Tesseract 是一款开源的 光学字符识别（OCR）引擎，由 HP 实验室于 1985 年开发，2005 年由 Google 接手维护并开源。它能够从图像中提取文字，支持 100+ 种语言，是当前最流行的 OCR 工具之一。
特点：
- 支持 Windows、macOS、Linux 等操作系统。
- 提供命令行工具和 API，方便集成到其他程序（如 Python、Java、C++ 等）
- 内置主流语言（英语、中文、日语等），支持通过训练数据扩展小众语言。
- 支持 垂直文本 和 复杂排版（如多列文档）
- 从 Tesseract 4.0 开始，引入基于 LSTM（长短期记忆网络） 的 OCR 引擎，显著提升了识别精度
- 允许用户训练自定义模型，优化特定场景（如票据、车牌、手写体等）的识别效果
使用场景就可以非常广泛，可以做PDF扫描件的数据提取、发票数据数字化、号牌识别、名片识别等，相比类似有25K star EasyOCR来说，准确性相对高一些(EasyOCR的在线试用真的很不满意)。
如何安装
以下主要是CentOS7 、MacOS 的安装方式，其他更多Linux版本的安装详见官方，源码包还是编译包安装的形式也可自选。
主要是安装tesseract和tesseract-lang两部分，在ubuntu可采用我们熟悉的apt的方式
CentOS7
CentOS上，就采用yum的方式安装
- 添加仓库地址
$ yum-config-manager --add-repo https://download.opensuse.org/repositories/home:/Alexander_Pozdnyakov/CentOS_7/
已加载插件：fastestmirror
adding repo from: https://download.opensuse.org/repositories/home:/Alexander_Pozdnyakov/CentOS_7/
[download.opensuse.org_repositories_home_Alexander_Pozdnyakov_CentOS_7_]
name=added from: https://download.opensuse.org/repositories/home:/Alexander_Pozdnyakov/CentOS_7/
baseurl=https://download.opensuse.org/repositories/home:/Alexander_Pozdnyakov/CentOS_7/
enabled=1
- 刷新仓库链接
$ sudo rpm --import https://build.opensuse.org/projects/home:Alexander_Pozdnyakov/signing_keys/download?kind=gpg
$ yum update
已加载插件：fastestmirror
Determining fastest mirrors
epel/x86_64/metalink | 5.1 kB 00:00:00
* base: mirrors.aliyun.com
* epel: ftp-stud.hs-esslingen.de
* extras: mirrors.aliyun.com
* remi-php74: ftp.riken.jp
* remi-safe: ftp.riken.jp
* updates: mirrors.aliyun.com
base | 3.6 kB 00:00:00
download.opensuse.org_repositories_home_Alexander_Pozdnyakov_CentOS_7_ | 1.3 kB 00:00:00
extras | 2.9 kB 00:00:00
irontec | 2.5 kB 00:00:00
mysql-connectors-communi
......
