Extracting Text From an Image

Years ago, extracting text from images seemed to be one of the greatest challenges to all developers. Now, with the arrival of great tools, reading and extracting text from images is easy.

Today's I'll be explaining how to extract text from images using the Java Tesseract API from net.sourceforge.tess4j.

Extracting text from an image means that you are considering the flowchart imagery that's processed to extract the text components and then extracting the geometrical shapes components. The text components are extracted with geometrical components, as well. The internal relationship between the components is set up by tracing the flow lines that connect different components. The extracted components are output to metadata (in XML format), which is machine-readable. This metadata can be archived, stored in a knowledge base, or shared with others.

Below is the code for extracting text from images using the Java Tesseract API from  net.sourceforge.tess4j. 

1. Adding the API

Add the net.sourceforge.tess4j.*; API to your pom.xml:

<dependency> 
 <groupId>net.sourceforge.tess4j</groupId> 
 <artifactId>tess4j</artifactId> 
 <version>3.2.1</version> 
</dependency>

This is the image that we're extracting the text from:

2. Download the CAPTCHA Language Extractor

Download the CAPTCHA language extractor and put it in the tessdata folder.

For example, if you download eng.trainedata from the above URL, put the file at the project root folder tessdata/eng-trainedata .

 3. Read the Code

Here's the Java code that will read the text from an image in any format:

package com.amudabadmus.awfa;
import net.sourceforge.tess4j.*;
import java.io.*;
public class App {
    public String getImgText(String imageLocation) {
      ITesseract instance = new Tesseract();
      try 
      {
         String imgText = instance.doOCR(new File(imageLocation));
         return imgText;
      } 
      catch (TesseractException e) 
      {
         e.getMessage();
         return "Error while reading image";
      }
   }
   public static void main ( String[] args)
   {
      App app = new App();
      System.out.println(app.getImgText("C:\\Users\\User\\Pictures\\img.png"));
   }
}

For more information, check out the source code and the demo.