Optical Character Recognition

Chapter 172: Optical Character Recognition

Optical Character Recognition is converting images of text into actual text. In these examples find ways of using OCR in python.

Section 172.1: PyTesseract

PyTesseract is an in-development python package for OCR.

Using PyTesseract is pretty easy:

try:
import Image
except ImportError:
from PIL import Image
import pytesseract

Basic OCR

print(pytesseract.image_to_string(Image.open('test.png')))

In French

print(pytesseract.image_to_string(Image.open('test-european.jpg'), lang='fra’))

PyTesseract is open source and can be found here.

Section 172.2: PyOCR

Another module of some use is PyOCR, source code of which is here.

Also simple to use and has more features than PyTesseract.

To initialize:

from PIL import Image
import sys
import pyocr
import pyocr.builders
tools = pyocr.get_available_tools()
The tools are returned in the recommended order of usage tool = tools[0]
langs = tool.get_available_languages()
lang = langs[0]
Note that languages are NOT sorted in any way. Please refer
to the system locale settings for the default language
to use.

And some examples of usage:

txt = tool.image_to_string(
Image.open('test.png'),
lang=lang,

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builder=pyocr.builders.TextBuilder()
)

txt is a Python string

word_boxes = tool.image_to_string(
Image.open('test.png'),
lang="eng",
builder=pyocr.builders.WordBoxBuilder()
)
list of box objects. For each box object:
box.content is the word in the box
box.position is its position on the page (in pixels)
Beware that some OCR tools (Tesseract for instance)
may return empty boxes
line_and_word_boxes = tool.image_to_string(
Image.open('test.png'), lang="fra",
builder=pyocr.builders.LineBoxBuilder()
)
list of line objects. For each line object:
line.word_boxes is a list of word boxes (the individual words in the line)
line.content is the whole text of the line
line.position is the position of the whole line on the page (in pixels)
#
Beware that some OCR tools (Tesseract for instance)
may return empty boxes
Digits - Only Tesseract (not 'libtesseract' yet !) digits = tool.image_to_string(
Image.open('test-digits.png'), lang=lang, builder=pyocr.tesseract.DigitBuilder()
)
digits is a python string

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