Installing tesseract for python on Ubuntu 14.04

Building and installing tesseract for python on Ubuntu 14.04.

root@server:/home/user/tesseract# cat /etc/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=14.04
DISTRIB_CODENAME=trusty
DISTRIB_DESCRIPTION="Ubuntu 14.04.1 LTS"

Install packages

sudo apt-get install python-distutils-extra tesseract-ocr tesseract-ocr-eng libopencv-dev libtesseract-dev libleptonica-dev python-all-dev swig libcv-dev python-opencv python-numpy python-setuptools build-essential subversion

sudo apt-get install autoconf automake libtool

sudo apt-get install libpng12-dev libjpeg62-dev libtiff4-dev zlib1g-dev

For tesseract training install the next packages:

sudo apt-get install libicu-dev libpango1.0-dev libcairo2-dev

Download leptonica

wget http://www.leptonica.com/source/leptonica-1.71.tar.gz

tar xvf leptonica-1.71.tar.gz

and build it

cd leptonica-1.71

./configure

make

make install

Download tesseract-ocr

wget https://bitbucket.org/3togo/python-tesseract/downloads/tesseract-3.03-rc1.tar.gz

tar xvf tesseract-3.03-rc1.tar.gz

and build it

cd tesseract-3.03

./autogen.sh

./configure

make

sudo make install

sudo ldconfig

Download (checkout) python-tesseract

svn checkout http://python-tesseract.googlecode.com/svn/trunk/src python-tesseract

I've used 659 revistion.

and build it

cd python-tesseract

python setup.py clean

python setup.py build

python setup.py install

After that try to run your python example.

If you'll get such error:

Error opening data file ./tessdata/eng.traineddata

Please make sure the TESSDATA_PREFIX environment variable is set to the parent directory of your "tessdata" directory.

Failed loading language 'eng'

Tesseract couldn't load any languages!

AdaptedTemplates != NULL:Error:Assert failed:in file adaptmatch.cpp, line 174

Segmentation fault (core dumped)

You could fix it by patching "mainblk.cpp" file inside tesseract-3.03\ccutil\ folder the next way:

In the "mainblk.cpp" file code:

  if (argv0 != NULL) {

    datadir = argv0;

  } else {

    if (getenv("TESSDATA_PREFIX")) {

      datadir = getenv("TESSDATA_PREFIX");

    } else {

#ifdef TESSDATA_PREFIX

#define _STR(a) #a

#define _XSTR(a) _STR(a)

    datadir = _XSTR(TESSDATA_PREFIX);

#undef _XSTR

#undef _STR

#endif

    }

  }

  // insert code here

  // datadir may still be empty:

  if (datadir.length() == 0) {

    datadir = "./";

add:

  if (getenv("TESSDATA_PREFIX")) {

      datadir = getenv("TESSDATA_PREFIX");

  } else {

    // check dir with tessdata

    struct stat sb;

    if (stat("/usr/share/tesseract-ocr/tessdata", &sb) == 0 && S_ISDIR(sb.st_mode)) {    

      datadir = "/usr/share/tesseract-ocr";

    }

  }

and include:

#include <sys/stat.h>

And rebuild and reinstall tesseract-ocr:

cd tesseract-3.03

make

sudo make install

So, after that, if you have TESSDATA_PREFIX env variable, it will be loaded, and if you have tessdata folder with files in /usr/share/tesseract-ocr/ it will be loaded, otherwise directory with your python example module (./) will be checked for tessdata folder.

P.S. Take a look at the repo, by the way, there are already built deb package: https://bitbucket.org/3togo/python-tesseract/

Update:

If you have the next error message when importing tesseract module in Python:
Traceback (most recent call last):
  File "test_module.py", line 5, in
    from tesseract_ocr import TesseractOCR
  File "/home/user/ocr/module/tesseract_ocr.py", line 9, in
    import tesseract
  File "/usr/local/lib/python2.7/dist-packages/python_tesseract-0.9-py2.7-linux-x86_64.egg/tesseract.py", line 28, in
    _tesseract = swig_import_helper()
  File "/usr/local/lib/python2.7/dist-packages/python_tesseract-0.9-py2.7-linux-x86_64.egg/tesseract.py", line 24, in swig_import_helper
    _mod = imp.load_module('_tesseract', fp, pathname, description)
ImportError: /usr/local/lib/python2.7/dist-packages/python_tesseract-0.9-py2.7-linux-x86_64.egg/_tesseract.so: undefined symbol: cvSetData

Check that opencv library is linked in the _tesseract.so, because cvSetData is opencv's function.

ldd _tesseract.so | grep libopencv

If the output is empty try to build _tesseract.so using this command:

sudo c++ -pthread -shared -Wl,-O1 -Wl,-Bsymbolic-functions -Wl,-Bsymbolic-functions -Wl,-z,relro -fno-strict-aliasing -DNDEBUG -g -fwrapv -O2 -Wall -Wstrict-prototypes -D_FORTIFY_SOURCE=2 -g -fstack-protector --param=ssp-buffer-size=4 -Wformat -Werror=format-security build/temp.linux-x86_64-2.7/tesseract_wrap.o build/temp.linux-x86_64-2.7/main.o -lstdc++ -ltesseract -llept -lopencv_superres -lopencv_video -lopencv_videostab -lopencv_ml -lopencv_ocl -lopencv_contrib -lopencv_flann -lopencv_calib3d -lopencv_imgproc -lopencv_core -lopencv_legacy -lopencv_stitching -lopencv_features2d -lopencv_photo -lopencv_ts -lopencv_objdetect -lopencv_highgui -lopencv_gpu -o build/lib.linux-x86_64-2.7/_tesseract.so

NB: The command python setup.py build must be executed before the above one, otherwise next errors will be printed:

c++: error: build/temp.linux-x86_64-2.7/tesseract_wrap.o: No such file or directory

c++: error: build/temp.linux-x86_64-2.7/main.o: No such file or directory

After successful build of _tesseract.so copy it to python-tesseract directory:

sudo cp ./build/lib.linux-x86_64-2.7/_tesseract.so .

And check again that opencv library is linked in the _tesseract.so.

ldd _tesseract.so | grep libopencv

Should be something like:

libopencv_core.so.2.4 => /usr/local/lib/libopencv_core.so.2.4 (0x000070d310313370)

Now install python-tesseract:

python setup.py install

After that the problem "undefined symbol: cvSetData" will be solved.

If you have the next error:
>>> import tesseract
Traceback (most recent call last):
  File "", line 1, in
  File "/usr/lib/python2.7/dist-packages/tesseract.py", line 28, in
    _tesseract = swig_import_helper()
  File "/usr/lib/python2.7/dist-packages/tesseract.py", line 24, in swig_import_helper
    _mod = imp.load_module('_tesseract', fp, pathname, description)
ImportError: /usr/lib/python2.7/dist-packages/_tesseract.x86_64-linux-gnu.so: undefined symbol: pixGenerateFlateData

Try to use old python-tesseract svn revision (e.g. 659 or 660).
https://code.google.com/p/python-tesseract/source/detail?r=659

Update: 
I've added a new tutorial Installing tesseract for python on Ubuntu 15.10.