PImage myImage; //define an image object
void setup(){
  myImage = loadImage("memorial.jpg"); //load it
  size(myImage.width,myImage.height); //size it to fit the window
  image(myImage, 0,0); //display the image
  loadPixels(); //load the pixels
}
//**********
void draw(){
}
//********* drag to simulate a paint brush
void mouseDragged(){
  for(int y=mouseY-10; y<mouseY+10; y++) //for a 20x20 brush area
    for(int x=mouseX-10; x<mouseX+10; x++){
      int xx = constrain(x,0,width-1); //do not exceed the screen
      int yy = constrain(y,0,height-1);
      pixels[yy*width+xx] = pixels[yy*width+xx]^0x0000FF;
    } //invert blue
  updatePixels();
  //update to see the changes
}
//********** Save just in case it is needed
void keyPressed(){
  save("memorial_inverted.jpg");
}