Mac Java 使用 tesseract 进行 ORC 识别

在 Java 开发中使用图片转文字时，难免会遇到问题，比如我使用 Mac (M1 芯片) 系统进行开发，就出现报错。

博主博客

https://blog.uso6.com
https://blog.csdn.net/dxk539687357

一、直接使用

1. 使用 brew 进行安装

brew install tesseract

如果是其他系统的，建议看官方文档进行安装。

2. 查看版本

nukix@nukixPC ~ % tesseract --version
tesseract 5.5.0
leptonica-1.85.0
libgif 5.2.2 : libjpeg 8d (libjpeg-turbo 3.0.4) : libpng 1.6.44 : libtiff 4.7.0 : zlib 1.2.12 : libwebp 1.4.0 : libopenjp2 2.5.2
Found NEON
Found libarchive 3.7.7 zlib/1.2.12 liblzma/5.6.3 bz2lib/1.0.8 liblz4/1.10.0 libzstd/1.5.6
Found libcurl/8.7.1 SecureTransport (LibreSSL/3.3.6) zlib/1.2.12 nghttp2/1.62.0

3. 查看安装路径

brew list tesseract

比如我安装路径是 /opt/homebrew/Cellar/tesseract/5.5.0，下面会用到。

4. 在图片中识别文字（英文）

tesseract abc.jpg out.txt -l eng

命令 tesseract 图片路径输出文件 -l 语言码，我上面的命令识别出来的结果会在 out.txt 文件中。

语言码可以在这里找到。

5. 语言包下载

语言包传送门： tessdata

根据自己需要下载对应的语言包，比如中文的语言包是 chi_tra.traineddata。

下载后放到 tessdata 目录下面，比如我的目录在 /opt/homebrew/Cellar/tesseract/5.5.0/share/tessdata。

二、Java API 调用

2.1 导入 Maven 库

因为 tesseract 是一个 C 语言库，所以不能直接使用，官方推荐了其他语言一些第三方封装库可以在这里查看，而 Java 是 tess4j。

Gradle(short)

implementation 'net.sourceforge.tess4j:tess4j:5.13.0'

Maven

<dependency><groupId>net.sourceforge.tess4j</groupId><artifactId>tess4j</artifactId><version>5.13.0</version>
</dependency>

2.2 Java 调用

根据文档的案例，可以这样调用。

package tess4j.example;import java.io.File;
import net.sourceforge.tess4j.*;public class TesseractExample {public static void main(String[] args) {// System.setProperty("jna.library.path", "32".equals(System.getProperty("sun.arch.data.model")) ? "lib/win32-x86" : "lib/win32-x86-64");File imageFile = new File("eurotext.tif");ITesseract instance = new Tesseract();  // JNA Interface Mapping// ITesseract instance = new Tesseract1(); // JNA Direct Mapping// File tessDataFolder = LoadLibs.extractTessResources("tessdata"); // Maven build bundles English data// instance.setDatapath(tessDataFolder.getPath());try {String result = instance.doOCR(imageFile);System.out.println(result);} catch (TesseractException e) {System.err.println(e.getMessage());}}
}

2.3 java.lang.UnsatisfiedLinkError: Unable to load library ‘tesseract’

