SOURCE

let img;

function preload() {
  img = loadImage('https://i.loli.net/2018/10/19/5bc9db906f615.jpg')
}

function setup() {
  createCanvas(img.width, img.height)
  img.loadPixels();
  for (let x = 0; x < img.width; x++) {
    for (let y = 0; y < img.height; y++) {
      let index = (x + y * img.width) * 4;
      let c = img.pixels[index];
      let b = brightness(c) // 获取亮度
      if (b > 95) { // 这样做问题还有很多
        img.set(x, y, color(0, 0))
      }
    }
  }
  img.updatePixels()
  background(img)
}