On 25/01/12 10:23, Federico Leva (Nemo) wrote:
OCRs generally
work by finding lines of text on a page, splitting the
lines
into letters, then recognizing each letter separately. So, an OCR would
know,
for each letter of the recognized text, what is its bounding box on
the page.
However, to my knowledge there is not a single OCR that exports this
data, nor
is there a standard format for it. If an open
source OCR could be
modified to
do this, then it would be easy to inject data
retreieved from
captchas back
into OCR-ed text. And it could be used for so
much more :)
I don't understand, what data are you talking about? DjVu is an open
If you know what is the bounding box of the image of the word you are
sending to the captcha, how the OCR read that word, and how the users
have corrected it via the captcha, it should be easy to move the
corrected word back into the OCR output.
format and can store character mappings, which is what
the wikicaptcha
proof of concept is based on. There's also
https://en.wikipedia.org/wiki/HOCR and IA uses some proprietary ABBYY
xml format which AFAIK can be somehow read and converted to hOCR.
I have to say I didn't knew about these developments :) (I knew about
ABBY's format, but it's, as you said, proprietary.)
The real problem is character training which could be
used for
subsequent OCRs. I doubt we can do much here, because everyone uses
ABBYY, and even tesseract users don't seem to share such data in any way.
It is a pity, for as I said many things could be done with this data.
For example, it would be possible to read the same text with multiple
different OCRs and quickly find errors (if a text is read the same then
it's likely correct, and if it's read differently then it's certainly
wrong). It would be possible to use this data to retrain the OCR or to
develop new OCRs and so on.
