsu algorithm to find a single threshold value. The threshold is used to set gray pixels to binary values depending on whether a gray level is below or above the threshold. I use Leptonica for my own pre-OCR image processing and the performance seems to be fine.

On Sat, Jan 26, 2019 at 9:54 AM Scott Thibault <sathi...@gmail.com> wrote:

I want to do my own pre-processing including binarization so I can remove borders and other artifacts.  However, the performance seems to be worse.  Perhaps Tesseract has better binarization?  What algorithm does it use?

--Scott

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[Lars Fricke]

I get far better results with bad quality scans using a local threshold. A very nice tool to find the  best algorithm for your case is http://imagej.net/Auto_Threshold in the Fuji Distribution of ImageJ. I got awesome results with Phansalkar.

Am Sa., 26. Jan. 2019, 18:05 hat farhad khalafi <farhad....@gmail.com> geschrieben:

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[Scott Thibault]

Which Leptonica method do you use?

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[Scott Thibault]

Thanks, I think I'll try some of Leptonica's methods since I'm already linking to that library anyway.  They have both local and global methods.

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