问题

不出意外的话会有这一个异常，运行库中没有 tesseract 库。

java.lang.UnsatisfiedLinkError: Unable to load library 'tesseract':
dlopen(libtesseract.dylib, 0x0009): tried: 'libtesseract.dylib' (no such file), '/System/Volumes/Preboot/Cryptexes/OSlibtesseract.dylib' (no such file), '/Users/nukix/Library/Java/JavaVirtualMachines/openjdk-18.0.2.1/Contents/Home/bin/./libtesseract.dylib' (no such file), '/Users/nukix/Library/Java/JavaVirtualMachines/openjdk-18.0.2.1/Contents/Home/bin/../lib/libtesseract.dylib' (no such file), '/usr/lib/libtesseract.dylib' (no such file, not in dyld cache), 'libtesseract.dylib' (no such file), '/usr/lib/libtesseract.dylib' (no such file, not in dyld cache)
dlopen(libtesseract.dylib, 0x0009): tried: 'libtesseract.dylib' (no such file), '/System/Volumes/Preboot/Cryptexes/OSlibtesseract.dylib' (no such file), '/Users/nukix/Library/Java/JavaVirtualMachines/openjdk-18.0.2.1/Contents/Home/bin/./libtesseract.dylib' (no such file), '/Users/nukix/Library/Java/JavaVirtualMachines/openjdk-18.0.2.1/Contents/Home/bin/../lib/libtesseract.dylib' (no such file), '/usr/lib/libtesseract.dylib' (no such file, not in dyld cache), 'libtesseract.dylib' (no such file), '/usr/lib/libtesseract.dylib' (no such file, not in dyld cache)
dlopen(/Users/nukix/Library/Frameworks/tesseract.framework/tesseract, 0x0009): tried: '/Users/nukix/Library/Frameworks/tesseract.framework/tesseract' (no such file), '/System/Volumes/Preboot/Cryptexes/OS/Users/nukix/Library/Frameworks/tesseract.framework/tesseract' (no such file), '/Users/nukix/Library/Frameworks/tesseract.framework/tesseract' (no such file), '/System/Library/Frameworks/tesseract.framework/tesseract' (no such file, not in dyld cache)
dlopen(/Library/Frameworks/tesseract.framework/tesseract, 0x0009): tried: '/Library/Frameworks/tesseract.framework/tesseract' (no such file), '/System/Volumes/Preboot/Cryptexes/OS/Library/Frameworks/tesseract.framework/tesseract' (no such file), '/Library/Frameworks/tesseract.framework/tesseract' (no such file), '/System/Library/Frameworks/tesseract.framework/tesseract' (no such file, not in dyld cache)
dlopen(/System/Library/Frameworks/tesseract.framework/tesseract, 0x0009): tried: '/System/Library/Frameworks/tesseract.framework/tesseract' (no such file), '/System/Volumes/Preboot/Cryptexes/OS/System/Library/Frameworks/tesseract.framework/tesseract' (no such file), '/System/Library/Frameworks/tesseract.framework/tesseract' (no such file, not in dyld cache)
Native library (darwin-aarch64/libtesseract.dylib) not found in resource path (/Users/nukix/AndroidStudioProjects/nukix/TestWeb/build/classes/java/main:/Users/nukix/AndroidStudioProjects/nukix/TestWeb/build/resources/main)at com.sun.jna.NativeLibrary.loadLibrary(NativeLibrary.java:325) ~[jna-5.14.0.jar:5.14.0 (b0)]at com.sun.jna.NativeLibrary.getInstance(NativeLibrary.java:481) ~[jna-5.14.0.jar:5.14.0 (b0)]at com.sun.jna.Library$Handler.<init>(Library.java:197) ~[jna-5.14.0.jar:5.14.0 (b0)]at com.sun.jna.Native.load(Native.java:618) ~[jna-5.14.0.jar:5.14.0 (b0)]at com.sun.jna.Native.load(Native.java:592) ~[jna-5.14.0.jar:5.14.0 (b0)]at net.sourceforge.tess4j.util.LoadLibs.getTessAPIInstance(LoadLibs.java:83) ~[tess4j-5.13.0.jar:5.13.0]at net.sourceforge.tess4j.TessAPI.<clinit>(TessAPI.java:42) ~[tess4j-5.13.0.jar:5.13.0]at net.sourceforge.tess4j.Tesseract.init(Tesseract.java:353) ~[tess4j-5.13.0.jar:5.13.0]at net.sourceforge.tess4j.Tesseract.doOCR(Tesseract.java:202) ~[tess4j-5.13.0.jar:5.13.0]at net.sourceforge.tess4j.ITesseract.doOCR(ITesseract.java:59) ~[tess4j-5.13.0.jar:5.13.0]

解决

根据报错的路径，把文件复制过去，比如我报错的路径是 /Users/nukix/Library/Frameworks/tesseract.framework/tesseract。

先创建文件夹

mkdir -p /Users/nukix/Library/Frameworks/tesseract.framework

复制文件

cp /opt/homebrew/Cellar/tesseract/5.5.0/share/tessdata /Users/nukix/Library/Frameworks/tesseract.framework

2.4 Error opening data file ./eng.traineddata

问题

不出意外的话，会提示找不到语言包。

Error opening data file ./eng.traineddata
Please make sure the TESSDATA_PREFIX environment variable is set to your "tessdata" directory.
Failed loading language 'eng'
Tesseract couldn't load any languages!