Sunday, 25 March 2012

Android OCR tutorial - image to text

This tutorial will show how to use and implement OCR library (tesseract) in android application. Tesseract is open source library for OCR originally developed by HP.

1. Download tesseract library for android https://github.com/rmtheis/tess-two/downloads. Download as .zip for
    windows, as .tar.gz for linux user.

2. Software requirement
    - Eclipse
    - Java JDK
    - Android SDK
    - Android NDK
    - Cygwin ( for windows users)
    - Apache-ant
3. For windows user, make sure you already installed cygwin ( you can download it  and install it from http://www.cygwin.com/ make sure during the cygwin installation, install also these source and library gcc-core, gcc-g++, make, swig)

4. Download apache-ant from http://ant.apache.org/bindownload.cgi choose .zip for windows, .tar.bz for linux user.

5. Unzip the apache and set the environment variable (mine is C:\apache-ant-1.8.3\bin)


6. Run cygwin (for windows user only,for linux user,run terminal)
     a.cd <project-directory>/tess-two
     b.export TESSERACT_PATH=${PWD}/external/tesseract-3.01
     c.export  LEPTONICA_PATH=${PWD}/external/leptonica-1.68
     d.export LIBJPEG_PATH=${PWD}/external/libjpeg
     e.ndk-build(for windows user, /cygdrive/<ndk-directory>/ndk-build)
     f. android update project --path . (for windows user, sometime cygwin cannot execute this command, so
        use command prompt to execute this command).
        Note: The “.” after --path must be included in the command.
     g. ant release ( sometimes you will get error like java tools.jar not found, set environment variable
         JAVA_HOME to the jdk folder, mine is C:\Program Files\Java\jdk1.7.0)

7. Run Eclipse. Right click on package explorer, import>> General >> Existing Project into Workspace >> 
    Next >> Select Root Directory >> Browse the tess-two folder location >> Finish.
    You will see tess-two folder in your package explorer.
    
8. Right click on the project >> Android Tools >> Fix Project Properties. Right click >> Properties >> 
    Android >> Check Is Library. 
    Download the simple OCR android app from https://github.com/GautamGupta/Simple-Android-OCR.
    Right click on package explorer, import the simple OCR android app folder.

9. Right click on the project >> Android >> Add >> click tess-two >> OK
   
10. Run the app. Good luck



References
[1] http://gaut.am/making-an-ocr-android-app-using-tesseract/
[2] http://ant.apache.org/bindownload.cgi
[3] http://wolfpaulus.com/journal/android-and-ocr
[4] http://rmtheis.wordpress.com/2011/08/06/using-tesseract-tools-for-android-to-create-a-basic-ocr-app/
[5] https://github.com/rmtheis/tess-two


70 comments:

  1. you can download tess-two library by clicking tot this link
    http://www.4shared.com/folder/SinVRg1O/_online.html

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  5. unzip the one http://www.4shared.com/folder/SinVRg1O/_online.html

    -using msdos, cd to the extracted tess-two folder then type "/android-sdk-windows/tools/android update project --path . "
    -create new Environment (computer -> properties->advance) for JAVA_HOME, value: C:\Program Files\Java\jdk1.7.0, ANT_HOME value: C:\apache-ant-1.8.4, PATH, value:;C:\Program Files\Java\jdk1.7.0\bin; C:\apache-ant-1.8.4\bin
    -then on cygwin, cd the tess-two then type " ant release "
    -sometime the environment does not update without restarting ur pc
    -then follow the upper example starting from no 7.

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  6. usually android-sdk-windows folder in C, so, after cd to tess-two folder, if using command prompt,type "C:\android-sdk-windows\tools\android update project --path ." or "/cygdrive/c/android-sdk-windows/tools/android update project --path ." if using cygwin. you can try either one.

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  7. how can i use other language?

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  8. I haven't try other language yet.. but this link might be useful for you http://vannait.blogspot.com/2009/06/how-to-train-tesseract-ocr.html

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  9. can you make video for this tutorial sorry but i'm beginner with android

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  10. Later we will provide the video for you

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  11. i'm widnows use and i'm getting this error at step 6,e

    E:/adt-bundle-windows-x86_64/android-ndk-r8d/ndk-build
    SharedLibrary : liblept.so
    E:/adt-bundle-windows-x86_64/android-ndk-r8d/toolchains/arm-linux-androideabi-4.6/prebuilt/windows/bin/../lib/gcc/arm-linux-androideabi/4.6/../../../../arm-linux-androideabi/bin/ld.exe: error: cannot open ./obj/local/armeabi/libgnustl_static.a: Permission denied
    collect2: ld returned 1 exit status
    /cygdrive/e/adt-bundle-windows-x86_64/android-ndk-r8d/build/core/build-binary.mk:397: recipe for target `obj/local/armeabi/liblept.so' failed
    make: *** [obj/local/armeabi/liblept.so] Error 1

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  12. Hi Firas, here I found some post about permission denied at libgnustl_static.a. Check this http://stackoverflow.com/questions/12469711/building-tesseract-with-android-ndk

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  13. would you tell me whats this command for ??
    chmod 777 obj/local/armeabi/libgnustl_static.a

    I don't know how to thank you for your thread and you quick response :-)

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  14. This comment has been removed by the author.

