Google Releases Tesseract as Open Source

An anonymous reader writes "Google recently released Tesseract as open source. Originally developed at the HP Labs from 1985-1995, it has been touted as one of the most accurate Optical Character Recognition (OCR) programs available. Having sat on the shelf gathering dust for so many years, Google cleaned up some of the more outdated portions of the code and released it for general consumption. You can download Tesseract over at Sourceforge.

I take back every bad thing I said about Google

[OrangeTide (124937)]

HOORAY! Good free OCR software is in short supply. I wonder if this will have a positive impact on Project Gutenberg?

Un-Finishable

[Kadin2048 (468275)]

In all honesty, I doubt Project Gutenberg will have run out of pre-1923 books by the time that new stuff starts coming out of Copyright under the new rules. They have everything written by humanity before that date to digitize: not just English language books and "classics," but government documents, records, foreign language texts, ancient manuscripts ... everything. That's as close to an un-finishable task as you can set yourself, I think.

Just assuming that somehow they did manage to digitize everything that was out of copyright, then I think what they should do is start archiving everything that they can. Even if they can't disseminate the information, they could still scan documents in and store them for later OCR-ing, thus preserving them against deterioration. I think this would be covered by fair use law even if the work was still protected. Perhaps this sort of archival work is not exactly the aim of PG, but it's still critically important.

With that said, I don't mean to in any way excuse the disgusting abuse of our political and legal system that was and is the "Sonny Bono Copyright Term Extension Act." That thing is a disgusting example of pretty much everything that's wrong with our government today.

Re:Un-Finishable

[mrchaotica (681592)]

In all honesty, I doubt Project Gutenberg will have run out of pre-1923 books by the time that new stuff starts coming out of Copyright under the new rules.

Your argument makes the fundamentally flawed assumption that the "new rules" will remain constant. The reality is that Copyright will continue getting extended so that new content never comes into Public Domain. (I hope the copyright fuckers are the first against the wall when the revolution comes!)

Even if they can't disseminate the information, they could still scan documents in and store them for later OCR-ing, thus preserving them against deterioration.

I'm sure they could even OCR them... they just couldn't make them available to the public. Of course, given the community-driven mechanism by which Project Gutenberg works, they couldn't legally distribute them to the volunteers either...

Re:

[gweeks (91403)]

> This is patently false. New stuff comes out of copyright every day.

This is just so un-true. In the United States (the only place that project Gutenberg worries about) nothing is entering the Public Domain except unpublished manuscripts where the author died 70 years ago. Nothing else will enter the public domain until 2019. Congress has affectivly frozen the public domain.

Re:

[fotbr (855184)]

Unless estate holders release it early. Or the author and holder of the copyright declares in his/her will that his/her work be released into the public domain upon his death, etc.

Just because its not common (or likely) doesn't mean it can't happen.

Anti-spam

[Bacon Bits (926911)]

This should be useful for adding anti-image spam capabilities to FOSS anti-spam programs.

Re:

[Phroggy (441)]

Following that logic, wouldn't this then also be just as usefull a tool to spammers looking to crack those crazy registration verification images?

Yes, absolutely, and spammers are already using image obfuscation techniques: using italic difficult-to-read fonts spaced very close together (difficult to separate the image into individual characters and difficult to identify each character once you do), using colored backgrounds to make the text very low-contrast when converted into a monochrome image the OCR

I call bullshit

[quigonn (80360)]

The very first CAPTCHA implementation was broken, but the funny thing about CAPTCHAs is that it's absolutely no effort to make an image completely unreadable for current OCR software. And even if one certain implementation is broken, just add another layer of distortion. Human brain is capable of coping with it, OCR software usually is not.

And after all, it's not about authentication, it's about making a service accessible only for humans.

BTW, it's funny that you praise your own cryptography solution in your blog, but it's obvious that you have the problem of replay attacks, you even mention it in the "caveat" section below the text box.

Re:I call bullshit

[johansalk (818687)]

If captcha is using humans, wasn't there an anti-captcha thing spammers were doing by having people answer some captcha to get into some free porn that is then used (their answer) to get the bots through legitimate sites the spammers wanted to get into?

improvements

[Anonymous Coward]

Google cleaned up some of the more outdated portions of the code
i.e., added AdSense to the OCR output.

Hoping OCR will improve?

[smileytshirt (988345)]

My guess is that they are doing this in the hope the open source community will build on and improve OCR technology. This would be in Google's interest, as it can then index text from images (such as their own Books project) more accurately and efficiently.

