Extracting lines from an image to feed to OCR - Tesseract

Question

I was watching this talk from pycon http://youtu.be/B1d9dpqBDVA?t=15m34s around the 15:33 mark the speaker talks about extracting lines from an image (receipt) and then feeding that to the OCR engine so that text can be extracted in a better way.

I have a similar need where I'm passing images to the OCR engine. However, I don't quite understand what he means by extracting lines from an image. What are some open source tools that I can use to extract lines from an image?

3 years later.. did you find an answer to above question? – joost May 29 '16 at 18:45 — joost, May 29 '16 at 18:45

score 5 · Answer 1 · edited May 23 '17 at 12:31

Take a look at the technique used to detect the skew angle of a text.

Groups are lines are used to isolate text on an image (this is the interesting part).

From this result you can easily detect the upper/lower limits of each line of text. The text itself will be located inside them. I've faced a similar problem before, the code might be useful to you:

All you need to do from here is crop each pair of lines and feed that as an image to Tesseract.

score 0 · Answer 2 · answered Mar 28 '13 at 15:46

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i can tell u a simple technique to feed the images to OCR.. just perform some operations to get the ROI (Region of Interest) of ur image, and localize the area where the image after binarizing it.. then you may find contours, and by keeping the threasholding value, and setting the required contour area, you can feed the resulting image to OCR :) .. (sorry for bad way of explaination)

answered Mar 28 '13 at 15:46

Zeeshan

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and for tools, i'll suggest Emgu CV. it is kinda wrapper for OpenCv liberary, to use it in C# .. i performed the same task in Emgu CV – Zeeshan Mar 28 '13 at 15:55
Could you fix your grammar? I.e. "i can tell u". – sashoalm Mar 29 '13 at 07:28

score 0 · Answer 3 · answered Mar 29 '13 at 08:31

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Direct answer: you extract lines from an image with Hough Transform. You can find an analytical guide here. Text lines can be detected as well. Karlphillip's answer is based on Hough Transform too.

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answered Mar 29 '13 at 08:31

LovaBill

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Extracting lines from an image to feed to OCR - Tesseract

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