Pointillism

/**
 * Pointillism
 * by Daniel Shiffman. 
 * 
 * Mouse horizontal location controls size of dots. 
 * Creates a simple pointillist effect using ellipses colored
 * according to pixels in an image. 
 */

PImage* img;
int smallPoint, largePoint;

void setup() {
  size(640, 360);

  img = loadImage("moonwalk.jpg");

  smallPoint = 4;
  largePoint = 40;

  imageMode(CENTER);
  noStroke();
  background(255);
}

void draw() {
  float pointillize = map(mouseX, 0, width, smallPoint, largePoint);

  int x = int(random(img->width));
  int y = int(random(img->height));

  color pix = img->get(x, y);

  fill(pix, 128);
  ellipse(x, y, pointillize, pointillize);
}