- 获取安装包
$ yum install tesseract
已加载插件：fastestmirror
Loading mirror speeds from cached hostfile
* base: mirrors.aliyun.com
* epel: ftp-stud.hs-esslingen.de
* extras: mirrors.aliyun.com
* remi-php74: ftp.riken.jp
* remi-safe: ftp.riken.jp
* updates: mirrors.aliyun.com
正在解决依赖关系
--> 正在检查事务
---> 软件包 tesseract.x86_64.0.4.1.3+git4271-3.1 将被 安装
--> 正在处理依赖关系 tesseract-langpack-osd >= 3.99，它被软件包 tesseract-4.1.3+git4271-3.1.x86_64 需要
--> 正在处理依赖关系 tesseract-langpack-eng >= 3.99，它被软件包 tesseract-4.1.3+git4271-3.1.x86_64 需要
--> 正在处理依赖关系 liblept.so.5()(64bit)，它被软件包 tesseract-4.1.3+git4271-3.1.x86_64 需要
--> 正在检查事务
---> 软件包 leptonica.x86_64.0.1.76.0-2.5 将被 安装
--> 正在处理依赖关系 libwebp.so.4()(64bit)，它被软件包 leptonica-1.76.0-2.5.x86_64 需要
---> 软件包 tesseract-langpack-eng.noarch.0.4.00~git30-5.5 将被 安装
---> 软件包 tesseract-langpack-osd.noarch.0.4.00~git30-5.5 将被 安装
--> 正在检查事务
---> 软件包 libwebp.x86_64.0.0.3.0-11.el7 将被 安装
--> 解决依赖关系完成
依赖关系解决
============================================================================================================================================================================================================
Package 架构 版本 源 大小
============================================================================================================================================================================================================
正在安装:
tesseract x86_64 4.1.3+git4271-3.1 download.opensuse.org_repositories_home_Alexander_Pozdnyakov_CentOS_7_ 10 M
为依赖而安装:
leptonica x86_64 1.76.0-2.5 download.opensuse.org_repositories_home_Alexander_Pozdnyakov_CentOS_7_ 1.0 M
libwebp x86_64 0.3.0-11.el7 updates 170 k
tesseract-langpack-eng noarch 4.00~git30-5.5 download.opensuse.org_repositories_home_Alexander_Pozdnyakov_CentOS_7_ 1.6 M
tesseract-langpack-osd noarch 4.00~git30-5.5 download.opensuse.org_repositories_home_Alexander_Pozdnyakov_CentOS_7_ 3.4 M
事务概要
============================================================================================================================================================================================================
安装 1 软件包 (+4 依赖软件包)
总下载量：17 M
安装大小：55 M
Is this ok [y/d/N]: y
Downloading packages:
(1/5): libwebp-0.3.0-11.el7.x86_64.rpm | 170 kB 00:00:00
(2/5): leptonica-1.76.0-2.5.x86_64.rpm | 1.0 MB 00:01:05
(3/5): tesseract-langpack-eng-4.00~git30-5.5.noarch.rpm | 1.6 MB 00:01:45
(4/5): tesseract-4.1.3+git4271-3.1.x86_64.rpm | 10 MB 00:04:30
(5/5): tesseract-langpack-osd-4.00~git30-5.5.noarch.rpm | 3.4 MB 00:03:28
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
总计 45 kB/s | 17 MB 00:06:20
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
正在安装 : tesseract-langpack-eng-4.00~git30-5.5.noarch 1/5
正在安装 : libwebp-0.3.0-11.el7.x86_64 2/5
正在安装 : leptonica-1.76.0-2.5.x86_64 3/5
正在安装 : tesseract-langpack-osd-4.00~git30-5.5.noarch 4/5
正在安装 : tesseract-4.1.3+git4271-3.1.x86_64 5/5
验证中 : tesseract-4.1.3+git4271-3.1.x86_64 1/5
验证中 : tesseract-langpack-osd-4.00~git30-5.5.noarch 2/5
验证中 : libwebp-0.3.0-11.el7.x86_64 3/5
验证中 : tesseract-langpack-eng-4.00~git30-5.5.noarch 4/5
验证中 : leptonica-1.76.0-2.5.x86_64 5/5
已安装:
tesseract.x86_64 0:4.1.3+git4271-3.1
作为依赖被安装:
leptonica.x86_64 0:1.76.0-2.5 libwebp.x86_64 0:0.3.0-11.el7 tesseract-langpack-eng.noarch 0:4.00~git30-5.5 tesseract-langpack-osd.noarch 0:4.00~git30-5.5
完毕！
继续安装lang包
$ yum install tesseract-langpack-deu
已加载插件：fastestmirror
Loading mirror speeds from cached hostfile
* base: mirrors.aliyun.com
* epel: ftp-stud.hs-esslingen.de
* extras: mirrors.aliyun.com
* remi-php74: ftp.riken.jp
* remi-safe: ftp.riken.jp
* updates: mirrors.aliyun.com
正在解决依赖关系
--> 正在检查事务
---> 软件包 tesseract-langpack-deu.noarch.0.4.00~git30-5.5 将被 安装
--> 解决依赖关系完成
依赖关系解决
============================================================================================================================================================================================================
Package 架构 版本 源 大小
============================================================================================================================================================================================================
正在安装:
tesseract-langpack-deu noarch 4.00~git30-5.5 download.opensuse.org_repositories_home_Alexander_Pozdnyakov_CentOS_7_ 763 k
事务概要
============================================================================================================================================================================================================
安装 1 软件包
总下载量：763 k
安装大小：1.5 M
Is this ok [y/d/N]: y
Downloading packages:
tesseract-langpack-deu-4.00~git30-5.5.noarch.rpm | 763 kB 00:00:03
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
正在安装 : tesseract-langpack-deu-4.00~git30-5.5.noarch 1/1
验证中 : tesseract-langpack-deu-4.00~git30-5.5.noarch 1/1
已安装:
tesseract-langpack-deu.noarch 0:4.00~git30-5.5
完毕！
MacOS
在MacOS中更为简单，同样是更新仓库，拉取安装包安装
$ brew install tesseract
==> Auto-updating Homebrew...
