void setup() { 
  /*
  here is the init setup of my sketch
  */

  img = createImage(width, height, RGB);
  refreshImg();

  ripple = new Ripple(img);

} 

void draw() {
  /*
  here I do my stuff, this is what I capture in the refreshImage method
  */

  refreshImg();
  ripple.update();
} 


void refreshImg() {
  img.loadPixels();
  for (int y = 0; y < height; y++) { 
    for (int x = 0; x < width; x++) {
      // this can be optimize to use only get();
      // need to sort it out
      int px = get(x, y);
      img.pixels[x + y * width] = px;
    }
  }
  img.updatePixels();
}