Getting Image Pixels

In this simple program, when a button is clicked, the RGB values of an image are displayed on a text area.

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import java.awt.*; import java.awt.Image; import java.awt.image.BufferedImage; import java.awt.event.*; import java.io.*; import javax.imageio.ImageIO; import javax.swing.*; import javax.swing.event.*; import java.util.*; public class GettingPixel extends JFrame{ private File imagefile=null; private BufferedImage bufimage=null; private JLabel label=null; private ImageIcon icon=null; private JButton button=null; private JTextArea tarea=null; public static void main(String[] args){ GettingPixel ap=new GettingPixel(); } public GettingPixel(){ super("Getting Pixel"); setSize(1220,540); label=new JLabel(); try{ imagefile=new File("robot.jpg"); bufimage=ImageIO.read(imagefile); }catch(Exception e){ } icon=new ImageIcon(bufimage); label.setIcon(icon); button=new JButton("Get Pixel"); button.addActionListener(new ButtonHandler()); tarea=new JTextArea(30,40); JScrollPane scroll=new JScrollPane(tarea); setLayout(new FlowLayout(FlowLayout.LEFT,10,10)); add(label); add(button); add(scroll); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); show(); } class ButtonHandler implements ActionListener{ public void actionPerformed(ActionEvent e){ int width=bufimage.getWidth(); int height=bufimage.getHeight(); int count=0; for(int i=0;i<height;i++){ for(int j=0;j<width;j++){ Color c=new Color(bufimage.getRGB(j,i)); tarea.append("("+j+","+i+")"+" "+c.getRed()+","+c.getGreen()+","+c.getBlue()+"\n"); } } } } }

try{
     imagefile=new File("robot.jpg");
     bufimage=ImageIO.read(imagefile);
}catch(Exception e){
}
icon=new ImageIcon(bufimage);
label.setIcon(icon);

The first line opens the image file "robot.jpg". ImageIO.read reads the image file. As image read write operation can throw an IOException, the code is placed inside a try/catch block. The BufferedImage object holds the image. The ImageIcon class is used to add the image to the label.

int width=bufimage.getWidth();
int height=bufimage.getHeight();

These two lines of code get the width and height of the image. The values will be used to access each pixel through a nested loop (one loop inside another).

int count=0;
for(int i=0;i<height;i++){
     for(int j=0;j<width;j++){
          Color c=new Color(bufimage.getRGB(j,i));
          tarea.append("("+j+","+i+")"+" "+c.getRed()+","+c.getGreen()+","+c.getBlue()+"\n");
     }
}

All pixels are fetched, starting from the upper left corner of the image (coordinate 0,0).

Color c=new Color(bufimage.getRGB(j,i));
tarea.append("("+j+","+i+")"+" "+c.getRed()+","+c.getGreen()+","+c.getBlue()+"\n");

This is the code to get the pixel value. The getRGB method returns a single int. To get the individual color components, we use getRed(), .getGreen(), and getBlue methods. The results are then displayed on the text area using append method.