Java Tutorial/2D Graphics/RGBImageFilter

Extend RGBImageFilter ColorFilter class

import java.awt.image.RGBImageFilter;
class ColorFilter extends RGBImageFilter {
  boolean red, green, blue;
  public ColorFilter(boolean r, boolean g, boolean b) {
    red = r;
    green = g;
    blue = b;
    canFilterIndexColorModel = true;
  }
  public int filterRGB(int x, int y, int rgb) {
    int r = red ? 0 : ((rgb >> 16) & 0xff);
    int g = green ? 0 : ((rgb >> 8) & 0xff);
    int b = blue ? 0 : ((rgb >> 0) & 0xff);
    return (rgb & 0xff000000) | (r << 16) | (g << 8) | (b << 0);
  }
}

Extend RGBImageFilter to create AlphaFilter class

import java.awt.image.RGBImageFilter;
class AlphaFilter extends RGBImageFilter {
  int alphaLevel;
  public AlphaFilter(int alpha) {
    alphaLevel = alpha;
    canFilterIndexColorModel = true;
  }
  public int filterRGB(int x, int y, int rgb) {
    int alpha = (rgb >> 24) & 0xff;
    alpha = (alpha * alphaLevel) / 255;
    return ((rgb & 0x00ffffff) | (alpha << 24));
  }
}