Tesseract-ocr gem issue on mac os x

Question

I've installed a tesseract-ocr (0.1.5) gem.

Dependencies are also installed (tesseract/3.04.00 and leptonica/1.72)

Mac OS X Yosemity.

When I do rake db:migrate an error appears:

rake aborted!
CompilationError: compile error: see logs at /var/folders/xg/g9n7qvns5z1gsr_yjh09n1nm0000gn/T/.ffi-inline-501/d2f8bb8a1867b800ff8ad69a3b850c91521b3760.log
/Users/user/.rvm/gems/ruby-2.2.2@project/gems/ffi-inline-0.0.4.3/lib/ffi/inline/compilers/gcc.rb:35:in `compile'
/Users/user/.rvm/gems/ruby-2.2.2@project/gems/ffi-inline-0.0.4.3/lib/ffi/inline/builders/c.rb:114:in `shared_object'
/Users/user/.rvm/gems/ruby-2.2.2@project/gems/ffi-inline-0.0.4.3/lib/ffi/inline/builders.rb:90:in `block in build'
/Users/user/.rvm/gems/ruby-2.2.2@project/gems/ffi-inline-0.0.4.3/lib/ffi/inline/builders.rb:87:in `instance_eval'
/Users/user/.rvm/gems/ruby-2.2.2@project/gems/ffi-inline-0.0.4.3/lib/ffi/inline/builders.rb:87:in `build'
/Users/user/.rvm/gems/ruby-2.2.2@project/gems/ffi-inline-0.0.4.3/lib/ffi/inline/inline.rb:54:in `singleton_inline'
/Users/user/.rvm/gems/ruby-2.2.2@project/gems/ffi-inline-0.0.4.3/lib/ffi/inline/inline.rb:39:in `inline'
/Users/user/.rvm/gems/ruby-2.2.2@project/gems/tesseract-ocr-0.1.5/lib/tesseract/c/baseapi.rb:30:in `<module:BaseAPI>'
/Users/user/.rvm/gems/ruby-2.2.2@project/gems/tesseract-ocr-0.1.5/lib/tesseract/c/baseapi.rb:27:in `<module:C>'
/Users/user/.rvm/gems/ruby-2.2.2@project/gems/tesseract-ocr-0.1.5/lib/tesseract/c/baseapi.rb:25:in `<module:Tesseract>'
/Users/user/.rvm/gems/ruby-2.2.2@project/gems/tesseract-ocr-0.1.5/lib/tesseract/c/baseapi.rb:25:in `<top (required)>'
/Users/user/.rvm/gems/ruby-2.2.2@project/gems/activesupport-4.2.3/lib/active_support/dependencies.rb:274:in `require'
/Users/user/.rvm/gems/ruby-2.2.2@project/gems/activesupport-4.2.3/lib/active_support/dependencies.rb:274:in `block in require'
/Users/user/.rvm/gems/ruby-2.2.2@project/gems/activesupport-4.2.3/lib/active_support/dependencies.rb:240:in `load_dependency'
/Users/user/.rvm/gems/ruby-2.2.2@project/gems/activesupport-4.2.3/lib/active_support/dependencies.rb:274:in `require'
/Users/user/.rvm/gems/ruby-2.2.2@project/gems/tesseract-ocr-0.1.5/lib/tesseract/c.rb:83:in `<top (required)>'
/Users/user/.rvm/gems/ruby-2.2.2@project/gems/activesupport-4.2.3/lib/active_support/dependencies.rb:274:in `require'
/Users/user/.rvm/gems/ruby-2.2.2@project/gems/activesupport-4.2.3/lib/active_support/dependencies.rb:274:in `block in require'
/Users/user/.rvm/gems/ruby-2.2.2@project/gems/activesupport-4.2.3/lib/active_support/dependencies.rb:240:in `load_dependency'
/Users/user/.rvm/gems/ruby-2.2.2@project/gems/activesupport-4.2.3/lib/active_support/dependencies.rb:274:in `require'
/Users/user/.rvm/gems/ruby-2.2.2@project/gems/tesseract-ocr-0.1.5/lib/tesseract/api.rb:26:in `<top (required)>'
/Users/user/.rvm/gems/ruby-2.2.2@project/gems/activesupport-4.2.3/lib/active_support/dependencies.rb:274:in `require'
/Users/user/.rvm/gems/ruby-2.2.2@project/gems/activesupport-4.2.3/lib/active_support/dependencies.rb:274:in `block in require'
/Users/user/.rvm/gems/ruby-2.2.2@project/gems/activesupport-4.2.3/lib/active_support/dependencies.rb:240:in `load_dependency'
/Users/user/.rvm/gems/ruby-2.2.2@project/gems/activesupport-4.2.3/lib/active_support/dependencies.rb:274:in `require'
/Users/user/.rvm/gems/ruby-2.2.2@project/gems/tesseract-ocr-0.1.5/lib/tesseract-ocr.rb:35:in `<top (required)>'
/Users/user/.rvm/gems/ruby-2.2.2@project/gems/bundler-1.10.6/lib/bundler/runtime.rb:76:in `require'
/Users/user/.rvm/gems/ruby-2.2.2@project/gems/bundler-1.10.6/lib/bundler/runtime.rb:76:in `block (2 levels) in require'
/Users/user/.rvm/gems/ruby-2.2.2@project/gems/bundler-1.10.6/lib/bundler/runtime.rb:72:in `each'
/Users/user/.rvm/gems/ruby-2.2.2@project/gems/bundler-1.10.6/lib/bundler/runtime.rb:72:in `block in require'
/Users/user/.rvm/gems/ruby-2.2.2@project/gems/bundler-1.10.6/lib/bundler/runtime.rb:61:in `each'
/Users/user/.rvm/gems/ruby-2.2.2@project/gems/bundler-1.10.6/lib/bundler/runtime.rb:61:in `require'
/Users/user/.rvm/gems/ruby-2.2.2@project/gems/bundler-1.10.6/lib/bundler.rb:134:in `require'
/Users/user/work/project/config/application.rb:17:in `<top (required)>'
/Users/user/work/project/Rakefile:4:in `<top (required)>'