Finally!

[nihilatron (32440)]

Now I can finally see how to tell the difference between the 'A'-ness of 'A' and the 'P'-ness of 'P'!

(Credit to S.G.)

From the Project

[Gopal.V (532678)]

> It was open-sourced by HP and UNLV in 2005.

So google basically did what ? Fix bit-rot ? Google has re-released some open source code, essentially forking off the orginal ?

> License: (None Listed)

I'm a fan of the FOSS idea. Basically that makes sures that the whole work to which I contributed, always remains available to me (and others). It might not always work for a company, but as a developer it makes sense to me. And the second thing I need to see is a License after I see some code.

So explain to me how exactly this is open source (other than the "compile, but don't touch" version of it) and *then* I might think of downloading it and probably fix a few bugs or write docs.

Re:

[kevlarman (983297)]

if you had bothered to browse cvs you would find that it has been released under the apache license: http://tesseract-ocr.cvs.sourceforge.net/tesseract -ocr/tesseract/COPYING?view=markup [sourceforge.net]

License

[mapinguari (110030)]

Here's what's in the COPYING file distributed with the source, with some punctuation stripped to placate the lameness filter:

This package contains the Tesseract Open Source OCR Engine.
Orignally developed at Hewlett Packard Laboratories Bristol and
at Hewlett Packard Co, Greeley Colorado, the majority of the code
in this distribution is now licensed under the Apache License:

** Licensed under the Apache License, Version 2.0 (the "License");
** you may not use this file except in compliance with the Licen

Re:

[mrchaotica (681592)]

The Aspirin/MIGRAINES system in the aspirin directory is separately licensed thus: [proprietary junk license]

Anybody know how important this headache library is to the software, and how easily replaced it is?

Re:

[lisaparratt (752068)]

It's a neural networking system, so I'd hazard a guess that it's pretty vital to the project :(

I'm sorry Dave...

[macadamia_harold (947445)]

Originally developed at the HP Labs from 1985-1995, it has been touted as one of the most accurate Optical Character Recognition (OCR) programs available.

Yeah, but how is it on lip-reading? That's when we really need to worry.

Re:

[MichaelSmith (789609)]

Yeah, but how is it on lip-reading? That's when we really need to worry.

Given that my laptop has a microphone I was a bit worried about the recent article on google sampling sound on peoples computers. But my wife's laptop also has a webcam. Should I tell my wife not to google in bed? If the mic is off will they still catch what she is talking about?

Dave why don't you take a stress pill and lie down. If you are looking for something to read there is always google news.

Hosting

[truthsearch (249536)]

Is there any particular reason google isn't hosting [google.com] the project themselves?

Re:Hosting

[larry bagina (561269)]

Yes. They need the 99.9999% uptime (6 9s) that only sourceforge can provide.

Re:Hosting

[Leto-II (1509)]

I think you need to recalibrate your sarcasm detector.

my thoughts

[br00tus (528477)]

I would love to use a free (speech and beer) OCR engine that works as well as a commercial one, or even nearby as good as a commercial one.

I just checked out tesseract. One thing I have to look at more is the license. It appears to be the Apache license, which seems like a decent free license. But it also includes MITRE's aspirin. I'm not sure how dependent it is on aspirin and what the license restrictions of aspirin are.

The two best free OCR engines out right now are clara and gocr. While they are the best, they are not that great yet. I just ran the same tiff I had run with those two (I also have the document in pbm and other formats). Tesseract did not read it, it bailed with "IMAGE::check_legal_access:Error:Can't seek backwards in a buffered image!"

Clara and GOCR are written in C, Tesseract is written in C++, a language I don't know. Tesseract did well in the UNLV challenge so it probably has some good features. It does say it has no page layout analysis though.

Hopefully this can be improved, or good parts of it can be borrowed and incorporated into gocr or clara. It couldn't handle my test that both clara and gocr could, but it probably has strengths the other two doesn't. One day hopefully we'll have a free OCR that handles things as automagically as the commercial ones do. I will see what I can contribute to that as well. Although this is C++ and I don't know that language.

HP decided to got out of the OCR business?

[Frosty Piss (770223)]

In 1995 it was one of the top 3 performers at the OCR accuracy contest organized by University of Nevada in Las Vegas. However, shortly thereafter, HP decided to get out of the OCR business...

Actually, shortly thereafter, HP decided to get out technology innovation business, and into the printer ink business.

