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Ask HN: Open source OCR library?

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Re: Ask HN: Open source OCR library?

#81

Post by physcab »

totalcookie wrote: post #39
physcab wrote: post #28

I tried using Tesseract and could not get it to work reliably. I tried a bunch of different pre-processing techniques and it turned into a very frustrating experience. When I compared Tesseract to Abbyy, the difference was night and day. Abbyy straight out of the box got me 80%-90% accuracy of my text. Tesseract got around 75% at best with several layers deep of image pre-processing. I know you said open source, and…

Finereader engine Abbyy for Linux looks fine, but I can't find price data, is it <10k/year? One time license?

You can get Abbyy OCR Cloud SDK and its $0.10 per page (goes down with volume).

http://ocrsdk.com/plans-and-pricing/

Re: Ask HN: Open source OCR library?

#82

Post by zo1 »

totalcookie wrote: post #73
zo1 wrote: post #69

Earlier quoted context omitted.

And they limit you to scanned pages per year on the corporate/server offerings. Doubly-so for all their dev/api license options. And the kicker: You can't buy those licenses from them directly. They put you in contact with some randome monopoly local distributor that usually has mandatory "training" charges. Messy, and I'm planning on staying away from that with a ten-foot pole.

If there is no opensource/free software with the same quality, what then? What are you using as an OCR server side system on Linux? I'm sure not good enough to write my own OCR better than Abbyy.

As the others in the thread have mentioned. Constrain your problem as a computer-vision one to segment nice pieces of work for Tesseract. Along with some nice training data, and possibly human validation if that's feasible.

All do-able within Linux.

Re: Ask HN: Open source OCR library?

#83

Post by awfullyjohn »

I've tried using Tesseract before, the biggest of the open source libraries. It goes from "okay" to "terrible" depending on the application.

Our particular application was OCRing brick and mortar store receipts directly from emulated printer feeds (imagine printing straight to PDF). We found that Tesseract had too many built-in goodies for image scanning, like warped characters, lighting and shadow defects, and photographic artifacts. When applied directly to presumably 1 to 1 character recognition, it failed miserably.

We found that building our own software to recognize the characters on a 1 to 1 basis produced much better results. See: http://stackoverflow.com/questions/9413216/simple-digit-reco...

Re: Ask HN: Open source OCR library?

#84

Post by smackfu »

Osmium wrote: post #49
physcab wrote: post #28

I tried using Tesseract and could not get it to work reliably. I tried a bunch of different pre-processing techniques and it turned into a very frustrating experience. When I compared Tesseract to Abbyy, the difference was night and day. Abbyy straight out of the box got me 80%-90% accuracy of my text. Tesseract got around 75% at best with several layers deep of image pre-processing. I know you said open source, and…

A counter anecdote, I've used Tesseract for a largish project and it's worked wonderfully. Typically, on a full page of text, there'd be one or two minor errors, easily 99% accuracy. Irritatingly for me, but also impressively, it seemed to detect ligatures correctly (it used the unicode 'fl' instead of 'fl').

That unicode ligature would be an interesting surprise if you wanted plain text.

Re: Ask HN: Open source OCR library?

#85

Post by stevewepay »

kornish wrote: post #22
stevewepay wrote: post #6

I used Tesseract and OpenCV to process Words With Friends tiles.

Haha, this is awesome. Have you written about your program anywhere? Would love to hear more about it.

It's pretty much as other people talked about, I used OpenCV to try to detect the board, and then isolate each tile, and then used Tesseract to try to figure out the letter. The biggest problem I had was whenever the red score bubble landed on a tile, it would fall on top of the latter and thus lose information so I ended up having to create training data and associating that to get the letter. I was able to get to about 98% accuracy and it was relatively robust until they created a new app that I haven't had time to adjust for.

Re: Ask HN: Open source OCR library?

#86

Post by extempore »

bittersweet wrote: post #37

I was actually looking in to Tesseract yesterday, so this post coincides nicely. I have a hobby project where I scrape instagram photos, and I actually only want to end up with photos with actual people in them. There are a lot of images being posted with motivational texts etc that I want to automatically filter out. So far I've already built a binary that scans images and spits out the dominant color percentage, if…

> But I would really appreciate it if anyone else has more thoughts about how to filter out images that do not contain people :-)

Google allows image searches to be filtered by is/isn't a face. I think you could tap into that knowledge, although it isn't immediately clear what the route would be.

Here's a detailed rundown of the more obscure google search paramters: https://stenevang.wordpress.com/2013/02/22/google-search-url...

The relevant one to your interest is "tbs=itp:face".

Re: Ask HN: Open source OCR library?

#87

Post by stevewepay »

uptown wrote: post #52
stevewepay wrote: post #6

I used Tesseract and OpenCV to process Words With Friends tiles.

A best-word solver I presume?

I did it to count the tiles, and was going to work on a full-on cheating program but never got around to it. I did find the algorithm online though, it's pretty interesting.

Re: Ask HN: Open source OCR library?

#88

Post by kargo »

piyush_soni wrote: post #62
kargo wrote: post #32

Does it have to be open-source? If free, but not trainable and restricted to Windows apps/phone is good enough, then I recommend the Microsoft OCR library. It gives you very, VERY good results out of the box. An excellent piece of work from Microsoft Research. To test it, see for example https://ocr.a9t9.com/ which uses Microsoft OCR inside. And for comparison, an OCR application with Tesseract inside: It has a drama…

Are you talking about this library from Microsoft: https://www.nuget.org/packages/Microsoft.Windows.Ocr/ ?

Yes

Re: Ask HN: Open source OCR library?

#89

Post by kargo »

pc86 wrote: post #61
kargo wrote: post #32

Does it have to be open-source? If free, but not trainable and restricted to Windows apps/phone is good enough, then I recommend the Microsoft OCR library. It gives you very, VERY good results out of the box. An excellent piece of work from Microsoft Research. To test it, see for example https://ocr.a9t9.com/ which uses Microsoft OCR inside. And for comparison, an OCR application with Tesseract inside: It has a drama…

How does the PDF OCR process compare to images? I uploaded a sample PDF with very clear sans-serif text (printed to PDF from a webpage) and there seems to be some odd substitutions. "prohibitecL" instead of "prohibited", "ac" instead of "QC" (as part of an address), random clipping of the first letter in a few lines and random use of a capital i instead of 1. Overall very good, I'm just wondering if the library is be…

Interesting... I see it now. I assume some issue during the PDF to image conversion in the web app. PDF support is just a few days old.

The OCR library itself supports only image formats as input and is "innocent" with regards to this issue ;)

Re: Ask HN: Open source OCR library?

#90

Post by cinjon »

loumf wrote: post #44
totalcookie wrote: post #39

Earlier quoted context omitted.

Finereader engine Abbyy for Linux looks fine, but I can't find price data, is it <10k/year? One time license?

Abbyy, and most good commercial OCR, charge a runtime royalty based on the number of cores you are deploying to. Depends on volume.

Where do you see this? I'm actually thinking of buying the software right now and I explicitly asked what other charges are there besides the initial fee (~$100) and they said there wasn't any. Am I not asking the right question?
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