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  16. Hi firas, chmod =sets permissions for a file eg: read, write, execute for the owner (you) and guests (any one who views the file...this includes programs). 777 means anyone can do anything with the file. If the suggestion does not work, try chmod -R 777 /cygdrive/(eclipse workspace folder)

    I found it at http://stackoverflow.com/questions/11551742/ndk-build-error-with-cygwin

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  17. building tesseract library with ndk a bit tiring, you can just download the already built library at http://www.4shared.com/folder/SinVRg1O/_online.html then follow the suggestion did by wany (see the earlier comments).

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  18. thank you very much, I did it with chmod -R 777 /cygdrive/(eclipse workspace folder) and chmod -R 777 file without permission.

    now my engine work perfectly,
    do you know how to add continuous mode or crop the image to let the user choose the text from the image ??

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  19. This comment has been removed by the author.

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    1. This comment has been removed by the author.

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  20. i dont know how do the step 6 i'm not aware of cygwin could u please help me

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  21. Hi Rex,
    If you use windows, you should install cygwin to do step 6.
    Then run cygwin and just write the command as in step 6 for example, for 6 a,cd /tess-two, in my case, my workspace is in D:\workspace\opencv\tess-two , so the command that i should write will be cd /cygdrive/d/workspace/opencv/tess-two . Hope this can help

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  22. i dont know why but when my application runs i run the camera take the picture and when i save it my application crashes saying that the application stopped unexpectedly! any reasons in mind why??

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  23. and oh yea when i ran the logcat on eclipse i could see something like could not find class 'com.googlecode.tesseract.android.TessBaseAPI' referenced from method com.datumdroid.android.ocr.simple.SimpleAndroidOCRActicity.picturetaken'. Just to help you know the problem specifics! :)

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  24. Why sometimes the recognized text is a bunch of random characters? I get this result even if there is no character in the picture.

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  25. The OCR tutorial in this blog is quite simple and sometimes unstable. Follow this tutorial for more stable http://gaut.am/making-an-ocr-android-app-using-tesseract/

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    Replies
    1. Thank you! But what is the difference between these two tutorials?

      Delete
  26. This comment has been removed by the author.

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  27. can you send us video tutorial? i have done all the steps but the ocr app shows 'force close' message

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  28. Please make a video on you tube !

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  29. Yup it is working for me... thanks kurup ;)

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  30. i have and error when building the ndk, this is the error: jni/../external/libjpeg/jidctfst.S: Assembler messages:
    jni/../external/libjpeg/jidctfst.S:66: Error: missing ')'
    jni/../external/libjpeg/jidctfst.S:66: Error: garbage following instruction -- ` pld (r2,#0)'
    jni/../external/libjpeg/jidctfst.S:259: Error: missing ')'
    jni/../external/libjpeg/jidctfst.S:259: Error: garbage following instruction -- `pld (sp,#32)'
    jni/../external/libjpeg/jidctfst.S:271: Error: missing ')'
    jni/../external/libjpeg/jidctfst.S:271: Error: garbage following instruction -- `pld (ip,#32)'
    /cygdrive/d/Programming/Programs/android/android-ndk-r8d/build/core/build-binary .mk:267: recipe for target `obj/local/armeabi/objs/jpeg/jidctfst.o' failed
    make: *** [obj/local/armeabi/objs/jpeg/jidctfst.o] Error 1


    i already checked this file and didn't find that missing ')'

    can any one help ?

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  31. i'm windows use,too
    and i'm getting this error at step 6,f

    cygwin cannot execute command "android update projrct --path ."
    here's what i got [-bash: android:Command can not find]

    so I use command prompt to execute same command above, and I got " 'android' is not internal or external command, operable program or batch file"

    did i make any mistakes about commands?

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    Replies
    1. Oh! Finally! I got it!!
      but now I have a new error to be solved..
      after I execute "android update projrct --path ."
      I got
      Error: Expected verb after global parameters but found 'projrct' instead.

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    2. I also not sure about this.. but maybe because you misspell "project" with "projrct" in the command.. maybe..

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    3. I cant believe I make such mistake...
      THANNNNK you!!!!
      still a little question : why do I need to download Apache-ant, what is it for?

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    4. How did you correct this error ... im stuck in this phase .. pls help

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  32. $ /cygdrive/c/adt-bundle-windows-x86_64-20130219/adt-bundle-windows-x86_64-20130219/sdk/tools/android.bat update project --path .
    Error: The project either has no target set or the target is invalid.
    Please provide a --target to the 'android.bat update' command.