W0W1

[Anonymous Coward]

TH18 IS GRLAT NEWf4 FOR TH0Sj OF US U$1NZ BA) O(R RLCOGN1+ION!

THAHKS, G00GLL!1!!!

Non-English Charsets?

[TheoMurpse (729043)]

As there seems to be no documentation on the Sourceforge page about what this can actually do, does it learn or follow rules? If it learns, can it learn to recognize, say, Japanese characters?

Re:

[Yvanhoe (564877)]

Google specifically said in the article it doesn't work for non-english texts. I suppose it means it incorporates an english dictionnary too, so other roman language wouldn't work either.

Re:As much as I like open source software ...

[aweinert (969529)]

CAPTCHAs are specifically meant to break OCR... and if you RTFA, it say it does poorly with grayscale and color documents. Baisically its meant for reading typed text... like in a book.

Re:

[ajs (35943)]

That's no problem! All I really need it to do is allow all of those geeks out there to share those great Playboy articles with me over p2p networks! I'm tired of just getting the filler photography! ;-)

Re:As much as I like open source software ...

[asifyoucare (302582)]

In any case, spammers can defeat captchas by getting humans to solve them - e.g. by requesting that a user type the captcha to view free porn. The result from the user is then used by the spammer's program to enter the captcha-protected site.

Don't know how widespread this is, but it is certainly possible.

Re:As much as I like open source software ...

[Otto (17870)]

Or write up a quick script to cut the images in half down the middle and save them as a series of other images.

Re:

[Dan Ost (415913)]

As someone who has been involved in applying OCR to real world problems, there's nothing
trivial about generating a good binary images from images taken in the field (in my case,
images of boxes moving down a conveyor belt or hand imaged by workers).

Even if you disregard such problems as uneven lighting, glare, and distortion due the
unavoidable vibration inherrent to plant settings, most forms that are interesting to
OCR are handwritten and not designed to be OCR friendly. Hopefully this will change as
the peop

Re:

[Arancaytar (966377)]

Yes, by using contrasting colors that convert to the same tone in grayscale. A side effect being that most such technologies also shut out colorblind people...

Re:As much as I like open source software ...

[illuminatedwax (537131)]

You're right! Let us never delve into research that could conceivably overturn weak software security! Some things man was never meant to discover! Turn back, before we fly too close to the sun and our wings melt!! O, Prometheus, why hast thou given us this OCR technology??

Re:As much as I like open source software ...

[djtack (545324)]

Plus, good OCR could help recognize image spam (where they send the text in an image attachment, to avoid filtering, and fill the message body with "bayes poison").

Re:

[Phroggy (441)]

I am currently using the FuzzyOcr plugin to SpamAssassin, and it uses gocr to do the character recognition. To be sure, gocr is improving (the stable released version is practically useless, but the CVS version actually works, mostly), but if Tesseract is better, great!

Image spam

[Lonewolf666 (259450)]

A good idea, and if significant amounts of text are in an image, I'd view the mail as dubious anyway.
If not because of spam, then because of the idiotic format. Images are for illustrations, but using them to transfer major amounts of text is just stupid and inefficient.

Re:

[maxwell demon (590494)]

Unless it's a scanned page, where you might be interested in more than just the raw text, or simply don't want to risk errors in converting it to text (think official documents).

Re:As much as I like open source software ...

[binarybum (468664)]

careful, statements like that are likely to get you voted governor in some states.

Re:

[Carthag (643047)]

OCR is most effective when the letter boundaries are clear and well-defined, such as fixed-width text, or text that is at least on a straight line. Most CAPTCHAs put the letters on a curved path, as well as distorting the letters so they are no longer within a clearly defined rectangular shape. This makes it very hard to identify which parts of the images are letters and which parts are not, making OCRing CAPTCHAs a non-trivial problem.

NFB owns you

[tepples (727027)]

CATCHAs have been very effective in stopping spammers in the past, but if they can now just read them and answer correctly, then they are effectively rendered useless ...

They're already useless if installing one will subject your business to boycotts and/or lawsuits from National Federation of the Blind [nfb.org] and other advocates for people with disabilities.

Re:NFB owns you

[MrNonchalant (767683)]

You can build accessible CAPTCHAs, using images with a sound backup for blind users. My girlfriend is visually impaired and non-accessible CAPTCHAs are a real problem for her, she can't register at some sites without assistance.

