var img = new SimpleImage("hilton.jpg");
for (var pixel of img.values()){

  if(pixel.getX() < img.getWidth()/3){
        var newR = 255 - pixel.getRed();
        pixel.setRed(newR);
    }

 else if ( pixel.getX()  < img.getWidth()*2/3 ) {
     var newG = 255 - pixel.getGreen();
     pixel.setGreen(newG);
     var newG1 = 100 - pixel.getRed();
     pixel.setRed(newG1);
    }

  else {(pixel.getX() > img.getWidth()/3)
        var newB = 255 - pixel.getBlue();
        pixel.setBlue(newB);
    }
  }

print(img);