What is Alpha Mask in p5.js?

p5.js - Interview Questions

Loads a "mask" for an image to specify the transparency in different parts of the image. The two images are blended together using the mask() method of p5.Image.

let img;
let imgMask;

function preload() {
  img = loadImage('assets/moonwalk.jpg');
  imgMask = loadImage('assets/mask.png');
}

function setup() {
  createCanvas(720, 400);
  img.mask(imgMask);
  imageMode(CENTER);
}

function draw() {
  background(0, 102, 153);
  image(img, width / 2, height / 2);
  image(img, mouseX, mouseY);
}â€‹