createCanvas(256,256); // coordinates are always between 0-255 for colors 

  pixelDensity(1);

}

​

function draw() {

  loadPixels();

  for (var y = 0; y < height; y++) {

    for (var x = 0; x < width; x++) {

      var index = (x + y * width) * 4; // nested for loop, one for the x's and one for the y's 

​

      pixels[index + 0] = x;

      // red value changes horizontally

​

      pixels[index + 1] = random(255);

      // green value random

​

      pixels[index + 2] = y;

      // blue value changes vertically

​

      pixels[index + 3] = 255;

      // no transparency

    }

  }

  updatePixels();

}

​