Image: Picker

var img;

​

function preload() {

  // 500 x 500 px

  img = loadImage("nasa_buzz.jpg");

}

​

function setup() {

  createCanvas(500, 500);

  background(0);

}

​

function draw() {

  background(0);

  image(img, 0, 0);

  var c = get(mouseX, mouseY);

  fill(c);

  noStroke();

  ellipse(width/2, height/2, 100, 100);

  fill(255);

  text(red(c), 20, 20);

  text(green(c), 20, 40);

  text(blue(c), 20, 60);

}