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How to Do OCR Text Recognition on Mac - Supports M1 Mac

1. Background​

Recently I wanted to do something fun with OCR text recognition. Although I know there's Baidu OCR's mature product API, I still wanted to make one myself using tess4j. After all, life is about tinkering.

And Baidu OCR isn't completely free, as shown below:

There's a limit of 1,000 calls per month.

image.png

1.1 Tess4J​

Official website: Tess4J

Tess4J is a Java JNA wrapper for the Tesseract OCR API. It allows us to easily call Tesseract for text recognition. Tesseract is an optical character recognition engine. It supports multiple operating systems and is free software under the Apache license, sponsored by Google. Tesseract is considered one of the most accurate open-source optical character recognition engines.

2. Installing Tesseract​

2.1 Mac Environment​

brew install tesseract

Download may fail due to the Great Firewall. It's recommended to change the mirror source. Here's how:

2.2 Changing Mac Brew Mirror Source​

# Replace brew.git:
$ cd "$(brew --repo)"
# Tsinghua University:
$ git remote set-url origin https://mirrors.tuna.tsinghua.edu.cn/git/homebrew/brew.git

# Replace homebrew-core.git:
$ cd "$(brew --repo)/Library/Taps/homebrew/homebrew-core"
# Tsinghua University:
$ git remote set-url origin https://mirrors.tuna.tsinghua.edu.cn/git/homebrew/homebrew-core.git

# Replace homebrew-bottles:
# Tsinghua University:
$ echo 'export HOMEBREW_BOTTLE_DOMAIN=https://mirrors.tuna.tsinghua.edu.cn/homebrew-bottles' >> ~/.bash_profile
$ source ~/.bash_profile

# Apply changes:
$ brew update

After installation is complete, enter tesseract -v to see the version information:

image.png

2.4 Getting libtesseract.dylib Information​

Then enter brew list tesseract and record the libtesseract.dylib information - you'll need it for the demo later:

asher@AsherdeMBP homebrew-core % brew list tesseract
/opt/homebrew/Cellar/tesseract/5.0.1/bin/tesseract
/opt/homebrew/Cellar/tesseract/5.0.1/include/tesseract/ (12 files)
/opt/homebrew/Cellar/tesseract/5.0.1/lib/libtesseract.5.dylib
/opt/homebrew/Cellar/tesseract/5.0.1/lib/pkgconfig/tesseract.pc
/opt/homebrew/Cellar/tesseract/5.0.1/lib/ (2 other files)
/opt/homebrew/Cellar/tesseract/5.0.1/share/tessdata/ (35 files)
asher@AsherdeMBP homebrew-core %

2.5 Downloading tessdata Files​

Click the GitHub address, then git clone locally to download. The file content is quite large, so download slowly.

3. Creating a Demo Project for Testing​

Here I've prepared a Chinese image - feel free to use it:

chitemp.jpg

3.1 Create a New Maven Project​

image.png

3.2 Add the Tess4J Dependency​

<!-- https://mvnrepository.com/artifact/net.sourceforge.tess4j/tess4j -->
        <dependency>
            <groupId>net.sourceforge.tess4j</groupId>
            <artifactId>tess4j</artifactId>
            <version>5.1.1</version>
        </dependency>

3.3 Copy the libtesseract.dylib File​

Go back to step 2.4, open the corresponding directory, for example mine is:

/opt/homebrew/Cellar/tesseract/5.0.1/lib

Copy the libtesseract.5.dylib file to the project's resources directory, then rename it to libtesseract.dylib.

