java - 即使图片中存在条形码，也会出现 NotFoundException

Question

我正在尝试制作一个简单的条形码扫描仪项目来娱乐。我遇到了一个小问题。为此，我使用 zXing 和 Webcam Capture。

即使图片中存在条形码，Java 也会通过 NotFoundException 不断告诉我没有找到条形码。我每次运行 webcamImageObtained 时都会查找一个帧(我假设是每一帧？)，然后在捕获的帧中查找条形码。

我用那个网络摄像头拍了这张照片(讽刺的是使用代码哈哈):

当我将鼠标悬停在这个条形码上时，它报告每秒大约 30 个图像，否则当它从我的屏幕上看我时大约每秒 7-8 个图像(如果这意味着什么的话)。

每当我找到代码时，我都想将其添加到 JList (尚未考虑重复项和类似内容)。

每次 webcamImageObtained(WebcamEvent we) 触发时，我都会调用此代码:

@Override
    public void webcamImageObtained(WebcamEvent we) {
        BufferedImage myImage;
        try {
            myImage = webcam.getImage();
            LuminanceSource source = new BufferedImageLuminanceSource(myImage);
            BinaryBitmap bitmap = new BinaryBitmap(new HybridBinarizer(source));
            Result result = reader.decode(bitmap);
            DefaultListModel dlm = (DefaultListModel) list.getModel();
            dlm.addElement(result.toString());
            list.setModel(dlm);
        } catch (NotFoundException ex) {
            Logger.getLogger(AdvancedWebcamPanelExample.class.getName()).log(Level.SEVERE, null, ex);
        } catch (ChecksumException ex) {
            Logger.getLogger(AdvancedWebcamPanelExample.class.getName()).log(Level.SEVERE, null, ex);
        } catch (FormatException ex) {
            Logger.getLogger(AdvancedWebcamPanelExample.class.getName()).log(Level.SEVERE, null, ex);
        }
    }

这是整个类(class):

package sandbox_webcam;

import com.github.sarxos.webcam.Webcam;
import com.github.sarxos.webcam.WebcamDiscoveryEvent;
import com.github.sarxos.webcam.WebcamDiscoveryListener;
import com.github.sarxos.webcam.WebcamEvent;
import com.github.sarxos.webcam.WebcamListener;
import com.github.sarxos.webcam.WebcamPanel;
import com.github.sarxos.webcam.WebcamPicker;
import com.github.sarxos.webcam.WebcamResolution;
import com.google.zxing.BinaryBitmap;
import com.google.zxing.ChecksumException;
import com.google.zxing.FormatException;
import com.google.zxing.LuminanceSource;
import com.google.zxing.NotFoundException;
import com.google.zxing.Result;
import com.google.zxing.client.j2se.BufferedImageLuminanceSource;
import com.google.zxing.common.HybridBinarizer;
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import java.awt.event.WindowEvent;
import java.awt.event.WindowListener;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.lang.Thread.UncaughtExceptionHandler;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.imageio.ImageIO;
import javax.swing.DefaultListModel;
import javax.swing.JButton;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JList;
import javax.swing.JPanel;

public class AdvancedWebcamPanelExample extends JFrame implements Runnable, WebcamListener, WindowListener, UncaughtExceptionHandler, ItemListener, WebcamDiscoveryListener {

    private Webcam webcam = null;
    private WebcamPanel panel = null;
    private WebcamPicker picker = null;
    private JButton button = null;
    private JList list = null;
    private ActionListener buttonListener = null;
    private com.google.zxing.Reader reader = new com.google.zxing.MultiFormatReader();

    @Override
    public void run() {
        Webcam.addDiscoveryListener(this);

        setTitle("Java Webcam Capture POC");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setLayout(new BorderLayout());

        addWindowListener(this);

        picker = new WebcamPicker();
        picker.addItemListener(this);

        webcam = picker.getSelectedWebcam();

        if (webcam == null) {
            System.out.println("No webcams found...");
            System.exit(1);
        }

        webcam.setViewSize(WebcamResolution.VGA.getSize());
        webcam.addWebcamListener(AdvancedWebcamPanelExample.this);

        panel = new WebcamPanel(webcam, false);
        panel.setFPSDisplayed(true);

        buttonListener = new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                if (webcam != null) {
                    BufferedImage image = webcam.getImage();
                    JFileChooser filechooser = new JFileChooser();

                    int saveValue = filechooser.showDialog(button, "Save");
                    if (saveValue == JFileChooser.APPROVE_OPTION) {
                        try {
                            File f = filechooser.getSelectedFile();
                            ImageIO.write(image, "png", new File(f.getAbsolutePath() + ".png"));
                            System.out.println("Picture saved at: " + f.getAbsolutePath());
                        } catch (IOException ex) {
                            System.err.println("Failed to save the picture!");
                            ex.printStackTrace();
                        }
                    }
                } else {
                    System.err.println("no webcam found to take a picture");
                }
            }
        };

        button = new JButton("Snap a Picture!");
        button.addActionListener(buttonListener);
        list = new JList();
        list.setMinimumSize(new Dimension(200,this.getHeight()));

        add(picker, BorderLayout.NORTH);
        add(panel, BorderLayout.CENTER);
        add(button, BorderLayout.SOUTH);
        add(list, BorderLayout.EAST);

        pack();
        setVisible(true);