In the log:

g++ -dynamic -bundle -fPIC    -o /var/folders/xg/g9n7qvns5z1gsr_yjh09n1nm0000gn/T/.ffi-inline-501/d2f8bb8a1867b800ff8ad69a3b850c91521b3760.dylib /var/folders/xg/g9n7qvns5z1gsr_yjh09n1nm0000gn/T/.ffi-inline-501/d2f8bb8a1867b800ff8ad69a3b850c91521b3760.cpp -ltesseract 2>>/var/folders/xg/g9n7qvns5z1gsr_yjh09n1nm0000gn/T/.ffi-inline-501/d2f8bb8a1867b800ff8ad69a3b850c91521b3760.log
/Users/user/.rvm/gems/ruby-2.2.2@project/gems/tesseract-ocr-0.1.5/lib/tesseract/c/baseapi.rb:171:10: error: no matching member function for call to 'SetImage'
                                api->SetImage(pix);
                                ~~~~~^~~~~~~~
/usr/local/include/tesseract/baseapi.h:354:8: note: candidate function not viable: 1st argument ('const Pix *') would lose const qualifier
  void SetImage(Pix* pix);
       ^
/usr/local/include/tesseract/baseapi.h:341:8: note: candidate function not viable: requires 5 arguments, but 1 was provided
  void SetImage(const unsigned char* imagedata, int width, int height,
       ^
/Users/user/.rvm/gems/ruby-2.2.2@project/gems/tesseract-ocr-0.1.5/lib/tesseract/c/baseapi.rb:183:49: error: cannot initialize a parameter of type 'tesseract::TessResultRenderer *' with an lvalue of type 'STRING *'
                                return api->ProcessPages(filename, NULL, 0, output);
                                                                            ^~~~~~
/usr/local/include/tesseract/baseapi.h:542:63: note: passing argument to parameter 'renderer' here
                    int timeout_millisec, TessResultRenderer* renderer);
                                                              ^
/Users/user/.rvm/gems/ruby-2.2.2@project/gems/tesseract-ocr-0.1.5/lib/tesseract/c/baseapi.rb:189:65: error: cannot initialize a parameter of type 'tesseract::TessResultRenderer *' with an lvalue of type 'STRING *'
                                return api->ProcessPage(pix, page_index, filename, NULL, 0, output);
                                                                                            ^~~~~~
/usr/local/include/tesseract/baseapi.h:558:40: note: passing argument to parameter 'renderer' here
                   TessResultRenderer* renderer);
                                       ^

How can I solve it?

Update: It's not duplicate question. It doesn't help Error setting up the tesseract OCR in gem in rails

Answer 1

Tesseract developers changed quite some stuff in version 3.0.4 and tesseract-ocr gem lost compatibility with it. The best solution I see is to downgrade for now. You may have previous versions of Tesseract installed on your mac, use brew info tesseract to find that out. If so, just use brew switch. I did brew cleanup recently, so I had to uninstall tesseract and install it from the old formula, like so:

$ brew uninstall tesseract
$ brew install https://raw.githubusercontent.com/Homebrew/homebrew/8ba134eda537d2cee7daa7ebdd9f728389d9c53e/Library/Formula/tesseract.rb

This will install Tesseract 3.02.02_3d that seems to be working. You can find more info and track this issue at tesseract-ocr repo.

Answer 2

If you don't want to downgrade Tesseract, an alternative quick and dirty method would be to execute Tesseract as a shell command and open the file it saves to get access to the content (note: string interpolation works in shell commands)

input_image = 'input.tif'
`tesseract #{input_image} output -l eng`
file = File.open('output.txt')