c# OCR can't recognize digits (tesseract 2)

Question

I'm trying to extract digits from the following:

It fails, I get a ~ in return. I'm using google's tesseract 2, using C# (open source c# wrapper) and now I'm wondering, is this image too crappy to be used for OCR?

Because imho the digits are straight clear.

Do you have any other OCR engine in mind that would nail this down?

EDIT

I've also tried with Asprise OCR (http://asprise.com/product/ocr/selector.php) but it fails to parse the image too...

Probably any engine you pay $ for would be able to get the digits - Abbyy or Oce' for example. — Otávio Décio
This is for my company. And judging the tasks size, I'm sure they won't pay bucks for this, and I can't pay for it neither ^_^. This is the dilemma :/. But do you think my image is too crap for let's say weak ocr engines? — CoolStraw
Would you recommend any other open source or even free engine? — CoolStraw
I am yet to find a good open source OCR. I would be very interested on finding out if such exists as well. From what I know there is a lot of money that goes in document processing where things are charged by the click (document or page). — Otávio Décio
Yes, that's a crappy image. The point size is way too small, the text isn't anti-aliased and thus too blocky. The latter could be a scanner artifact. — Hans Passant

FastAl FastAl · Accepted Answer · 2011-03-30T14:38:01

I suggest resizing. I zoomed this page to 200% in IE, Took a screenshot, printed it to PDF and imported it into my program that uses tessnet. Tess nailed it! Unless I read the #s wrong :-)

Although confidence = 140 (under 100 is preferred if you wondered). Of course When i tried the original size, I didn't get ~; I got about 1/2 the #s right, a bunch of letters, and other garbage. Not good enough, but better.

t2 seems to like images a certain size.

My program does processing to get that to work. Suggest using .net GDI+ for converting to 32 bit, resizing with Interpolation mode High Quality Bicubic. This seems to 'fill in the gaps' a bit.

Play with sizes that work - I have found, too big, or too small, and tesseract performs differently.

Both issues are preprocessing, that's easy and you'd thing tesseract would try; however, I know how to resize and interpolate; I don't know how to OCR! So I am willing to settle.

c# OCR can't recognize digits (tesseract 2)

2 Answers