驗證碼識別

其實，驗證碼識別其實就是用好用好tesseract-ocr，下面我先說下步驟：

1、去https://github.com/tesseract-ocr/tesseract/wiki 下載tesseract-ocr，然後安裝一下；

2、代碼中pom中加入：

<dependency>
    <groupId>net.sourceforge.tess4j</groupId>
    <artifactId>tess4j</artifactId>
    <version>3.1.0</version>
</dependency>

3、使用最最基本的圖片識別API

ITesseract instance = new Tesseract();

String ocrResult = null;

try {
   ocrResult = instance.doOCR(imgFile);
} catch (Exception e) {
   e.printStackTrace();
}

4、以上識別只能識別最最最簡單的驗證碼圖片，要想提高準確率，就需要去除噪音，先上傳個簡單的例子吧

package util;

import net.sourceforge.tess4j.ITesseract;
import net.sourceforge.tess4j.Tesseract;

import java.awt.Color;
import java.awt.color.ColorSpace;
import java.awt.image.BufferedImage;
import java.awt.image.ColorConvertOp;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;

public class ClearImageUtil {
    
    public static void cleanImage(File sfile, String destDir)throws IOException{
        File destF = new File(destDir);
        if (!destF.exists()){
            destF.mkdirs();
        }

        BufferedImage bufferedImage = ImageIO.read(sfile);
        int h = bufferedImage.getHeight();
        int w = bufferedImage.getWidth();

        // 灰度化
        int[][] gray = new int[w][h];
        for (int x = 0; x < w; x++){
            for (int y = 0; y < h; y++){
                int argb = bufferedImage.getRGB(x, y);
                // 圖像加亮（調整亮度識別率非常高）
                int r = (int) (((argb >> 16) & 0xFF) * 1.1 + 30);
                int g = (int) (((argb >> 8) & 0xFF) * 1.1 + 30);
                int b = (int) (((argb >> 0) & 0xFF) * 1.1 + 30);
                if (r >= 255){
                    r = 255;
                }
                if (g >= 255){
                    g = 255;
                }
                if (b >= 255){
                    b = 255;
                }
                gray[x][y] = (int) Math.pow((Math.pow(r, 2.2) * 0.2973 + Math.pow(g, 2.2)* 0.6274 + Math.pow(b, 2.2) * 0.0753), 1 / 2.2);
            }
        }

        // 二值化
        int threshold = ostu(gray, w, h);
        if (threshold < 160 && threshold > 100)
            threshold -= 50;
        else if (threshold < 50)
            threshold = 50;
        BufferedImage binaryBufferedImage = new BufferedImage(w, h,BufferedImage.TYPE_BYTE_BINARY);
        for (int x = 0; x < w; x++){
            for (int y = 0; y < h; y++){
                if (gray[x][y] > threshold){
                    gray[x][y] |= 0x00FFFF;
                } else{
                    gray[x][y] &= 0xFF0000;
                }
                binaryBufferedImage.setRGB(x, y, gray[x][y]);
            }
        }

        ImageIO.write(binaryBufferedImage, "png", new File(destDir, sfile.getName()));
    }

    
    public static int getColorBright(int colorInt){
        Color color = new Color(colorInt);
        return color.getRed() + color.getGreen() + color.getBlue();
    }

    public static int ostu(int[][] gray, int w, int h){
        int[] histData = new int[w * h];
        // Calculate histogram
        for (int x = 0; x < w; x++){
            for (int y = 0; y < h; y++){
                int red = 0xFF & gray[x][y];
                histData[red]++;
            }
        }

        // Total number of pixels
        int total = w * h;

        float sum = 0;
        for (int t = 0; t < 256; t++)
            sum += t * histData[t];

        float sumB = 0;
        int wB = 0;
        int wF = 0;

        float varMax = 0;
        int threshold = 0;

        for (int t = 0; t < 256; t++){
            wB += histData[t]; // Weight Background
            if (wB == 0)
                continue;

            wF = total - wB; // Weight Foreground
            if (wF == 0)
                break;

            sumB += (float) (t * histData[t]);

            float mB = sumB / wB; // Mean Background
            float mF = (sum - sumB) / wF; // Mean Foreground

            // Calculate Between Class Variance
            float varBetween = (float) wB * (float) wF * (mB - mF) * (mB - mF);

            // Check if new maximum found
            if (varBetween > varMax){
                varMax = varBetween;
                threshold = t;
            }
        }

        return threshold;
    }
    //圖片灰度，黑白
    public static void gray(String srcImageFile, String destImageFile) {
        try {
            BufferedImage src = ImageIO.read(new File(srcImageFile));
            ColorSpace cs = ColorSpace.getInstance(ColorSpace.CS_GRAY);
            ColorConvertOp op = new ColorConvertOp(cs, null);
            src = op.filter(src, null);
            ImageIO.write(src, "JPEG", new File(destImageFile));
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

//只獲取數字和字母
    public static String getRcode(String imgfile) {
        String destDir ="img_des\\";
        String graydir = "img_gray\\";
        String reg = "[0-9a-zA-Z]";
        File f = new File(imgfile);
        System.out.println(f.getName());
        System.out.println(destDir + f.getName());
        try {
            cleanImage(f, destDir);
            cleanImage(new File(destDir + f.getName()), graydir);
            ITesseract instance = new Tesseract();
            String ocrResult = instance.doOCR(new File(graydir +f.getName()));
            String rcode = StringUtil.regstr(reg, ocrResult);
            return rcode;
        } catch (IOException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }
    public static String getRcode(File f) {
        String destDir ="img_des\\";
        String graydir = "img_gray\\";
        String reg = "[0-9a-zA-Z]";
        try {
            cleanImage(f, destDir);
            cleanImage(new File(destDir + f.getName()), graydir);
            ITesseract instance = new Tesseract();
            String ocrResult = instance.doOCR(new File(graydir +f.getName()));
            String rcode = StringUtil.regstr(reg, ocrResult);
            return rcode;
        } catch (IOException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }
    public static void main(String[] args) throws IOException{   
        File testDataDir = new File("C:\\Users\\你好\\Desktop\\驗證碼\\");//去噪
        String destDir ="C:\\Users\\nihao\\Desktop\\s2\\";
        String graydir = "C:\\Users\\nihao\\Desktop\\s3\\";
        for (File f :testDataDir.listFiles()) {
            System.out.println(f.getName());
            System.out.println(destDir + f.getName());
            cleanImage(f, destDir);
            cleanImage(new File(destDir + f.getName()), graydir);
        }
    }
}