private void setGrayFilterProperty(String prop, int value) {
    GrayFilter filter = getGrayFilter();
    int brightness = filter.getBrightness();
    int contrast = filter.getContrast();
    int alpha = filter.getAlpha();

    if ("brightness".equals(prop)) {
      brightness = value;
    }
    else if ("contrast".equals(prop)) {
      contrast = value;
    }
    else if ("alpha".equals(prop)) {
      alpha = value;
    }
    else {
      return;
    }

    String key = getGrayFilterKey();
    UIManager.getDefaults().remove(key);
    UIManager.getDefaults().put(key, new GrayFilter(brightness, contrast, alpha));
  }
private void setGrayFilterProperty(String prop, int value)