PImage img;

void setup() {
  img = loadImage("https://upload.wikimedia.org/wikipedia/commons/thumb/e/ec/Mona_Lisa%2C_by_Leonardo_da_Vinci%2C_from_C2RMF_retouched.jpg/800px-Mona_Lisa%2C_by_Leonardo_da_Vinci%2C_from_C2RMF_retouched.jpg");
  img.loadPixels();
  size(600, 900);
  img.resize(width, height);
  //background(img);
  noStroke();
}

int x = width/2;
int y = height/2;
int x2, y2;
void draw() {

  //pointalize
  for (int i=0; i<10; i++) {
    x=(int)random(width);
    y=(int)random(height);
    fill(img.pixels[y*width+x]);
    ellipse(x, y, 30*mouseX/width, 30*mouseX/width);
  }
}