Tesseract: Tesseract segmentation fault when using Arabic and English

[Freedomafia]

When I tried the Arabic only and English only text copying it worked. However when I tried to use them both simultaneously on the picture of the scanned page I got a 'segmentation fault'. I have attached a link to the image of a scanned page of the Arabic-English dictionary : https://imgur.com/a/K8bqz.

My bashscript was:

tesseract Arabic_to_English.png -l eng+ara output

However the terminal returned the message that there was a 'segmentation fault'. Full error message:

Tesseract Open Source OCR Engine v3.04.01 with Leptonica
Detected 24 diacritics
no best words!!
no best words!!
no best words!!
no best words!!
Segmentation fault (core dumped)

I wanted to ask whether tesseract is able to work with English and Arabic simultaneously.

---

Environment

• Tesseract Version:
  tesseract 3.04.01
  leptonica-1.73
  libgif 5.1.2 : libjpeg 8d (libjpeg-turbo 1.4.2) : libpng 1.2.54 : libtiff 4.0.6 : zlib 1.2.8 : libwebp 0.4.4 : libopenjp2 2.1.0

Current Behavior:

Expected Behavior:

Suggested Fix:

[Shreeshrii]

Please try

tesseract Arabic_to_English.png -l Arabic output

and report the result.

[Shreeshrii]

I have attached an image of a scanned page of the Arabic-English dictionary.

Image is not attached.

[amitdo]

Tesseract Version: latest

From the master branch?

From which repo did you download the traineddata?

[Freedomafia]

@Shreeshrii
(1) I have edited my Original Post with a link to the image
(2) I tried the command you suggested : tesseract Arabic_to_English.png -l Arabic output. However it returned the error message:

Tesseract Open Source OCR Engine v3.04.01 with Leptonica
Error opening data file /usr/share/tesseract-ocr/tessdata/Arabic.traineddata
Please make sure the TESSDATA_PREFIX environment variable is set to the parent directory of your "tessdata" directory.
Failed loading language 'Arabic'
Tesseract couldn't load any languages!

[Freedomafia]

@amitdo I have updated my OP. I did not download any test data

[amitdo]

Duplicates #235

[Freedomafia]

@amitdo Thank you for the link. Is there any way I can get an alert if and when tesseract will work with ara+eng in the future?

[stweil]

That combination should already work with the latest experimental Tesseract 4 (which also supports an alternative combination Arabic+Latin), but I have no personal experience with ara.traineddata or Arabic.traineddata.

[amitdo]

I have updated my OP. I did not download any test data

An interesting discussion:
https://english.stackexchange.com/questions/424366/does-op-mean-original-poster-or-original-post

[amitdo]

Repeating myself, just to try this GitHub feature:
https://github.com/githubteacher/github-for-developers-sept-2015/issues/705#issuecomment-315299288

Duplicate of #235

[Shreeshrii]

@Freedomafia If you use tesseract4 (LSTM engine) with Arabic (which has both ara and eng already), it works fine. See attached.

Arabic_English-png-Arabic-tessdata_best3.txt

[Freedomafia]

Hi @Shreeshii I did manage to use it with Tesseract v4 two days ago but I encountered some issues which I will post as a comment on this thread later today. Many thanks.

[Aspiringarabist]

Hi @Shreeshrii @amitdo @stweil . Thank you for your help thus far. I have two questions:

(1) The text file produced from the arabic and arabic+english are not great. However when I use english only it gets all the english words correctly however it guesses the english characters when it meets the arabic letters. I am thinking of returning the arabic letters with empty spaces by utilising what I believe to be the fact that the english only LSTM will produce a low confidence score when it comes across arabic letters. Is there anywhere to extract confidence scores per letter/character?

(2) I could not run all the tesseract4 features.