Adjust how often this is run with HOMEBREW_AUTO_UPDATE_SECS or disable with
HOMEBREW_NO_AUTO_UPDATE. Hide these hints with HOMEBREW_NO_ENV_HINTS (see `man brew`).
==> Auto-updated Homebrew!
Updated 3 taps (homebrew/services, homebrew/core and homebrew/cask).
==> New Formulae
adapterremoval bagels feluda gowall identme koji mac pdfly sby threatcl yices2
aqua bazel@7 ggh havener jsrepo lazyjj md2pdf ratarmount soft-serve vfkit yor
arelo code2prompt git-mob hk jupytext libpostal mummer reuse sql-formatter wfa2-lib zimfw
bacon-ls dockerfilegraph go@1.23 hl keeper-commander libpostal-rest nping rustywind symfony-cli yamlfix
==> New Casks
autogram font-big-shoulders font-comic-relief losslessswitcher pinwheel ui-tars
badgeify font-big-shoulders-inline granola luanti precize vezer
browser-actions font-big-shoulders-stencil kunkun mitti structuredlogviewer
You have 15 outdated formulae installed.
继续安装
$ brew install tesseract-lang
==> Downloading https://formulae.brew.sh/api/formula.jws.json
==> Downloading https://formulae.brew.sh/api/cask.jws.json
==> Fetching tesseract-lang
==> Downloading https://mirrors.aliyun.com/homebrew/homebrew-bottles/tesseract-lang-4.1.0.all.bottle.2.tar.gz
##################################################################################################################################################################################################### 100.0%
==> Pouring tesseract-lang-4.1.0.all.bottle.2.tar.gz
🍺 /usr/local/Cellar/tesseract-lang/4.1.0: 165 files, 654.0MB
==> Running `brew cleanup tesseract-lang`...
Disable this behaviour by setting HOMEBREW_NO_INSTALL_CLEANUP.
Hide these hints with HOMEBREW_NO_ENV_HINTS (see `man brew`).
