createCanvas(400, 400);

}

​

function draw() {

  background(220);

  stroke(255, 0, 255);

  line(0, 0, width, height);

  //something to show the pixel color of the pixel

  //which the mouse is over

  stroke(255);

  fill(getPixel(mouseX, mouseY));

  rect(width / 2 - 10, height / 2 - 10, 20, 20);

}

​

function getPixel(x, y) {

  loadPixels();

  var xy = (x + y * width) * 4;

  return color(

    pixels[xy],

    pixels[xy + 1],

    pixels[xy + 2],

    pixels[xy + 3]

  );

}

function setPixel(x, y, color) {

    loadPixels();

  var xy = (x + y * width) * 4;

  pixels[xy] = red(color);

  pixels[xy + 1] = green(color);

  pixels[xy + 2] = blue(color);

  pixels[xy + 3] = alpha(color);

  updatePixels();

}