        Thread t = new Thread() {
            @Override
            public void run() {
                panel.start();
            }
        };

        t.setName("example-starter");
        t.setDaemon(true);
        t.setUncaughtExceptionHandler(this);
        t.start();
    }

    @Override
    public void webcamOpen(WebcamEvent we) {
        System.out.println("webcam open");
    }

    @Override
    public void webcamClosed(WebcamEvent we) {
        System.out.println("webcam closed");
    }

    @Override
    public void webcamDisposed(WebcamEvent we) {
        System.out.println("webcam disposed");
    }

    @Override
    public void webcamImageObtained(WebcamEvent we) {
        BufferedImage myImage;
        try {
            myImage = webcam.getImage();
            LuminanceSource source = new BufferedImageLuminanceSource(myImage);
            BinaryBitmap bitmap = new BinaryBitmap(new HybridBinarizer(source));
            Result result = reader.decode(bitmap);
            DefaultListModel dlm = (DefaultListModel) list.getModel();
            dlm.addElement(result.toString());
            list.setModel(dlm);
        } catch (NotFoundException ex) {
            Logger.getLogger(AdvancedWebcamPanelExample.class.getName()).log(Level.SEVERE, null, ex);
        } catch (ChecksumException ex) {
            Logger.getLogger(AdvancedWebcamPanelExample.class.getName()).log(Level.SEVERE, null, ex);
        } catch (FormatException ex) {
            Logger.getLogger(AdvancedWebcamPanelExample.class.getName()).log(Level.SEVERE, null, ex);
        }
    }

    @Override
    public void windowOpened(WindowEvent e) {
        // do nothing
    }

    @Override
    public void windowClosing(WindowEvent e) {
        // do nothing
    }

    @Override
    public void windowClosed(WindowEvent e) {
        webcam.close();
    }

    @Override
    public void windowIconified(WindowEvent e) {
        System.out.println("webcam viewer paused");
        panel.pause();
    }

    @Override
    public void windowDeiconified(WindowEvent e) {
        System.out.println("webcam viewer resumed");
        panel.resume();
    }

    @Override
    public void windowActivated(WindowEvent e) {
        // do nothing
    }

    @Override
    public void windowDeactivated(WindowEvent e) {
        // do nothing
    }

    @Override
    public void uncaughtException(Thread t, Throwable e) {
        System.err.println(String.format("Exception in thread #s", t.getName()));
        e.printStackTrace();
    }

    @Override
    public void itemStateChanged(ItemEvent e) {
        if (e.getItem() != webcam) {
            if (webcam != null) {
                panel.stop();

                remove(panel);
                webcam.removeWebcamListener(this);
                webcam.close();

                webcam = (Webcam) e.getItem();
                webcam.setViewSize(WebcamResolution.VGA.getSize());
                webcam.addWebcamListener(this);

                System.out.println("selected " + webcam.getName());

                panel = new WebcamPanel(webcam, false);
                panel.setFPSDisplayed(true);

                add(panel, BorderLayout.CENTER);
                pack();

                Thread t = new Thread() {
                    @Override
                    public void run() {
                        panel.start();
                    }
                };

                t.setName("example-stopper");
                t.setDaemon(true);
                t.setUncaughtExceptionHandler(this);
                t.start();
            }
        }
    }

    @Override
    public void webcamFound(WebcamDiscoveryEvent event) {
        if (picker != null) {
            picker.addItem(event.getWebcam());
        }
    }

    @Override
    public void webcamGone(WebcamDiscoveryEvent event) {
        if (picker != null) {
            picker.removeItem(event.getWebcam());
        }
    }

}

我是否遗漏了有关该库如何扫描条形码的信息？

编辑

不确定这有多大帮助..

Mar 02, 2015 10:04:34 PM sandbox_webcam.AdvancedWebcamPanelExample webcamImageObtained
SEVERE: null
com.google.zxing.NotFoundException

这里抛出异常:

Result result = reader.decode(bitmap);

Answer 1

有一个不同的问题，有一些可用的答案:Android zxing NotFoundException

正如詹姆斯所说，如果条码不起作用，并且在不同的环境和照明条件下，尝试在不同的介质(纸张/屏幕)上使用条码是一个好主意。特别要确保光线充足，并且摄像头对准条码时的 FPS 足够高。

为了进行调试，还可以将BinaryImage转换回可查看的格式，并检查转换为黑白后条形码是否实际上可见。