Check out example codes for "java change image color". It will help you in understanding the concepts better.

Code Example 1

import java.awt.image.BufferedImage;
import java.awt.image.WritableRaster;
import java.io.File;
// w w w  . jav  a 2s  . com
import javax.imageio.ImageIO;

public class Main {

  public static void main(String[] args) throws Exception {
    BufferedImage img = colorImage(ImageIO.read(new File("NWvnS.png")));
    ImageIO.write(img, "png", new File("Test.png"));
  }

  private static BufferedImage colorImage(BufferedImage image) {
    int width = image.getWidth();
    int height = image.getHeight();
    WritableRaster raster = image.getRaster();

    for (int xx = 0; xx < width; xx++) {
      for (int yy = 0; yy < height; yy++) {
        int[] pixels = raster.getPixel(xx, yy, (int[]) null);
        pixels[0] = 0;
        pixels[1] = 255;
        pixels[2] = 255;
        raster.setPixel(xx, yy, pixels);
      }
    }
    return image;
  }
}

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