I must read some image and then I have to change brightness and contrast of this image I create main class and constructor where are panels, sliders and other stuff, I added changeListener to slider to take current value. My imagePanel is new Object of that class:

public class Obrazek extends JPanel{

  public static BufferedImage img = null;

  public Obrazek() {
    super();
    try {
        img = ImageIO.read(new File("D:\\ja.jpg"));
    } catch (IOException e) {}
}
@Override
public void paint(Graphics g) {
    g.drawImage(img, 0, 0, null);
}
}

This is my load button

private void przyciskWczytaj(java.awt.event.ActionEvent evt) {                                 
    int odpowiedz = jFileChooser1.showOpenDialog(this);
if (odpowiedz == jFileChooser1.APPROVE_OPTION) {
    File file = jFileChooser1.getSelectedFile();
    try {
           BufferedImage im = ImageIO.read(new File(file.getAbsolutePath()));
       Obrazek.img = im;
    } catch (IOException ex) {
            System.out.println("Error");
    }
}
}  

And now I want to create class where I will change that brightness. I have to use but I don't know how to use that thing:

BufferedImage(256, 256, Bufferedmage.TYPE_INT_RGB)

and to get each pixel of image I need to do something like:

int rgb []=((DataBufferInt)img.getRaster().getDataBuffer()).getData();

And here I is next problem: How can I change the value of each r,g,b and show that new image on my panel