利用java打开一张图片，并提取其边缘。功能有打开文件，以及提取边缘。

算法原理

由于边缘提取的算法有很多种，而提取的精度在相同阈值的情况下也会有不同的结果。

这次我的边缘提取使用索贝尔算子(Sobel operator)。

该算子会把图像每一点的灰度矢量计算出来。而分别为横向及纵向，将之与图像作平面卷积，即可分别得出横向及纵向的亮度差分近似值。

算法核心：

public int getGrayPoint(int x, int y) {

return grayData[y * width + x];

}

protected final int GradientX(int x, int y) {

return getGrayPoint(x - 1, y - 1) + 2*getGrayPoint(x - 1, y)+ getGrayPoint(x - 1, y + 1) - getGrayPoint(x + 1, y - 1)- 2*getGrayPoint(x + 1, y) - getGrayPoint(x + 1, y + 1);

}

protected final int GradientY(int x, int y) {

return getGrayPoint(x - 1, y - 1) + 2*getGrayPoint(x, y - 1)+ getGrayPoint(x + 1, y - 1) - getGrayPoint(x - 1, y + 1)- 2*getGrayPoint(x, y + 1) - getGrayPoint(x + 1, y + 1);

而利用JAVA 的GUI界面将图片打开且直接进行操作：

setTitle("Test");

setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);

label = new JLabel();

add(label);

chooser = new JFileChooser();

chooser.setCurrentDirectory(new File("."));

JMenuBar menubar = new JMenuBar();

setJMenuBar(menubar);

JMenu menu = new JMenu("文件");

JMenu menu2 = new JMenu("操作");

menubar.add(menu);

menubar.add(menu2);

JMenuItem openItem = new JMenuItem("打开");

JMenuItem Clicktime = new JMenuItem("提取边缘");

menu.add(openItem);

menu2.add(Clicktime);

JMenuItem exitItem = new JMenuItem("关闭");

menu.add(exitItem);

SobelEdgeDetect tp=new SobelEdgeDetect(50);

openItem.addActionListener(new ActionListener() {

@Override

public void actionPerformed(ActionEvent arg0) {

// TODO Auto-generated method stub

int result = chooser.showOpenDialog(null);

if(result == JFileChooser.APPROVE_OPTION){

String name = chooser.getSelectedFile().getPath();

label.setIcon(new ImageIcon(name));

try {

tp.readImage(name);

} catch (IOException ex) {

Logger.getLogger(ImageViewerFrame.class.getName()).log(Level.SEVERE, null, ex);

}

}

}

});

exitItem.addActionListener(new ActionListener() {

@Override

public void actionPerformed(ActionEvent arg0) {

// TODO Auto-generated method stub

System.exit(0);

}

});

Clicktime.addActionListener(new ActionListener() {

private int heightWMI;

@Override

public void actionPerformed(ActionEvent e) {

String desImageName = "1.jpg";

tp.createEdgeImage(desImageName);

label.setIcon(new ImageIcon(desImageName));

}

});

}

private JLabel label;

private JFileChooser chooser;

private static final int DEFAULT_WIDTH = 1280;

private static final int DEFAULT_HEIGHT =800;

执行后可将图片边缘提取：(这里设定阈值为50)

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