I ran the following lines:

tesseract --oem 3 Arabic_to_English.png -l ara+eng outputs/outputoem3_AE
tesseract --oem 2 Arabic_to_English.png -l ara+eng outputs/outputoem2_AE
tesseract --oem 1 Arabic_to_English.png -l ara+eng outputs/outputoem1_AE
tesseract --oem 0 Arabic_to_English.png -l ara+eng outputs/outputoem0_AE
tesseract --oem 3 Arabic_to_English.png -l eng+ara outputs/outputoem3_EA
tesseract --oem 2 Arabic_to_English.png -l eng+ara outputs/outputoem2_EA
tesseract --oem 1 Arabic_to_English.png -l eng+ara outputs/outputoem1_EA

oem 1 and 3 produced results (see attached). However all the --oem 0 and 2 failed to produce an OCR text and they returned the error message (for both):

utputs/outputoem0_AE
mgr->GetComponent(TESSDATA_INTTEMP, &fp):Error:Assert failed:in file adaptmatch.cpp, line 537
Segmentation fault (core dumped)

Many thanks :)

outputoem1_AE.txt
outputoem1_EA.txt
outputoem3_AE.txt
outputoem3_EA.txt

[Shreeshrii]

1. tessdata_best and tessdata_fast do NOT have the legacy tesseract model in it, hence --oem 0 (tesseract) and --oem 2 (tesseract+LSTM) won't work.

--oem 1 is LSTM, and --oem 3 is default - which should fallback to --oem 1. So the results should be the same.

1. Please also test with Arabic traineddata, which is different from ara. It has both Arabic and English.

[Shreeshrii]

Is there anywhere to extract confidence scores per letter/character?

see
https://github.com/tesseract-ocr/tesseract/wiki/APIExample#result-iterator-example

https://github.com/tesseract-ocr/tesseract/issues/681

There is a debug type of config variable you can set to see details such as
https://github.com/tesseract-ocr/tesseract/issues/681#issuecomment-275389685

[Freedomafia]

You’re a star @Shreeshrii . I will test this out and report back here.

Many thanks.

[Shreeshrii]

For enabling the debug info related to this,

update the config called logfile to the following and then use 'logfile' as the last variable in your command.

logfile config

debug_file tesseract.log
multilang_debug_level 3
stopper_debug_level 3

command

time tesseract --tessdata-dir /tesseract_ocr/tessdata_fast/   "${img_file}" "${img_file%.*}-Arabic-tessdata_fast-debug"  --oem 1  -l Arabic+ara --psm 6 logfile

The tesseract.log generated by above will be on the following lines.

Processing word with lang Arabic at:Bounding box=(93,1820)->(126,1851)
Trying word using lang Arabic, oem 1
Best choice: accepted=0, adaptable=0, done=1 : Lang result : ینہ : R=2.97306, C=-8.12302, F=1, Perm=8, xht=[0,3.40282e+38], ambig=0
pos NORM    NORM    NORM
str ی   ن   ہ
state:  1   1   1 
C   -0.195  -0.324  -1.160
1 new words better than 0 old words: r: 2.97306 v 0 c: -8.12302 v 0 valid dict: 1 v 0
Trying word using lang ara, oem 1
Best choice: accepted=1, adaptable=0, done=1 : Lang result : ىنب : R=3.02201, C=-2.14964, F=1, Perm=2, xht=[0,3.40282e+38], ambig=0
pos NORM    NORM    NORM
str ى   ن   ب
state:  1   1   1 
C   -0.208  -0.307  -0.297
1 new words worse than 1 old words: r: 3.02201 v 2.97306 c: -2.14964 v -8.12302 valid dict: 0 v 1

[Freedomafia]

Thank you very much @Shreeshrii . This is very detailed and beneficial

[kkkabariya]

tesseract imgara.png -l ara output
tesseract imgara.png -l Arabic output

get error like

mgr->GetComponent(TESSDATA_INTTEMP, &fp):Error:Assert failed:in file adaptmatch.cpp, line 537