java文字识别技术
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 = (ImageReader) 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 }