验证与命令行测试
使用命令确认下是否安装成功
$ tesseract -v
tesseract 5.5.0
leptonica-1.85.0
libgif 5.2.2 : libjpeg 8d (libjpeg-turbo 3.0.4) : libpng 1.6.46 : libtiff 4.7.0 : zlib 1.2.11 : libwebp 1.5.0 : libopenjp2 2.5.3
Found AVX2
Found AVX
Found FMA
Found SSE4.1
Found libarchive 3.7.7 zlib/1.2.11 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 nghttp2/1.63.0
使用命令行测试基础功能，是否能够实现图片转文字，可以自备几张英文字、中文字、中英文结合的图片，尽量不要网页那样过于复杂。
# tesseract demo.png stdout -l eng
prod_lua.lua
# tesseract demo2.png stdout -l eng
org.apache.zookeeper.server.quorum.QuorumPeerMain
org.elasticsearch. hootstrap.Elasticsearch
# tesseract demo3.png stdout -l chi_sim
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Python & Java 调用
Java
Tess4J是一款开源的、易于使用的Java API封装，提供了对Tesseract OCR引擎的便捷调用。它使得开发者能够在Java应用程序中轻松实现光学字符识别功能。Tess4J的开发使得Tesseract能够更加贴近Java社区，降低学习曲线，并且为Java开发者提供了一个强大的文字识别工具。
java需要调用主要是服务可以访问到 tesseract 命令、java服务中明确work dir(需要包含tesseract)、maven 引入tess4j
实际调用的方式十分简答
public static void main(String[] args) throws TesseractException {
ITesseract iTesseract = new Tesseract();
iTesseract.setLanguage("chi_sim");
iTesseract.setDatapath("/files/spring-ai-demo/src/main/resources/tessdata");
File img = new File("/Users/admin/Downloads/demo.png");
String ocrResult = iTesseract.doOCR(img);
System.out.println("识别结果: \n" + ocrResult);
}
- language: ocr识别的库，命令行 -l 可选eng/chi_sim/以及trainedata中包含的语种
- datapath: 指向语言traineddata的目录，需要去搜寻匹配的语言
- doOCR: 执行识别
期间遇到的问题有： MacOS + IDEA 程序找不到 tesseract
Suppressed: java.lang.UnsatisfiedLinkError: 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)
通过启动指定work directory解决，Run -> Edit Configurration -> Environment: Work Directory
在系统中查询到 tesseract 的路径
$ whereis tesseract
tesseract: /usr/local/bin/tesseract
将 /usr/local/bin/ 填入 Work Directory
启动后即可执行 OCR。
Python
在AI领域，Python基本是排名第一的，Python有丰富的lib包可以支持这样的功能
确认本地pip和python环境，我这边使用pip3和python3
1、引入依赖：
$ pip3 install pillow
Requirement already satisfied: pillow in /usr/local/lib/python3.11/site-packages (11.1.0)
[notice] A new release of pip is available: 24.3.1 -> 25.0.1
[notice] To update, run: python3.11 -m pip install --upgrade pip
$ pip3 install pytesseract
Collecting pytesseract
Downloading pytesseract-0.3.13-py3-none-any.whl.metadata (11 kB)
Requirement already satisfied: packaging>=21.3 in /usr/local/lib/python3.11/site-packages (from pytesseract) (23.2)
Requirement already satisfied: Pillow>=8.0.0 in /usr/local/lib/python3.11/site-packages (from pytesseract) (11.1.0)
Downloading pytesseract-0.3.13-py3-none-any.whl (14 kB)
Installing collected packages: pytesseract
Successfully installed pytesseract-0.3.13
[notice] A new release of pip is available: 24.3.1 -> 25.0.1
[notice] To update, run: python3.11 -m pip install --upgrade pip
2、编写脚本：
# USAGE
# python ocr.py --image images/example_01.png
# python ocr.py --image images/example_02.png --preprocess blur
# import the necessary packages
from PIL import Image
import pytesseract
import argparse
import cv2
import os
# construct the argument parse and parse the arguments
ap = argparse.ArgumentParser()
ap.add_argument("-i", "--image", required=True,
help="path to input image to be OCR'd")
ap.add_argument("-p", "--preprocess", type=str, default="thresh",
help="type of preprocessing to be done")
args = vars(ap.parse_args())
# load the example image and convert it to grayscale
image = cv2.imread(args["image"])
gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
# check to see if we should apply thresholding to preprocess the
# image
if args["preprocess"] == "thresh":
gray = cv2.threshold(gray, 0, 255,
cv2.THRESH_BINARY | cv2.THRESH_OTSU)[1]
# make a check to see if median blurring should be done to remove
# noise
elif args["preprocess"] == "blur":
gray = cv2.medianBlur(gray, 3)
# write the grayscale image to disk as a temporary file so we can
# apply OCR to it
filename = "{}.png".format(os.getpid())
cv2.imwrite(filename, gray)
# load the image as a PIL/Pillow image, apply OCR, and then delete
# the temporary file
text = pytesseract.image_to_string(Image.open(filename),lang='chi_sim+eng')
os.remove(filename)
print(text)
3、执行脚本
$ python3 ocr.py --image demo.png
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