Re:

[Millenniumman (924859)]

Why can't captchas just say "the letter at the beginning of the word that is spelled the reverse of the 3 letter name for an underwater vehicle or sandwich"? If someone can make a program that interprets that and gets the answer right after getting it off a captcha with OCR, then Google probably wants to know so they can hire them.

Two reasons

[patio11 (857072)]

You've got two constraints. One is that you have to be able to compose an arbitrarily large numbers of capchas algorithmically. For example, that example you just used is human-composed. If its the only CAPTCHA you have, the following program gets me a job at Google: gawk 'BEGIN{print "b"}' . If you have 100 CAPTCHAS, I only need to add a switch statement and some elbow grease and then I get to break your CAPTCHA a trillion times.

The other contraint is that you have to have your problem be trivially solvable by humans. I know plenty of people who cannot solve the CAPTCHA you have given: one obvious example would be, umm, all of my coworkers, because I live in Japan and "sub sandwitch" is not generally on the Japanese English curriculum. Similarly, you could any number of parsing problems which are very difficult for machines ("Here are 10 pictures chosen from HotOrNot. Click the three hot chicks.") but which may also be difficult for some users, such as Slashdotters who have never met a girl before.

By the way, you can find an implementation of that CAPTCHA at http://www.hotcaptcha.com/ [hotcaptcha.com]

Since you ask, here's why:

[patio11 (857072)]

The name of the system you propose is called challenge/response (CR). CR is not a good idea for the following reasons:

1) It says "My time is more important than yours" to all your correspondents, because you're not willing to look at a few spams getting past your Bayesian filter every day so instead you offload that time burden to people who want to talk to you.
2) Dueling CR systems ("Hey, [e-mail], I don't recognize you. Please prove you are a human" "Re: Hey, bob -- [e-mail], I don't recognize you. Please prove you are a human"). Even more fun in a potentially infinite loop. Any system you can make to shortcircuit this loop can be abused by spam to avoid the CR altogether.
3) Doesn't survive the Chinese Sweatshop Spam Attack, which will be ubiquitous if CR becomes popular. (Take poor Chinese person, teach them 10 words of English, pay them 2 cents an hour to answer CAPTCHAs so you get guaranteed delivery of your Maximize Your Mr. Wiggly offers.)
4) Breaks legitimate bulk mail senders, such as Amazon, Paypal, eBay, mailing lists, etc etc. Mailing lists in particular are going to be very fun, since a lot of CR systems would spam the entire list -- perhaps provoking 100 challenges! Which then leads to combinatorial hilarity!

Re:As much as I like open source software ...

[Jerf (17166)]

In order to pose the question, you have to generate it randomly. If it's not random, you already lost.

In order to generate it, you're going to end up using a grammar.

Running grammars in reverse is merely a matter of patience (to explore the space of problems the test program will pose) and the right tools; it's a fundamental bit of computer science.

Granted, expecting spammers to be conversant with the fundamental elements of computer science is a pretty high bar, but it only takes one to leap it and the rest to buy the program from him.

The image tests have the advantage that done properly, it takes more than just patience and computer science fundamentals to crack, it would require fundamental advances in the art.

(Note that nowhere in this message do I claim that image tests are perfect; in fact everything I know is vulnerable to the "feed it to a human in another context (viz, 'porn') and let them do the work" attack, and there are also points to be made about how widespread any given grammar/image test becomes; I know a website where the image test actually is a constant and so far it doesn't seem to be a problem because of scale issues. My point is that text tests have an additional disadvantage. It's not an intrinsically bad idea, though.)

Google wouldn't be interested in hiring people who could crack this, merely because they can crack this. Might make a decent interview question, though.

(You might also be tempted to think that you could just use a really complicated grammar, but you are constrained by two things, the human supposedly reading and taking the test, and the complexity of the human language itself. By the time you write some problem generator that could reliably throw off a parser, you'll be reliably confusing the hell out of your human users, too.)

Re:

[Anonymous Coward]

You're a secretary? Do you do anal? If so, I can double your pay.

Re:

[Scaba (183684)]

I'm sick and tired of a piece of dust being interpreted as a meter change.

You're just not avant-garde enough.

Re:Music OCR

[lowieken (522530)]

There is a piece of non-free software that runs quite well under Wine and exports nice MusicXML. You will find it linked to from http://www.recordare.com/software.html [recordare.com] .

I really should ask google to help buy this technology and set it free.

Re:

[CXI (46706)]

A screen shot is typically much lower resolution than what you'd normally scan documents at for OCR. It's not a good test.