Tesseract-ocr

• http://www.raywenderlich.com/93276/implementing-tesseract-ocr-ios
• https://www.howtoforge.com/ocr_with_tesseract_on_ubuntu704
• http://stackoverflow.com/questions/11489824/how-do-i-choose-between-tesseract-and-opencv
• https://realpython.com/blog/python/setting-up-a-simple-ocr-server/

  yum search tesseract

or

  git clone 
  ./configure --prefix=$(pwd)/prefix
  make install
  

  mkdir -p working_dir/images
  mkdir -p working_dir/texts
  cp -rp tessdata working_dir/
  cp image.tif working_dir/images

Note: There are some errors

./tesseract-ocr/prefix/bin/tesseract --tessdata-dir ./working_dir/tessdata ./working_dir/images/Lenore.png ./working_dir/texts/lenore
Tesseract Open Source OCR Engine v3.04.00 with Leptonica
libpng warning: iCCP: Not recognizing known sRGB profile that has been edited
[dang@dai142 71_ocr]$ cat ./working_dir/texts/lenore.txt 
Lenore

Lenore, Lenore, mon amour
Every day I love you more
Without you, my heart grows sore
Je te aime encore trés beaucoup, Lenore

Lenore, Lenore, don’t think me a bore
But I can go on and on about your charms
forever and ever more
On a scale of one to three, I love you four

Mon amour, je te aime encore trés beaucoup,

Lenore

This is the picture: