OCR lib for math formulas

问题:

I need an open OCR library which is able to scan complex printed math formulas (for example some formulas which were generated via LaTeX). I want to get some LaTeX-like output (or just some AST-like data).

Is there something like this already? Or are current OCR technics just able to parse line-oriented text?

(Note that I also posted this question on Metaoptimize because some people there might have additional knowledge.)

The problem was also described by OpenAI as im2latex.

回答1:

SESHAT is a open source system written in C++ for recognizing handwritten mathematical expressions. SESHAT was developed as part of a PhD thesis at the PRHLT research center at Universitat Politècnica de València.

An online demo:http://cat.prhlt.upv.es/mer/

The source: https://github.com/falvaro/seshat

Seshat is an open-source system for recognizing handwritten mathematical expressions. Given a sample represented as a sequence of strokes, the parser is able to convert it to LaTeX or other formats like InkML or MathML.

回答2:

InftyReader is the only one I'm aware of. It is NOT free software (it seems the money goes to a non-profit org, IIRC).

http://www.sciaccess.net/en/InftyReader/

I don't know why PDF can't have metadata in LaTeX? As in: put the LaTeX equation in it! Is this so hard? (I dunno anything about PDF syntax, but I imagine it can be done).

LaTeX syntax is THE ONE TRIED AND TRUE STANDARD for mathematics notation. It seems amazingly stupid that folks that produced MathML and other stuff don't take this in consideration. InftyReader generates MathML or LaTeX syntax.

If I want HTML (pure) I then use TTH to read the LaTeX syntax. Just works.

ABBYY FineReader (a great OCR program) claims you can train the software for Math, but this is immensely braindead (who has the time?)

And Unicode has lots of math symbols. That today's OCR readers can't grok them shows the sorry state of software and the brain deficit in this activity.

As to "one symbol at a time", TeX obviously has rules as to where it will place symbols. They can't write software that know those rules?! TeX is even public domain! They can just "use it" in their comercial products.

回答3:

According to the answers on Metaoptimize and the discussion on the Tesseract mailinglist, there doesn't seem to be an open/free solution yet which can do that.

The only solution which seems to be able to do it (but I cannot verify as it is Windows-only and non-free) is, like a few other people have mentioned, the InftyProject.

回答4:

Check out "Web Equation." It can convert handwritten equations to LaTeX, MathML, or SymbolTree. I'm not sure if the engine is open source.

回答5:

Considering that current technologies read one symbol at a time (see http://detexify.kirelabs.org/classify.html), I doubt there is an OCR for full mathematical equations.

回答6:

Infty works fairly well. My former company integrated it into an application that reads equations out loud for blind people and is getting good feedback from users.

http://www.inftyproject.org/en/download.html

回答7:

Since the output from math OCR for complex formulas will likely have bugs -- even humans have trouble with it -- you will have to proofread th results, at least if they matter. The (human) proofreader will then have to correct the results, meaning you need to have a math formula editor. Given the effort needed by humans, the probably limited corpus of complex formulas, you might find it easier to assign the task to humans.

As a research problem, reading math via OCR is fun -- you need a formalism for 2-D grammars plus a symbol recognizer.
In addition to references already mentioned here, why not google for this? There is work that was done at Caltech, Rochester, U. Waterloo, and UC Berkeley. How much of it is ready to use out of the box? Dunno.

回答8:

You know, there's an application in Win7 just for that: Math Input Panel. It even handles handwritten input (it's actually made for this). Give it a shot if you have Win7, it's free!

回答9:

there is this great short video: http://www.youtube.com/watch?v=LAJm3J36tLQ explaining how you can train your Fine Reader to recognize math formulas. If you use Fine Reader already, better to stick with one tool. Of course it is not free ware :(