识别率很高的java文字识别技术

2019-04-25 06:52:03来源：博客园阅读 ()

java文字识别程序的关键是寻找一个可以调用的OCR引擎。tesseract-ocr就是一个这样的OCR引擎，在1985年到1995年由HP实验室开发，现在在Google。tesseract-ocr 3.0发布，支持中文。不过tesseract-ocr 3.0不是图形化界面的客户端，别人写的FreeOCR图形化客户端还不支持导入新的 3.0 traineddata。但这标志着，现在有自由的中文OCR软件了。

java中使用tesseract-ocr3.01的步骤如下：

1.下载安装tesseract-ocr-setup-3.01-1.exe（3.0以上版本才增加了中文识别）

2.在安装向导中可以选择需要下载的语言包。

3.到网上搜索下载java图形处理所需的2个包：jai_imageio-1.1-alpha.jar，swingx-1.6.1.jar

4.java程序清单：

ImageIOHelper 类：

 1 import java.awt.image.BufferedImage;
 2 import java.io.File;
 3 import java.io.IOException;
 4 import java.util.Iterator;
 5 import java.util.Locale;
 6  
 7 import javax.imageio.IIOImage;
 8 import javax.imageio.ImageIO;
 9 import javax.imageio.ImageReader;
10 import javax.imageio.ImageWriteParam;
11 import javax.imageio.ImageWriter;
12 import javax.imageio.metadata.IIOMetadata;
13 import javax.imageio.stream.ImageInputStream;
14 import javax.imageio.stream.ImageOutputStream;
15  
16 import com.sun.media.imageio.plugins.tiff.TIFFImageWriteParam;
17  
18 public class ImageIOHelper { 
19    
20  public static File createImage(File imageFile, String imageFormat) { 
21   File tempFile = null; 
22   try { 
23    Iterator readers = ImageIO.getImageReadersByFormatName(imageFormat); 
24    ImageReader reader = readers.next(); 
25     
26    ImageInputStream iis = ImageIO.createImageInputStream(imageFile); 
27    reader.setInput(iis); 
28    //Read the stream metadata 
29    IIOMetadata streamMetadata = reader.getStreamMetadata(); 
30      
31    //Set up the writeParam 
32    TIFFImageWriteParam tiffWriteParam = new TIFFImageWriteParam(Locale.CHINESE); 
33    tiffWriteParam.setCompressionMode(ImageWriteParam.MODE_DISABLED); 
34      
35    //Get tif writer and set output to file 
36    Iterator writers = ImageIO.getImageWritersByFormatName("tiff"); 
37    ImageWriter writer = writers.next(); 
38      
39    BufferedImage bi = reader.read(0); 
40    IIOImage image = new IIOImage(bi,null,reader.getImageMetadata(0)); 
41    tempFile = tempImageFile(imageFile); 
42    ImageOutputStream ios = ImageIO.createImageOutputStream(tempFile); 
43    writer.setOutput(ios); 
44    writer.write(streamMetadata, image, tiffWriteParam); 
45    ios.close(); 
46      
47    writer.dispose(); 
48    reader.dispose(); 
49      
50   } catch (IOException e) { 
51    e.printStackTrace(); 
52   } 
53   return tempFile; 
54  } 
55   
56  private static File tempImageFile(File imageFile) { 
57   String path = imageFile.getPath(); 
58   StringBuffer strB = new StringBuffer(path); 
59   strB.insert(path.lastIndexOf('.'),0); 
60   return new File(strB.toString().replaceFirst("(?<=//.)(//w+)$", "tif")); 
61  } 
62   
63 }

OCR 类：

 1 package com.hhp.util;
 2  
 3 import java.io.BufferedReader; 
 4 import java.io.File; 
 5 import java.io.FileInputStream; 
 6 import java.io.InputStreamReader; 
 7 import java.util.ArrayList; 
 8 import java.util.List; 
 9 import org.jdesktop.swingx.util.OS; 
10   
11 public class OCR { 
12  private final String LANG_OPTION = "-l"; //英文字母小写l，并非数字1 
13  private final String EOL = System.getProperty("line.separator"); 
14  private String tessPath = "C://Program Files (x86)//Tesseract-OCR"; 
15  //private String tessPath = new File("tesseract").getAbsolutePath(); 
16    
17  public String recognizeText(File imageFile,String imageFormat)throws Exception{ 
18   File tempImage = ImageIOHelper.createImage(imageFile,imageFormat); 
19   File outputFile = new File(imageFile.getParentFile(),"output"); 
20   StringBuffer strB = new StringBuffer(); 
21   List cmd = new ArrayList(); 
22   if(OS.isWindowsXP()){ 
23    cmd.add(tessPath+"//tesseract"); 
24   }else if(OS.isLinux()){ 
25    cmd.add("tesseract"); 
26   }else{ 
27    cmd.add(tessPath+"//tesseract"); 
28   } 
29   cmd.add(""); 
30   cmd.add(outputFile.getName()); 
31   cmd.add(LANG_OPTION); 
32   cmd.add("chi_sim"); 
33   //cmd.add("eng"); 
34     
35   ProcessBuilder pb = new ProcessBuilder(); 
36   pb.directory(imageFile.getParentFile()); 
37     
38   cmd.set(1, tempImage.getName()); 
39   pb.command(cmd); 
40   pb.redirectErrorStream(true); 
41     
42   Process process = pb.start(); 
43   //tesseract.exe 1.jpg 1 -l chi_sim 
44   int w = process.waitFor(); 
45     
46   //删除临时正在工作文件 
47   tempImage.delete(); 
48     
49   if(w==0){ 
50    BufferedReader in = new BufferedReader(new InputStreamReader(new FileInputStream(outputFile.getAbsolutePath()+".txt"),"UTF-8")); 
51      
52    String str; 
53    while((str = in.readLine())!=null){ 
54     strB.append(str).append(EOL); 
55    } 
56    in.close(); 
57   }else{ 
58    String msg; 
59    switch(w){ 
60     case 1: 
61      msg = "Errors accessing files.There may be spaces in your image's filename."; 
62      break; 
63     case 29: 
64      msg = "Cannot recongnize the image or its selected region."; 
65      break; 
66     case 31: 
67      msg = "Unsupported image format."; 
68      break; 
69     default: 
70      msg = "Errors occurred."; 
71    } 
72    tempImage.delete(); 
73    throw new RuntimeException(msg); 
74   } 
75   new File(outputFile.getAbsolutePath()+".txt").delete(); 
76   return strB.toString(); 
77  } 
78 }

测试类TestOCR ：

 1 import java.io.File;
 2 import java.io.IOException;
 3  
 4 import com.hhp.util.OCR;
 5  
 6 public class OcrTest {
 7  
 8  public static void main(String[] args) {
 9   String path = "C://temp//OCRcode//4.png";  
10   System.out.println("ORC Test Begin......");
11   try {  
12    String valCode = new OCR().recognizeText(new File(path), "png");  
13    System.out.println(valCode);  
14   } catch (IOException e) {  
15    e.printStackTrace();  
16   } catch (Exception e) { 
17    e.printStackTrace(); 
18   }  
19   System.out.println("ORC Test End......");
20  } 
21  
22 }