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Tesseract OCR

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Re: Tesseract OCR

#42

Post by connorproctor »

an_opabinia wrote: post #27
atonse wrote: post #17

I must’ve done things spectacularly wrong cuz the two times I’ve tried tesseract (second time to recognize factory printed 8 inch tall letters on a trash can), I got 0% accuracy. 0%. Not even close. So I gave up.

Most people are best served by the big vendor OCRs. In my experience Amazon’s works the best, followed closely by Microsoft and Google at a distant third.

When did you do this comparison? A couple years ago I did a comparison and found Google the best and Amazon to be not very good.

Agree it’s best to skip tesseract unless the free cost is important. We spent a lot of time trying to preprocess and tune tesseract before realizing cloud OCR solutions are much better and fairly cheap.

Re: Tesseract OCR

#44

Post by hkt »

bredren wrote: post #5
hkt wrote: post #4

> Tesseract was originally developed at Hewlett-Packard Laboratories Bristol and at Hewlett-Packard Co, Greeley Colorado between 1985 and 1994, with some more changes made in 1996 to port to Windows, and some C++izing in 1998. In 2005 Tesseract was open sourced by HP. From 2006 until November 2018 it was developed by Google. I have used Tesseract for OCRing scanned books and it was great. I had no idea it was so old,…

I have permission to publish an ebook edition of an out of print history of Portland, Oregon. I haven’t found the time to work on the project. One point of friction has been selecting an OCR workflow. Any chance you would share what you’ve been successful with?

I use a £15 arm with a vice grip for my phone from Amazon, copy the files to my laptop and then run a bash for-loop of the tesseract CLI over the resultant files.

I use https://github.com/4lex4/scantailor-advanced to deskew the images and generate the PDF.

It isn't perfect but my purposes are more around research than publication, so, YMMV!

Re: Tesseract OCR

#45

Post by knuthsat »

sandreas wrote: post #32

If you are trying to detect text from document images / photos: tesseract is strongly focused mainly on the OCR part of the whole preprocessing(1). If you would like to get better results on that, you could use the wolf binarization tool (2) as an easy adaptive thresholding to remove shadows and uneven areas, which should improve your OCR results a lot on document photos! (1): https://towardsdatascience.com/pre-proce…

I know that tesseract uses leptonica which does have capabilities of binarization and thresholding. Interesting that it's not enough.

Re: Tesseract OCR

#46

Post by MayeulC »

I've been looking for something similar with hadwriting recognition in mind (and maybe math formulas). I got a few leads (unfortunately I don't have the list at hand right now).

Any open-source solution you'd recommend for handwriting recognition?

Re: Tesseract OCR

#47

Post by gary_0 »

knuthsat wrote: post #45
sandreas wrote: post #32

If you are trying to detect text from document images / photos: tesseract is strongly focused mainly on the OCR part of the whole preprocessing(1). If you would like to get better results on that, you could use the wolf binarization tool (2) as an easy adaptive thresholding to remove shadows and uneven areas, which should improve your OCR results a lot on document photos! (1): https://towardsdatascience.com/pre-proce…

I know that tesseract uses leptonica which does have capabilities of binarization and thresholding. Interesting that it's not enough.

Leptonica appears to use Sauvola binarization instead of the improved Wolf version.

Re: Tesseract OCR

#48

Post by oriolid »

sandreas wrote: post #32

If you are trying to detect text from document images / photos: tesseract is strongly focused mainly on the OCR part of the whole preprocessing(1). If you would like to get better results on that, you could use the wolf binarization tool (2) as an easy adaptive thresholding to remove shadows and uneven areas, which should improve your OCR results a lot on document photos! (1): https://towardsdatascience.com/pre-proce…

Ah, the nostalgia. More than 10 years ago I wrote a local adaptive binarization tool to improve Tesseract's results, and the upstream still hasn't picked up the idea.

Re: Tesseract OCR

#50

Post by fridif »

connorproctor wrote: post #42
an_opabinia wrote: post #27

Earlier quoted context omitted.

Most people are best served by the big vendor OCRs. In my experience Amazon’s works the best, followed closely by Microsoft and Google at a distant third.

When did you do this comparison? A couple years ago I did a comparison and found Google the best and Amazon to be not very good. Agree it’s best to skip tesseract unless the free cost is important. We spent a lot of time trying to preprocess and tune tesseract before realizing cloud OCR solutions are much better and fairly cheap.

I have been tasked with developing a Textract tool at work and so far I have been impressed with the complete accuracy of it for non-handwritten, non-photocopied documents.

I haven't seen it make any mistakes at all and responses take less than 3 seconds usually.

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