    I am not sure hot to set target

    any help

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    Replies
    1. /cygdrive/c/adt-bundle-windows-x86_64-20130219/adt-bundle-windows-x86_64-20130219/sdk/tools/android.bat update project -p . --target android-17

      worked

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    2. I am getting this problem.. can u plss help me out??
      /cygdrive/f/adt-bundle-windows-x86_64-20130522/sdk/tools
      $ android.bat update project --p. --target android-10
      -bash: android.bat: command not found

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  33. hi .. i am stuck on the 6th step.. in the ndk-build part i am getting the following error



    Manish@Kadaba-PC /cygdrive/c/Users/Manish/Downloads/tess-two-master
    $ /cygdrive/C:\android-ndk-r8d/ndk-build
    -bash: /cygdrive/C:android-ndk-r8d/ndk-build: No such file or directory

    Manish@Kadaba-PC /cygdrive/c/Users/Manish/Downloads/tess-two-master
    $ /cygdrive/C:/android-ndk-r8d/ndk-build
    -bash: /cygdrive/C:/android-ndk-r8d/ndk-build: No such file or directory



    someone please help me out here...thank you

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  34. Hi Manish.
    Try this:-
    Instead using /cygdrive/C:\android-ndk-r8d/ndk-build, try this way
    /cygdrive/c/android-ndk-r8d/ndk-build
    hope it will works :)

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    Replies
    1. hey kurup one question
      will it recognise power functions and other math expressions like +,-,= etc ??

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  35. =============================================
    Nicky Valiant@Nicx-7 /cygdrive/c/android/android-ndk-r8e
    $ cd /cygdrive/c/android/android-ndk-r8e/

    Nicky Valiant@Nicx-7 /cygdrive/c/android/android-ndk-r8e
    $ ndk-build
    -bash: ndk-build: command not found
    ====================OR==========================
    Nicky Valiant@Nicx-7 /cygdrive/c/android/android-ndk-r8e
    $ cd /cygdrive/c/android/android-ndk-r8e/ndk-build
    -bash: cd: /cygdrive/c/android/android-ndk-r8e/ndk-build: Not a directory
    ==============================================
    my problem is same as Manish...at 6,e....

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  36. I am downloading NDK build now, heavy download, meanwhile could I get an apk of this project? Not the source, the apk file. :)

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  37. after scanning with ocr, i want to save the ocr text into a .txt or .png file for other purpose. how to do that?

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  38. Thanks for the tutorial. Anyway, why do you need cygwin to build the project? In the official site of tess-two, they only need Android NDK.

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    1. This comment has been removed by the author.

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    2. Ok. Finally, I can build it (Anyway, I did not use the cygwin terminal). So, which part I can use to import to my project? Do i need to include the whole project?

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  39. Thanks a lot, it is working, but does not recognize the characters, my intention is to read characters in a lottery ticket, how can I improve it?

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  40. While importing the project to workspace it shows ERROR:resource directory'S:\tess-two-master\tess-two\res' does not exist.. what should I do to solve this issue? ?

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  41. can you share to me your whole project ? :D

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  42. do you have the video, cause its hard for me to follow as a beginner, thanks~

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    Replies
    1. http://androidtesstwo.blogspot.com/2014/03/making-android-ocr-app-using-tess-two.html?spref=fb

      no need for ndk, ant and cygwin. just need to import it eclipse.

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  43. Hello, i made an installation beginners guide for Android NDK and Tesseract Library on Windows 7 (64bit). I am a beginner too,so I assume similar steps on 32-bit..

    I uploaded on my github:
    https://github.com/GiorgosPap/androidndk-tesslib

    I hope finding it useful.

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  44. hey please tell me any libray or api to use convert image to text for phonegap or sencha touch.......
    because i am using cross platform for mobile development

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  45. Hi, I have done up to Step 6f and it works. But when come to Step 6 g. Ant release, it shows
    " 'ant' is not recognized as an internal or external command, operable program or batch file. "
    So, what should I do in order to continue this?
    Please help. Thanks.

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  46. how many fonts does it detect without additional training?

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  47. hey can u please tell i directly need to run this command where i executed ndk-build.. or change the direcotry path to execute this command "android update project --path . " ?
    plss reply need urgent help.. i want to know how to proceed to step 6f..

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  48. nice tutorial helped me a lot

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  49. Replies
    1. http://androidtesstwo.blogspot.com/ check an easy solution here. You don’t need ndk, ant, setting environment variables

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    2. Android Ocr tess-two library Without ndk-build: Making Android OCR app using tess-two v3.03..

      http://androidtesstwo.blogspot.com/

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  50. What is the required Andriod NDK version for OCR ??

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    Replies
    1. http://androidtesstwo.blogspot.com/ check an easy solution here.

      Delete
  51. Ultimate solution. See my blog here http://androidtesstwo.blogspot.com/

    you will not need ant, ndk, setting environment variables. very easy way.

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