Why not directly copy libtesseract.dylib? Because that's a symbolic link, like a shortcut in Windows.

image.png

3.3 Writing Test Code​

public static void main(String[] args) throws TesseractException {
        ITesseract instance = new Tesseract();  // JNA Interface Mapping
        instance.setDatapath("/Users/asher/gitWorkspace/tessdata"); // path to tessdata directory
        instance.setLanguage("chi_sim");
        String result = instance.doOCR(new File("/Users/asher/Desktop/temp/chi_temp.jpg"));
        System.out.println(result);

    }

Code explanation:

  • instance.setDatapath(String); Sets the path to the tessdata files downloaded in step 2.5, which contains Simplified Chinese training data
  • instance.setLanguage(String); Sets what language you want to recognize

You can see the text is correctly recognized:

image.png

4. Troubleshooting Some Errors​

4.1 Language Not Found​

You need to set the correct language and download the corresponding language pack:

instance.setLanguage("chi_sim");

4.2 (mach-o file, but is an incompatible architecture (have 'x86_64', need 'arm64')​

Your libtesseract.dylib file has a problem. Refer to step 3.3.

5. Reference Blogs​

Mac Install Tesseract, Use Tess4j for OCR Recognition

Text Recognition on Mac (Tesseract-OCR for Mac)

Solving tess4j Text Recognition Errors on Mac

5.1 Want Some Extended Knowledge?​

JAVA Using Tess4J for OCR Recognition

ANDROID--TESSERACT Training Recognition

A demo for Tesseract in Java with JNA (Tess4J).

Library Name - Language Table​

Library Name	Language
afr	Afrikaans
amh	Amharic
ara	Arabic
asm	Assamese
aze	Azerbaijani
aze_cyrl	Azerbaijani - Cyrillic
bel	Belarusian
ben	Bengali
bod	Tibetan
bos	Bosnian
bul	Bulgarian
cat	Catalan; Valencian
ceb	Cebuano
ces	Czech
chi_sim	Chinese - Simplified
chi_tra	Chinese - Traditional
chr	Cherokee
cym	Welsh
dan	Danish
dan_frak	Danish - Fraktur
deu	German
deu_frak	German - Fraktur
dzo	Dzongkha
ell	Greek, Modern (1453-)
eng	English
enm	English, Middle (1100-1500)
epo	Esperanto
equ	Math / equation detection module
est	Estonian
eus	Basque
fas	Persian
fin	Finnish
fra	French
frk	Frankish
frm	French, Middle (ca.1400-1600)
gle	Irish
glg	Galician
grc	Greek, Ancient (to 1453)
guj	Gujarati
hat	Haitian; Haitian Creole
heb	Hebrew
hin	Hindi
hrv	Croatian
hun	Hungarian
iku	Inuktitut
ind	Indonesian
isl	Icelandic
ita	Italian
ita_old	Italian - Old
jav	Javanese
jpn	Japanese
kan	Kannada
kat	Georgian
kat_old	Georgian - Old
kaz	Kazakh
khm	Central Khmer
kir	Kirghiz; Kyrgyz
kor	Korean
kur	Kurdish
lao	Lao
lat	Latin
lav	Latvian
lit	Lithuanian
mal	Malayalam
mar	Marathi
mkd	Macedonian
mlt	Maltese
msa	Malay
mya	Burmese
nep	Nepali
nld	Dutch; Flemish
nor	Norwegian
ori	Oriya
osd	Orientation and script detection module
pan	Panjabi; Punjabi
pol	Polish
por	Portuguese
pus	Pushto; Pashto
ron	Romanian; Moldavian; Moldovan
rus	Russian
san	Sanskrit
sin	Sinhala; Sinhalese
slk	Slovak
slk_frak	Slovak - Fraktur
slv	Slovenian
spa	Spanish; Castilian
spa_old	Spanish; Castilian - Old
sqi	Albanian
srp	Serbian
srp_latn	Serbian - Latin
swa	Swahili
swe	Swedish
syr	Syriac
tam	Tamil
tel	Telugu
tgk	Tajik
tgl	Tagalog
tha	Thai
tir	Tigrinya
tur	Turkish
uig	Uighur; Uyghur
ukr	Ukrainian
urd	Urdu
uzb	Uzbek
uzb_cyrl	Uzbek - Cyrillic
vie	Vietnamese
yid	Yiddish